So I finally got the new (used) head onto my GS, got the chain tensioner in and have it all in time. However, the valve clearances are still messed. Similar to the problem that prompted me to replace the head in the first place (see original thread: http://gstwins.com/gsboard/index.php?topic=58232.msg660637#msg660637). My intakes valves have basically 0 clearance. The right intake valve won't take a .02 mm feeler gauge and the left intake valve actually spat the shim out there is so little clearance and the tip of the cam lobe is contacting the bucket right when that valve opens.
I don't think its bent valves this time as I can feel compression cranking the engine over by hand and I was very careful to make sure everything was in-time before turning the engine, however I don't truly know the condition of the valves in this used cylinder head.
Could this be because I am using the cams from my original head? I can't think of anything else that would cause the cam lobe to contact the bucket.
sounds like you have valves and valve seats that have receded from grinding or normal wear and tear.if the valves have plenty of metal behind the seat area and not razor edged from being lapted in you could grind the end of the valve stem by say .010" to get you in clearance .this is an experience call ,such as,, do the valve collets have enough metal behind them to allow you to do this .If your valves and seats are so warn you may need to get new seats and valves fitted but it dosnt stop there, then you would need new valve springs to get every thing back into spec.if your valves are badly reccesed your valve springs may not have there proper fitted clearance and you could get float at high rev'es.
The head I bought supposedly had 15,000 miles on it. Is the valve wear you speak of possible in this amount of time?
Sounds like this head isn't so good after all.
the valves Can be "Slightly" bent as well tho.
im by far no expert, but the new used head I got recently had at least 1 pretty noticeable bent intake valve.
only difference was the opposite in clearance.
My intake valves were not closing fully to allow combustion.
also, had WAYYYYYYYY too much clearance when I checked with my feeler gauges.
So im not 100% sure if the opposite can happen (no clearance)
I was also getting compression from the pistons the entire time too.
Put in the 2 good intake valves from my old head and she started right up with ease.
(still have to check the clearance tho)
blue smudge i would be extremly supprised if this happend in 15000 miles .with some on here with very high miles and have never had there head off .The factory would build them to cope with at least one valve grind or more before this happened. some one may have had both seats restored for what ever reason and it was installed to deep .
That doesn't seem very likely, I don't think the engine this came out of had any engine work done. I'm going to try switching to the other intake cam I have to see if that makes any difference. This all just doesn't make any sense to me. :dunno_white:
If the valves were bent, that would increase the clearance, right? So it can't be bent valves causing this. --just trying to think through it all.
EDIT:
:bowdown: Hey, it worked! I swapped to the other set of cams and put in smaller shims and it no longer wanted to spit the shim out, but it was still no clearance on the left side so I put in the smallest shim I had and now its sitting perfectly at .06mm clearance on both intake valves! :woohoo:
Thanks for all the help guys!
Tombstones81, I read through your build thread and it gave me the confidence/motivation to get back to work on the bike and figure out what was wrong. I think the shims that came in the head were just extremely out of spec making me think there was a more complex problem.
On a side note: My exhaust valves now have a clearance of .11 mm and .13mm (was the closest to spec I could get them with the shims I currently have). I know GsJack and others like to run their exhaust valves a little on the loose side, but is .13mm pushing it too far?
Quote from: Bluesmudge on February 02, 2012, 10:48:08 PM
.....................On a side note: My exhaust valves now have a clearance of .11 mm and .13mm (was the closest to spec I could get them with the shims I currently have). I know GsJack and others like to run their exhaust valves a little on the loose side, but is .13mm pushing it too far?
No I don't think so, my spec is .003-.005" (.08-.13 mm) for exhaust valves so you're right where I'd put them. The last 2 exhaust shims I changed on my 02 GS increased clearace to .004 and .005" at 86k miles and I have 92k on it now and expect to go to 100k miles without further checks and still running mid size shims.
My 97 GS had one exhaust valve running to the tight side of Suzi specs and it started with frequent shim changes around 40k miles and was down to a min 215 shim before 80k miles. When I noticed the same pattern on my 02 GS starting again around 40k miles I went to the wider gaps on exhaust, chose .003-.005" which was about the same as spec was for my 82 CB750 Honda that I put 80k miles on.
I suggested a 9500 rpm redline for GSs with the wider gaps which was the same as the CB750 was and my
stock GSs had no need to rev higher since power drops off fast after the 8500 rpm peak. Since then burning1 has been running the wider gaps on his race bike so it's probably good to the GSs 11k redline but I have no need to go there. Throwing a shim at high speed can make a mess of an engine.
http://img.photobucket.com/albums/v443/jcp8832/GSvalvelogs.jpg
glad you got it sorted out.
and glad my crazy thread helped out. haha