Author Topic: Front right exhaust .13  (Read 173 times)

Offline user11235813

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Front right exhaust .13
« on: September 18, 2019, 05:01:27 AM »
I hate to say that the bike is running really well because last time I said that my carburettor had a very unusual problem which busted my brain for 6 months. Having said that, it is running very well, idle is perfect no problems whatsoever.

However when I got the bike the inlets were .06 and the exhausts were .05 the inlets have remained constant over this time at .06 however about 18 months ago the exhausts were .08-.09.

Last check a few days ago, the inlets are .06 the left exhaust is .09 up from .08 but the right exhaust is now at .13

Both the spark plugs looks normal.

Should so it does appear to be getting worse on the right side. This seems to indicate some build up on the valve and not closing properly, but I'm not feeling it.

Offline The Buddha

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Re: Front right exhaust .13
« Reply #1 on: September 18, 2019, 01:44:48 PM »

Should so it does appear to be getting worse on the right side. This seems to indicate some build up on the valve and not closing properly, but I'm not feeling it.

No, its likely, cam wear, likely shim wear and top of valve stem wear.
Valves going tight is seat and vale mating face to that seat wearing. On some bikes the clearance stays the same because both these wear at near equal rates.

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Offline Bluesmudge

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Re: Front right exhaust .13
« Reply #2 on: September 19, 2019, 12:24:51 AM »
You may find the wear slows down with the wider valve clearance.
I run my exhaust valves at .08 - .13 based on GSJack's 180,000 miles of GS500 experience. With the wider spacing my valve clearances haven't changed in the last 10k miles.

Are you close to the end of the shim size range? If not, swap in shims as needed and ride the bike!
« Last Edit: September 19, 2019, 12:25:51 AM by Bluesmudge »

Offline user11235813

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Re: Front right exhaust .13
« Reply #3 on: September 19, 2019, 12:51:28 AM »
@Buddha, these would be the original shims, I've never had any of them out yet, I was under the impression that this indicated some carbon build up on the valve and that wear would tighten up the gap, I might need to have a look at the engine diagram. I mainly worried if this is going to do any damage.

@Bluessmudge, I've got the shim tool but never had 'em out yet.

Offline The Buddha

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Re: Front right exhaust .13
« Reply #4 on: September 19, 2019, 04:48:07 PM »
Now carbon build up enough to cause increase in valve clearance will also cause it to run poorly because it will leak compression from not fully sealing and its likely not your problem, the exhaust valves run hot enough to clean themselves off by burning carbon very well. Intake - yes gets carbon built up, exhaust no.

A valve with higher clearance sits in the seat for a fraction longer, and the cooling is a shade better, it cools by putting it into the seat which then transfers it to the aluminum head which transfers to air and to the oil etc.

However that reduces valve seat wear and prevents the clearance from getting tighter, will not keep the cam wear or top of the stem or shim wear down. In fact, that extra clacking noise may be accompanied with extra wear. Remember sound is energy, it means more energy is getting dissipated and that part of which is sound is also higher, so running it loose has no advantage, the only reason for a valve clearance to even exist is to allow the valves to close when hot, cold and everywhere in between especially when these motors are warming up and each component is warming up at different rates. The valve clearance also will increase when hot compared to cold, so only reason for valve clearance to even be spec-ed out in anything is because the valve warms a lot faster than everything else in the head, especially exhaust valve. That would mean a 0 clearance valve will be hanging open as it warms up, warming up even faster, not sealing and generally causing all sorts of starting problems and burning.

The general thought I have is, if your valves are getting tighter - run em loose. If the valves are getting looser, run em tighter end of spec. You may also just be having a wearing shim. Pull it, look at its number and mic it and you may have lost a few of those 13 right in that shim.

Cool.
Buddha.
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