cuttin out

[modock84]

i have a drr 90 stock cylinder (exhaust port has been worked on) 24mm carb-hetrick pipe-v-force reeds-koso intake-----problem im having is i can rev it up 1/2 throttle even 3/4 throttle and it runs like a champ but the second i give it full throttle it cuts out, backfires, even shoots a flame out the exhaust pipe ------------ any ideas ---does it with my son riding it or on the stand free reving it

thanks

[Coley'sdad#8]

Don't run until you find the problem.
Backfiring is classic of ignition problem, check all of your grounds, make sure you have good ground from frame to engine, wire shorting ect, kill switch. Backfiring and cutting out are 2 different things, if you continue to run it like it is you WILL bust your reeds and maybe reed block and blow crank seals. The description of shooting flame out is definately ignition, good description on your part. do you still have the entire wiring harness on it or has it been shelled out?????

[modock84]

no i dont have all the wiring harness --just have what we need.
thanks for the help

[DAVYS DAD]

check the coil,my 50 was doing the same thing changed the coil and the problem was gone.hope you get it fixed.

later
DW

[Ryki3r]

Does this still have the stock ignition?

[modock84]

Ya its stock

[Ryki3r]

Check the mounting of your stator.was The exhaust port work done before any of the backfiring issues? Your exhaust timing might be off a little? Just something to look at.

[modock84]

not the exhaust timing it ran to good before

[bulldogfallon]

Have you tried a leak down test?

If all you have changed is the cylinder then you may developed a leak or require different jetting.

I also go back to the basics.....leak down and comp tests on all new patients :)

Does it happen at a certain rpm (independent of throttle position) or is directed link to throttle position?