TE/TC All About Setting the Squish Clearance

After. I forgot to test before. Yes 1.3mm (0.050") is still pretty big but seems to be an accepted setting for the 300. I will test and then likely go more. I have snow so testing is curtailed for a few months. Cam.

Good stuff Cam. Winter sucks.

You should be taking advantage of the Winter down time and turn it into build time.......

Working on it. Once my back heals up I’m planning to go through mine.

We have found the squish clearance to NOT be the dominant force in having a better performing engine.

We have designed and tested hundreds of different chamber designs using the SAME squish design and changing only the chamber geometry. The HP changes and how it effects the power-band width was staggering.

While having excessive squish clearance is usually not a good thing, to state that is makes up 75% of the benefits is not inline with our testing results (and we have tested ALOT).

Also to state that spooge is related to squish would also be against what we have found.

Great topic.. but what Bell (who is a genious) determined using a 1970 air cooled engine (any cc) or what Blair determined at QUB using 50cc test platforms is relative in theory and much of it is applicable. Those guys (and others) were 2 stroke pioneers and without their R&D, the 2 stroke would surely be less advanced than it is today. BUT..having said that, those test beds sparsley resemble anything we are running today and so the data should be taken with that in mind.

Gotta say that we have several bikes running Kels' head now... those bikes rip!

Some good info on squish band, about halfway down the page.
http://www.2strokeheads.com/tech1.htm



Thanks Kelsey

Hey guys I tried doing a squish test on my bike with 1.6mm solder, it hasnt squished it one bit, seems way off. I have a pretty nasty low rpm ping i have been trying to get rid of for a while now. I put solder L's off to both left and right sides of the piston (over the pin basically) and not to the front of rear so I know its where it needs to be. I was wondering if I wasnt getting it in the actual combustion chamber but moved the solder up and down while turning over the engine to make sure I was actually hitting the piston. This seems like a crazy amount of squish for a TE150. I also did a compression test while i was at it- Im at 160 after 4 different tests with 56hrs on original top end. Any ideas?

Use thicker solder and then at least you know where it's at and you can also see the squish profile so you can machine it right. 160 psi is low for a race 150.

Does anyone know what the stock base gasket thickness is before I start machining maybe I can just go to a shorter gasket? I will try to get my hands on thicker solder for a proper measurement.

Time for rings or should I think about a full top end? Whats the stock compression for a 150?

I got about .025 thickness on the base gaskets on my 150 to set the correct piston height of .004 below the cylinder.

On the stock head the squish band is about .049 deep when you add the X distance it’s over .05


I’m getting 178 to 185 psi on my setup but I’m not running stock.

You can twist 2 pieces of solder together to get a larger diameter. Cam

Hey lugi,
You might as well pull the head and verify your solder placement... sounds like you're gonna want to fix whatever number you come up with. While you're in there you can also verify your X dimension and determine if a base gasket change would move you in the right direction. And if you choose to move the cylinder up or down you'd want to do that before you machine the head. Ya, I know... DUH... but I had to say it.

Testing has proved out well. Running 94 oct with 40:1 971 then 60:1 k2. At 35c temp 3000' no sign of detonation or anything odd. Very happy with the results. Cam

Just pulled my cylinder for a little voodoo. Here's what I found, stock 18 150xcw:
Two base gaskets: One 0.2mm, one 0.4mm
Piston .003 ABOVE the cylinder.
Stock squish .048" via solder.
Stock e-start compression 170psi at sea level.

I've since moved on to other head designs, but this was all with the stock settings.