cr500 tuning help

[coolcatmat11]

ok, im pretty new to two stroke tuning, so im going to ask for some help to diagnose my engine problems, ill list everything in as much detail as possible.
I may use some un-tecnical terms but ill try my best to make it easy..

the problem is when you try to rev to wide open the engine seems to stop at a certain rpm and do a constant sputter. maybe just a bit more then 3/4 throttle. the enigne has no other problems reving up to that rpm and is very powerful and responsive(power band comins in alittle before half throttle) , as of right now im guessing I need bigger jets, becuase it sounds like its is leaning out when W.O. but I have done quite a few mods to the engine that could have hampered it other wise
this is for my trx500r

-its a 1984 cr500r air cooled,new head and base gasket, 32:1 mix, starts easily

-the exhuast was a PSI, but has been cut at many places and turned to fit
through frame, but lenght and shape i tryed to keep the same, maybe a total of
1/2" removed from the cuting it has maybe 2-3 pin sized holes i havent patched yet, trace amounts of smoke come out of one sometimes

-it has an answer silencer but about 3 1/2 " cut off the end, the area where the packing is,..... CAN you run it with any packing or back on silencer?? just wondering

-the intake, i had to cut a wedge out to make it straight instead of curved to the left, so its shorter then stock,

- the carb has all stock jets and is clean and has all new hoses

-the air breather assembly is one larger then stock tube( same size as carb opening all the way down), with a UNI(or k&N) filter with the sock thing on it, the tube is from a ford F-150 for (size reference).

-another thing i noticed was that on down rev it would sometimes let out a couple pops or small back fires type thing

hopefully somebody can help me, im going to try a couple things still and ill post if they make a differnce, thanks -Mat ,,,if you need any more info just ask

[RumbleB]

http://cr500riders.com/cgi/yabb/YaBB.pl?num=1173903663

Check that link. It should be helpful.