squish

[dobo]

im just about finished a re build does any have the best way to check the squish and at what should it be

[faucon]

dobo said:

im just about finished a re build does any have the best way to check the squish and at what should it be

the gp3 stock have .75mm (same for my 2 engin). its around that for alote of bike. more room you have, more engin speed, less room= more compress. you need a bit of solder and a digital galiper.

get your spark plug out, make your piston go up to make sure your solder dont go in a transfer port, it will cut it, then you need to get your engin apart to get it out. then enter your solder in the same way the wrist pin are, to prevent any fliping of the piston that will give false reading. make sure the solder go hit the cylinder wall since the squish band was not very long. anyway it leave a nice mark when you crank it whit your starter. may be a little hard to squeeze. then read the mark it leave on your solder whit your degital galiper. that it, very easy.

[faucon]

hummm sorry details, but, i remember now, after my rebuilt whit polini gazket set, i was only able to get .7mm, it run fine anyway.

[dobo]

thanks for your help will give it a go at w/end

[tony811976]

this guy is a polini engine expert. it states .5mm for 40cc and .45 for 50 cc
seewww.minimotogarage.com/polini_engines.html

but there seems to be so much difference i guess its up to the builder what he needs more low, end top end, or revs.

.5 or .6 seems the norm on any bike higher the compression(lower squish ) will give you better bottom and mid range
lower compression (higher squish) better revs

im new to these settings myself and all information ive given is what ive found on the net to help