Bandit Alley
GENERAL MOTORCYCLE FORUMS => GENERAL MECHANICAL & TECHNICAL => Topic started by: fritobandito on February 08, 2006, 12:54:31 PM
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Hey dudes, anybody ever replace valve seals? Was it a difficult job? I stopped by the shop and asked and they said about $500.00. Too much for me. Thanks.
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We don't have too many posts on valve seal replacement, not a common problem. What is your bike doing that makes you think the seals (guides maybe?) are bad. You wouldn't happen to have a '01 with the bad pistons do you?
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It's not as hard as you think but is a bit labour intensive, hence the $500. Makes a great winter project. If you can adjust your valves yourself, chances are you'll be able to do it yourself. THe tricky part is to make sure the cams and cam chain are in the right position. Other than that its all wrench turning. I pulled my engine to do a top end rebuild but you may get away with doing it on the bike I've never done a top end rebuild(new valves seals and springs) on these guys but my '84 GS750EF, which is basically the same enging but in 750 form wasn't too bad.
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I don't think it's the pistons because it doesn't smoke continually. It only happens after it has sat for a long time without running. And, it only smokes for a few minutes, then clears up. So, it sounds like leaky seals to me. Any other suggestions would be greatly appreciated.
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Could be as simple as a leaky head gasket. I would start with simple stuff first. Taking the engine apart is not fun.
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You still have to pull the head either way. But, granted just replacing the gasket is much easier. That would be nice it that was all it was. But, how can I tell?
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I don't think it's the pistons because it doesn't smoke continually. It only happens after it has sat for a long time without running. And, it only smokes for a few minutes, then clears up. So, it sounds like leaky seals to me. Any other suggestions would be greatly appreciated.
Define "long time" is it like overnight, or weeks?
How many miles/km are on the engine?
I'm leaning towards, if it clears up, then the seals aren't that bad - they're sealing fine when the engine is up to temp.
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After pulling the head, look into the ports with a flashlight. You can see the valve stems, if the valve guide seals are bad the stems will show it by being oily and dirty.
Shop cost is all labor. The seals themselves should not be more than $50-60. They are very easy to change, but you will need a valve spring compresser to disasemble the valvetrain to gain access to the seals. Buy a factory service manual, if you do not have one, it will explain everything in detail. The seals sit right on top of the guides and require the valves to be removed to replace.
It is time consuming, the hard part is paying close attention to detail on reassembly. All the valve keepers have to go back on just right to avoid any mishap.
BTW, what kind of mileage do you have?
I would expect valve guide seals at upwards of 30,000-40,000 miles. If that is the case, refresh the entire top end while you are at it.
Good Luck, Ed.
2005 GSF1200SZ
1983 GS750ED
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The bike usually has to sit 3-4 or more days before it'll smoke. To be honest, I'm not really sure. I know that if I ride it every day, it doesn't smoke when I start it. I believe the shortest time period that it sat and I noticed smoke was about a week. The bike has about 20,000 miles on it. I'm not really scared of the job. But, I don't have a valve spring compressor. Thanks guys for the input. :beers:
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Seals are something you would only replace when rebuilding the head.
Jay
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Frito, if you are going thru the hassle of pulling the head (not bad actually, even with it in the frame) then consider having the head gone thru.
It can probably be done for under $350.00. I had a Serdi valve job, head skimmed and it was under $200.00. I inquired about valve seals because my bike was doing the same thing and the shop said rarely do they replace suzuki seals. I had other problems and my seals were fine. They said it might add another $100 or so if they had needed replacing.
I had 24K on my bike at that time.
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I have more experience with cars than wrenching on the internals of the Bandit but with cars there are specific symptoms. If rings are worn, smoke on cold start up is normal until they heat and expand, which may explain why it takes 2-3 days of sitting to get smoke. Usually when you have bad valve seals they smoke the most when under hard deceleration, no matter what the engine temp. I could be off on this, is there a difference between a valve seal and valve guide?
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The guide is the bore in the head the valve stem reciprocates in. The seal is at the top of the guide to keep oil out.
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Frito:
What oil are you running if I may ask? Too light of an oil will also give you this condition. (I went though this with a previous car I owned & let's just say I will never purchase Amsoil again) If your running less than 10w40, this could be your problem.
If you ask, most mechanics will tell you it is very comon for an air cooled bike engine to puff smoke on start-up. Some do, some don't. If your oil usage is within limits, I would not let the occasional puff of blue smoke bother me.
Also, if you apply the choke too long while it is warming up, this can also cause the occasional puff of blue.
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Not just a puff. I mean it completely fogs up the inside of my garage, unless I point the back end out the door. I don't know what weight oil is in it now. I just bought the bike last September and haven't changed it yet. Perhaps I should do that before persuing anything major. Thanks for the insight.