Aug 11, 2021
07 crf150r

bike will only run on choke. this started as a rare thing that just happened some days and didn’t happen sometimes. one day it would barely start and wouldn’t do anything off of choke but sputter pop and die, some days it went right off choke after first kick and ran perfect all day.
it has gotten worse, now the bike won’t run off choke.

it runs if you feather the throttle but eventually bogs down and dies. it WONT start OFF choke. it only starts on choke and runs 100x better on choke.

the jets aren’t clogged, they’re brand new. and have already been cleaned.

new spark plug, new air filter, new 45 pilot jet, i set the needle to the very bottom (it was previously only 1 above the very bottom) i adjusted the hot start, cleaned the carb multipleeee times. i bought the bike with an already recently rebuilt carb. i changed the throttle out, checked the valves, put new clamps on the intake manifold and airbox manifold

off choke, the bike pops really freaking loud, bogs down, won’t idle. on choke, the bike bikes not bad at all. it revs out and doesn’t bog. it idles super super high tho.

and if i’m not mistaken, this only started the day i put standard 87 in the bike (straight from the pump) i rode the bike to the gas station then 2 hours after filling the tank boom this all started happening. i just don’t think that should be correlated at all??


Damn Yankees
Nov 21, 2000
North East USA
When ever a bike runs better with he coke on it's because there is a lean condition that can be caused by several things. It sounds like you hit the obvious stuff (carb jets, boot clamps, etc). When you said it's been getting progressively worse I think about stuff the wears out. You said you checked the valves but did you do a leak down test to make sure they are sealing properly? Adjusting the clearance is one thing but if the seats wear they can leak and cause problems. The bike is 4 years old and not knowing the history, I'd say a valve job is in order.

You mentioned 87 octane gas. The compression on those bikes require at least 91 octane or they will detonate and ping. One tank of gas my not have cause the problem but over time all of the detonation can cause some serious problems from holes in the piston to valve damage.

Once you figure out the problem you may want to rejet the carb. It sounds like you were chasing the issue with jetting so make sure it gets put back to where it once ran good.

Carl jr

Aug 22, 2022
I have a brand new 2022 crf150 rb expert changed main jet from 40 to a 45 out o ring on and still boggs I think I'm going to change the pilot jet to a 42 I pray that does it getting very tired of this brand new bike
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