Exhaust Valve Question

[straxcla]

Ok so decided to check my valves for the first time today (17k on the bike) since I've been having some issues with it. One intake valve was tight and the other i could slide in a .038mm feeler. Figure I'll just go a shim size down on the tight one. NOW the exhaust valves, one is tight and has 0 clearance (go 2 shim sizes down?). The other has WWAAYYY too much clearance, I slid my biggest feeler gauge in there and it even had a little room to spare (.832mm I think). I've heard the exhaust valves should be run loose but this seems a little excessive. So how do I fix it?  Here's pictures if that helps at all.        

[straxcla]

oops, uploaded two of the same picture, sorry guys. Here's the loose valve

[BockinBboy]

Wow, you can see that clearance fairly easily - very odd that exhaust valves would be loose like that.  I'm not sure what would remedy that other than a thicker shim - but how thick do they go? lol, never even pay much attention to larger sizes since they always seem to need smaller and smaller.

For the tight valve for which you are unsure how much to go down on shim size - the typical way to figure out an unknown clearance is to put in there what some would call a 'test shim'.  A test shim is just a really thin shim/many sizes smaller shim that will go in there with plenty of clearance no question.  Then you can measure the gap, and know exactly what the gap is, and know exactly what shim should give you a clearance within spec.  The reason you would do this rather than just ordering two sizes down is because you can force thinner gauges in gaps that they actually should not fit in, making you think that you have more clearance than you do - and, it could really be more than two sizes down that you need.  You want to be able to measure the gap with the greater certainty of a thicker gauge, especially if you do not have much experience in using them.  Yes, I know it sounds silly that much 'experience' would be needed for measuring a gap, but you'd be surprised at how often folks can mess up sizing using the really thin gauges.  For this reason, you want to measure your clearances before and after not just to check your math.  You also want to measure the shim you took out and the shim you put in with calipers to confirm they are the thicknesses they say they are. 

- Bboy

[gsJack]

.832 mm is about 1/32 inch and way too much.  I set exhaust valves wider at .003-.005" (.08-.13 mm) and leave intakes at Suzuki spec .001-.003" (.03-.08 mm).  But it sounds from what you said that your 02 might have a sticking bucket or buckets, there were quite a few around that time.  My 02 bought in 03 with 4k miles on it had a sticking exhaust valve bucket and the valve wouldn't close tighter than .008" on a cold engine.  Valve finally broke while cranking one very cold morning and had to be replaced.

Check your buckets first.  With cam lobe away from the shim and some clearance you should be able to turn the bucket with your finger tip, if not you have a problem. 

My 97 GS which needed many exhaust shim changes frequently would require a shim 2 sizes smaller to get to spec.

http://www.gs500.net/gallery/data/500/GSvalvelogs.jpg

[Jimbob]

Did you by any chance make a video on how to replace a broken valve?

[gsJack]

Sorry no video made of broken valve replacement unless someone else made one.  Might be worth a search, I didn't look for one.

[Jimbob]

Looking at that first picture is that a long crack in the metal or is it just the way the light shines on it?

[straxcla]

If it is the bucket how do you replace those? Can you do it without pulling the head or is it a more intensive project? Also, where is the best/cheapest place to get shims, not feeling the $160 for the full Suzuki kit.

[gsJack]

I bought my shims from a local dealer for $5 each starting about 15 years ago and they were $13 each when I last bought them about 10 years ago.  Had a lot of shim changes on my 97 GS I put a fast 80k miles on and had enough left over to do my current 02 GS over the past 10 years.  Some here are ordering shims from 2 online places, I only remember one that sells them for $6.95 each, make sure you get the Suzuki 29.5 mm ones:

http://www.newmotorcycleparts.com/motor_parts/valve_shims.html

I discovered my tight bucket at first valve check on my used 02 at 10k miles.  Decided to run it longer to see if it would wear in some since it would free up within a minute when starting up as head heated in the morning and be OK the rest of the day.  But one very cold morning cranking to start with about 20k miles on it, it went bang and broke an exhaust valve off.  So I had to pull the head to replace valve and bucket.  That bucket was so tight I had to drive it out all the way with a long punch coming up thru the guide.  My engines has been good as new for another 80k miles but have another problem now with just over 100k miles on it.

Best to see if yours are tight first and then search to find many threads on the subject.  If they are real tight they can be very difficult to get out without pulling the head.

[straxcla]

SO the exhaust bucket is definitely too tight, wouldn't turn with the push of a finger as all the others do. I have carb issues as well (hanging idle). However, is the sticky bucket what has been giving me so much trouble starting the bike and keeping it running at an idle? And should I fix this before I try cranking on the bike anymore, I REALLY don't want to snap a valve.

[Jimbob]

Going by the post above I would fix it first

[JAS6377]

Why not just try swapping the two exhaust shims? Perhaps that'll even them out.

[straxcla]

I had a guy come check out the bike the other day and he noticed a cracked valve guide on that left exhaust valve. He also found out that the exhaust valve isn't closing so that cylinder has no compression. I'm thinking the valve may very well need to be pulled out to check if it's bent, so I pulled off the head today. BOTH exhaust buckets are stuck, oh joy, however the right side doesn't appear to be stuck enough to keep the valve open. I put a heat gun on the left exhaust valve just to see if it would heat up enough to turn the bucket, no luck. But the valve did pop shut a little more after it had been heated, still isn't sealing however. My question is can I pull the valve out with the bucket still in there, and how do i remove and fix a stuck bucket? Another thing I'm considering is just buying a used head off e-bay for roughly a hundred dollars to avoid fooling with all the above nonsense. Opinions and advice is greatly appreciated here.

[gsJack]

When I discovered my sticking bucket at 10k miles and decided to keep on running to see if it would loosen up with wear the valve was always stuck open a bit when cold but when starting up to run it would always loosen up and smooth out in a minute or less as the aluminum head heated and expanded more and faster than the steel bucket.  Didn't consider that when I cranked to start that cold below freezing morning I broke the valve at 20k miles.  I had no compression cold on that cyl but had good running compression after warm up.

One side of my valve guide was broke off and gone but I left it that way, changing guides is as hard as removing tight buckets.  One guy had some luck heating the head to 400F in the oven but others have just given up and replaced with a used head.  I was lucky my valve broke off and I could drive the bucket out from the inner side of the head I guess, it drove hard all the way although I didn't heat it. 

Never know when buying an ebay head why it's being sold, could be a good or bad one.  I got 4 buckets free from a forum member that was parting out a low mileage engine and still have 4 including the tight one I removed and will send them on to you free if you think it will help.  The smallest one of the lot was used on mine.

Can't think of a good way to get an unbroken valve out with the bucket still stuck in the head but maybe someone will come up with an idea that worked for them.

[frylockjim]

I had a guy come check out the bike the other day and he noticed a cracked valve guide on that left exhaust valve. He also found out that the exhaust valve isn't closing so that cylinder has no compression. I'm thinking the valve may very well need to be pulled out to check if it's bent, so I pulled off the head today. BOTH exhaust buckets are stuck, oh joy, however the right side doesn't appear to be stuck enough to keep the valve open. I put a heat gun on the left exhaust valve just to see if it would heat up enough to turn the bucket, no luck. But the valve did pop shut a little more after it had been heated, still isn't sealing however. My question is can I pull the valve out with the bucket still in there, and how do i remove and fix a stuck bucket? Another thing I'm considering is just buying a used head off e-bay for roughly a hundred dollars to avoid fooling with all the above nonsense. Opinions and advice is greatly appreciated here.

a good way of checking if the valve is bent or sticking open is to hold a piece of paper over the exhaust. if it gets sucked in at all then the valve isnt shutting all the way or is burnt. i have a tight buckets on my exhaust valves but i found that if the engine is still warm, then it makes it a hell of a lot easier to rotate them. Warm up the engine, take off the cams, and use pliers to get those suckers out if you plan on replacing them. As for pulling the valves, you will definitely need to pull those buckets off first as well as pulling of the head. be careful if you do it yourself though. do plenty of research on how to pull the head off. if im not mistaken, i believe theres an entire tutorial on youtube by BaltimoreGs (i believe thats his name). Most likely your valves arent bent though, but they may be burnt if they are extremely tight. If they are bent, however, then that means your timing is off

[frylockjim]

If it is the bucket how do you replace those? Can you do it without pulling the head or is it a more intensive project? Also, where is the best/cheapest place to get shims, not feeling the $160 for the full Suzuki kit.

you can most definitely remove the buckets without pulling the head. you just need to remove the camshafts. if the buckets are tight, warm up the engine first. itll make it easier to remove. If you know what shim size you need, you can try either bikebandit.com for individual shims or http://www.chaparral-racing.com. Chaparral delivers all over i think.

[gsJack]

................ I'm thinking the valve may very well need to be pulled out to check if it's bent, so I pulled off the head today. BOTH exhaust buckets are stuck, oh joy...............

The head is off now so heating in oven might help do it.  If you get the bucket out you can pour some water in the port to see if the valve leaks.

[straxcla]

Ordered an E-bay head, which came today. No sticky buckets on this one and valves look like they're seating ok, might try the water trick to make sure. I'll let you know how everything goes once it's on the bike and all that jazz.

[straxcla]

Used head went on and works just like it should. I forgot how nice it was to have a bike that doesn't stall at every other red light and stop sign. I even had enough shims between the two heads to do a valve job. Feels great to be back on the road. 

[Gorilla]

Nice man nejoy that ride beofre the next problem sets in!