arceeguy
Active Member
The dynamat will reduce the clatter at idle, and the gear whine to a certain degree.
The danger is in the possibility that the engine is "leaning out" at high revs/load.
I have found that the "80cc" (66cc) models tend to run a bit rich at idle/mid range, but lean out as RPM's go up.
To check idle mixture, warm up the engine and shut off the fuel valve. As the fuel bowl runs dry, the engine RPM should rise slightly before the engine stalls. If the engine RPM's rise quite a bit before the engine stalls, you need to lower the jet needle by raising the c-clip a notch and re-testing.
To get rid of the "lean bog" at high RPM, I use a .80mm miniature drill in a pin vise to open up the main jet. Some people here have reported that their carbs are jetted too rich, so be sure that yours leaning out at top RPM. If your engine has more power at a lower setting than WOT, it is too lean. Continued operation will eventually kill the engine.
The problem with the rich low end is that it can fool you into thinking the mixture is rich enough because the plug might be wet with oil.
I've read that the problem lies in the fact that many factories use the exact same carb regardless of engine displacement, and the carb is designed for 50cc engines.
To add to fetor56's suggestion, replace the acorn nuts with standard hex nuts with washer and lockwasher, and torque to 12 lb/ft in several stages. (in an X pattern)
The danger is in the possibility that the engine is "leaning out" at high revs/load.
I have found that the "80cc" (66cc) models tend to run a bit rich at idle/mid range, but lean out as RPM's go up.
To check idle mixture, warm up the engine and shut off the fuel valve. As the fuel bowl runs dry, the engine RPM should rise slightly before the engine stalls. If the engine RPM's rise quite a bit before the engine stalls, you need to lower the jet needle by raising the c-clip a notch and re-testing.
To get rid of the "lean bog" at high RPM, I use a .80mm miniature drill in a pin vise to open up the main jet. Some people here have reported that their carbs are jetted too rich, so be sure that yours leaning out at top RPM. If your engine has more power at a lower setting than WOT, it is too lean. Continued operation will eventually kill the engine.
The problem with the rich low end is that it can fool you into thinking the mixture is rich enough because the plug might be wet with oil.
I've read that the problem lies in the fact that many factories use the exact same carb regardless of engine displacement, and the carb is designed for 50cc engines.
To add to fetor56's suggestion, replace the acorn nuts with standard hex nuts with washer and lockwasher, and torque to 12 lb/ft in several stages. (in an X pattern)
