Low end bog, could it be the cam or jetting?

4 replies to this topic
  • TimFurryBalls

Posted June 24, 2004 - 04:54 PM


Okay, I just finished installing my 450 cam. The bike rips in the mid range to top end. No knocking, or strange noises. Kicks over first kick when hot. BUT, I noticed this horrendous bog from about 1/4 throttle on up. I started off with stock main, needle clip one up from stock, with a 40 pilot. Played with the AC pump, BK mod screw, fuel screw, idle, etc. Bog went away somewhat, but out of tight turns and up big jump faces, I wasn't too confident with the response. When cruising in 2nd gear at 1/8 throttle, I peg it and it goes "BO-Waah". When it kicks into the midrange it hauls. So, after all of this, I went to a 45 pilot, readjusted the AC pump to spec, timed the BK mod to spec, and put the clip back to stock position. Took it up the road, "Bo-Waah", back to square one, just as bad as when I first started. Could my cam timing have something to do with this, cause I'm stumped! I'd like to really ring her out, but I'm not too confident on the big stuff right now. Please help!

  • sirthumpalot

Posted June 25, 2004 - 01:03 AM


Check your cam timing. My buddy installed the 450 cam in his 400 and was off by one tooth on the cam sprocket and he said it killed his low end power, to the point he had to clutch it out of turns. Found the problem, fixed the timing and said it was a whole new bike. Worth checking!

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  • TimFurryBalls

Posted June 25, 2004 - 12:26 PM


I double checked my cam timing and I think the intake cam was off by one tooth. Re-set it, double checked my jetting, and on the road it seems like the bog has been greatly reduced. Still has a slight hesitation, but I think that's as clean as a 426 can get! Will ride it and see at the track tomorrow.

  • wrenchard01

Posted June 25, 2004 - 06:49 PM


Keep reading, their talkin bout this all the time in the jetting forum. There's all kinda carb mods people are doing to fix this, just got my 426, haven't worked it out yet, bogs pretty good and aparently common for this bike.jettings prob. you're big issue though. Good luck!

  • wrenchard01

Posted June 25, 2004 - 06:57 PM


Sorry, didnt read youre last post, missed it, I'm tired. glad you found it, but heres some friendly advice, if you ever do a timing chain or belt you're supposed to turn the engine over twice to line up youre marks again (valve train is aways half of engine speed) if you do this you'll never put one together wrong, this can be dangerous. Have fun.

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