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Anyone finding almost All valve clearances at or tighter than spec at 15,000 miles?

tbraunreiter

Big Wheel
Forum Subscriber
Just checked clearances at 15,000 miles and almost all were at or below minimum recommended clearance. Previous posts I read didn’t seem to find this. Anyone else find similar tight readings?
 

2andblue

Moped
Forum Subscriber
What were your clearance measurements?

I am no engineer: however given valve tightening is due to compression of the head material under the seat what sort of RPM’s do you run?

It would make sense to me if you are seeing consistently tight valves at this low mileage you have opened/ closed valves more than average (higher average RPM). What is average - no idea...

Blue (my machine) is due the initial valve clearance check.
 

tbraunreiter

Big Wheel
Forum Subscriber
Five intakes were at .11mm, two were at .12, one at .14. Three exhausts were at .17, three at .18, two at .19. I do ride a lot at higher rpm because I live in Montana with a lot of curvy mountain roads, but the rest of the time I drone along in 6th gear at 70-80. I don’t feel that I ride much differently than anyone else. I do hit the redline occasionally when accellerating, but, again, not much more than anyone else.
 

danmcdermott@me.com

Member
Member
tbraunreiter,

If you mean your motorcycle just turned 15,000 miles and those are your measurements it is well to know most see movement in valve clearance in the first few thousand miles and less after that. Also, many experience valves tightening (getting more narrow) over time as well. There is a thought to move valves to the largest in spec gap at each adjustment understanding that after break in they seem to always get tighter. I choose to inspect mine at the prescribed intervals and bring out of spec valves into the middle of spec as possible.

If I misunderstood your post and question please disregard.
 

tbraunreiter

Big Wheel
Forum Subscriber
tbraunreiter,

If you mean your motorcycle just turned 15,000 miles and those are your measurements it is well to know most see movement in valve clearance in the first few thousand miles and less after that. Also, many experience valves tightening (getting more narrow) over time as well. There is a thought to move valves to the largest in spec gap at each adjustment understanding that after break in they seem to always get tighter. I choose to inspect mine at the prescribed intervals and bring out of spec valves into the middle of spec as possible.

If I misunderstood your post and question please disregard.
Thanks, that’s my plan, but obviously not cheap to change out 16 shims. Will set to upper middle of suggested range.
 

gsun

Member
Member
My first check there were 15 out of 16 out of spec. Second one not so bad but still 5 or 6 out.
 

rogracer

Member
Member
At 25K miles, mine where all in Spec...but 1 valve just barely (didn't bother to adjust), but I don't bounce off the rev limiter as normal practice either.
 

2andblue

Moped
Forum Subscriber
My first check there were 15 out of 16 out of spec. Second one not so bad but still 5 or 6 out.
gsun - what mileage was your first valve clearance check? Did you set to the looser side? Mileage in between first / second maintenance. Finally are you at the higher RPMS often, close to redline?
 

4bikes

COG#9715 AAD
Member
I checked mine the first time at 13,750 miles and I found 2 exhaust valves and 4 intake valves out of spec and tight, and the remaining 10 valves were on the tight side of the spec. They we’re loosened back to center at 0.009 on the Exhaust, and 0.006 on the Intakes. On the second check at 40,000 miles, 15 of the 16 Didn’t move at all, and one actually loosened closer to the loose end of the spec. if you don’t check them, you have no idea where they stand.
 

Daytona_Mike

Member
Member
Valve gaps will always get tighter.. that is normal. Valve gaps getting looser is not normal and is usually just caused by carbon build up on the valve head itself which on the older carbureted bikes were more common .. not so common on Fuel Injected bikes. This is why the propensity to always regap to the max specifications if possible to extend out the next inspection interval. High revving the engine to redline does not seem to effect valve clearances however.. maintaining a high rev over long periods will have an effect.. which makes sense.. the engine has many more revolutions on it for the same amount of miles... Bottom line.. red lining the engine is fine.. Holding it at redline...... that will shorten the maintenance intervals. Most people find doing their first 'Adjustment' at 24k miles is perfect. Many people suggest not doing inspections (unless you have the funds or do it yourself-- inspections are not cheap).. just plan on having them re-gapped at 24k miles. That is up to you. Mine were all on the cusp of 'Out of Spec' at 24k miles. All where tight. All were adjusted to the max spec as best as possible
 
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rogracer

Member
Member
I've heard it said high RPM use doesn't effect valve clearance, and I'm sure there are anecdotal accounts where that is true. But I struggle with that conclusion as the impact loads at the valve seat scale with the square of engine speed. So I would need an explanation as to why that does not matter before accepting that conclusion as fact.
 

zrxmax

Member
Member
Valve gaps will always get tighter.. that is normal. Valve gaps getting looser is not normal and is usually just caused by carbon build up on the valve head itself which on the older carbureted bikes were more common .. not so common on Fuel Injected bikes. This is why the propensity to always regap to the max specifications if possible to extend out the next inspection interval. High revving the engine to redline does not seem to effect valve clearances however.. maintaining a high rev over long periods will have an effect.. which makes sense.. the engine has many more revolutions on it for the same amount of miles... Bottom line.. red lining the engine is fine.. Holding it at redline...... that will shorten the maintenance intervals. Most people find doing their first 'Adjustment' at 24k miles is perfect. Many people suggest not doing inspections (unless you have the funds or do it yourself-- inspections are not cheap).. just plan on having them re-gapped at 24k miles. That is up to you. Mine were all on the cusp of 'Out of Spec' at 24k miles. All where tight. All were adjusted to the max spec as best as possible
This valve adjusting philosophy mirrors that of my 05 Busa. On the Busa you can tell the valves need adjusting when the bike gets harder to start... that is... it takes more revolutions for it to fire. The good news is this... once the valves are adjusted again its often been said that if you don't beat the crap out of it you may never have to set them again. I don't know if that is true... just what I have heard from people that build these motors for performance. Like you mentioned... carbon under the valves could be an issue... so... a shot of Sea FOAM ( dam auto correct ) or the equivalent combined with some wide open throttle can be a good way to keep the valves closing like they should.
 

2andblue

Moped
Forum Subscriber
I've heard it said high RPM use doesn't effect valve clearance, and I'm sure there are anecdotal accounts where that is true. But I struggle with that conclusion as the impact loads at the valve seat scale with the square of engine speed. So I would need an explanation as to why that does not matter before accepting that conclusion as fact.
I have always understood and accepted the premise it is cycles not necessarily speed of closure that dictates the frequency of valve clearance adjustments.

Naturally higher number of RPM’s results in more cycles per period of runtime / compressing the softer head under the seat which displaces the clearance gap by thinning the thickness of the head. After head material has compressed the denser material provides for less movement and hence less frequency in valve clearance adjustments.

Not certain policy on posting commercial articles of other sources than COG however there are good online articles in circulation explaining more eloquently what I describe above.

Given about half the 29K miles I have on my machine were always low RPM miles and not until the recent times have I enjoyed the higher RPM’s I have delayed the maintenance. Will be a late fall exercise.

To OP
1) Your measurements although a few below spec they don’t appear alarming - exhaust of course being the biggest of concern, so I would not be concerned.
2) You are right on the mark of mileage check.
3) Lastly - I have never hit redline so given higher RPMs I again would not be concerned. Set to higher end and go until 35K at least is my bet.
 

zrxmax

Member
Member
Is anybody using aftermarket shims? I see the ones from China on E Bay... given my level of buy American first I really don't want to give any more money to the CCP indirectly unless no other choice is available.
 

gsun

Member
Member
gsun - what mileage was your first valve clearance check? Did you set to the looser side? Mileage in between first / second maintenance. Finally are you at the higher RPMS often, close to redline?
First one was at about 25K kms. Second about 50. I set it in the middle. I don't ride full out normally.
 

2andblue

Moped
Forum Subscriber
Gsun I am surprised to hear at such a low mileage 15 of 16 valves were outside the specification range... Very interesting.

OP here is another low mileage testimony with practically all valves were outside spec. What you experienced doesn’t sound like it is abnormal. My guess folks who wait longer just aren’t discovering they are out of specification.

In the next few weeks when I tackle this task will post individual measurements. I have close to 30K miles so it’s overdue. To my knowledge valves have not been a chronic issue with the C14 and I am quite certain many NEVER touch their valves or do so infrequently - not right but can see how this could be true.
 
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