Clutch engadement for green slide?

Running green slide on lo206 was wondering clutch engadement on bully clutch highest rpm reading was 5200 rpm last race but clutch was set for black slide on those numbers thx any help would be helpful thx


Engine RPM (based on one dyno)Green Slide HP

alvin l nunley

Premium User
Apologies to those who have often heard this before.
Clutch engagement should be set at peak torque RPM. At what ever RPM the clutch is holding the engine, the torque the engine is producing at that RPM is transferred through the chain to the rear axle. You can calculate the horsepower (HP) at the rear axle. Torque X RPM/5252.1 = HP. From this it's easy to see that, with maximum torque at the rear axle, you are producing maximum HP at the rear axle. Always set the clutch, while it is slipping, to hold the engine at peak torque.


Premium User
2800 RPM is a good start.

Assuming its a 2 Disc, bolts in both holes, black springs, .235" spring height.

If its a 1 Disc, brass weight on the levers, red springs, .275" spring height

alvin l nunley

Premium User
An easy way to test for peak horsepower at the rear axle is; put an analog bathroom scale between a strong wall and the front of your kart. Sitting in the kart, just start it up, warm it up, hit the throttle. The RPM setting (clutch slip) where you get the highest reading on the scale is the setting you want to take to the track.


Engine(rpm) Torque (ft-lbs) HP (hp) Green Slide

2500 7.5 4.1

3000 7.75 5.0

3500 7.9 5.28

4000 7.3 5.5

4500 6.8 5.8

5000 6.3 5.9

5500 5.4 5.85

6000 4.7 5.55

Sorry....the columns won't line up!


Premium User
So, you're looking at 3500 according to Dan's chart. My experience has been slightly lower than that.
You're carb tune could affect this some, don't be afraid to experiment to get the best results.
You could try Al's method, or put that rascal on the dyno.
A big problem that we have getting accurate data on these long slide (small plate) restrictor engines is that the peak torque is so low that it falls dangerously close to the clutch engage on our dyno. Still not as bad as the long black slide JR LO206 with the 4100 limiter. LOL
Tell me why we dyno tune those things again.:unsure:

🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
Carlson Motorsports on Facebook
30 years of service to the karting industry
Linden, IN