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Grrr....Valve Clearance

CBJoe

Tuned and Synch'ed
GT Contributor
Joined
May 23, 2015
Messages
63
Location
Indianapolis
Glad I'm doing a full service myself before riding much this year. Decided to check valve clearance while doing full fluid changes. Bike has maybe 20k miles on it...I think dealer checked valves about 7K miles ago.

I know the clearances are .15mm - .2mm ....Bike is Dead Cold....sitting for days. I'm getting .1mm - .11mm for all valves.

thats pretty dang low....I'm gonna adjust them and drink a beer and hope that no damage was done. I'm guessing all is well, but I know too little valve clearance is worse than too much. Boo
 
Glad I'm doing a full service myself before riding much this year. Decided to check valve clearance while doing full fluid changes. Bike has maybe 20k miles on it...I think dealer checked valves about 7K miles ago.

I know the clearances are .15mm - .2mm ....Bike is Dead Cold....sitting for days. I'm getting .1mm - .11mm for all valves.

thats pretty dang low....I'm gonna adjust them and drink a beer and hope that no damage was done. I'm guessing all is well, but I know too little valve clearance is worse than too much. Boo

I'm guessing it'll probably be fine. It's normal for the gaps to shrink as you put on miles, so it might have been set correctly 7k miles ago and you checked and caught it in time. In addition the gaps quickly get bigger (not smaller) as the engine warms up due to different rates of thermal expansion between metals.
 
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When I check a Valve clearance I raise the rockers with one hand and put the jauge with the other.
So I measure a slightly larger clearance.
 
To eliminate the clearance beetwin the rod-camshaft, to measure accurately the full clearance without
force on the measurement gauges.
 
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I push on the other side of rocker, no lifting but it gives actual w/o oil. I always push slightly on the cam follower side of rocker to set valves, then recheck after a rotation with out any pushing on rocker.
 
Got intakes all adjusted to .15mm(in)/.20mm (ex).....engine cold as can be. I assume the valve train will be a little louder since all of them were extremely tight (.1-.11mm).

Be a while till I'll know as I need to order a Demand Sensor to fix my P0155 issue. Unless I find a smoking gun with a loose connector pin or something.

joe
 
On this motor, yes, clearances increase with engine heat, the opposite of what is usually expected.
So, even the 0.1mm clearance (instead of 0.15mm) should have been fine, as it would have opened up in operation, not closed.

Stephen
 
No because it is impossible to make a measure when the engine is loaded and valves are really hot. :wasntme:
 
Someone on another board measured hot vs cold on a V11 and he said found that clearances opened up as the motor got hot as I recall. It seemed backwards, but unless I am willing to do the same tests I will take his word for it. The difference between hot and cold was minor, but hot was slightly looser than cold.
Either way, valve clearances should be set according to spec or slightly looser in my experience. But I doubt the exact clearance will be critical on a Guzzi.
And while there is nothing wrong with pushing on the rocker when measuring I really don't think it will change the actual measurement. Pushing the feeler gauge in the gap will do the same thing, any available clearance will be taken up. But doing that might make it easier to get the feeler gauge in the gap. So, either way should be fine.
 
Someone on another board measured hot vs cold on a V11 and he said found that clearances opened up as the motor got hot as I recall.

My experience too, I measured it happen on a 1200 Sport. I was temped to reduce the gap close to zero to minimize the rattley tappets, but in the end I decided against it.
 
Different engine configurations will change valve clearances differently based on temp. While the valves do get hot and thus expand, that is not the only factor. The aluminum that is a typically Guzzi head is aluminum and as such it also expands when hot. Plus, a typical Guzzi being a push rod motor the aluminum cylinder getting hot and expanding also plays a part, as does the push rod getting hot and expanding. Also making a difference in this is the different metals used for those parts, as some metals like aluminum tend to have a different rate of expansion than other metals like steel.
The reality is that a push rod motor like a Guzzi won't react the same valve clearance wise as, say, an overhead cam motor.
Testing from two different people I know of indicates that valve clearances on a two valve Guzzi don't tighten up when the motor is hot. As I have not done the testing myself, but I trust those that did, I go with what they found.
 
I responded to a similar statement about Moto-Guzzi valve clearances (Le Mans 2) . After years of working on too many
Harleys ( valve clearances grew noticably when hot) I expected the same from my Le Mans . I checked the clearances cold
and then went on a spirited 50 km ride and quickly removed the rocker covers and rechecked the clearances , they were
.002" tighter ! I can't speak for other Guzzi's , but the round head ones definitely tighten up when hot . Try what I did and get back
to us ! (Don't take anyones word for it , do it !) . Peter
 
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