Help Please: Bike bogging when throttled up

[doubld250]

I have a nearly new 09 WR450F with 3 rides on it, it has a powerbomb and a power core TI. It has set up for a few months, gas smells fine it starts and idles fine but when I twist the throttle it bogs And will not run, if I leave the choke on it's a little better but still it will not rev up much. Any suggestions?

[FORMA MOTO]

I have a nearly new 09 WR450F with 3 rides on it, it has a powerbomb and a power core TI. It has set up for a few months, gas smells fine it starts and idles fine but when I twist the throttle it bogs And will not run, if I leave the choke on it's a little better but still it will not rev up much. Any suggestions?

Sounds like a clogged acclerator pump nozzle or mainjet.

If a slow roll-on throttle is fine, but a quick whack gives you a bog that you never had before, you either have a rotted accelerator pump diaphram, or you have a clogged accelerator pump nozzle.

If any attempt and turning the throttle gives you a bog, you have a fuel delivery problem. Start with the tank vent, then the tank fuel line, then the carb inlet, then the mainjet.

[GuyGraham]

I agree

if all else fails, take carb off bike and hang it at the side of the bike

look down the venturi and confirm you get a squirt of fuel

it should be approx 1 sec duration on a full throttle opening, and should not hit the slide

Use a digital camera to film it to confirm

you want the squirt to just miss the slide as it lifts

[doubld250]

Thanks for the advice gents, I'll check those things and hopefully get her up and running soon.

[FORMA MOTO]

Thanks for the advice gents, I'll check those things and hopefully get her up and running soon.

You don't need to remove the carb. Just lift the subframe and watch it 'squirt'.

[GuyGraham]

You don't need to remove the carb. Just lift the subframe and watch it 'squirt'.

removing it stops it flooding the engine plus you get better film clip from a digital camera due to the venturi being lit by daylight rather than being in darkness due to still being fitted to engine

takes a few goes to get a good film clip

yes, if just to confirm it working then no need to remove

[YamaLink]

Fingers crossed it is the simple main jet. While you're in there make sure the pilot isn't clogged.