I have a yd 100cc bicycle motor it has a windowed piston, 2in reed valve, a hp carburetor, with a 65 jet in it, expansion chamber, and a bbr stage one cdi ignition. It idles good and runs OK down low mid and high it just doesn't want to go. Could eny one help me out
Can't get it to run right
- Thread starter lyonsteve
- Start date
Chainlube
Well-Known Member
Those HP carbs aren't very good, I have a couple and could never get them to run right. Sounds like not enough fuel for higher rpms, do you have a 68 or 70 jet to try? You need a hand full of jets and they always leak air.
streetcruiserzdc
New Member
Im having the same issue with my bike. Ive tried the 62 the 65 the 68 jets. The 68 jet made it 4 stroke at full throttle...the 65 made it run ok but with a slight four stroking at full throttle and the 62 made it run good but the engine was reallllly hot. I have the hp head, hp carb ,bbr f2 thruster pipe and she still wont run as good as it should be. Im going back to the HT carb they make your bike run better once properly jetted.
That is the jet you want then, it is also desirable to have slight four stroking at WOT, it helps in the extra cooling and lubrication that is necessary during those short durations of time at WOT.
Wyvern
Well-Known Member
The way I see it is basically the 2 stroke "governor."
robe
Well-Known Member
Yes. The worst is it runs better and better the higher you go. What people don't realize is it is getting leaner and leaner. Ideally as you say it gets richer on the top end saving the motor from over heating from a lean condition.
