• Hi everyone,

    As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.

    When he passed, I worked with his kids to gather the necessary credentials to keep this site running. Since then (and for however long they worked with Coffee), Woodschick and Dirtdame have been maintaining the site and covering the costs. Without their hard work and financial support, CafeHusky would have been lost.

    Over the past couple of weeks, I’ve been working to migrate the site to a free cloud compute instance so that Woodschick and Dirtdame no longer have to fund it. At the same time, I’ve updated the site to a current version of XenForo (the discussion software it runs on). The previous version was outdated and no longer supported.

    Unfortunately, the new software version doesn’t support importing the old site’s styles, so for now, you’ll see the XenForo default style. This may change over time.

    Coffee didn’t document the work he did on the site, so I’ve been digging through the old setup to understand how everything was running. There may still be things I’ve missed. One known issue is that email functionality is not yet working on the new site, but I hope to resolve this over time.

    Thanks for your patience and support!

  • 2 Stroke Husqvarna Motorcycles Made In Austria - About 2014 & Newer
     TE = 2st Enduro & TC = 2st Cross

TE/TC All About Setting the Squish Clearance

um, maybe you are being funny. Guess you have moved on from them? Not to many Cam's from Kamloops, BC on moto boards with nice bikes.
 
Hi Cam, good thread you started.

2 stroke head design has too many variables and I think should be considered a black art, your case in point, “Squish Thickness.”

From my understanding the squish band design’s main roll is charge velocity but its design can change greatly from road racings to off road enduro riding. Band width is narrower when road racing compared to the wider band width of off road bikes. The other variables to consider are parallel band surface to the piston or up to 3 degree difference, the minimum distant (squish thickness) at the piston OD, the radius size at the blend to the dome, the cc of the head, and of course the never ending different dome sizes and designs.

I’m attempting to try my hand at machining some different head designs for my TE150. I’ll turn them from 7075 but noticed that the SX insert looks to be made out of brass or aluminum-bronze (Ampco) so might make a few out of that material as well.

Also, on the newer KTM-Husky the combustion chamber insert inlay should be about .002 proud of the outer cylinder head.




Input from other members on this subject would be greatly appreciated.
 
KXcam22,
Very nice information. Thanks for taking the time to put it on the forum. I'm also a squish band guy, and I get frustrated by all the misinformation out there.

John Bunker,
Not sure if we've discussed this (I think we have) but I flat sanded my 150xcw head for a squish of .040" and then .036". When I had the insert and shell in my hands, I realized that a slight clamping distance would be necessary. I had to flat sand the shell a bit after going to .036" on the insert. Good to see you mention this.
 
I can vouch for Dave at Two Stroke Performance here in Oz (http://twostrokeperformance.com.au).
I had my TE300 head machined for the correct squish band and combustion chamber profile. The result was 30% better fuel range and a much smoother engine.
 
KXcam22 said:
Picklito, I can't believe you sanded yours down. You get the superman award!!! Can you explain how you flat sanded yours. Cam.
Click to expand...
. I have a 3" thick granite flat plate that makes flat sanding very easy. Took it slowly and mic'd the perimeter to make sure it stayed square. It did! Started at .048", test ran at .040", then another sand and test at .036. Planning to try .032.
 
Started with 80. Finished with 220. Thought the 220 would still be a little too "open" but the head surface was very nice so I left it. I'll see if I still have the pics.
 
KXcam22 said:
Retest: With a squish clearance of 1.27mm and without the muffler plug my compression was 197psi, cold at 1100 ft. That's more like it. I expected close to 200 psi since the squish clearance could be tighter. Cam.
Click to expand...


.05 seems like a lot, is this reading before you shaved the head?
 
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.
 
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?
 
hakkalugi said:
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?
Click to expand...

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.
 
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