Hot Start Issues - 2004 wr450

Hey guys,

lately I have been having an issue with the hot start on my 2004 WR450f. it just started happening, as far as i'm aware, all at once with no changes made by me to the carb. first time was on the line of a hare scramble, dead engine start - all of the sudden my bike didn't fire first kick (when warm using the hot start) like usual...

Bascially, it doesn't work - when i push the hot start lever (even when running, warmed up) instead of revving the engine like it always has in the past, it now just spits/sputters/dies/pops etc.

it was time for a good once over on the bike so i was hopeful i would cure the issue - but i have failed :banghead:

I cleaned the carb - total dissasemble and soak in yamalube carb dip, inspeced all rubber parts, reassembled as it was. The bike runs great - starts easy when cold using choke - starts easy with no choke or hot start when coolant is ~100 deg F - has a great snap to it, doesn't pop

checked valve clearance - in spec

new spark plug - old looked fine (maybe a little rich, some carbon deposits)

the bike runs perfect - just the hot start sucks now. this is a major issue for harescramble starts (dead engine) so i've got to figure it out. any ideas??? :ride: :ride: :ride:

Are you saying that when you pull the hotstart lever and open the passageway, instead of the engine rev's increasing, the bike spit/sputters/dies/pops?

Are you saying that when you pull the hotstart lever and open the passageway, instead of the engine rev's increasing, the bike spit/sputters/dies/pops?

that is exactly what happens - which has me dumb founded. the passage way is clean, the only thing i can think of is that the weather has cooled off and i'm jetted lean now???

for reference - i have the following on the carb as far as jets

stock pilot jet (42? or maybe it's 45? not sure) - gytr thumb adjustable throttle screw 1-3/4 out

165 main jet

JD red needle in the 4th clip (right in the middle)

Have you adjusted the fuel screw? It changes the behavior of the hot start.

just to report back and update - perhaps help someone in the future...

it seems to have been a jetting issue, and fuel screw issue.

i went back to the jd recommended needle and main jet, also turned in the fuel (or air?) screw 1/4 turn.

during the summer (very hot) i had put in the lean needle (blue) from the jd kit as recommended in their instructions, and also dropped the main jet 2 sizes. well, it's winter now and cold - so went back up on the main and put the in the rich (red) needle and whala, all is well.

thanks guys

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