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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Big Bore Engine - Part 6 - Test & Tune /cgi-bin/YaBB.pl?num=1600759429 Message started by DragBikeMike on 09/22/20 at 00:23:49 |
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Title: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:23:49 This is the sixth in a series of reports outlining my big bore engine project. Part 1 covered the cylinder. Part 2 covered the cylinder head. Part 3 covered the head cover. Part 4 covered the crankcase. Part 5 covered assembly. If you haven’t read Parts 1, 2, 3, 4 or 5, you can find them here. http://suzukisavage.com/cgi-bin/YaBB.pl?num=1593567475 http://suzukisavage.com/cgi-bin/YaBB.pl?num=1595224521/0 http://suzukisavage.com/cgi-bin/YaBB.pl?num=1596951230 http://suzukisavage.com/cgi-bin/YaBB.pl?num=1597910972 http://suzukisavage.com/cgi-bin/YaBB.pl?num=1598775774/0 Part 6 covers test & tune. Now we get to see how good or bad the big motor runs. It has a hodge podge of parts. In Hawaii, we refer to something like this as “chop suey”. With a hobby-lathe bore-job, piston & camshaft intended for a completely different engine, Subaru valve springs, Honda valves & spring retainers, a wad of epoxy stuffed in the intake port, a smoke-stack for an exhaust header, and a re-plumbed muffler that looks like it came off a tractor, there’s a good chance something might go wrong. Let’s get started. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:25:36 In preparation for this bigger engine, I did a bunch of timed acceleration runs to gather baseline info for comparison. I am now at the point where I evaluate each modification to the engine by performing three different timed runs, each in a unique location. Those runs include one 2nd gear pull to 7500 rpm on a paved agricultural road, one 2nd gear pull to 7500 rpm on a level freeway on-ramp, and a final 3rd gear pull to 7500 rpm on a paved agricultural road. If the 2nd gear pulls are duds, I don’t waste my time with the 3rd gear pull. The 3rd gear pull is the gold standard. If the modification is a success, it is very evident on that 3rd gear pull. The 94mm engine I replaced ran good. It has my Stage II ported head, a Wiseco piston, Web 340b camshaft, a VM38 carburetor, a K&N cylindrical air filter, a 3” flywheel, and a Mac 1.79” exhaust header with a modified LS650 muffler. It’s best 3rd gear pull from 4000 rpm to 7000 rpm was 7.72 seconds. The acceleration benchmark for the 97mm Big Bore is 7.72 seconds. If it won’t beat 7.72 seconds, it’s a dog. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:27:07 I have concerns about heat. The increased displacement will generate more heat. The larger bore exposes more cylinder surface to the combustion process. The cylinder head temperature (CHT) and oil temperature are probably gonna go up. Anticipating this might be a problem, I installed a CHT gage and an oil temperature gage on the 94mm engine. I observed those instruments for about 500 miles of operation and collected data under a variety of conditions. The highest CHT observed on the 94mm was 343°F. The highest oil temperature observed was 242°F. The average cruising temps were 310°F (CHT) & 210°F (oil) on surface streets and 330°F (CHT) & 230°F (oil) on long freeway hauls. I was able to find a lot of information on CHT for air-cooled aircraft engines. The general consensus seems to be a max desireable of 400°F and a target cruising temperature of about 350°F. Those values seem a bit high to me considering airplanes have an unlimited supply of really cold air coming off the propeller, but if it’s OK for an airplane I guess it’s good enough for a Savage. I should also note that the engine manufacturers actually allow temps up to 500°F. I know some of you are running CHT gages. It would be beneficial if you could post what sort of CHT you typically observe, and exactly where your thermocouple is installed on the head. That would be some very useful information directly applicable to the Savage. I have several books that indicate oil temperature should run about 200 - 230°F under normal conditions, and remain below 250°F if you expect the engine to survive. That sounds reasonable to me. But as you can see from the 94mm data, it might be impossible to maintain 200-230°F with an engine that is stressed to a higher level. I run synthetic oil (except for break-in) so I have a little margin. The temperature benchmarks for the 97mm Big Bore are 350°F for CHT and 230°F for oil. I want the Big Bore to run close to those benchmarks. I’m willing to accept a bit more heat but would like to hold the increase to a maximum of 10°F. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:28:10 These are the temperature gages. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:28:59 I’m reading CHT off the 8mm stud just below the exhaust port. I’m sure this is not an ideal location since the stud penetrates the exhaust port, but it’s located in a very high region of the cylinder and most certainly one of the hottest locations on the engine. I think it’s a good place to keep an eye on. If any of you are running a gage connected to a head stud or the spark plug, it would be most helpful to know what sort of CHT you are running and the location of your thermocouple. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:29:38 The oil temperature is read right off the oil gallery, so I am getting a good measurement of the temperature of the oil being fed to the engine. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:30:15 To monitor ring seal, I installed a compound gage on the crankcase. If crankcase pressure starts to build, I will know that the rings aren’t doing their job. The gage connects to the alternator cover. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:30:56 The compound gage is liquid filled and reads both pressure & vacuum. It can handle the vibration from the big thumper. This shows the instrument cluster. Air/Fuel ratio, engine speed, oil pressure (liquid filled), crankcase pressure, cylinder head temperature, and oil temperature should be sufficient to keep an eye on things. The GoPro camera records the parameters so I can review later. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:32:03 Installation of the engine was straight forward. Valve clearance was set at .004” all around. Once it was filled with oil (20W-50 API SG dino oil) and ready to crank, I primed the system and checked compression. First, I filled the oil trough under the cam and went through a priming regimen to ensure that I had oil to the top end. With the spark plug removed, crank ten chuffs then let the starter cool for about five minutes. I repeated this until I observed oil pressure on the gage. It took about thirty chuffs. The oil pressure gage reads pressure off the top end. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:32:43 Now that I knew I had lubrication, I screwed in the compression gage and cranked away. It pumped a solid 200 psi. I expected that would go up a bit once everything bedded in. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:33:59 Since this engine is bigger, I figured I should jet-up a bit. I installed a 220 main jet. Everything else related to tune-up remained the same. Same spark plug. Same ignition timing (retarded 2°). Same cam timing (factory marks). Same idle mixture and speed setting. Same slide needle position (middle groove). Same valve lash. The tank was topped off with 92 octane pump gas (Aloha E-10). It fired right up and settled into a sweet idle. Didn’t have to touch a thing. No smoke, no unusual noise. So far so good. A quick lap around the block didn’t reveal anything bad. I let it cool off and inspected it for leaks. Looked good. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:36:13 The next day I started the break-in. I break-in my engines by lightly accelerating and then chopping the throttle completely, then repeat. It’s a constant cycle, accelerate, chop, accelerate, chop… I’m sure it drives anyone behind me nuts, but a man’s gotta do what a man’s gotta do. The plan was a solid 500 miles of that nonsense. The hobby-lathe bore-job would need to be handled with kid gloves. The cylinder is flimsy, and I probably didn’t have the best surface finish. I didn’t want it seizing. Right away things seemed on the warm side. The oil temp and CHT came up rapidly, much faster than the 94mm. I stuck close to home and kept the speeds low, constantly workin the throttle. I would put about 10 miles on it and then come home and let it cool. Everything seemed to be working well. It was quiet. The vibration seemed lower than the 94mm. Then I noticed a little oil around the right rear corner of the cylinder head. I wiped it off and took it for another short ride. It wasn’t a fluke. It had a leak. Observing it running in the garage it looked like it was coming out of the area adjacent to the oil feed slot in the cylinder. I continued to wipe it up and go for short rides. Once I was confident that it wasn’t going to melt-down I took it on the freeway. What a mess. By the time I got back home oil was all over the right side. I tried doing an air test. I used a bicycle pump attached to the breather. I could pump it up to 3 or 4 psi and it would remain pressurized above 2 psi for at least 15 seconds or so. It just wouldn’t make bubbles when I applied soap solution. Even when I continuously pumped, I couldn’t make bubbles. Only thing I could figure was that the oil passage was full of oil, so no air was gonna bubble out. The engine would have to come out to fix that leak, but I wanted to get it broken-in and also wanted to do some acceleration tests. I didn’t want to drag that engine back out until I knew there weren’t other problems that needed correction. Situations like this always bring out the stone-axe in me. I figured I could patch the leak good enough to finish the break-in and testing. JB Weld to the rescue. It took several iterations and I ended up with the entire right side of the head epoxied to the cylinder, but it held good enough to start doing some serious riding. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:38:12 The engine started to loosen up and the temps came down a bit. Oil pressure was fine. Vibration levels were clearly much better than the 94mm. It felt like it had a lot more low-end. It started great, idled great, and pulled great. The Web 402 cam seemed like a good fit to the head, carb & exhaust. The crankcase pressure/vacuum was neutral throughout the 500-mile break-in. Never went off zero. No pressure, no vacuum. CHT was clearly higher than the 94mm. On long grades it was concerning. I saw the CHT hit 360°F on a number of occasions. Oil temp would routinely climb to 230°F but didn’t seem too much higher overall. Once coming off a long grade I had to chop the throttle for slower traffic. It almost felt like it started to seize. The higher CHT wasn’t a fuel issue. I was running way rich everywhere and the A/F meter confirmed that. At the 500-mile mark I did an inspection. Compression was still right at 200 psi. That was disappointing. I was hoping it would bump up a bit. Valve lash was still in spec on all four valves, and the cam lobes looked good. Even the oil was still amazingly clear. Time to beat it up. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:41:49 I spent the next 350 miles testing and tuning. It ran best with a 210 main jet. The 3rd gear acceleration test was not disappointing. It ran from 4K to 7K in 6.17 seconds. That’s an improvement of 1.55 seconds faster than the 94mm Wiseco engine. Very gratifying. I didn’t have any 3rd gear acceleration data for the 94mm tight-quench (TQ) engine, but I did have videos of some of my LSR attempts that showed 3rd gear operation from about 5500 rpm up past 7000. That allowed me to time 3rd gear from 6K to 7K. The tight-quench engine was faster than the 94mm Wiseco engine, so I thought it would be interesting to compare the 97mm to the tight quench. BTW, the TQ engine dynoed at 41 HP. The 97mm pulls 6K to 7K in 2.83 seconds. The tight quench pulled it in 3.28 seconds. The big 97mm is .45 seconds faster 6K to 7K. Since I was in the mood for testing, I decided to see how the big engine would like a bonafide exhaust system. I threw on a complete Mac system. After a bit of tuning I settled on a 230 main jet. It was a tossup between the 220 and 230. I didn’t have the benefit of the air/fuel meter with the Mac system. The Mac exhaust was good for another .23 seconds. It now pulled 4K to 7K in 5.94 seconds. I must admit, it loved that open exhaust system. The engine really woke up (and so did my neighbors). The mid-range was killer. But man, that thing is just too darned loud. Looks like I have a new project. Here’s a look at the Mac Attack. It’s a nice lookin exhaust, but too loud. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:43:03 This is a look through the Mac muffler. It has a baffle, so I’m baffled as to why it’s so loud. If you’re lookin for horsepower, you’ve gotta be willing to accept the inevitable. I’m not quite there yet. I need to tame that bark and maintain the free flow. It’s a tall order. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:43:52 The big engine has a very broad power band with no obvious “hits”. It just starts pulling and remains linear all the way through about 6800 rpm. It doesn’t seem to run up as high as the 94mm but who cares, it gets you to 7K so much faster. I have seen some comments on the forum to the effect that the 97mm won’t be much faster than a 94mm, it will just have better low-end torque. That’s not the case at all. It’s way faster than the 94mm, everywhere. It has excellent manners. Idles great (much better than my 94mm). I attribute that to the cam. The 402 grind is a lot tamer than the 340b in my 94mm. The VM38, Mac header, and Stage III head all work well with the 402 cam. It’s like a different motorcycle. It feels like a big motorcycle now. In terms of performance, I give this project an “A”. It was well worth the effort. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:45:27 I had to address the higher CHT. Other than drowning it with fuel there weren’t a lot of options. All the literature I have indicates this engine should run best with ignition timing retarded from the stock setting. The higher compression and free flowing components should require less advance, but the larger bore dictates a bit more advance. One book indicated that for a four-valve head with 100 mm bore, optimum total advance should be about 28° BTDC. My timing was set at 28°. I tried advancing the ignition timing back to the factory setting (30°). The CHT came down quite a bit. It was definitely better. The looser engine probably helped too. Now the cruising temps were about the same as the 94mm engine. Long grades were better too. On the long grade, the CHT stayed below 340 and the oil temp didn’t exceed 230. I still had the fuel mixture on the fat side. I guess I could live with that, but I would prefer a mixture closer to 12.5:1 at WOT and probably 13:1 at cruise. Once the oil leak is squared away, I will fiddle with the air/fuel ratio a bit more. I decided that I would add an additional 2° of advance when I had the engine out of the frame to fix the oil leak. That might bring the temps down some more. I removed the engine to repair the oil leak. It had 850 miles on the clock. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:46:02 The cam, springs, retainers, and cotters all looked fine. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:46:44 And so did the rockers. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:47:34 There was some discussion on the forum regarding the center oil-hole in the cam shaft. Would the smaller hole in the DR-based cam provide enough oil for the steady-bearing and cam chain? My 402 cam has the small #53 hole. The oil trough next to the steady bearing was topped-off and the steady bearing looked fine. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:48:08 There was also a load of oil in the cam plug. No indication that there is a problem with oil supply in this area. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:48:54 The tensioner had extended about 3.5mm, which didn’t surprise me. The chain and guides are new, so I expected them to bed in. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:49:30 The 34mm intake valves are slightly longer than stock. I was a bit concerned about geometry. Looks like rocker geometry won’t be an issue. The wear patterns on the valve tips were perfectly centered. I think this will be OK. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:50:02 Once I popped the head off, I could see that oil was being pulled through the entire joint. I suspect capillary action was at play. Oil was everywhere. And that Copper Coat spray sealant was LG (long gone). It even looked as if I had some combustion gas leakage. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:50:35 The oil wasn’t just confined to areas where there was an oil passage. This is the right front corner. No pressurized oil here, not even splash oil, strictly crankcase vent. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:51:17 Oil was even running down the left rear cylinder stud. That’s a normally dry stud, no oil close to it. So much oil reached the stud that the dowel filled up????? |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:51:56 The cylinder bore looked fine, and the piston had no evidence of seizure. Whew!!! |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:53:14 All the cylinder head fasteners were tight. I estimate it took at least The sealant was gone. I won’t be using Copper Coat again. The other option provided on the Copper Gaskets Unlimited (CGU) instructions is Permatex Ultimate Grey. I have the Optimum Grey. It’s rated at a higher temperature. Maybe that will do the trick. I checked the head and the cylinder for flatness. They were both well within the manual specification of .002”, but when I stacked the head onto the cylinder, I could just get a .003” feeler into the joint in the right rear corner. That could be a problem. After pondering the dilemma, I decided to try the Optimum Grey sealant. If it’s not gonna hold when the surfaces meet the factory specs, maybe I don’t wanna run the copper gasket. The copper base gasket held just fine, and the copper one I’m runnin on the 94mm is leak free after many miles, but the head gasket looks like a different animal. Here’s a look at a brand-new copper head gasket coated with a uniform layer of the Optimum Grey. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:53:57 The process is tricky since the sealant must be tacky when you assemble the joint. Pretty hard to put a uniform coat on both sides of the gasket. So, I coated the underside of the gasket and placed it on the cylinder, then coated the underside of the head and placed that on top of the gasket. This is what the head looked like. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:54:44 While it was apart, I took a good look at the head cover bolts along the right side. The right rear bolt was fine. The internal threads in the cylinder looked great. If you recall, I had a problem with the center bolt. The internal threads in the cylinder stripped, so I drilled through and installed a grade-8 bolt & nut. The forward hole had partially stripped threads, so I did the same repair to that fastener while I had the engine apart. It works fine. You can definitely put the squeeze on things with these grade-8 fasteners. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:55:20 I modified the ignition pickup so I could dial in an additional 2°of advance. Maybe I can bring the temperatures down a bit more. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:56:47 When it was all back together, I let it sit for several days to allow the sealant time to set up, then the engine went back in the frame. By this time, I’m getting pretty good at the R&R. Now it’s time for some advice. I’m getting old, slowin down, things get a bit foggy sometimes. If you are in the same boat, take heed. I poured the first quart of oil down its throat and was twistin the cap off the second jug when I got an itch to glance at the bullseye. It was maxed out. Did I pour in two quarts???? No way. Why is it maxed out with only one-quart of oil? Is it level? Ummmmmmm! Did I remove the cleanliness plugs? I like to plug up the holes in the crankcase with paper towels to keep little parts from getting lost in the engine. It’s easy for an old geezer wandering around in a fog to forget something like that. I guess I have to come up with a tag-out system. This could have been disastrous. From now on, I’m gonna place a zip tie through one of the cover bolt-holes whenever I use cleanliness plugs. Hopefully, that will remind me to check before I install the cover. How did I miss this??? |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:58:19 A quick compression check showed it now pumped 210 psi. That extra 350 miles of break-in must have done the trick. It ran great. Started right up and everything seemed the same, including the oil leak. Ya gotta be kiddin. The joint looked solid. You could see a fine bead of sealant squeezed out completely around the circumference. The fasteners along the right side of the head were squared away and plenty tight. It met the flatness spec. But the leak was still there. I put another 150 miles on it so I could evaluate the advanced timing. The temperatures remained about the same and it ran just a tad slower. Looks like the factory setting (30°) is the way to go. Before I tore the engine out of the frame again, I did another air test. No bubbles. I spent a good long time pumping it up and soaping everything down. I even evacuated all the oil out of the lubrication system to make sure air was filling all the passages. Still no bubbles. I can see this is going to be a tough problem. I’m leaning toward using the stock multi-layer steel (MLS) gasket. The cylinder is really beat up. It’s a junker that I bought on eBay. It’s got a bunch of bent fins and one is broken. There’s also evidence of some separation between the sleeve and the aluminum cylinder. I thought it was the perfect candidate for learning how to bore a cylinder. I might try and round up a dye penetrant kit and see if there is a hairline crack. Not sure yet. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 00:58:53 This is a shot of my sophisticated air test equipment. How could any leak hide from this test gear? |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 01:01:13 The 94mm is back in the motorcycle. I have some other projects I want to play with. In the meantime, I will keep plugging away at the 97mm. It runs too darned good to give up on it. I will solve the leak. What have I learned so far? The cam, head, carb, exhaust-header combination is totally sweet. The components work great together. The beast is blazin fast with a broad linear power band. The oversize 1.79” header pipe is not too large. It works good on the 94mm and great on the 97mm. Contrary to popular belief, it doesn’t kill torque. The Stage III head works great. The Honda 34mm intake valves don’t present geometry problems. The SuperTech Subaru valve springs work perfect and are a bargain. The Kibblewhite spring retainers and cotters also fit & work perfectly, and they didn’t crack. The supersized exhaust port doesn’t kill torque. The engine signs-off a bit earlier so I might revisit the intake port, maybe see if I can squeeze a bit more flow out of it. The Wiseco 97mm runs significantly smoother than the 94mm. The additional 41 grams of weight brings it much closer to the stock piston weight and keep vibration levels close to stock. The forged 97mm runs quiet, it’s not rattling around in the cylinder. The dreaded forged piston slap is not a problem. The 10:1 compression ratio and 210 psi cranking pressure do not cause detonation problems. It runs great on 92 octane pump gas. The hobby lathe bore job is within the capability of the average bear. The rings bedded in nicely and it doesn’t have blow-by problems. It doesn’t build up pressure in the crankcase at WOT. The ignition timing is critical to limiting oil and cylinder head temperatures. Retarding the timing just 2° makes a big difference. The Mac exhaust system is good for some more power. Its too loud, but there is a measurable increase in performance. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/22/20 at 01:02:37 I hope you find this report informative. So far, it has been a fun project and I have learned a lot. As always, I invite your comments and questions. If any of you have CHT data to share, please post it. Oh yea, be sure to remove those rags before you close up your engines. :-X Knowledge is power. Mike |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by zipidachimp on 09/22/20 at 01:37:21 Mike, you are a bloody inspiration! Who needs more than 1 cylinder ? no one ! cheers! 8-) |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by LANCER on 09/22/20 at 08:39:01 Very informative as always Mike. Thanks for all your efforts. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by justin_o_guy2 on 09/22/20 at 09:27:33 Information like this, contacts with people,, folks.. this place is a trasure trove,, and I worry about it just going away. I dont know how to set up contacts or find a way to archive the How To stuff,, but I hafta admit, after seeing a forum I really enjoyed go away, and I lost touch with everyone,, and , well,, Its a bummer. I dont wanna repeat performance.. But I DO wanna know whats so tricky about a copper head gasket? Why would the OIl be the problem? Compression is a lot stronger pulse.. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by Dennisgb on 09/22/20 at 09:59:01 Fun read and awesome results. Can you skim the surfaces to get rid of that .003”? I don’t use copper gaskets anymore. Old school solid copper where you could anneal and reuse were okay but the laminated ones suck. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by Ruttly on 09/22/20 at 11:30:49 DBM , What do you think ? Does your butt think you have broken thru the 40 H/P mark ? Or not. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by Armen on 09/22/20 at 17:27:54 As always, awesome! Thanks for sharing! Moving these days. Just packed the box with the 97mm top end. Maybe this winter at the new digs. I have a slightly different break in ritual than you, but yours seems to work well. Keep 'em coming! thanks, -Armen |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/23/20 at 00:00:54 Thanks for the kind words. I really enjoy doing these reports. JOG, your comment regarding combustion pressure vs oil is excellent. It is a mystery to me. The thing seems to restrain the combustion pressure reasonably well, but the oil slips through the joint like greased lightening. Crazy. The combustion pressure is through the roof and the oil pressure barely makes 6 psi. There are some visual indications that look like there might be combustion leaks, but when it's running there's no evidence of combustion leakage. Usually you can hear a combustion leak. You can see from the pictures that the oil is everywhere in the joint. It's nuts. Maybe the iron cylinder liner seals better than the adjacent aluminum material. I just don't know. In a few days I will get up enough motivation to pop the head off and start working on it again. Right now, I'm taking a break from it. Sometimes it helps to step back for a while. Dennis, the copper gasket I'm using is a solid copper gasket. I've never seen a multi layer copper gasket. I haven't annealed the head gasket yet. I used a new copper gasket each time I assembled it. Ruttly, of course I broke the 40 HP mark. The 94mm tight quench (TQ) engine dynoed at 41 HP. This 97mm is significantly faster (stopwatch, not butt dyno) than the TQ. It has to be making well over 41 HP. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by justin_o_guy2 on 09/23/20 at 10:37:37 ennis, the copper gasket I'm using is a solid copper gasket. I've never seen a multi layer copper gasket. I haven't annealed the head gasket yet. I used a new copper gasket each time I assembled it. You gonna anneal it first? Oven? What about a copper washer at the oil passages,, Or maybe a circular wrinkle, induced with some appropriate diameter piece of tubing? I like the wrinkle idea better,, if you have room, one from each side, like ripples on a pond. If I was gonna do that I dont think Id anneal it. Ya now,, a wrinkle slightly outside the hole and a punch shoulder to press the hole the other way might get it,, Could ya anneal Just the part that the liner squishes? Naaah.. probaly heatin that would induce warping,, Hell I dont know,, Im not your level of mechanic, at all.. You can play with the one that comes out and see how it acts with heat applied, Or maybe steal some of it to use as a washer, if that looks plausible,, Which, it doesnt really,, an area twice as thick wouldnt come down flat,, Im kinda curious about the wrinkle thing,, |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by Dave on 09/23/20 at 17:48:33 Great project and report DBM......fun stuff for us gearheads! Like Jog, I wonder if a raised rib around the oil cavity would help get it sealed? Suzuki has the rib in their head gasket - and they also have the oil migration issue a bit. The oil doesn't seem to come out to the exterior - but it does migrate around to the studs at the intake and exhaust ports, and sometimes folks need to seal those points to keep the oil from weeping out. I also wonder if you shouldn't try to improve the flatness - I am not sure if the Suzuki standards that are applicable to the stock multi layer and coated steel head gasket are applicable to a copper gasket. I would sure be tempted to use the sandpaper and glass method of making a flat surface on the next try....and using a really soft copper gasket (new or annealed if necessary). I have my cylinder head sensor on the left rear cylinder stud. I chose that location as it is not at the exhaust port and isn't picking up heat from the stud that is exposed to the hot exhaust gasses. On normal 2,500 - 3,500 rpm back road cruising on 80 degree days the temps are around 240 degrees. If I get on the freeway and stay up at 70mph @ 4,000 rpm the temperature goes up about 20 degrees to 260. On days where the temperatures are in the 90's I can see 280 on the freeway. The hottest I have ever seen occurred while stuck in traffic on Main Street in Gatlinburg on a 90 degree day......the temperature got to 300. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 09/23/20 at 19:07:23 I don't think I have the skills to emboss fire rings into the copper gasket. I know some guys machine o-ring grooves into the head and cylinder and the use stainless steel wire in those grooves. The wire digs into the copper. The problem with those approaches is some of the sealing wire or embossed area would not be circular. The raised areas have to not only go around the bore but also the chain cavity, oil feed, and oil drain. The stock gasket uses a fire ring around the entire perimeter of the gasket. I have a bonafide granite plate that I used to lap both the head and the cylinder. They're both pretty darned flat and smooth. But the area along the chain case is just a tad low in relation to the majority of the sealing surface. The copper gaskets may just not be forgiving enough to deal with the irregularities, especially if they are additive. I intend to do a thorough check once it's all apart. Maybe a skim cut or two. But I am reluctant to use the copper again. It's just too unforgiving. Dave, thanks very much for the temp data. It helps a lot. That area of the head obviously operates much cooler. I suspect that's probably because it's adjacent to the intake port. All the cooling from the fresh charge and fuel vaporizing pulls a lot of heat out of the area around the intake. The spark plug is the recommended location for the CHT thermocouple, but the cavity is just too cramped. With your data, we are starting to get a better idea of what to expect on the various regions of the head. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by Jdvt600 on 09/26/20 at 07:47:22 DragBikeMike I just wanted to say thank you for posting this. This entire build has been fascinating to read. Your posts are inspirational to a newbie like myself. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by eau de sauvage on 09/27/20 at 19:02:02 A fantastic project, I predict by the time it's finished your LS650 will definitely be able to pull a fat kid across greased linoleum. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by Dennisgb on 09/27/20 at 19:30:01 Mike, When you get the engine out check the head torque too see if it changed. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by Ruttly on 09/28/20 at 14:46:29 75677370676163060 wrote:
That’s some funny $hit ! ;D ;D ;D |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 01/16/21 at 17:01:10 Just wanted to fill you all in on the oil leak. I was able to fix the leak by skim cutting the cylinder and cylinder head. It helps to mark up your work piece with a felt-tip pen. Then, when you kiss it with the tool bit you can see how exactly flat it is. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 01/16/21 at 17:01:54 Just kiss the sealing surface with the tool bit. The low spots will still have the felt pen marks. Bingo, right at the pressurized oil passage. It was barely .001” low but that solid copper gasket just couldn’t conform to the irregular surface. Capillary action didn’t help either. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 01/16/21 at 17:02:56 To mount the cylinder head in the lathe, I modified a torque plate. The torque plate is fastened to the head with socket head cap screws, and then the torque plate is bolted to the head stock. It’s a pretty simple setup. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 01/16/21 at 17:03:41 More of the same with the cylinder. Wouldn’t you know, the errors on the head and cylinder were in the same locations, so they stacked up. It was destined for failure. I won’t make that mistake again. Note the copper strips between the acorn nuts and the cylinder bore. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 01/16/21 at 17:04:18 The setup for the cylinder is more elaborate. It’s a fixture with a machined fit for one end of the cylinder and an adjustable system for the other end. You hold it with a 4-jaw chuck on the fixed side and a live center on the adjustable side. Now you can adjust both ends to zero-out the workpiece. You must use soft-rolled copper tubing between the adjusting nuts and the cylinder bore. The adjusting nuts are aluminum acorn nuts, but I learned the hard way that they can still put a dimple in your workpiece. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 01/16/21 at 17:05:01 Here you see the workpiece in the lathe. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by DragBikeMike on 01/16/21 at 17:07:21 Once the sealing surfaces were cleaned up, its was time to reassemble the engine. I used Permatex Optimum Grey sealant again. Since this final repair, I’ve logged about 650 miles on the 97mm engine. It’s solid. No leaks whatsoever. Lesson learned, if you want to use a copper head gasket, the sealing surfaces must be perfectly flat. The factory spec won’t work. It must be flat within .000”. While I was giving it a good shakedown, I tested some mufflers to see if I could squeeze out a little more power. The LCGP muffler with 1.75” baffle tube worked well. It pulled 4K to 7K in 5.72 seconds. That was a nice improvement. The Cherry Bomb brought the time down to 5.44 seconds. It runs nice with that C-Bomb, but the noise is excruciating. Both the LCGP and the C-Bomb wanted a lot more fuel. For both mufflers, best performance was with a 240 main jet. I didn’t have the benefit of the air fuel meter on the C-Bomb, but with the LCGP the 240 main jet yielded an A/F ratio of 12.1 to 12.5 at WOT. The best acceleration times for both mufflers were with the 240 main jet. Every chain has a weak link. The weakest link on this project was the clutch. Once I switched to the C-Bomb and dialed in the jetting, the clutch couldn’t hold the power. It developed a slip in 5th gear. I was on the freeway running about 4500 rpm. There was no traffic. You simply can’t resist the urge. Once it hit about 5500 rpm at WOT, the tach took off. The clutch just couldn’t hold the power. It wasn’t gonna let me try and barge through a brick wall of air. A quick inspection showed that all clutch components were like brand new. All the discs met factory specs for a new clutch. The spring load was the same as it was two years ago. There was no discoloration or warpage. So, it’s not worn out and it’s not burned up, it just can’t hold the power. A Barnett clutch kit fixed the slipping. I learned a few things on that project and am working on a report. I will post that later. The 97mm project was a complete success. It’s a sweet powerplant. Excellent manners, gobs of torque, blazing acceleration. Now its time to move on to the next project. I’ll start removing the 97mm in a few days so I can replace it with an engine that utilizes the 94mm Wiseco flat-top piston. It will have significantly more compression and super-tight quench. I can’t wait to see how the new engine stacks up against the Big Bore 97mm. |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by Jdvt600 on 01/17/21 at 07:44:02 17111E62606763530 wrote:
I'm not sure what Lances's supply looks like, but I'm very interested to see how the 94mm Wiseco stacks up against your 97mm. I've got zero experience working on the internals of an engine. Although, I'm pretty sure with enough time I can git-r-done. I'm debating doing the 94mm in the garage myself, or trying to find a shop here in San Antonio that can bore it over and install the 97mm. I can't wait to hear about the torque, acceleration, and manners of the 94 Wiseco vs your custom 97mm. Looking forward to your next project results! |
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Title: Re: Big Bore Engine - Part 6 - Test & Tune Post by Dave on 01/18/21 at 03:46:46 Mike: I am looking forward to your clutch modification. My clutch is fine so far with my 95mm Wiseco and improvements - however there is very little extra strength in the clutch. I have never used an oil with any kind of friction modifier or oil thickener (STP or Lucas). I have the the Kevlar fiber plates and they work about the same as the stock plates - you have to make sure the clutch is completely engaged before you roll on the throttle. If you try and grab a handful of throttle before the clutch is completely engaged it will slip. I don't believe adding stronger springs is a solution - as the clutch throw out lever in the left side case is easily broken. Even adding a washer under the springs has resulted in the throw out breaking - and a few people have broken that piece with all stock parts. Machining a new throw out is a bit tough - as it has a "round with two flats" center hole that would require a broach to machine......I have considered the possibility of welding or brazing reinforcing metal on both sides of the throw out. Badwolf has modified his clutch to eliminate the thin spring washer inside the outer plate. His thought was that it resists some of the pressure applied by the 4 clutch springs. He reports that he did not notice any change in the smoothness of the clutch after making the change. I have been considering the idea of adding an extra friction plate. If the fiber and steel plates were to be thinned down enough to allow an extra steel and fiber plate - there would be extra surface area after this change and the clutch would have more holding power. It may be possible to machine away some of the clutch basket inside or outside face to provide more room. MMRanch found that on his high mileage bike the soft wearing surface of the clutch had worn away a bit and his clutch was slipping - so he added an extra steel plate to take up the room and resolved his slipping problem. If I have a thickness sander - thinning down the plates would be easy. I am not sure if I could machine the plates on my lathe as they would be hard to hold, and the metal may be a bit too hard to machine well. |
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