I changed to a 41 from a 44 and my top speed went down, a 2 stroke has to stay at a higher rpm to make max horse power. I would wait if it were mine till it is broken in.
Bike starts up as if it ant to start!
- Thread starter T james
- Start date
I was wondering what to do to get more out of full throttle. Seems to top out at 22-23mph. But was doing 27mph out of box. Has good low end. 1/4-3/4 throttle is pretty good. Just doesn't seem to increase rpm at full throttle. Just rides at a consistent 22mph at full throttle. Just wondering what could be done to get about 3mph more. Have stock jet in and have a kit of 66-70. Not sure what size is stock jet. So don't know which direction to go in.
If the engine is not turning fast enough to get flow through the carb then opening the throttle more will not gain you anything. You may go faster if you put a slightly larger rear sprocket on and get the engine RPM up a little higher where it can be making more power. Lots of things influence the power a two stroke will make including the length of the intake pipe and the exhaust. To go twice as fast takes 4 times the energy, Larry
Try removing the air cleaner and do a test run, if you get a higher top speed you need a jet with a smaller orifice. Most engine kits come with a jet a little on the rich or large side, I have a orifice drill bit set that I use, I solder them up and drill them to the size needed.
About 3 full tanks and you should feel a difference, somewhere around 200- 250 miles.
Ok, I tested a few jets. The 69 jet made it run shitty no matter clip position. 67 ran like it was too much fuel. Which I never got started (just bogged a few times). 66 jet was the closest results (21mph ran pretty good with good low end torque) to stock jet (which runs 23mph with good low end torque). But none out performed the stock jet. But I'm going to mimic all the stock setting from spark plug gap, to c-clip. And post results. What would you suggest trying after getting good results with 66 jet and shitty results with any jet above it. Asking because I thought stock jet was 70mm jet....
Don't confuse jet size and jet number, the higher the jet number the bigger the orifice. A number #71 drill bit is what is standard,(most of the time). The chart below is from a carting site but it applies to our engines as well.
https://affordablegokarts.com/pages/how-to-drill-the-main-jets
https://affordablegokarts.com/pages/how-to-drill-the-main-jets
This is what I have.
https://www.google.com/aclk?sa=l&ai...MIwoCy0PGF2AIVliSBCh3YqgklEAQYASABEgJ0SfD_BwE
https://www.google.com/aclk?sa=l&ai...MIwoCy0PGF2AIVliSBCh3YqgklEAQYASABEgJ0SfD_BwE
Never mind....now it seems the cam shaft arm is barely pushing the push pin to engage clutch. Unless its pushed so far in that it sits under the carb before clutch engages. Where as it use to start to engage when cam shaft arm aligned parallel with motor. Now it has to be pushed/pulled in so far it sits directly under the carburetor. I've notice clutch assembly has no spring between the drive gear and plate that flower key holds in place!
That's the adjustment you made on the flower nut, that's why I said to turn the nut in one notch or two and try it. It only needs enough tension to keep the clutch from slipping, more will stretch the cable and is bad on all parts.
Don't over think it and work on one adjustment at a time, if you change spark plug heat range and gap and then the jet and needle clip position you don't know which adjustment helped or hurt. I know it is tempting to try and rush to get it tuned but take it slow so you don't have to back track.