Piston Wash and Squish Gap

kawishaul

kawishaul

I bleed GREEN!
Location
lake City, FL
I decided to take the head off my 650 x-2 tonight. Here is what I found. Is this good or Bad? :scratchchin:
I'm running: wiseco's .005 clearance, PJS head at 175 psi and squish at .04 something, oceanpro cylinder, westcoast exhaust, bn44, and stock ignition. What do the engine docs think is wrong?:brap: IMG_0667.jpgIMG_0671.jpgIMG_0666.jpg IMG_0668.jpg
 
SUPERTUNE

SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
Are you sure you have about .045 squish on both cylinders? If so, you might have rod bearings getting loose and the pistons are tapping the head. Piston wash says a little lean as the piston is carboned all the way across and has a glossy look to the color, but with the squish not correct could be misleading.
Too tight of squish with high squish ratio designed chamber will also cause the MSV to be too high and show signs of extra piston crown heat.
 
kawishaul

kawishaul

I bleed GREEN!
Location
lake City, FL
Darn, I'm glad I checked it. I will remeasure the squish tomorrow. How long do you have to run the motor to see initial and change in the piston wash? Before I put the head on the pistons were completely clean. It had only been ridden a couple of hours though. less than 10hr. I'm running 93 octane and about 45:1 oil.
 
X

-XXX-

Location
PA
Not only is the squish clearance too tight, you also have conflicting angles on the piston dome and the combustion chamber. Danger!
 
#ZERO

#ZERO

Beach Bum
Location
Florida - U.S.A.
Between .035" to .045" would be good for the squish gap depending on the angle used.

A thicker base gasket or head gasket would be the quickest and least expensive fix.

Also richen the fuel mixture up before something worse happens.
 
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SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
Why did you use a copper headgasket?
When I ran PJS heads I always used a ultimate green performance gasket.
PM Troy here on the board at: SUPERJET-113 and I'm sure he can get you one.
Yes, you'll drop a little compression, but way better than blowing up the engine!
And a side benefit you might not be as lean with the jetting with less compression ratio.
Don't get over excited about the squish angles as your ok for now if you get the new headgasket.
The only true way to have perfect squish angles is you will have to machine the piston tops, as they're more of a rounded dome than a straight angle dome.
 
kawishaul

kawishaul

I bleed GREEN!
Location
lake City, FL
I'm running the copper head gasket and a thick plastic (don't know what kind to make up for the shorter cylinder. The ocean pro cylinder is a couple mm shorter than stock.
I know for sure (especially after comparing to stock) that when I first set up the engine with the stock head my clearance was around .03-.04.
How many psi could I lose with the thicker gasket over reshaping the squish band and cutting the head?
 
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SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
If you were to do the math...2.3cc would be the difference you would gain in combustion chamber volume with the .020 thicker headgasket.
You would have to mill about .030-.035 off the head surface then re-cut the squish band to the proper depth to get the squish to .045.
Or you could just cut the squish bands only now another .025 and reuse the copper headgasket. (I personally don't like the copper headgaskets as they do fail and leak more than not, over a long period of time)
I don't go to crazy by using pumping compression as I use measured cc volumes to calculate the true compression ratio #'s against the port mapping.
 
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