06 yzf 450 vs 06 crf dyno graphs.

does it seem worse when it get hot?

yes when the bike is warmed up and running. although it is freezing outside

its only when I roll the throttle on slow and steady. right after I reach 1/4 throttle it hessitates, kinda like skips, then with the throttle rolling on more it goes past and continues all the way up fine. This is first, second and third gear roll ons.

has the throttle been fully opened at that point.

when it starts to hesitate and skip, I am holding the throttle right at 1/4. if I roll it more it goes past it, but if I roll the throttle from all the way closed to full open slowly it will hesitate when I get to 1/4 throttle, if I hold the throttle there it will keep doing it, if I roll the throttle on more it goes away. when I twist the throttle really quickly, it goes past it with the tiniest skip. If I just pin the throttle I haven't noticed it yet, just spins the tire and hits the rev limiter.

try one more needle clip.if that doesnt fix it you will need to go to a needle with a richer straight diameter.

must be pretty cold out?

yeah it was 12 degrees this morning, about 30 right now. thats pretty much how its been while i've been testing

48 pilot, 170 main, stock needle, clip in 6th, 2 turns a.s. 25 degrees when I rode, no issues what so ever, ran absolutely perfect, cold I have to use the hot start, choke, 4 pumps of throttle to start it up, once warm it starts first kick by itself, also became locked up once when it was cold, had to put it in gear and roll the wheel backwards to free it up, I couldnt even move the kick starter!

also became locked up once when it was cold, had to put it in gear and roll the wheel backwards to free it up, I couldnt even move the kick starter!
:applause::bonk::cry:

thats not good........

48 pilot, 170 main, stock needle, clip in 6th, 2 turns a.s. 25 degrees when I rode, no issues what so ever, ran absolutely perfect, cold I have to use the hot start, choke, 4 pumps of throttle to start it up, once warm it starts first kick by itself, also became locked up once when it was cold, had to put it in gear and roll the wheel backwards to free it up, I couldnt even move the kick starter!

Once and a while my 04 and 05 would do that it is like the compression release does not work, its not locked up you just cant push the kick starter down because of too much cylinder pressure.

Once and a while my 04 and 05 would do that it is like the compression release does not work, its not locked up you just cant push the kick starter down because of too much cylinder pressure.
I get that now and then; it's normal. It can sometimes happen if the engine is stalled suddenly just as it hits the compression stroke and while the decompression flyweight is in the outward, or "normal" postion. The flyweight return spring can hold the decomp mechanism out well enough to lift the valve as the cam rotates past it, but isn't nearly strong enough to actually lift the valve all by itself. So, if it happens to stop in that particular postion, you can either stand on it and wait for the compression to leak through, or put it in gear and back it down from compression so the decomp can operate normally again.

Ive got to say what ace and informative thread, and Ive just sat and read all 8 pages.

The problem i have with my 426 is it pops on decel and Ive been told that theres a flame from the end can. As far has i can work out there's no leaks in the exhaust system, any help would greatfull has this driving me nuts.

I would say you need to either adjust the air screw out, or go to a richer pilot jet. What size pilot jet do you currently have? How cold is it?

Hey Burned,

Dude,i gotta tell you. You really know your stuff. I just bought an 05 450 and am learning the way of the 4stroke ( just sold 98 KX250). Its a whole new world. I have been taking notes on your insight of jetting- although I don't really have any probs at this moment.

Neways, I was noticing my 450 is a little boggy around the corners in 2nd gear ( i find myself trying to go to 1st, and then thats too low) so i was thinking about going to a taller rear sprocket. Was just talking to a local shop and he told me to advance the cam and it would add all kinds of TQ so I could stay w/ stock gears. Any of this sound right?

Any advice for jetting in Missouri (stock motor)?

I would say you need to either adjust the air screw out, or go to a richer pilot jet. What size pilot jet do you currently have? How cold is it?

The carb is stock and its running the standard pilot jet and the UK temps in the last few weeks have been freezing or near freezing. but the strange thing is the bike runs OK with no boggyness, and its a piece of cake to start.

The carb is stock and its running the standard pilot jet and the UK temps in the last few weeks have been freezing or near freezing. but the strange thing is the bike runs OK with no boggyness, and its a piece of cake to start.

That confirms my belief the European models are richer jetted than the U.S. bikes.

I have never owned a four stroke before, and have read about a couple of jetting problems that people have had. I think my jetting may be off a bit and wondered if someone could point me in the right direction. The bike has a bit of a bog just off idle and when decelerating pops and crackles from the exhaust. I live and ride at 2500ft - 4000ft, (starting elevation to top of the ride and back) in the high desert of cali. the bike is totally stock any suggestions about what the jetting should be?

Burned, is the man. Rejetted my bike to 48/170, fuel screw 2 turns out, temp is mid 40s, bike starts easier, no bogs or popping on decel.

The carb is stock and its running the standard pilot jet and the UK temps in the last few weeks have been freezing or near freezing. but the strange thing is the bike runs OK with no boggyness, and its a piece of cake to start..

That confirms my belief the European models are richer jetted than the U.S. bikes.

I'm in South Australia, 44m above sea level and my 06 is waaaaay too lean. I only just got it last Saturday, so I jumped on TT to see what the go is on jetting. I'll sort it out this week.

ThumperMx365 posted this link to Pro circuit's jetting specs.http://www.procircuit.com/PCJETTING.htm They say 50 pilot, 170 main, needle NFPR in fifth position, fuel screw 2.5, and leak jet 50. Pretty similar to Burned's specs.

I'm in South Australia, 44m above sea level and my 06 is waaaaay too lean. I only just got it last Saturday, so I jumped on TT to see what the go is on jetting. I'll sort it out this week.

ThumperMx365 posted this link to Pro circuit's jetting specs.http://www.procircuit.com/PCJETTING.htm They say 50 pilot, 170 main, needle NFPR in fifth position, fuel screw 2.5, and leak jet 50. Pretty similar to Burned's specs.

Ben, the bikes are jetted similar all over, also here in Europe, too lean. My bike runs perfect with 48/170/5th clip std. needle/FS 2 turns out at sea level.

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