06CRF450R Hard Start and carb backfire
  • 06hondacrf450r
    Posts: 1
    Joined: Mon Jun 10, 2019 1:47 pm

    06CRF450R Hard Start and carb backfire

    by 06hondacrf450r » Mon Jun 10, 2019 2:12 pm

    Hi all,
    New here because clearly you only get half-serious answers on Facebook. Hoping to get some insight from ACTUAL 450r owners.

    I have an 06450r that was a frame up restore in 2017-2018, basically everything down to the cases were bought brand new - its got about 10 hours on it, (7 by previous owner, less than 3 by me) assuming the previous owner was genuine, but who knows. Has a 14.0:1 JE Piston in it, 3 mil stroker crank, was ported and polished. bought the bike 3 months ago, started first or 2nd kick right from the day I bought it. took it for a light 2 hour ride that week, and over the next two months, I'd start it a few times a week for a few minutes. well, I didn't start it for over a week and then it took a bunch of kicks to get it started, but ran fine.

    Then I blew out my knee, so I was looking to sell it. had a friend and his "track mechanic" come by bc he was interested in it. well, I got it started for him, took it for a quick ride, and although it rode fine, the "mechanic" said the bike could be "dialed in" better, mainly because if its tuned "right", you should be able to pull the hot start in and the rpms should go up momentarily...well, mine was cutting out... so he made some "adjustments" to the carb, got it to where the rpms would go up briefly with the hotstart.

    They leave, I have another guy come to potentially buy it the next day, and the bike never started again. I've spent the last 3 weeks trying to fix this thing when I have time... I've tried getting the carb back to where I think stock settings were, no good. clean the jets, no good. then I noticed that at the base of the coil,spark jumped from there to the head, so there was clearly a break in the coil.. I buy a brand new OEM coil and plug, no good. I then buy a new stator bc I think the pulsar coil failed the ohm test, turns out I had the DMM set wrong and the coil was good. reinstalled that, then noticed the cdi had a small crack at the neck. I replaced the cdi with a known good one, as well as tested ALL of the harness and harness was good.. still NO START. I decided to dribble a little fuel into the spark plug hole, then quickly hooked the tank and fuel line back up..
    I FINALLY got it to start! it ran until I hit the kill switch. went to go start it a little later, NO START....did another small dribble of fuel into the spark plug hole, and started RIGHT back up, I took it for a ride, bike ran GREAT.

    Got home, shut it off.... tried starting it again, NO START.

    later on last night, I wanted to see if taking the filter out, making it less restrictive would make any difference. All I got was an ear-piercing backfire through the carb, but no start.

    So, conclusion is, bike will start and run fine off of its own fuel supply if I put gas in the plug hole.

    Did backfire thru the carb.

    I know people say if the bike can BUMP START but not kick start, it could be the valves. but what if it starts with fuel in the plug hole, but not on its own, is that a valve symptom as well?

    If the bike truly only has 10 hours on it, i'm not sure the valves would be an issue. I will be checking them tonight or tomorrow.

    Anyone have any thoughts?
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