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View Full Version : TGB R9 151cc gy6-B stuck at 40mph 🧐 please help.


HelplessinMinnesota
06-02-2021, 01:24 AM
First day here,I looked around the posts, but it's pretty overwhelming.



So I bought a used TGB laser R9 with 6k miles on it. Guy hasn't used it since 2010, cleaned the carb and it fires up on the 3rd kick (no battery currently in it) It runs perfectly but wouldn't go over 35-ish mph (gps). So I took apart the CVT and pulled the rollers they had flat spots. I replaced the variator and rollers, also replaced the belt as it appeared worn. I purchased the wrong roller weights, I didn't weigh the originals ��. With 13 gram rollers the bike would do 40 mph even, but wouldn't go over 5500 RPMS . Today I finally got around to checking the original rollers. They came in at 11.34 grams. I figured they were 11.5's and lost some material from the flat spots. I'm getting closer with 11.5 gram rollers running 6400 rpms now, but still can't go over 40 mph! I replaced the CDI box with one of the no REV ones and still the same thing. I put 3 of the 13 gram rollers in the variator for a test, it rev's to almost 8k rpms but only goes 25-30 mph. So it's getting enough fuel and air to hit the rpms... I also adjusted the valves, they were a little tight.. The belt is not using the last inch or so of the front pulley. I'm at a loss now, I just want it to go 50-55, nothing crazy, just stock speed. I'm 160 lbs, tires pressure is good, adjusted the air fuel mixture . Thing runs absolutely perfectly ��. I'm about to just do a top end rebuild on the thing.

HelplessinMinnesota
06-02-2021, 09:12 AM
Is it possible that the CDI isn't producing enough spark since I'm running without a battery, keeping the machine limited to 40mph �� .

Snailspace
06-03-2021, 01:58 AM
Does it seem to "brake" when going downhill?