Tight Valves

[simon79]

>trumpetguy:

Thank you, too
When I checked valve play (a few weeks ago), I could spin by hand the suspect valve's bucket (left EX), but I could actually feel that it was harder to spin compared to the other three (which were all in their 0.06-0.07 mm). And the feeler gauge measurement confirmed this impression of mine.
At this point, I think I can live with it till next March, when I'll reactivate my insurance, autumn is coming so there are gonna be lesser and lesser riding opportunities. I'm planning to suspend it from November till then, this spring I might do a valve re-check and adjustment (the 12-months used vehicle warranty will have expired by then ), have new tyres installed and possibly try and sync my carbs.

[ben2go]

I am new to this type of valve train,but I posed this question to an mc mechanic I know.Here is what I was told,if an engine is over reved or the valve to cam clearence is to great,it can cause the valve to slam shut, in turn causing the valve to receed into the seat further than is acceptable.This over time can cause tight valve clearences and valves that hang partially open at operating temps.DON'T COME GIVING ME GREEF IF THIS IS WRONG.I AM REPEATING WHAT WAS SAID TO ME BY A MOTORCYCLE MECHANIC.Thanks and happy riding.

[trumpetguy]

ben2go:

I don't have any experience in the results of over-revving a GS, so what the mechanic said may very well be true. 

The bigger worry, to me, is the result of a too tight clearance on the exhaust valve.  The exhaust valve is blasted by VERY hot gas passing around it every 2 engine revolutions.  It is cooled by contacting the seat and thus transferring its heat during most of those 2 revolutions.  If the clearance gets too tight, it spends less and less time on the seat and more time getting burnt.  Pretty soon, the valve is burnt enough that it doesn't seal even when you adjust the clearance and it must be replaced.   Buying shims and/or tools is MUCH cheaper and easier than replacing valves.

[ben2go]

ben2go:

I don't have any experience in the results of over-revving a GS, so what the mechanic said may very well be true. 

The bigger worry, to me, is the result of a too tight clearance on the exhaust valve.  The exhaust valve is blasted by VERY hot gas passing around it every 2 engine revolutions.  It is cooled by contacting the seat and thus transferring its heat during most of those 2 revolutions.  If the clearance gets too tight, it spends less and less time on the seat and more time getting burnt.  Pretty soon, the valve is burnt enough that it doesn't seal even when you adjust the clearance and it must be replaced.   Buying shims and/or tools is MUCH cheaper and easier than replacing valves.

+1

[NWDave]

well I got the shim tool and pulled and measured them all, one intake was a 2.75 all others where 2.80.  I put the 2.75 in one of the buckets that had a 2.80 and it was still too thick.  So I just broke down and ordered a $100 29.5mm shim kit, should be here in a few days.

[galahs]

What do you get for that $100 

[NWDave]

2ea shims in size 2.40-3.00mm.  And it worked, I came home tonight to find an opened package on my porch (why it was opened I know not, but nothing was missing) and I got it worked out with new shims that meet the clearance.  Out of respect for my neighbors I won't run and tune a yoshi piped 500 at 10 in the evening, if I was a real bastard I'd pull the GSXR and the 500 out to let them warm up.  Anyway but I did start it up to make sure everything was ok, and for the first time since I've owned the bike the damn thing would idle stone cold (after I reset the idle adjust screw).. the choke worked nicely.  I might actually find out how a well tuned, instead of a monkey tuned, 500 runs like. 

And on the plus side I told my roommate (who actually is the new owner of the 500) that it wouldn't be ready, but damn the place I ordered the shims from had the kit to me in a day (what service!).  So now she gets to come home tonight to a big surpize, she wanted to go riding tomorrow but I told her it wasn't going to happen  looks like I made a lier out of myself twice in one week.  Anyway I'll let you know how it goes.

Tight Valves = Bad thing.

[trumpetguy]

for the first time since I've owned the bike the damn thing would idle stone cold (after I reset the idle adjust screw).. the choke worked nicely.  I might actually find out how a well tuned, instead of a monkey tuned, 500 runs like.

Tight Valves = Bad thing.

That was also my experience on doing my valves for the first time.  The bike idled amazingly well and puled better from idle on up.

[NWDave]

I'll tune in the carbs after I get up in the morning and then we shall see what is up.  The Idle Air/Fuel mixture screw has been something I have had the mechanic tweak with before, but now I got the damn screw driver to do it on my own.   We'll see what magic I can work.

[simon79]

Wow, quite a hot topic
Just one more question came into my mind to ask you all...
When I did my valve check, after reassembling everything, it fired up all right; thing is, from that very moment I can notice, no matter if engine is cold or hot, a strange smell coming from the tight left EX valve region (don't know if there may be a link), it's quite hard to describe, is smells like...well, hot/overheated metal??
I did nothing else than taking the valve cover off and back on, I re-used the same gasket (it has only some very, very small leaks, almost unnoticeable), didn't bother take shims off or something like that, and I'm pretty sure I put everything back into place.

[trumpetguy]

Wow, quite a hot topic
Just one more question came into my mind to ask you all...
When I did my valve check, after reassembling everything, it fired up all right; thing is, from that very moment I can notice, no matter if engine is cold or hot, a strange smell coming from the tight left EX valve region (don't know if there may be a link), it's quite hard to describe, is smells like...well, hot/overheated metal??
I did nothing else than taking the valve cover off and back on, I re-used the same gasket (it has only some very, very small leaks, almost unnoticeable), didn't bother take shims off or something like that, and I'm pretty sure I put everything back into place.

Maybe it's just hot oil or a little oil burning.  I cannot think of anything you could have done to cause that (unless the gasket itself moved a bit and is letting more oil out OR you didn't get even torque all the way 'round.

For my bike, a little oil burning smell is the norm.  I have a small base gasket leak I've been putting off changing.  I'd rather ride and check the oil more often. 

[simon79]

^^^^^^^^^^^^^
I cannot think of something I may have messed up either, since basically I did not fiddle with any mechanical element of sort...but you know, I'm on the paranoid side sometimes
Oil level...hmm, checked it yesterday, it's roughly from 1/3 to 1/2 of the full range. It was changed by the dealer (or so they said) when I got my bike, that is 7000 km/4350 mi ago.
4000 mi...4000 mi...this remembers me of...oh damn, it's time for an oil change.
This is going straight into the to-do list for next spring:
-new tyres
-valve re-check and adjustment (will our heroes be able to deal with this? ), with a new head gasket (better)
-change oil and oil filter
-sell it for an SV650N (...just kidding )