squish

[87_shee]

What should my squish be set at with 65mm wisecos and 20cc domes?

Thanks

[sinisterboo]

that is something you have to measure, as each setup is different. Im sure someone on here may be able to give you a estimate, but just like jetting, til ya check it, ya dont know....

[J-Madd]

You can't tell without checking it. Depends on how the domes are cut and base gasket thickness. Not sure cc has anything to do with the squish. Most run 0.035'' - 0.045''.

[87_shee]

Ok sorry i guess i worded that wrong. I wanted to know what i should be looking for when i measure it. I know how to do it, just looking to for a number to compare to when i do meausre it. I have a few different size base gaskets cause I want to make sure its all good.

 

So 0.035'' - 0.045'' is what i should be looking for, correct?

[bbcmudtruck]

I have had a few different builders tell me to shoot for .045.

[J-Madd]

I have had a few different builders tell me to shoot for .045.

 

TABLE 2.1 Minimum squish clearances

Cylinder size (cc) Clearance (mm)

50-80 0.6-0.8

100-125 0.7-0.9

175-250 1.0-1.4

300-500 1.1-1.5

 

If this is correct, it should be 0.040'' - 0.055''.

 

Squish on most of my engines is 0.045''

 

The0.035 that I stated before may be a little tight.

[trex banshee]

thats what i was told...not to go any tighter than .040" My trex is .0415" and my 350 is .049"

[Snopczynski]

actual squish you need to setup at is going to depend on the rpm the motor will achieve.

[magz]

actual squish you need to setup at is going to depend on the rpm the motor will achieve.

 

 

i just got my motors back together and done with break in and im running .047 and it runs like a raped ape

[deckheight]

Yepper... That's what I was going to say, beat me to it...

 

i just got my motors back together and done with break in and im running .047 and it runs like a raped ape

[Snopczynski]

Yepper... That's what I was going to say, beat me to it...

 

With T5's and a dune port (or slightly raised exhaust port) I would be running .050"-.055" Thats roughly gonna be for a 9,500-10,000 rpm motor.

[hercalmighty]

Hey Snop. What does Rpm have in relationship with the squish? I know a bunch of motor stuff but the squish thing is still a little forgein to me. I get that the squish is the space between the piston and the head but how doesn RPM effect what you should run.

[trex banshee]

Hey Snop. What does Rpm have in relationship with the squish? I know a bunch of motor stuff but the squish thing is still a little forgein to me. I get that the squish is the space between the piston and the head but how doesn RPM effect what you should run.

 

Snopczynski can chime in and correct me if im wrong but what i believe he is getting at is a tighter squish will create higher pressures and not allow the engine to rev quite as easy or as much...but then again that kinda contradicts the fact that he runs .050"-.055" on a dune port to rev 9500 to 10000 and my bike is just over .041" and i know it revs that hard, so honestly i don't know! :biggrin:

 

I would like to hear his take on this too cause my bike with .041" squish is only about 145psi due to the dome size/shape...so me saying the tighter squish will make higher pressures isn't always true. Im confused too

[Snopczynski]

The higher the rpm motor, the more stuff stretches out in lenght. Therefore, if you have a high rpm motor with .045" squish, the piston can smack the head. You dont want to go to far though, then the flame front wont burn even and cause the bike to run like pooh.

[bellracing2]

what is the min squish I should be running on a stock motor with dynoport 2 into 1 pipe for 93 octane ?