Measuring squish band and deck height

[blowerbike]

Ok now I'm confused BB. I may not be a master engine builder, but I can certainly add. The piston sits .022" above the cylinder. How is that zero deck height? Unless zero deck does not refer to the amount of piston above the cylinder...

if your .022 above the liners then you need a .022 compressed base gasket for zero.
that would be if you checked it without a base gasket.
you checked it with a .022 base so you have .022 over and .022 under.
that means you need .044 to have the pistons even with the liners.
what don't you understand?

Ok, I measure everything one more time.

Base gasket .022"
Piston .022" above deck.
Solder laid across piston top - .028" at the flat part of the piston edge.
Head gasket quite thick - .044" compressed.

Now, with all that, looks like for optimum clearance of .035-.040", I need a base gasket that's .027-.029" thick correct?

What's the measurement for "squish"? I read somehwere that ideal it should be .043". Is that the same as the flat part of the piston to head distance?

Can someone double check my math?

Thanks.

Clay my calculation works out that you would need a .034" or .8mm base gasket.

Ok now I'm confused BB. I may not be a master engine builder, but I can certainly add. The piston sits .022" above the cylinder. How is that zero deck height? Unless zero deck does not refer to the amount of piston above the cylinder...

[blowerbike]

.022+.022=.044
.044 would put you at zero deck...simple math...

Ok, I measure everything one more time.

Base gasket .022"
Piston .022" above deck.
Solder laid across piston top - .028" at the flat part of the piston edge.
Head gasket quite thick - .044" compressed.

Now, with all that, looks like for optimum clearance of .035-.040", I need a base gasket that's .027-.029" thick correct?

What's the measurement for "squish"? I read somehwere that ideal it should be .043". Is that the same as the flat part of the piston to head distance?

Can someone double check my math?

Thanks.

Ok, here's my measurements. Like I figured, they are pretty close to Don's.

OEM Base gasket .020" compressed
Deck Height was .020'-.022"
Head Gasket compressed was .044"
.044-.022=.022" clearance.
Measuring clearance using pieces of solder measured .029" averaged

So, looks like I'm too tight as well. The .031" thick base gasket would give me an additional .011" of clearance for a total of .040" if using the solder measurement or .033" if using the piston above deck measurement. I will re-measure both to see why there is a .007 diff.

Does all the above look right and sound good?

Thanks.

Ok, I used an OEM gasket spare that I had just to make the math easy. Like Don's, my piston is .020"/.56mm ABOVE the cylinder with the 650 piston/cylinder combo. I'm betting my squish band measurement will turn out to be the same as Don's as well.

Don - would you be willing to make me a gasket just like the one you made for your engine? I really don't have the capability at my house. I guess I could order one from Cometic?

Thanks.

[blowerbike]

lets say you get an average of .020 above the liners.
if you want zero deck you add a .020 base gasket.
if your piston flats are in the hole say .010 you would/could mill the cyl. deck .010 and run no gasket for zero or run a .010 gasket for a -.010 deck or what ever combo your looking for.
it's just simple math.
measure twice..three times and assembly once

[rapidray]

You add in the base gasket thickness. Ray.

So when you guys Do this without the base gasket in place, how do you figure that part into your calculations?

[rapidray]

I do it EXACTLY the same way as Terry just stated. Ray.

[blowerbike]

i check deck height without a base gasket/rings or clips.
measure over the wrist pin center lines with calipers and get an average.
do the math.
zero is great but a few in the hole is better than the piston sticking out into the head gasket.
rods do stretch at high revs so be aware.

and yes i use old wrist pins on half of the studs snugged down.

Sweet! Ok, I'll put it together tomorrow and get the initial measurements. Thanks Don.

Ok cool. I did not know you could reuse the gasket. What's the grease coating for? I was always under the impression gaskets and their surfaces needed to be clean and grease free.

The grease has two benefits. The first is that it helps make a good seal and the second is that it makes the gasket easier to remove in the future. Just general purpose axle grease is fine.

Ok cool. I did not know you could reuse the gasket. What's the grease coating for? I was always under the impression gaskets and their surfaces needed to be clean and grease free.