Gx340 engine idles at full throttle

[Brad_R]

Hi,
I was just wondering if anybody knows why my GX340 automatically tuns at full throttle? I know it's meant to start at full and then back down into idle but it starts on full and stays at full. The throttle linkages move all the way so there isn't any reason to not work to my knowledge and the springs etc are all working as they should. could it be something to do with the governor? I've never ran this engine before as it is for an upgrade on my kart so I'm concerned that I don't want to start it if it's going to overrev because I've heard stories of the flywheels shattering.

Thanks in advance for any help you may have.

-Brad

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[KartFab]

Video? Pictures?

http://youtu.be/IPsZp7b8sYk

 

[Brad_R]

I would film it but it's at my grandparents house and I was hoping for an answer for when u go there tomorrow

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[mckutzy]

Reduce the idle down.
Is the throttle lever on the motor itself, sticky?

 

[Brad_R]

No its not stuck or sticky and the throttle idle screw isn't high

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[KartFab]

Just going off of what you said (assuming the return spring linkages, and gas pedal are all set up correctly), you may need to see if the governor arm is firmly attached to the governor shaft. I would go with the obvious stuff first. Return spring, idle screw, linkages and springs in the proper place, throttle cable not interfering with throttle arm, throttle cable has return mechanism at gas pedal or on a rod connected to the gas pedal, THEN

Then.... Look at the governor arm to make sure it is securely attached to the governor shaft. Follow mfr instructions to adjust/reset governor. If you still haven't figured it out by then, you will probably have to take off the crankcase cover to see if you still have a governor in the engine.... I still think it is probably something easy that you haven't thought of, might even be a bad seal in the carb letting air in.

 

[Brad_R]

Thanks for the reply.
I will check that the governor isn't loose and I'm sure it isn't a seal as when it starts you can hold the throttle at idle manually with the throttle arm.
I get back to you when I've had a look, I'm going to work on it tomorrow (gmt) so it get back to you.
Thanks again
Brad

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[KartFab]

Wait I think I misread what you were saying (thread topic vs body?!?)Are you saying that the engine when at "full throttle" idles?

If you hold the butterfly open by hand does it idle @ full throttle as well?

If so, you most likely have a dirty carb that needs to be cleaned.

 

[Brad_R]

Sorry for not being clear.

When I pull the cord it starts but it doesn't stay at a normal idle, it just races to full throttle. When it starts the butterfly automatically stays open.

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[Brad_R]

Bump?

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[fowler]

yea must be a linkage

take the air filter off and the filter box off the top of the carb
then u can see all the linkages

when it starts and goes full noise can u manually return it
or is it stuck at high rpm

it may a faulty governor

the little lever out the side only opreates via a spring so moving it wont tell u anything

u will have to manualy move the butterfly to narrow down the problem

EDIT re read the posts
so u can manually hold it at idle
ok so it is the govener

a stuffed seal wont affect rpm

the air must pass over the fuel port to draw up fuel
theres no seals between there and the butterfly

if the seal between the carb and the engine went then it would just fail to run

 

[Brad_R]

How would I go about resetting the governor? I can't find anything because all the tutorials I've seen are completely different,

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[itsid]

and that honda how to?
it's very minimal, but still complete.

the "special tool" is a torx screwdriver

'sid