Squish help.

[motopsycho87]

I run 3 0.5mm gaskets to get my piston in line with the bottom of the port, this gave me a squish of 3.6mm, i machined out 2.2mm for 1.4mm squish.

[celler]

Originally Posted by motopsycho87

I run 3 0.5mm gaskets to get my piston in line with the bottom of the port, this gave me a squish of 3.6mm, i machined out 2.2mm for 1.4mm squish.

What was the result of the changes. What happened to the over rev with the lower port height.


Sent from my iPhone using Tapatalk

[motopsycho87]

It raises the port height, thus increasing over rev, I had to drop 12 jet sizes to get it to run right (goes to show how much more efficient it is now!)

[rbreak]

Originally Posted by motopsycho87

It raises the port height, thus increasing over rev, I had to drop 12 jet sizes to get it to run right (goes to show how much more efficient it is now!)

How did it affect the low end power/torque/off idle response?

Thanks.

[celler]

[QUOTE=motopsycho87;127988]It raises the port height, thus increasing over rev, I had to drop 12 jet sizes to get it to run right (goes to show how much more efficient it is now!)

Don't know where my head was at. Yea raises port height. Probably my state of mind sitting in my center airplane seat When you took the squish to 1.4 what compression did you end up with? I would guess your low and mid improved with the head mod. So overall you gained everywhere.

[motopsycho87]

Every area of use was improved. The first thing I noticed was how incredible the off-idle performance was, and then when jetted correctly, the over rev is brilliant. It could be a bit more peaky, maybe I'll get it ported one day, but to be honest I'd never out ride it off-road, just when twatting it in a straight line!

Seriously, you'd make you money back in fuel after 6 or 7 tanks , couldn't believe how little I'd used on the last ride!

[toadl]

I was going to post this pic to ask if my cylinder was too low, but I guess my question has already been answered. I've never ridden the bike, just bought it. I'm trying to get it ready for this summer.

If I have to mill the head, is this something any good machinist can do? We have a machinist at work that is very precise as well as a lathe and end mill. Are there some magic secrets?

[(F5)]

Certainly are. Don't make the compression too high for the type of gas you are going to run.

Learn how to measure the comm. Often engines are a bit different so a double check is important. If I just skimmed mine to the squish number I wanted the comm got way to high.

read my recent thread might help.

The closing points of the ports are way more important than the fact that the piston doesn't go all the way open. that said it is nice if it does. What I haven't done is tried to raise the barrel & in that case these guys have a better experience of the ride afterwards.

[Jakobi]

Like F5 said. If you mill down enough to correct the squish the UCCR will go through the roof. Its even more noticable on the 250s. Very easy to end up over 16:1

[toadl]

Originally Posted by Jakobi

Like F5 said. If you mill down enough to correct the squish the UCCR will go through the roof. Its even more noticable on the 250s. Very easy to end up over 16:1

Cool! 16:1 I'll be ready to climb Mount Everest with race fuel.