Interesting jetting problem

[CJM]

Ya know this ones bothering me and before I yank everything apart and play with the jets I figured Id see what you guys thought.

Plug looks great, nice and tan. So we know jetting is good

It seems to rev up to the limiter WAY to quickly if anything. Like I can barely get outta 1st and 2nd especially b/c it wants to hit the limiter so quick. Feels like it I need to shift at like 1/2 to 3/4 throttle and cant fully rev out.

Im thinking I should go to the 3rd notch on the needle from the 4th and possibly drop the main slightly as its too rich in the middle of the throttle range. I had a 165 in there instead of the 168 and it was too lean before (was a bit colder tho). The EX carb I was running a 170-172.

[2001400exrida]

Is this the 400ex carb or the 450 carb? What changes have you made? You of all people should we need details to help ya :) False rev limiter almost always means you're rich.

[CJM]

450 carb of course.

Funny thing is it didnt seem rich to me b/c the plugs good. IDK

I mostly didnt want to yank everything apart (yea Im lazy) without seeking a bit of advice.

I spose I could drop to a 165 again and see...

[jman7290]

I had that issue so I changed my sprocket sizes, now it runs like a beast!

[JOHNDOE83]

If anything i would say your jetting is fine if it seems to rev out so good.

I know with 21in paddles at the dirt track I always start in 2nd sometimes 3rd depending on my sproket choice and i revved out quick in all the gears, 1st and 2nd in the EX seem way to short even in a stock EX to me.

Maybe change the sprokets up before you jett it again?

With your motor and tire choice I would try a 16t....:D

[2001400exrida]

did you guys read his post? he said it feels like it needs to shift at 1/2 throttle and CAN'T fully rev out.

i really think it's jetting, it sounds like the typical false rev limiter.

If it's actually winding out the rpm's that fast you should see if you slipped a tooth on the timing.

[JOHNDOE83]

Originally posted by 2001400exrida
did you guys read his post? he said it feels like it needs to shift at 1/2 throttle and CAN'T fully rev out.


Yes I read it, thats why I brought up drag racing and changed the subject to sprokets.....:blah:

J/K

But seriously, I think if it were as easy as jetting placement CJM would have fixed it by now or be 100% positive its jetting related.

Did you read it....:chinese:

J/k

It is possible that with slight weather differences the needle could be slightly rich this month, 450r carbs in my experience are very touchy to the weather.

[CJM]

It was the needle. Its been SUPER hot, like 90F + and 100% humidity. Original setup with 168 main and 4th notch was setup for more around 70F. I aint been riding much lately.

I put it on the 3rd notch and voila no more issues. I kinda figured that was it,. But I always like to confer with others, you never know.


Its a moot point now, a decent 04 450r followed me home today for a good price. It needs TLC but its all there, unlike many others Ive seen. Still keeping the EX but this is my new toy.

[2001400exrida]

glad you got it fixed. your 4th setting on the needle must have been right on the border line of too rich and the hot weather was just enough to make it affect the jetting.

I knew it was your jetting ;)

[CJM]

Originally posted by 2001400exrida
glad you got it fixed. your 4th setting on the needle must have been right on the border line of too rich and the hot weather was just enough to make it affect the jetting.

I knew it was your jetting ;)

I figured as much myself, but sometimes hey ya never know. 450r carbs a bit more finicky.