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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Ouch !! Exhaust valve stem Broke at 80 MPH /cgi-bin/YaBB.pl?num=1210170629 Message started by Steve M on 05/07/08 at 07:30:28 |
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Title: Ouch !! Exhaust valve stem Broke at 80 MPH Post by Steve M on 05/07/08 at 07:30:28 At 80 mph engine died, hit kill switch and pulled in clutch, got recovered home. On inspection Spark plug electrode smashed. Shone light through plug hole and there was something sitting on top of the piston. Strip cylinder head off to find one exhaust valve broken at foot of stem and the valve has smashed top of piston and gouged the inside of cylinder head. Not the sort of thing you expect from an engine that has only done 19,669 miles especially a low revver like a savage. This has never happened to me before and I have had loads of old bikes and cars over the last 30 odd years. On inspectiuon the middle of the stem looks like there could be a mafacturing flaw that was impossible to see before stem broke. Anyone else had this problem before? I am buying a second hand engine to get bike back on road, should I fit new valves, or do you'se think I just been unlucky and had a 1 in a million stroke of bad luck? The replacement is costing me £400 (about $800 dollars so I don't want that wrecked as well!!!) |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by verslagen1 on 05/07/08 at 08:53:14 Question: was the cam chain intact? |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by Steve M on 05/07/08 at 10:16:12 Yes cam cahin was still fine. Engine still turned np problem and internals all ok apart from damage to piston and bottom of cylinder head from the end of the valve when piston topped out. |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by T Mack 1 on 05/07/08 at 12:06:31 Several others had a valve die. Question: Have you rejetted the carb?? |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by Keith_T on 05/07/08 at 12:37:36 740D6D41434B11200 wrote:
Are you thinking the engine was running lean and hotter than normal? |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by vtail on 05/07/08 at 14:04:27 Stock, our engine is WAY TOO LEAN which causes the headerpipe (downpipe) to turn blue. On carburated aircraft engine we usually run 50-100'F rich of peak with the help of an EGT (exhaust gas temp) gauge as not to cause exhaustvalve overheating which then causes valveseat burning which in turn heats the seat and stem even more to a degree of total valve failure. A little extra fuel cools the exhaust. You hardly ever hear if intakevalve failure. My header is still chromed like new at over 6000 miles, so I recommand that all our engines should get the carb-mod. |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by T Mack 1 on 05/07/08 at 14:20:48 59575B465A574046320 wrote:
Are you thinking the engine was running lean and hotter than normal?[/quote] Well.... the second question would be to ask if he had changed pipe or air fitler to a hi-perf type......... |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by Steve M on 05/07/08 at 15:31:11 THX for replies in so far guys. being the 1988 model the carb was pre the lean white spacer model. No plug over the idle screw which was at standard setting of 3 and 1/4 turns out, so I doubt that led to failure. Bike doing about 55mpg (English gallons), so about 44 mpg, (US gallons). I hadn't thought of the exhaust. The exhaust was not standard when I bought bike. It has a straight pipe, one piece, same diameter for it's entire length, with a baffle built in which you can see if you look into the end of the pipe. Don't know make of exhaust but it is to european legal standard as it has the EU stamp on it. Air filter is standard. Bike was idling real nice and running sweet with just the occasional pop on over-run, and exhaust has some "blueing" near the cylinder head though I wouldn't say excessive. Perhaps I should run a larger main Jet? I have replacement low milage engine o it's way from a breakers, which will be fitted using the existing exhaust and carb. So I don't want that to end up with the same problem. Perhaps someone has an exhaust like mine and knows of better jet size than standard to use? |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by Reelthing on 05/07/08 at 18:45:09 sounds like a raask pipe |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by Kropatchek on 05/08/08 at 07:50:06 777575687F2F2A1A0 wrote:
Before you install the repl. engine I suggest you do the following inspection and repair. 1) Open the RH side cover to check the camchain, spanner and guides. 2) Remove headcover for check of the rockers, camshaft and -bearings. When you put the cover back on use your prefered sealant and don't forget to put sealant on the rubber plug. It's also easier to adjust the vanve claerance when the engine is on the bench. List is not complete but is what I did to my replacement engine among the obvious aas replacing the oil etc. |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 M Post by Rockin_John on 05/08/08 at 14:08:01 Thinking like Reelthing, I suspect your pipe is a Raask; which is a good thing (wish I had one) as long as the carb is tuned properly to it. As you do your re-assembly, take note of the carb adjustments and jetting, as there may be some tweaking you will want to do. For one thing, having to have your idle air/fuel screw out more than 3 turns makes me think you may need a larger jet in that circuit, and perhaps a larger main also. (Even despite the year of the bike, it's possible that someone else has been in there before and done god knows what to the carb. Better to go through it yourself and KNOW what you have in it! Personally, being an air cooled engine and all, I prefer to run bikes a bit on the rich side for just the heating reasons someone else already stated. As long as plugs don't foul! Good (better) luck! John |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by BurnPgh on 05/08/08 at 22:04:28 how's about this one fellas.... I have a '95. When did they start with all that spacer/lean running junk? Should I dive into my carb? MPG is a priority for me. Coupled with the size, weight, and easy maint/reliability, I chose the Savage as a step up from my 250 Rebel. However MPG doesnt mean a whole lot if Im gunna have to replace my engine in 20k mi. Or even 40k mi as a matter of fact. I don't want a drag beast or a race bike. Just a relaible, fuel efficient, lightweight cruiser that can pass a semi on the interstate in less than 20 minutes.... |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by Steve M on 05/09/08 at 01:13:35 THX for all this real good info guys. I have an original Suzuki manul for 86 model with 87, 88, update info. Also I have a clymer manual. Both say my model has 155 main jet as standard and the US model has a 133 main jet! So you folk in the US have a much leaner set up from the manufacturer. It also says for my model (86 to 88) that the base setting for the idle jet screw, (which does not have a plug in it), is 3 and a 1/4 turns out. The bike was idling nice at that setting and pulled away sweet. I have checked the size of hole in my main jet and couldn't get a 1.5mm drill through it!!! So when I bought mine it had a nice Raask exhaust on it, (I have looked at pictures on the net and it is a Raask), which is good. But it seems whoever fitted it didn't put in a bigger jet, VERY BAD! Something else I just thought of is that back in the days when this engine was designed we had lead added to our petrol, nowadays we have unleaded 95 octane in the UK which does run hotter than the old leaded used to! So mine is gonna get a 165 main jet, with the same pilot / idle jet left in, as it must have been running far to lean at high throttle openings. Just a thought for you chaps in the USA, over here the emissions are checked for car annual MOT checks, but motorcycles don't get tested for emmissions! So we can jet richer than standard. I don't know if the same applies to guys? If I was in the USA knowing what I have dicovered from this thread I think I would run a bigger main jet and put up with a slightly reduced range, then if they do check emmisions over there put in a smaller jet just for the annual MOT, (or whatever it is you have ), and ride easy to the test station. I am now convinced that my exhaust valve failed because the engine was running to lean when at high throttle openings, and I will be running richer with my replacement engine. Thanks to all who have replied to this thread. I think moral of this one is if you want to avoid the risk of losing an exhaust valve and trashing your engines piston and top end like happened to me, make sure your main jet is big enough. European spec that means at least a 155 main jet. many thanks to all who have replied on this thread it has helped me suss what happened and I should be able to prevent a recurrence. Might help others who read it as well. |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by rokrover on 05/09/08 at 08:21:22 Another possibility is your valve clearance(s) were too tight. The exhaust valve cools when seated and less seat time means more heat. Once I siezed an exhaust valve in its guide running almost zero clearance. |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by skrapiron on 05/09/08 at 16:51:52 I was just thinking..... You were running a 20 year old engine with 20,000 miles on the odometer at near full throttle for an extended period of time and you broke a valve. Sounds to me that you were going to break something sooner or later anyway.... Thats a heck of a load to put on any engine, let alone one as old and well worn as yours.. |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by Steve M on 05/12/08 at 05:21:19 all valves were correctly adjusted, prior to the valve failure I had only ridden about 10 miles and about 2 miles at 70 to 80 mph when the exhaust valve broke. The valve stem was moving easily in the valve guide. It was a simple case of the stem failing. The savage engine is over square and a fairly torqeuy low revver, max revs is about 5,400 ? So no way should a valve fail due to being ridden hard. In fact the savage engine is in such a low state of tune that it sounds very comfortable at 80 mph, so much so that to me it feels as though there should be another 20 mph or so left in it. I have had bikes that were built in the 60's, 70's and 80's that revved to over 10,000 rpm and covered 50, 60 thousand miles of hard riding. As a rule of thumb that would be 20 times more valve life used than my savage after 20 thousand miles. Of course those bikes ran on leaded fuel were and tuned to run richer than a savage. I sold a mate an old Yamaha XJ900F a couple of years ago that had done 64,000 miles, and he has added another 15,000. That bike has just had regular oil changes, diff oil changes, one new clutch set and tyres as needed. It is still running sweet as a nut. I am now convinced that the failure was due either to a flaw from manufacture, or lean running by previous owner(s), and the higher temperatures that would result. So convinced am I, that I am putting in a bigger main jet, and I will be putting 2 new exhaust valves in the replacement engine before I install and run it. |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 M Post by vroom1776 on 05/12/08 at 05:42:10 . |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 M Post by Savage_Rob on 05/12/08 at 14:25:49 083F38241A2D224A0 wrote:
There's a bit of a dilemma in there. Your best gas mileage will be with her her running slightly lean but the lean mixture will cause her to run hotter than if she were adjusted slightly richer (and lend to backfiring). Properly tuning her for performance will reduce mileage a bit but you'll have more power and a cooler engine. I get about 45 MPG with my Amal Mk2 carb and average riding habits. If I were to put the stock CV carb back on and ride in a more fuel-conservative manner (take longer to accelerate and don't exceed about 60 MPH), I'd get between 55 and 60 MPG. At this point, I like the response I get with a straight slide carb over a CV but I'm keeping my stock carb just in case. Either way, I live in Texas and I'll opt for a properly adjusted carb for a cooler engine. |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by justin_o_guy2 on 05/12/08 at 22:55:25 On the way home from church, I was on I 20 & finally got to ssee the needle on the speedo line up with the 9 0. I have almost 17,000 on it. Should I be afraid? I sure wouldnt like to have an "event" likle that. I think Id prefer that to hitting a groundhog at speed tho. |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by Steve M on 05/13/08 at 05:58:40 Justin, I reckon it's one of them classic dilema's where you "pay's your money and takes your chance". However, I personally now believe I had the valve failure because a previous owner fitted a Raask exhaust, and ran the bike with a 130 main jet, (a 155 or bigger should have been fitted), this along with running unleaded UK spec petrol has meant the engine had been running too hot for who knows how many miles. How many people on this forum have high mileage stock savages with over 20K and no problems? If you have a stock bike it may do 40k plus miles with no problem? Also what octane is the petrol you guys use in the states? Here in the UK it is unleaded 95 octane which can cause "pinking" and hot running in older high compression engines that were designed to run leaded fuel. I am having to buy a low mileage 2nd hand engine because of what happened to mine. I started the thread to try and discover if this was a "known problem" with these bikes. One reply from T Mack has said that he has heard of it happening before. I am getting 2 new exhaust valves from Alpha Sports which is in the USA sent over and will put them in before I use the replacement engine. Next bit is what I have deduced and would do if I had a nice savage with 15K plus on it. Run a bigger main jet, (US spec is 130, UK is 155 which is 20% bigger!) My carb had a 130 in it with a Raask exhaust. Every 15K to 20K check cam chain, replace exhaust valves, (inlet valves will not be affected by the heat issue), and fit new valve stem seals. If you replace the the exhaust valves and stem seals it will cost about $150, with new head gasket as well, as long as you can do the work yourself. These bikes are so cheap to run that I consider that well worth the cost for peace of mind, and to avoid a potential failure of the engine and major damage. However if you have a bike that has always used a stock carb / jets / exhaust, and has been well maintained it could possibly do a very high mileage no problems? |
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Title: Re: Ouch !! Exhaust valve stem Broke at 80 MPH Post by T Mack 1 on 05/13/08 at 06:06:31 US spec for California may be 130 (or 125) but the rest of the States it's 155 for 1986-88 and in the '90's dropped to 145 to meet the emissions standards. see: http://suzukisavage.com/cgi-bin/YaBB.pl?board=tech;action=display;num=1098869040 |
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