Rebirth is complete! After riding the mighty LC4 only once last year and putting it away disgusted due to how awful it ran with the Quicksilver carb, it is now all the bike it can be! Donât ask me how I put up with that carb all this time. Winter mods included selling off the Big Gun system (too loud!), reinstalling stock headpipe and a new SXC muffler (less sound = more ground), mainshaft bearing swap, valve adjust, starter clutch replacement and a Mikuni TM40-6 carb. I got the carb from Carburetor Parts Warehouse and they set it up with jetting similar to the Flanny guide and what most TM40 users have. So the big moment comes to start it and it is just idling super crappy, the mixture screw is doing nothing and the idle is hanging up. Blip the throttle and it just stays there. I changed the 17.5 pilot to a 20 but that didnât help. So I decided that since I donât have much jetting experience and an event I want to ride at the end of May Iâd let the pros figure it out. Off to the dyno I go. To get the idle right we ended up drilling the pilot to about a 30 then we strapped it to the dyno and it made 40.4 hp and 35.0 ft.-lbs. torque but the air/fuel ratio was off the chart rich. That was with a 160 main, ended up with a 145 main and the needle in the second clip from the top. That netted 47.7 hp and 40.8 ft.-lbs. torque with the air/fuel ratio in the correct area. The bike is transformed. Smoother running and better power plus easier starting. What I paid the dyno shop I gained in less frustration, time to sus the bike before the 4 State and knowledge that the jetting is right. Only thing left to do is RIDE IT! I wonder why my final jetting specs differ so much from others with a TM40? Oh yeah, I have the dyno charts if anyone is interested but I donât have a way to post them.