RE- suscitation

[wayne]

Try Jess at Rotary Recycle:

[e-mail]

[peaktopeak]

Making progress here after 3 months of work. The biggest improvement by far was opening the secondary valve on the carb mechanically. I fabricated a hook out of safety wire that effectively eliminated the diaphragm from the activation process. This resulted in a big increase in top end power.

Buying and using the degree gauge was less helpful. I found that the numbers recommended for the secondary port opening were not reachable. They were beyond mechanical limits.
The degree gauge was somewhat helpful on the primary and secondary valve timing. It was not very far off and the adjustments were minor. The air screw adjust did make a big difference. I just kept turning it out a 1/4 turn at a time until the stumble dissipated. Not completely gone , but manageable with throttle technique.

Jetting work was also quite effective. I am not a fan of the #100 main jet. I feel like it is a band-aid approach that results in poor fuel mileage and reduced power all in the name of throttle response. I wound up with a 92.5 main and a 175 secondary jet. It is true I can not slam the throttle to wide open from idle, but I have no problem with having to use a little throttle finesse. I'm getting around 27 MPG and power feels good. Leaning the mixture helps acceleration at the expense of worsening the hesitation issue. I tried the 87.5 but it was a bridge to far.

I also tried running my favorite two stroke oil (Redline Allsport) and that did not work. It was hard starting and smoked heavily at start up. I think it was just to thin and leaked past the injection system into the combustion chamber. I switched back to Castrol Classic GTX 20-50 and all is well.

I can now say I have RE-suscitated this cool, unique, smooth and nimble bike

[wayne]

If the numbers for the secondary port are unreachable, there's something wrong with your cabling. Have you undone all tensioners including the one under the throttle grip?

I'm assuming you really mean port valve? The carby has a primary and secondary port (the latter vacuum operated). The port valve has two cables running to it and is inside a little casing on the left side of the engine housing (more or less below the carby).

Make sure that when the angle gauge is attached, the primary port cables are loose and the zero must be set with the primary closed. You may need to push the primary closed using a wooden kebab stick as cable drag will cause it to hang slightly open. If so, angle gauge zero will be incorrect and affect all measures.

Yes, the 100 is a bandaid to get people up and running. It's not "the" way to fix the bike. Just reduces frustration and improves the riding experience until you learn more about the bike. Glad to hear you did the experiments and found something closer to "normal" on the jetting.

Interesting to hear your experience with the two stroke oil.