Jump to content
Sign in to follow this  

2002 cr125 squish clearance?

Recommended Posts

i have a 2002 cr125 and its got a milled head but i wonder how low can i go on the squish clearance right now i think i have 47 thousands unless somting was measured wrong? whats the most i can go without runing race gas

Share this post


Link to post
Share on other sites

You should measure the combustion chamber volume (well...actually the total volume at TDC as the piston sits down in the hole about .3mm if I remember correctly on that bike)

After that calculate static compression ratio (uncorrected....) and go from there.

That bike would like the squish at .035" but as stated would need a good chamber measurement to really determine fuel requirements.

The 125 I just did (2001...same bike) is at .033 right now, though I have a spare head I am going to do some more work to and bump static compression up to 15-16:1 on.

If your still waiting by time I do that...I can give you the specs I measure on it then....

Share this post


Link to post
Share on other sites

Just measure! It's not that hard...but I don't have the head around to do so.

I will have it in a week...so if you can wait....

Share this post


Link to post
Share on other sites
i have a 2002 cr125 and its got a milled head but i wonder how low can i go on the squish clearance right now i think i have 47 thousands unless somting was measured wrong? whats the most i can go without runing race gas

I think the lowest you'd want to take a 125 would be around 0.8mm, which i think is around 33/1000ths as harris said. You could go lower but not on anything that wasnt regualry stripped down and checked.

The main thing is compression though... if you reduce squish to 33 from 47 without increasing the combustion chamber volume you'll run into trouble. Generally you wouldnt want to increase compression by more than 0.5 points before looking at different fuel.

So you really need to know if the chamber was increased when the head was last milled... if it wasnt then you will need race gas if you go any further, if it was increased then you might be able to get away with a little more off, but not all the way to 33.

Share this post


Link to post
Share on other sites
Forgive my ignorance, but what is squish clearance?

Its the clearance between the top of the piston and the bottom of the head when the piston is at TDC.

Do a search and you'll find lots of info. Having the correct squish clearance can improve a bikes performance and make jetting much easier.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×