2 Stroke Compression Ratio/Tuning Help

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12/2/2017 1:36 PM

c0ncEpT wrote:

When it burns the oring it's detonating. Put higher octane fuel in it. Running tight squish speeds the flame travel up. It makes power but you need the octane to control the burn.

The closer you run the piston to the head the more power it will make. You just need the proper fuel to control the burn.

In NHRA prostock they reduce piston pin height by .001 until the head stops marking the piston on the deck surface.

THat will not work on a 2 stroke as they need the added squish clearance to cool the piston with the fuel charge. What you speak of will work to a point on 4 strokes only.

Paw Paw


12/4/2017 7:16 AM

98 Octane euro (RON) is equivalent to US R+M/2 93, and is approximately 90 MON.
Not to many tuners are going to recommend a squish that tight with that fuel.
I would add a gallon of leaded race fuel to 4 gals of that to be safe. Even 100LL avgas would help!


12/4/2017 7:39 AM

JoeKTM ,I have a 18 TC125 so I'm watching his closely. I run straight 110 race gas in my stock bike. Been leaning low end ,first pilot,then cutting slide,,as it will load up on the 9 plug if left to idle 10 seconds. Did cutting your deck clean up the jetting? Did opening the combustion chamber help and in what way? These where exactly my next moves on mine to improve the rideability


12/4/2017 8:46 AM

Loosen sq and put it at 14.5 comp
And run pump if you want. Thats. Assuming Stock pipe. As the pipe sets the cylinder pressure. Taking orings out. Means its not happy.
Little to aggressive


2 stroke performance engines
engine dyno

12/5/2017 8:13 AM

Besides the insert, did the head insert holder also get milled ?