Still Not Running Right.

[Ryan]

Well I recently did the cam mod on my YFZ450. And for the note- I have a FMF jet kit in it... My pilot is a 48, and the main is a 65. Which I am running the biggest jets in the jet kit, that came with a different needle. My elevation is at about 500ft above sea level.

I checked my plug when I first did the mod... The plug looked a little white, so I toke the 150 main out and put the next size up in it (165). It seems to run real good now... But I noticed a big loss in the low end from about 2,000 rpm to 4,000 rpm. And it doesn't seem to start as fast. It was about 65 degree's out, and I still had to use the choke to start it. Im wondering if I should try adjusting the needle to make it a little richer? I haven't spun the carb to mess around with the air/fuel screw, yet.

I've been real confused with this jet kit and can't figure out how to get it to run a little better. It seemed to loose alot of torque after I did this mod. Any input is well apreciated!

Thank You.

[Ride1Rob]

I keep posting this over and over again... THE CAM MOD IS FOR MORE MID AND TOP END POWER. YOU LOOSE BOTTOM WHEN YOU DO THIS!!!

[Ryan]

I understood that when I did the mod... But it seems that its in the carburator... I lost alot of torque down low. I expected to loose a little, but not constantly be downshifting in the loose corners.

Could my needle possibly be a little lean and causing this?

[Ride1Rob]

Running rich can rob hp also. Check your spark plug color. Run the bike at idle then shut it off and check it (Pilot jet), hold the throttle to mid throttle for about 10 secs and shut it off intsantly and check it (Needle position), then hold it WOT (preferably while riding it) and shut it off and cost to a stop (Main jet). Your plug reading should be a nice tan/brown looking color for the best performance on each check. It is time consuming but the best way to make sure your bike is dialed in CORRECTLY all throughout the powerband. Adjust your jets according to what your plug is telling you ;) .

[Ryan]

Yeah, im gonna try that... Sounds like the best way to fine tune it. Definitly a PITA though. I haven't done anything with it lately... Been in so much pain with the sciatic nerve in my leg I haven't been near the quad.

Thanks for the info :cool: