Checking squish clearance

[D-1]

I'm checking the squish on a 80 cube evo. I normally use plasticine or solder on twin cams which works great, but I'm finding on the evo with the single side squish band it's a bit inconsistent.

With the solder on the one side, the piston must rock to that side and the clearance is 0.050" with a 0.036" gasket. But if I have a straight edge along the top of the barrel (no gasket) and rock the piston past TDC, there is basically no clearance.

Bottom end has been done and wrist pin clearance is good, I think my testing method is flawed? On a TC, I think the solder placed on both sides of the combustion chamber balance out, but the single side evo not so much. How do you all do it?

[Ohio HD]

Best way is have the rings installed. I use clay or a dial indicator. Dial indicator works best.   

[attach=0]

[D-1]

So you bolt the bracket down and zero it on the barrel, then swing it over to the flat section of the piston? Sounds good, I'll make one tomorrow, thanks.

[Ohio HD]

Close, I use a known thickness flat bar across the cylinder bore. Mine happens to be 0.080" thick. I set the dial indicator to 0.080" while it rests on the bar stock. Then when the bar stock is removed, the virtual 0.000" depth is calculated from the actual piston height or depth. +/-

[D-1]

Roger, thanks.

[thumper 823]

The squish as you probably know is one of the biggest factors in good performance.
I run 0.30  thou on mine.
I checked it with mock up and clay.
I did not like that,  and the soft solder is no longer available.
SO, I ended using body filler as in drops around the edge.
Its much more EZ to measure and fool proof if there was inconsistency in machining.

[FSG]

Best way is have the rings installed.  ........   

  or put a wrap of masking/gaffer tape around the upper part of the piston

[D-1]

Made this today and it works great. Put 2 wraps of electrical tape around the ring lands so it was a neat fit in the bore. At TDC the indicator read 0.001" out of the hole, and trying to rock the piston side to side didnt have any effect on it, so im pretty happy its accurate.

Thanks for the help everyone. 

[Ohio HD]

Nice work.   

[thumper 823]

what number are you trying to achieve? (squish clearance )

[D-1]

Was aiming for zero with a 0.030" gasket, but it's already 0.001 out of the hole on the front and I haven't checked the rear yet. Depending on what the rear is, I may put the pistons 5 thou hi and use a 36 or 40 thou gasket.

[thumper 823]

ZERO ?
WOW
And everyone has always said my thirty thou was way too tight.
Next point-
I have always been under the impression the squish (a good one )
on the tight side,  is was gave the lift off  (OK push dwn ) .
So, no squish is what you are shooting for ?

[D-1]

The piston at zero deck height and a 0.030" gasket giving 0.030" squish clearance

[Deye76]

"0.030" squish clearance"

Make sure you warm it up before flogging it.

[thumper 823]

Now I got ya.
I was a little worried about 30 thou.
However, it has worked very well for me!
That and a 9 lb ring pack !

[koko3052]

Have 27 thou on my TC 95" & 70K kms on it now, never had an issue.

[thumper 823]

I guess I  now have a new goal line.
Is it double plugged?
Or ?

[Burnout]

Have 27 thou on my TC 95" & 70K kms on it now, never had an issue.

A TC has a shorter stroke, shorter cylinder less growth.
You can't compare a soulless-short-stroke-small-valve motor to a BT EVO.

[Deye76]

"You can't compare a soulless"..........

What Knuckle owners said about Pans, & Pan owners about Shovels, and Shovel owners about Evo's, and Evo about TC and TC about M8, and the beat goes on. 

[thumper 823]

I have Axtell Cast iron cylinders on my EVO with the o3o squish .
No base gasket just Yamabond.
They work purrfect!
The iron is much more stable than the aluminum.
If I had to use aluminum cylinders I would have them cut for an "O" ring on the bottoms.

[Hillside Motorcycle]

Axtell cyls on our racer.
No gasket on base or head.
Mini fire-lip interference crush.
.040" lip, .038" c/bore in the head.

[thumper 823]

I now have 0.026 and have run it a total of a couple of minutes with no obnoxious noises.
This remains to be seen if it holds or not.
It has 0.026 over a  3/4  to a one-inch area outside (of course) radius one the long side of the angle tops  [attach=0] 

[thumper 823]

Try this one more time

[attach=0,msg1300798]

[Burnout]

That looks like it uses a shovelhead piston?

[thumper 823]

Axtell angle tops with their redesigned combustion chamber.