Valve-Lash Affect On Cylinder Compression

Can valve-lash be utilized in an effort to balance compression readings between engine cylinders?

Valve lash can affect compression readings if it's tight and not closing the valve fully. If the valve seats are worn or dirty that will also affect compression.
Can you use valve lash to dilliberately equalise compression between cylinders? In a word no. 
Upto 10% difference is acceptable and fairly normal. 
Especially the middle cylinders being lower values as they run hotter than 1 & 4.
If you have more than that then you need to investigate why. Could be worn or broken ring/s. Worn or Scratched bore/s, Gasket leak or a number of other reasons. 

wrote:

Can valve-lash be utilized in an effort to balance compression readings between engine cylinders?

No.

Had a professional valve job done, and the head was installed last week.  Compression was checked immediately after the first run and carb sync.  Weather permitting, I'll check valve-lash and compression again after a good-long ride this weekend.

Now that I think about it, the perfect opportunity to have combustion chamber volumes measured was while the head was out for service...


 

It will take time for the rings/valves to seat in. May not happen if the engine is running cold.
Steve

If everything checks out  valve clearance wise and the bike goes well i wouldn't worry about comp figures and just ride it..

wrote:

It will take time for the rings/valves to seat in. May not happen if the engine is running cold.
Steve
 

Yessir, that makes sense.  Just gotta be patient and get some riding time in.  My current local weather forecast shows 50's for next week. 

 
 

wrote:

If everything checks out  valve clearance wise and the bike goes well i wouldn't worry about comp figures and just ride it..
 

Advice greatly appreciated, always!

What are the numbers?

Plus this is just static compression. Your dynamic compression may be much different.

Which means your engine may behave differently once it starts running and breathing at speed as opposed to a static measurement prediction.
 

wrote:

wrote:

Can valve-lash be utilized in an effort to balance compression readings between engine cylinders?

No.

Can I pile on and say HELL NO!  

Break in the rings firmly, but not harshly.  Drive the bike assertively around town.  Don't baby it.  Use a good handful of throttle but don't thrash the engine until you get up to a few hundred miles or so.  After that, let'er RIP!  (or to quote Steve: drive the shit out of it!)  

 Thanks ED but it's RIDE THE PISS OUT OF IT.   I'll be doing the same thing in a few days. 
Steve

wrote:

What are the numbers?

Plus this is just static compression. Your dynamic compression may be much different.

Which means your engine may behave differently once it starts running and breathing at speed as opposed to a static measurement prediction.

 

140, 130, 140, 140  readings taken 12/13/21 with engine hot immediately after a 100 mile ride, 330 miles after head was installed