SuzukiSavage.com /cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Big Bore Engine - Part 3 - Head Cover /cgi-bin/YaBB.pl?num=1596951230 Message started by DragBikeMike on 08/08/20 at 22:33:50

Title: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:33:50 This is the third in a series of reports outlining my big bore engine project.  Part 1 covered the cylinder.  Part 2 covered the cylinder head.  If you haven’t read Parts 1 or 2 you can find them here. http://suzukisavage.com/cgi-bin/YaBB.pl?num=1593567475 http://suzukisavage.com/cgi-bin/YaBB.pl?num=1595224521/0 Part 3 covers the cylinder head cover.  I have incorporated several modifications to the head cover for improved oiling.  Since I will be running a high lift cam and the associated heavy valve springs, the cam bearings, cam lobes, and rocker arms will need all the help they can get. Let’s get started.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:36:37 Some of the camshafts available for the LS650 are actually DR650 camshafts.  The DR650 does not incorporate oiling holes in the cam lobes.  If you intend to run a DR650 camshaft you should consider drilling oil holes in the cam lobes.  I will be running a Web 402 grind in my Big Bore engine.  The Web 402 is a DR cam so I drilled oil holes in the cam lobes. The cam lobes are hard faced.  You need a #1 solid carbide center drill and a #47 solid carbide drill bit.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:37:51 To properly locate the oil holes in the cam lobes, I start by installing the cam chain sprocket on the stock camshaft.  Then lightly clamp the sprocket in a machinist’s vice and adjust/align the camshaft by rotating it and using the cross feeds until the #47 drill bit aligns perfectly with the existing oil hole in the stock camshaft.  Lock the worktable in place and fully tighten the machinist’s vice.  That will lock the setup in proper alignment for drilling the first cam lobe.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:38:48 Now, swap out the stock cam with the new cam.  Make sure you loosen & tighten the bolts without shifting the sprocket in the vice.  The drill chuck will be in correct alignment for drilling the first cam lobe.   Start the hole and apply the chamfer with the #1 center drill, then finish up with the #47 drill.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:39:30 You end up with a nice chamfered hole.  Repeat the process for the other cam lobe.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:40:04 The rocker arms are not pressure lubricated.  They rely solely on splash lubrication.  There is a hole in the top of each rocker arm that acts as a reservoir for oil.  That’s not much oil.  To improve the footprint for catching oil, I apply a large chamfer to each rocker arm oiling hole.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:40:41 And I grind a feed notch in the thrust face on the left-hand side of each rocker arm.  There are wave washers on the right side so there is ample room for splash oil to work between the thrust face and wave washer, but on the left side the thrust face is in contact with the opposing aluminum surface so there’s not much room for oil to work it’s way into the joint.  I figure the notch will help a bit.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:41:25 Here you can see how tight the left side of the rocker arm is held against the aluminum head cover.  The wave-washer maintains constant pressure on the rocker arm.  The notch will allow splash oil to work into the joint from the top.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:42:41 The exhaust rocker shaft is locked in place by a bolt.  The rocker arm rotates on the shaft but the shaft can’t rotate in the aluminum head cover because of the bolt.  The wear is confined to the rocker shaft and the rocker arm.  Those components are relatively inexpensive as compared to the head cover, which comes as part of the cylinder head assembly.  Ya gotta buy the whole head to get a new head cover. In contrast, the intake rocker shaft is free floating.  It is not locked to the head cover, so it turns in the head cover.  That rotation results in wear.  I figure the bores in the head cover in way of the intake rocker shaft should have as much lubrication as possible.  The high lift cam with the heavy valve springs will put a lot more load on the rocker shafts. The right-side bore for the intake rocker shaft is well exposed to splash oil, but the left side bore is almost completely isolated.   To provide additional lubrication to the left side bore, I drill a small hole in the cavity adjacent to the left-hand cam bearing.  That allows pressurized oil to feed up to the rocker shaft bore in the head cover.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:43:23 Here you can see how the new feed hole breaks into the sealed void on the left side of the intake rocker shaft.  It’s a dead-end so I’m not worried about losing oil pressure, but at least the end of the shaft will be wetted with oil which will permit the oil to wick into the clearance between the shaft and the bore.  It has to help.  Note the sealant under the head of the bolt.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:44:05 I run an oil pressure gage that reads pressure off the head cover.  I currently tap into the head cover at the right-rear head cover bolt hole.   It works well but there isn’t a lot of material in this area.  You can only cut about two threads.  For this Big Bore project, I decided to move the pressure tap to the transverse oil passage.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:44:48 This location permits full thread depth, but the wall thickness is a bit thin.  I used a 90° fitting (1/8 NPT x 1/8 tube).  A 1/16 NPT fitting would have been ideal, but I couldn’t find one in a 90° configuration.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:45:37 You can see here how thin the wall gets.  With tapered threads you run the risk of cracking the wall when you tighten the fitting.  I opted for drilling and tapping slightly oversize (Letter “W” drill) and then setting the fitting with epoxy.  The epoxy will form the oil tight seal.  I think it came out good.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:46:13 The epoxy application was straight forward.  JB Weld is my go-to glue.  To prevent any epoxy from fouling the oil passage you must leave the first thread dry.  The copper washer is used to set the final position of the fitting when tight.  Just sand down the washer until you achieve the desired position when the fitting is tight.  Once you are comfy with the installed position of the fitting, take it apart, apply the epoxy, and make it up permanent.  You can do a full visual inspection by looking up through the oil passage to make sure no epoxy entered the passage.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:46:57 This story wouldn’t be complete without discussing the wave-washers.  Those rascals can be a real pain in the keester.  You can get em started easy enough, but then the edge of the washer always seems to get hung up in the bore.  They’re pretty sharp too.  Seems to me if you got carried away you could put a real bad slice in your finger.   It’s tempting to just leave those little suckers out, but I bet she would be one helluva rattle trap without those wavy little devils.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:47:45 I have found that a couple of .010” feeler gages (or some shim stock) make installation of the wave-washers a breeze.  Just sandwich the washer between the feelers, then shove the sandwich between the rocker and the head cover.  Once you have the washer in position, hold the edges with your fingers and pull out the first feeler gage.  Lightly push on the shaft until it slides though the center of the washer.  That will hold the washer in place.  Continue to apply light pressure on the shaft and pull out the next feeler.  The shaft will pass through and enter the head cover bore.  Mission accomplished.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/08/20 at 22:48:32 So, this completes Part 3.  The mods described above have been working fine on my Stage II head for the last 4600 miles or so.  No unusual noise.  Valve clearance checks have been fine.  Oil pressure did not change when I drilled the oiling hole for the intake rocker shaft.  Cam lobes look great.  I think these mods improve oiling to some critical areas and should add a little longevity to the valve train.  The heavier springs and high-lift cam will certainly take their toll on valve train life expectancy.  It goes with the territory.  Ya wanna play ya gotta pay. I hope you find this report informative.  As always, I welcome your questions & comments.  Knowledge is power. Best regards, Mike

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by Armen on 08/09/20 at 20:04:48 Awesome! Thanks so much! I look forward to stealing more of your ideas :-)

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/23/20 at 19:42:33 A forum member brought something to my attention regarding the modifications outlined in this post. “In your new article you posted, you mentioned drilling the cam lobes for oil holes – you did not mention drilling the center of the cam to make the interior hole the same size as the LS650.” The member went on to explain: “I believe the center hole allows oil to pass to the cam chain, and that the DR650 has a smaller hole to limit the oil flow to the cam, and it uses a smaller hole as there may be higher pressure since there are no holes in the cam lobes.  The LS650 needs a bigger hole so the lower pressure oil can flow.” I am embarrassed to admit that I did not take that hole into consideration.  It’s an important part of the system and I should have been looking at it, especially since I’ve seen it discussed a number of times on this forum. This is the hole in question.  The stock DR cam is on the left (.060” hole) and the stock LS cam is on the right (.079” hole).

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/23/20 at 19:44:57 In my reply, I stated that I wasn’t sure about the hole in the center of the cam, and that I felt the chain got an adequate dose of lubrication off the primary drive.  Then I rambled on about goofy things like “venting air” and the “the DR’s oil cooler feed comes off the cavity adjacent to the left-hand cam bearing”. That little hole started to gnaw at me, so I decided it was about time to take a proper look.  I started by doing a google search for “1995 Suzuki DR650 oil system”.  I got this nugget of gold (it’s from Wikipedia). The Suzuki Advanced Cooling System (SACS) was developed by Suzuki engineer Etsuo Yokouchi in the early 1980s. The system was used extensively on GSXR model bikes from 1985 through 1992. Suzuki continued to use the system in its GSF (Bandit) and GSX (GSX-F, GSX1400, Inazuma) lines until the 2006 model-year and DR650 from 1990 to present. Engines using the SACS system were generally regarded as being very durable. The SACS system uses high volumes of engine oil aimed at strategic points of the engine, like the top of the combustion chamber, which are not typically well served by air cooling alone. In order to provide enough oil for both cooling and lubrication, the system uses a double-chamber oil pump, using the high-pressure side for lubrication of the parts (crankshaft, connecting rods, valvetrain), while the low-pressure, high-volume side provides oil to the cooling and filtering circuit. The oil removes heat from hot engine parts through direct contact, is pumped away and subsequently routed through the oil filter, followed by routing through an oil cooler before being returned to the main sump. The cooling issue will be an important topic in future posts on the 97mm Big Bore.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/23/20 at 19:46:11 So, I was waaaaay screwy-wrong about that oil cooler feed.  I figured the cooler circuit was handling “unpressurized drain oil” from the head to the sump.  It is actually handling “pressurized cooling oil”.  Oooooops!  That’s a pretty big screw up on my part.  I’m not worthy.  :-[ It was time to put that cylinder head under scrutiny.  The oil flows through the stock LS650 camshaft as shown in this picture.  Please forgive my sloppy arrows.  The stock DR cam doesn’t have holes in the lobes so internal pressure will be higher and the center hole can be smaller.  The thought here is that if you put the holes in the lobes of a DR cam the internal pressure will go down.  If you want to keep the flow the same out the right side of the cam then you need to enlarge the center hole.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/23/20 at 19:47:00 When the cam is in the cylinder head and the rubber head plug is in place, there is hardly any space between the head plug and the end of the camshaft.  It looks to me like any oil coming out of the hole in the center of the cam will just squirt into the head plug.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/23/20 at 19:48:03 The oil that exits the right side of the camshaft fills a small reservoir adjacent to the steady bearing.  That reservoir of oil keeps the steady bearing wetted with oil.  The steady bearing can’t be pressure fed because it’s only half a bearing.  It serves as a cradle to steady the camshaft during the compression stroke.  During compression both valves are closed and the drive chain pulling down on the right side of the cam will load up the steady bearing. This is the steady bearing.  The oil reservoir is circled in red.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/23/20 at 19:49:13 I guess some of the oil flying off the right side of the cam may find it’s way to the chain, but if the designers wanted oil on the chain they could simply drill a hole/s in the circumference of the cam, adjacent to the sprocket, between the steady bearing and the sprocket. So now I believe the question becomes, will the smaller hole provide sufficient lubrication for the steady bearing.  I am humiliated.  How could I have overlooked this obvious question.   Time to look closer at the HammerHead.  It’s a test specimen I use for flow testing, trying various machining ideas (like the jack-bolt), and evaluations like this.  The HammerHead was donated to our cause by Fast650.  Let’s give a shoutout to The Fastman.  The HammerHead was subjected to a massive failure.  Word is that it was operated with zero oil.  That’ll do it every time. This shows the right-side cam bearing and the steady bearing.  You can see that the cam bearing looks wiped, but the steady bearing is just discolored with a few scratches.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/23/20 at 19:50:08 Let’s zero in on that cam bearing.  Yep, zero oil.  It’s wiped.  Look at how the aluminum is smeared.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/23/20 at 19:50:48 How does the steady bearing look?  Not too bad.  It appears as if the damage is more on the order of debris from the failure running through the clearance rather than zero lubrication.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/23/20 at 19:53:07 I’m still unsure which is better.  Should you enlarge the center hole on a DR650 cam, or leave it as is?  If you enlarge the hole, it will agree with the LS650 design.  I suspect it will increase oil flow through the cam and provide more oil to the steady bearing.  But if you leave the oil hole alone, it will increase oil flow through the cam lobes and provide additional lubrication to the rocker arms.  The rocker arms certainly are subjected to higher loads, especially now with the heavy valve springs and aggressive cam profile. Using the HammerHead as an example, it appears as if the steady bearing is pretty forgiving.  Looks to me like it can get by just fine on the oil available through the smaller hole in the DR cam.  Up to this point, I haven’t had any problems with the steady bearing.  But there’s a flaw in that mindset.  I don’t know if I have ever run a cam with holes in the cam lobes and the smaller (.060”) hole in the center of the cam. I have run a stock DR cam with the stock DR center hole and no holes in the lobes.  That worked fine for a long time. I have run two Web cams intended for the DR650.  I drilled holes in the lobes of both those cams, but I didn’t even look at the center holes other than to make sure they weren’t plugged.  Since I provided Web with LS cores, I might possibly have the larger holes in those Web cams.  It’s also possible that they sent me cams made from DR cores.  I never checked. This is where the forum comes into play.  Do any of you have experience with running a DR cam with holes drilled in the lobes and the standard .060” center hole?  If so, any problems with that setup?

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by justin_o_guy2 on 08/24/20 at 09:12:37 the system uses a double-chamber oil pump, using the high-pressure side for lubrication of the parts (crankshaft, connecting rods, valvetrain), while the low-pressure, high-volume side provides oil to the cooling and filtering circuit. Good answer right there.. Dunno how our pump delivers,, Too bad we dont have bearing shells, like a car crankshaft.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by hotrod on 08/24/20 at 11:20:45 I've been running the DR cam for about a year now. The hole in the center of the cam was drilled out to .080  No other holes were drilled anywhere. The engine is stock, except for the carb and muffler. Runs great. No strange noise or vibration . Shell T6 syn. Next time I get the cover off, I will inspect it carefully. I have a feeling that I will see everything fine. :)

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by justin_o_guy2 on 08/25/20 at 11:20:26 What are the gains ffom the DR cam and would it be good with an oversize bore and freed up exhaust and intake? I THINK I know that answer, but, maybe Im wrong and its up for the job,, And,, is it less expensive than the Stage 3 cam? IDK if that cam is even still available,, BUt if I cant get the W on the road, and I cant get that donk in the Savage frame, then Im gonna wanna punch out a jug and get a fat piston in it,, and do the other stuff to make it work out,, so I can haul stuff and shove that windscreen down the road and Go with traffic without feelin like Im guttin my motor,,

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by Fast 650 on 08/25/20 at 12:55:05 The DR cam has the same power curve as stock, just more of it.  DBM made better than 40 hp with a DR cam and port work, along with some intake and exhaust mods. All of the performance cams have very similar specs, so power is about the same with any of them. The stock DR cam is nearly identical to the stage 3 cam, so use whichever one that you like.  Both the DR and Stage 3 are drop in replacements. A big bore along with the above mods gives you even more. But if you are on a tight budget, improving the ports (especially the exhaust), a bigger diameter pipe and less restrictive muffler, airbox and filter mods (and a VM if your budget allows) along with a cam will yield big gains without breaking the bank.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by LANCER on 08/25/20 at 14:40:38 You can improve efficiency with a cam upgrade and a higher compression piston, and you can still use the stock carb if you wish to save $$. The Stage 3 is $299 with a refundable core exchange deposit of $100, so $399 total and $100 back upon my receipt of your usable cam core. The 94mm Wiseco is $199. Opening the exhaust port a bit is easy to do with a drill and a metal rasp bit and some sanding cones.  You don't necessarily need to go deep inside, just open the outer ring and smooth down the top of the ridge a little behind the outer ring. If you want a larger header and a good flowing muffler, a proper dyna works very well for the engine, and you can have a header made at a muffler shop for less than ... mine was done 8 years ago I think ...for: less than $20 for 8' of pipe and used 4', and $40 labor for cutting and welding, and that was in the Columbia SC area.  A custom unit will cost $250 for stainless and you've got to send them a pipe to duplicate. Anyway... You can improve your engine for not a lot of $$, and it can be done a piece at a time if needed.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by DragBikeMike on 08/25/20 at 15:52:40 Justin, I am in the testing phase of the Big Bore right now.  Still writing up Part 5 of this series.  Part 5 covers assembly & installation.  Part 6 covers test & tune.  Shouldn't take me too long to finish up.  There was a lot to learn and share.   FWIW, in Part 6 I will try to include my impressions regarding bang for the buck.

Title: Re: Big Bore Engine - Part 3 - Head Cover Post by Dennisgb on 08/25/20 at 16:08:05 This is interesting stuff. I would think if drilling the oil holes in the cam reduces oil pressure it would make sense to increase the center hole size to insure oil flow to the end of the cam. On the engine I am working on that was run without oil the two main cam bearing surfaces were only slightly damaged while the steady bearing was completely destroyed and that end of the cam had a groove worn into it. When inspecting it I found it very strange. There was a small amount of oil still in the engine. My guess is the steady bearing had less oil...

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