Combination 2 Stroke Tuning

[@bobbyratliff3349]

If love to hear your opinion on metering rod carbs. I’ve had decent success with them but I found size is key to getting great response and good fueling. With a large carb and rich rod down low you could get response but if dual sporting it would run really rich at low throttle opening and high rpm

[@MichaelForrestChnl]

Interesting. Wouldn't the same problem exist with a standard carb? When oversized both carbs need to enlarge the jets and the standard carb would need a skinnier needle to allow more clearance between it and the needle jet.

[@BillWrites-t2e]

Im very curious to adjust my squish and compression, mostly to go from a race head to a more mild "pump gas" head design. This is on a ktm250sx 1999, compression is 14.5:1 so i run 100llav gas and 927@40:1 , the stock head has some design flaws like sharp corners a big dome and small squish.The engine was designed from ktm for low rpm torque in mind. I purchased a used 2002 head with a wider squish band and smaller dome, known to have improved top end, I plan on using this head for performance and then modifying the 1999 head by lowering the compression so I can use 91 octane pump gas. I would prefer the new head design be for mid to high rpm if im loosing my high compression , the motor can rev out better . Would you have any advice on making a pump gas head out of a race head? My plan was to literally chuck a spark plug in a drill, held in a vice and re cut the dome until I get my target cc for head volume. I figured if i had less power Id be on the gas a little more to keep up with everyone. Also do you think I would need to time the stator for pump gas, if so how much should i start with?

[@MichaelForrestChnl]

I'd start off by getting my low cost squish program so you can know the starting squish velocity and volume before changing it. After any change you always need to test different timings to see which one gives the best performance. A narrow squish band is for high RPM power, not for mid range power. High RPM power needs higher squish velocity and less squish volume. www.dragonfly75.com/moto/sqVelocity.html