hard starting (hot)

[riderssb250x]

alright just got my topend all done and broken in and i got the 450r carb it seems like when the bikes hot its harder to start like you gota keep crankin it and it starts a second then shuts off and ill start it again and itl start?

pilot jet maybe?
valve adjustment ?

someone help

[riderssb250x]

im also runin the 450r carb
55 pilot
180 main
4th clip from the top on the needle


should i go up a size on the pilot..?

it backfires a bit wehen decellarating still which makes me think it needs a bigger pilot but a 55 already seems a bit big

[riderssb250x]

also I noticed if I rev it up high itl shoot flames out for a sec from the exhaust? could this somehow be to small of a main since im runnin just a straight k&n no box maybe 180 is to small and that's affecting the decel cause it runs pretty good idling and in low gear

[bbender85]

whats the rest of your build look like?

i'm running a 195 main on my 426 in an open box, and it's about right... i would think you'd need to fatten yours up with no box at all.

[riderssb250x]

well before I list the mods I got a question, if im to lean on the main it will pop on decel right? I thought it was just the pilot that affected the poping? also will the lean maine make it backfire flames when I rev it up really high and let off? cause my idle is real nice almost perfect with the 55 so im pretty sure iv got the pilot and needle dialed in im just worries about the flamse plus the decel backfiring,


mods,
-wiseco 11:1 89 mm piston (440)
-stage 3 hotcams
+lrd pro4 full exhaust with ceramic coated headers
-k&n filter no airbox
-450r carb
-ported and polished head
-stock valves and srings
-valves correctly adjusted
-crf450 timing chain and stock 400ex tensioner

that's all I can think of but I think I needa bump the main to like a 210 215 since im runnin no box

[ae13291]

might be your needle, and main. you are probably running too rich. i usually do my jetting test with a airbox lid and open airbox lid, i would rev it up and feel the differance both ways, and if i like the rev better with the airbox lid on then that means im running too lean. if u still have your stock lid, test it like that

[honda400ex2003]

if it is popping on decel. it could be your f/a screw too. that may also make it hard to start since it is starving for gas until you start to crank it for a while. just my .02 though, steve

[Gibson]

popping and backfiring on decel is because your pilot jet is too small, that would also cause it to be hard to start. Your carburetor uses the pilot jet to start the motor and let it idle. if it doesn't get enough fuel, it will be hard to start and will run hot.

Do you know how many turns your Air/fuel is turned?
If it's already 2 - 2 1/2 turns out, go up one or two sizes on the pilot jet, that should cure your problem.

sorry if that was too wordy:p

[honda400ex2003]

i would say that up to 3 turns out on the f.a would be ok to diagnose and see how it runs. if it is better at 3 turns out then go to a bigger pilot and go back down to 2 or so if need be. I have ran 3.5 turns before with no problems. just my .02 though. steve

[riderssb250x]

alright ill try that I have the 450r carb so I needa plug the hotstart food and start jeting all overi think tahts got a lot to do with it then ill probably try a 190 main 52 pilot and 3rd clip and 2 . 5 turns out I think that should be a good starting

[Gibson]

i wouldn't go smaller on the pilot jet, that's the reason it won't start. Keep the 55 pilot jet in and play around with the A/F screw. But the 190 main sounds about right