hi to all,
my story starts with buying a dodgy gs >:(, my own fault, bought from a "friend" :cookoo:
he had spent over £500 on the bike to sort the carbs,new battery,tires,sprokets etc,i have proove of this.he never put it on the road,i passed my test and bought it off him.
the initial problem never went away after he got it back from the garage that worked on it, the engine would race on to around 5-6000 revs when coming to a stop often and the bike would not go over 80mph (it is not restricied).checked coils,pick-ups which seemed ok-then a quick compression test with my thumb-NO COMPRESSION ON LEFT CYLINDER!!!!
anyway,i removed the head and valves and found the left exhaust valve letting by,and the head out of serviceable limit-
head and barrels were given to an engineer,he skimmed head,ground in the valves (these were all within there servicable limit) and honed the cylinders.
after i received the head and barrels back,i have been measureing the valve clearences as the Haynes manual states to do it and how Kerry Burton suggest to do it,both same results.
I knew i would need new shims- the results------>
left intake-2.58 shim, no clearence,CANNOT turn bucket
right intake-2.58 shim,no clearence,can turn bucket
left exhaust-2.72 shim,-no clearence,CANNOT turn bucket
right exhaust-2.72 shim,no clearence,can turn bucket
i bought a 2.15 shim to take clearence mesurements, result-->
left intake-requires 2.55 shim for 0.05 clearence
right intake-requires 2.55 shim for 0.05 clearence
LEFT EXHAUST-REQUIRES 2.15 SHIM FOR 0.04 CLEARENCE ?
right exhaust-requires 2.50 shim for 0.03 clearence
the difference between the left exhaust shim 2.15 and the other 3 shims (2.55-2.50) seems ALARMING!, is this fairly common?, has anyone ever came accross the same issue before?
all advise/input would be a great help guys,as i cant wait to get the bike back on the road :dunno_black:
thanks,
Ant.
The valves have been reground, this involves removing metal from the sealing faces so as a result they are now sitting slightly deeper in the head than before. Upshot is that the clearances will have been reduced, particularly the LH EX which because of the fact it wasnt seating fully beforehand will have been reground "more" than the others and will be sitting deeper in the head than the other 3, hence the requirement for a thinner shim..........I cant see an issue. Just set them up to manufacturers spec and you will be fine. Your head will now probably outlive the rest of the engine.
Like sledge said, if you grind the valve and/or seat you will reduce the clearance and require a smaller shim.
As far as your difference in exhaust valve shims goes I had just about the same on my 97 GS at 76800 mile check. One exhauet shim was 215 and the other was 255. Don't know what the intake shims were as they were still the originals and never removed for the 80k miles I used that bike. Here's my complete valve check record:
http://img.photobucket.com/albums/v443/jcp8832/valveclearances.jpg
Why was this? I believe it was due to the one exhaust valve running on the tight side for many miles not allowing for ample seat time for cooling thus accelerating valve recession into the seat.
My 02 GS began to start the same pattern and I seem to have stopped it by increasing exhaust valve clearances to allow for better exhaust valve cooling. Will verify it soon with my annual valve check. The cooler running intake valves don't have this problem and require little if any shim changes in my experience.
thanks sledge and gsjack, :bowdown:
this is my first bike and am trying my best to grasb the basics- :thumb:,thats a big wait off my mind,just got to search around this side of the pond for the 3 shims required at a fair price
sorry me again!
regarding the right exhaust shim size which would be the better size shim to buy- 2.45(0.08 clearence) or 2.50 (0.03 clearence) the 2.50 would give me a better ballance as the left exhaust is 0.04? correct?
sorry to be a pain in the ass!
I'd use the 245 for a max .08 clearance on an exhaust valve since my exhaust valve clearances have only got smaller.
thanks jack,dont worry off to bed now,no more hassleing you bud!,its gone 1am here.really appreciate your help :thumb:
Its called floating on oil genius.
Cool.
Buddha.
I really like Jack's conclusion. Why not choose exhaust shims that give max .08 clearance? They only get smaller, so setting it at the lower end of the service limit will only require you to check them more often. Set 'em at .08 and forget 'em!
cheers all,your a bunch of stars to us novices,ordered the 2.45 shim for .08 clearence on that exhaust valve :thumb:
If you're adjusting your own valves you're not a novice, mate! :thumb:
cheers bill :thumb: