Guzzi 750 valve clearance question

[pikipiki]

Setting the valve clearance on my V7 Classic (older engine model)
OK I checked the clearances and they are on the looser side of what I understand the tolerance to be.
In 0.10-0.15 Ex 0.15-0.20

My understanding is that for most engines but not all the valve clearances tend to reduce gradually if not adjusted.

My question is do the Guzzi 750 clearances tend to increase or decrease over time?

[Penderic]

Should decrease with wear, and increase when the cylinder head bolts loosen. 

[M0T0Geezer]

You will find lots of Moto Guzzi 750 ("small block") info here, including valve clearances:

http://dansher.com/bikepix/Guzzi/_V7_fyi.txt

To your question:
VALVE CLEARANCE       
   0.006 in (0.15 mm) intake
   0.008 in (0.20 mm) exhaust

In  15,000 miles the valve clearances on my 04 Breva 750 have not changed.

[pikipiki]

 So basically:
The clearances are Inlet 0.10-0.15 Exhaust 0.15-0.20
New bikes should be set on tight side of limit.
Engine run in. Cylinder head gasket compresses a little, everything else wears in.
Initial service - retorque cylinder head, check valve clearance it's likely changed to the looser end of the scale. If within tolerance and even nothing needs done.

Over high mileage clearance will slowly decrease as valves bed into seat but it's unlikely will need adjusted unless you do a lot of miles.

If you want to adjust don't set in 0.10,ex 0.15 unless you plan adjusting every service or you just had the heads off. Set 0.15,0.20 for peace of mind.

If your anal about stuff you can set in 0.125 ex 0.175.

[pikipiki]

V7 classic manual states tighter clearance. In 0.10 Ex 0.15
Having now checked other manuals all others for same engine quote In 0.15 Ex 0.20.
I guess from advice I should dismiss the V7 Classic manual.

Further reading although not specific to 744cc engine suggests tighter clearances at factory relate to noise reduction?

Your quote of 0.15, 0.20 seem correct.

[Cam3512]

Not really. 
The manual is quite specific.  There is no range for the valves.  0.15 and 0.20. Period. 
When you retorque the heads, the valves get tighter, not looser.  You just shortened the distance between the head and the cam, things will get tighter.

FWIW, when I did my first service I checked valve clearance BEFORE the re-torque and they were tight.  After the re-torque they were within spec.

[Kev m]

I think the answer is the possible variance between theory and practice.

The reason for the retorque is to MAKE SURE the bolts are properly tightened with the gasket compressed. But if the gasket was sufficiently compressed already, then clearance wouldn't change, right?

[sign216]

I think the answer is the possible variance between theory and practice.

The reason for the retorque is to MAKE SURE the bolts are properly tightened with the gasket compressed. But if the gasket was sufficiently compressed already, then clearance wouldn't change, right?

And if the groundhog sees his shadow ....

[Kev m]

And if the groundhog sees his shadow ....

Are you arguing the gasket could not be fully compressed at initial torque?

[oldbike54]

Are you arguing the gasket could not be fully compressed at initial torque?

 If the gasket was fully compressed , and the torque had remained constant , then the lash would only be affected by wear .
Doesn't Pete talk about the differences in head gasket material on the SBs ? Before a certain model the retorque must be done every time , after a certain model the gasket only squashes so far and then stays constant . Dang , you guys should have cut your teeth on old Brit bikes with copper head gaskets , the manuals recommended replacing the gasket at every lash adjustment , at a minimum pull the gasket and anneal the copper . Most of us didn't do that 

  Dusty

[Kev m]

IIRC gasket material has changed across the board, big blocks AND smallblocks, but for some reason the smallblocks are the only ones (and gezus, I'm not just taking Guzzis, I'm talking like might be the last production motor vehicle) that requires a retorque at the break-in service.

I also believe Pete says he's seen a few over the years that leaked if they didn't get it.

That said, I'm betting a whole lot don't get it and some don't leak. What might explain that?

Some report the clearances lose before retorquing and some tight?

What could explain all?

If the tolerances of the gasket are such that they MAY fully compress on initial torque, but since some don't it's reconnected to be sure there are no future problems.

Just a swag, but the only other explanation from variances in tolerances, is that some people just suck at checking valves.

I'm an optimist.... Ergo the SWAG.

YMMV