Hi there,

Im having trouble tuning my .91 four stroke. It either dies on low rpm when i remove the glowplug or cuts at higher rpm. My adjustments aren't helping. Does anyone have a technique or process that my help me get it closer to running correctly.

Any help or tips would be great thanks

Turn the high speed needle out 3 full turns and start it. Run it up to full power and use a tach to tune it. Lean the needle until it hits max RPM and then richen the needle until it drops off about 400RPM.

Low speed needle is the same thing. Drop to idle and let it sit for 30-45 seconds. Run it up to full throttle SLOWLY. Don't FLICK the throttle stick up with the tip of your finger. Thats for rookies. [>:] Run it up nice and easy. It should take 2 seconds to move the stick from idle to full throttle.

LISTEN to the motor as you advance the throttle.

Does it transition to full throttle?

Does it instantly die before it gets to full throttle?

Does it run up a bit and then die?

Does it transition, but it's gurgly and bubbly? Spitting lots of raw fuel out the pipe?

You adjust the low speed needle the same way as the high speed needle. Set the engine to idle and turn the screw in to lean it. As it leans out, it will speed up. Lean the low speed needle until the engine speeds up and listen as it eventually goes too lean and it will abruptly die or stumble and drop RPMs. Thats the spot you need to find. Where does it get to max RPMs at idle and then fall off? Lean it to max lean and then richen it 100-200RPMs

Go fly it.

If you think you have it right, let it idle, then pinch the fuel line and wait for the engine to quit and listen to the rpms as this happens. If the rpms increase as the engine dies, low end too rich. If the rpms decrease, low end too lean. No reason in the world not to have a perfectly tuned engine.

You wrote, " dies on low rpm when i remove the glowplug ." The above posts are good advice, but start with a new glow plug. A glow plug that loses RPM when the igniter is removed should be replaced before you start tuning. You will get better results.