All About Squish Band In 2 Stroke Heads

Also check out my list of videos at dragonfly75.co... and my squish band page at dragonfly75.co...

[@MichaelForrestChnl]

Does the Pipe Effect Needed Squish Specs ? Yes. The pipes return suction and pressure waves increase the delivery ratio and the amount of intake charge being compressed to ignite. But that mostly affects the peak combustion pressure, not the rate of flame propagation till peak pressure. Probably the rate of pressure decline stays the same but with more peak pressure it will take longer to go to zero. So the more effective a pipe is, the smaller the squish clearance needs to be. That increases the squish velocity and reduces the “guarded” squish volume which burns late and extends the pressure time. The most effective pipes are also the ones with the shortest pipe powerband. They have short/wide belly’s, increasing angle diffusers, and short baffles. A really short baffle is close to 150mm (6”) long, and a really long one is around 300mm (12”) long.

[@darkraft100]

Great!!! I recommend you to invest in video quality, at least a better mic,I think you will have more subs

[@Markko1986]

Great video Michael 👌🏽👌🏽

[@k5guy]

Always appreciate your videos. Love the in depth numbers and birth gritty details. What area of two strokes you focus in? Kart racing? Snowmobile? Dirt biking? They all got different power curves so I'm curious what goals your after

[@MichaelForrestChnl]

I focus on coming up with concepts and formulas that apply to all 2 strokes but as far as tuning and modifying I probably have more personal experience trying to get a nice wide powerband for street and trail bikes. I find that more challenging than going after maximum power at max RPM for racing. But the people that do that consider it the only worthwhile goal. I disagree. 2 strokes can have a wide variety of uses and the modifications need to suit the intended end goal.

[@k5guy]

@@MichaelForrestChnl Thanks for the time to respond. I agree a wide power curve is the primary goal. I ride big bore two strokes dual sport so all around performance is what I am looking for as well. I can definitely confirm some extra squish band on the ktm 380 makes a world of difference in ridability and jetting becomes actually possible.

[@rogerstafford-wakeinc.2088]

Thanks for another great breakdown. I mentioned you in one of my latest videos( shout out). Godspeed.

[@MichaelForrestChnl]

thanks man

[@rogerstafford-wakeinc.2088]

@@MichaelForrestChnl my Honor Sir. Thanks for your time and support.

[@troyplayer2576]

What is your squish 0.40 or what then I do the dome to 22 mm of water never had a problem am I Rong please help me champ thanks very much mate troy player 13 lismore rd allstonevile nsw Australia 😮

[@MichaelForrestChnl]

the only way to know is with a squish calculator which is why I made one

[@troyplayer2576]

@@MichaelForrestChnl I have been dowing this for,35 years pal wake up and get a life U are so good ant

[@troyplayer2576]

Vernear gage

[@cycletechperformance9581]

Great Vid

[@ashbridgeprojects6916]

Hi, Michael. Thanks for another great video. I have a few of your spreadsheets already. Is this one available, yet? Thank you.

[@MichaelForrestChnl]

That would be my updated squish calculator and its available for $10 dragonfly75.com/moto/calculators.html

[@vaggelhskarabigas2368]

Very good job..!!!! You build a cr 250 head.? How is it run.?

[@MichaelForrestChnl]

I didn't build a head. This information is theoretical but it agrees with real life situations.

[@axyww]

What about early 2 stroke head with no squish area (all dome heads)?

[@MichaelForrestChnl]

my AX100 had a no-squish head but I used it in a really hot country and so I modified it to have a squish band to help cool the piston. But if that bike was in a cooler country then it would of ran fine as is, maybe a little stronger with a squish band.

[@monej-gaming632]

so why the aprilia rsa has 50% squish area?

[@MichaelForrestChnl]

Yes it does but it also has a special powerful ignition to reduce the possibility of a high squish velocity blowing out the initial flame and its above port compression is only around 7.5/1. The compression also affects the flame speed, so with a low compression you can have a higher velocity. As to the squish volume it is only 2.7% more than what the base recommended amount is due to the 0.7mm squish clearance.

[@Patricks_Projects]

Are you telling us we need less sqa with higher durations? 😅😅😅

[@MichaelForrestChnl]

less squish volume for higher durations. Of course if you just lower the head that might give the right squish volume but too much squish velocity. That's why I recommend my squish calculator to eliminate all the guesswork.