CRF's Only Forums

I (my son) have a 2009 CRF50 that is stock except for the air filter. The thing runs fine except it bogs real bad when the throttle is open real fast. Any ideas where to go with this? The air mixture screw is capped. I am going to remove the carb and clean it as well as remove the tamper proof cover for the air screw. I have read some about rejetting after filter and pipe mods. I only have a different filter.

As long as the carb is clean, I would start looking for a vacuum leak, carb boot etc. 17-30?

i have the same prob on my kids 04 crf50. took off the stock airbox, put on a uni filter, now a bog rite off idle unless i roll it on real slow. then when up in rpm its fine. there is no pilot jet(its a slow jet circuit). so how do i fix the low end(from idle) bog??!! anybody have the fix for us??!!

i removed the end cap spark arrestor on the silencer to make sure it was not all clogged up. it was fine. i oiled the uni filter with foam filter oil. i adjusted the air screw to 1 full turn out, idle screw to 2 3/4 turns out. no more hesitation or bog when you snap open the throttle from idle. i ordered a ordered a 62 main jet that i will install next week when it comes in. the stock main jet is a 58. i know that when you add more air(removed stock restrictive air box and installed a uni filter foam element), you must add more fuel. she runs awesome now but might be a tad bit on the lean side, so i will do a plug chop test with a new spark plug to verify for proper air/fuel mixture. if 62 is too rich i will order a 60.