Bogging at WOT

I have a 2005 crf 70 with a big bore kit from tbolt usa and now its an 88cc. The kit came with everything including an air filter carburetor and extra jets and a race head that I installed the valves. I dont hear any valves knocking and i followed the instructions and installed them with a .002 gap so i dont think they are to tight.  


When in neutral if I hold the throttle wide open it spurts and then backfires and i can tell it wont rev to its limit. when in gear it rides nice until i hold it from about 50%-100% throttle then i can feel a lack of power and it bogs.

It has a #88 main jet and i went down to a#85 jet then #82 jet and up to a #92 jet cause i wasn't sure which way to go either bigger or smaller. The #92 jet felt the smoothest but it backfired once while riding so i thought it was to big a jet. If not i still have a #95 jet i believe. I messed with the air screw and its at the highest rpm. I havent touched the jet needle yet I'm not sure if I should.


Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Content

    • By Rixter
      A tiny clear rubber tube on bottom of carb.  On bottom sort of on side, by floats, the other end just hanging down.  Was it always like this? Or does the other end go somewhere?  Today after multiple trys with kick, choke on/off ,,,fuel keeps pouring out the tube.  This bike has always been hard to start.   Thanx  guys!
    • By Doukis1
      New spark plug, new air filter. Went for a ride and all was good. Hadn't run it in a week and a half. Now it won't start. Getting spark. The plug is dry. Is it possible I over oiled the filter and it has somehow gummed up the carb/ float? Thanks
    • By mbennett95
      My 01' yz125 seems to be requiring a large amount of throttle to get off the line. I've ridden plenty of properly jetted 125's and none required quite so much throttle work from a dead stop. Even slipping the clutch it wont get going without a pretty healthy amount of throttle. Thinking it just needs a clutch rebuild kit and maybe a basket. Any info appreciated!
      If it helps any here is what it has done.
      FMF Fatty, VForce 3 reeds, and an iridium plug.
    • By Sam W.
      Hey all, I just bought a street legal 2005 WR250F. Took it out once three weeks ago. Did about 60 miles on the dirt and 15 on the road, bike ran great. I took it out this past Sunday and was about 75 miles into my ride when the battery died. The battery is cheap, but it is brand new and was on a battery maintainer the whole time while it sat in the garage. I kick started it, and it fired right up. I was on the road for about 5-10 miles in fifth gear when I felt the bike slow down a little bit, and I noticed the sound coming from the bike sounded a bit deeper than usual. About a half mile later the bike started to bog down like it was out of gas. I filled the tank back up and experienced the same problem. The bike began to bog down, then puttered out like it was out of gas. Eventually the battery completely died and I was not even able to kick start it. I trailored it home, hooked it up to the maintainer, waited a couple hours, and the bike fired right up with the electric starter and the choke out. However, it was still puttering a lot when it was idling at this time. If anyone knows whats up, I would appreciate any and all help. Thank you. #Yamaha#wr250f 
    • By Ndh87
      I’ve got an old barn find ‘83 CR80R that needs either a new carb or a rebuild kit. I haven’t been able to find either anywhere. 
      Does anyone know where I can find either?
      housing, bowl and all the hard parts seem fine, if I can find a rebuild kit with a new float I think I’ll be ok. Right now it runs but only when I leave the choke on, smokes heavily and likes to bog down on takeoff