Any one noticed a rich spot at 1/4 throttle?Im running the dirt bike needle 45 pilot 168main cam mod,no lid,sparks pipe.The rich spot is only noticable trail riding at a steady speed on a long straight away.If im on and off the gas like motocross it runs perfect(zero hesitations or flat spots).Hold it at 1/4 throttle and It will start missing and popping then if I hold it wide open and it will usually clear up.I rode it around my house at 1/4 throttle and did a plug check and its pure black(base,porclien,ground strap all black and sooty)I was running the bike needle in the fourth position.

I had put the stock needle back in for awhile on the 5th position from top and had no problems with trail riding but its lean off the very bottom and in the midrange and the bike needle has better throttle response.I wonder if the bike runs a leaner slide cutaway than the yfz does?

I measured the two needles and the bike needle is richer than the quad needle every where ,a little richer off the bottom and way richer in midrange.You can not adjust the stock needle to be as rich as the bike needle is in the midrange and up top.

IM thinking about trying the james dean jet kit but it makes no sense to me that I cant run the same needle thats in the yzf dirt bike

 

try running the bike needle on the 4th clip down.use the 42 pilot with 2 1/2 out on the fuel scrw and a 165 main.
according to our dyno that is spot on jetting.

 

Jammer, killerkx was at monkey butt in janesville, WI. But I think he had to step out of line because he was suffering the "elec. start didn't want to keep working" syndrome that many yfz's with the cam mod or incorrectly wired tethers were experiencing. You sure do get defensive when a yamaha rider claims they beat a predator. The nicholas cycle bike is fast, and those that have seen it know it. But many predators out there are stock or just have the pipe, those are the ones that are getting smoked.

 

I was having the same problem with my raptor. I tried every needle postion and it never cleared it up. The problem ended up being the float level. Sixsixt has a post on how to check your float level. You might want to check it before you drive yourself crazy like I did.

 

Thanks for the replies,I had the float bowl off and it seemed ok(floats level) but the hose method seems like a better way to check it.

 

With the problem you describe are you in the 3rd or 4th from the top position on the YZ needle?

I have the GYTR carbon and header with GYTR dual stage foam filter, lid off and am running 4th position with 65 main, 45 pilot and 2 /12 turns on fuel mix screw... I have some signs of richness also in 1/2 throttle range and have been told that running the YZ needle in the 3rd from top and going to a larger main cures the problem.. like a 168, 170 or 175 main and run 3rd clip position..

 

mnrap I was in the 4th position on the yz needle I moved it to the second from top and it was too lean off the bottom and I was heading for the UP for a trail ride and threw the stock needle in to be sure I wasnt going to foul any plugs.

I recently put the yz needle back in on the third clip from top but havent had a chance to try it out(lots of rain lately).

Im currently running a 168 main and plan on going up.My buddy has a yfz also set up like mine but no aftermarket pipe yet.Once he gets a pipe and can keep up with me im going to keep raising the main and see what makes the most power.