TF125 mudbug idle issue

[tigertim20]

Got a mudbug thats idling funny - hanging idle.
usually starts and idles fine.
sometimes starts and idles high, but wont come down. giving the throttle a quick sometimes brings it back down - but only sometimes.
usually starts fine, then when you rev it, the idle stays up high where you revved it to.

Have checked for vacuum leak - couldnt find one.

Have removed and cleaned / lubed throttle cable - not the issue.

what else should I look at?

[Motu]

What you've already looked for - a vacuum leak. Check mains seals...left side will leak air, right side will suck gearbox oil.

[tigertim20]

What you've already looked for - a vacuum leak. Check mains seals...left side will leak air, right side will suck gearbox oil.

cheers, will look into that

[Akzle]

carb needle/main jet - they get a bit bendy and can stick up.
Slide also, in the top of carb.
Had a ts what would do that.

[F5 Dave]

On top of the above, try take the cable and lid off the carb & try move the slide with your finger.

Bolt on flange over-tightened, can distort the carb bore. + grit & stuff can get in.

[unstuck]

Any indentation on the idle groove in the slide?

[F5 Dave]

Haven't seen that on Mikuni round slides yet. Happens like a bitch on Flats

[tigertim20]

looks like Motu was right after having spent some time with it today.

anyone got a recommendation on best place to order online/ - I tried pyramid parts and bits4bikes, but neither list the stuff Ill need for a mudbug!

[jasonu]

Is this a Bucket motor? If yes then who cares if it idles or not? I vaguely remember one of my buckets actually idle but all the rest would die if you didn't keep on with the throttle.

[tigertim20]

not a bucket engine but I posted this originally in buckets as I know the motors are often used in buckets, and the bucket folk arent shy of fiddling with their engines . . .

[Grumph]

looks like Motu was right after having spent some time with it today.

anyone got a recommendation on best place to order online/ - I tried pyramid parts and bits4bikes, but neither list the stuff Ill need for a mudbug!

Last time i got OE Suzuki seals they were very reasonable - abt $8 ea. That was A50 about a year ago. Avon City in ChCh.

[ac3_snow]

looks like Motu was right after having spent some time with it today.

anyone got a recommendation on best place to order online/ - I tried pyramid parts and bits4bikes, but neither list the stuff Ill need for a mudbug!

Any local seal or bearing shop should be able to help you out. They are a pretty generic oil seal. Take in the old one as reference.

[tigertim20]

does the mudbug require the engine out and stripped to get at the seal, or can it be done in situ? - cant find a manual onlinr

[jasonu]

does the mudbug require the engine out and stripped to get at the seal, or can it be done in situ? - cant find a manual onlinr

Depends which side. IIRC ignition side can be done without stripping the motor, other side requires full motor strip.

[tigertim20]

Depends which side. IIRC ignition side can be done without stripping the motor, other side requires full motor strip.

yep - left hand side was easy. apart from my flywheel getting wrecked. sigh. one of the magnets is in pieces, literally. surprised it was running at all.

dont suppose anyone has a mudbug enine sitting around with a flywheel they could be encouraged to part with?

[jasonu]

dont suppose anyone has a mudbug enine sitting around with a flywheel they could be encouraged to part with?

Should be plenty of those flywheels around. Bucketeers have been ditching them in favor of mx ignitions since the beginning of time.

[unstuck]

dont suppose anyone has a mudbug enine sitting around with a flywheel they could be encouraged to part with?

I think I may still have some 185 bits laying around, but would imagine they would be different sizes. Will go through some boxes and see what is there though, cos I am not really sure what is in some of them now.:niceone:

[tigertim20]

I think I may still have some 185 bits laying around, but would imagine they would be different sizes. Will go through some boxes and see what is there though, cos I am not really sure what is in some of them now.:niceone:
would be handy if ya had something laying around!

[unstuck]

Only a gn and 2 xl ones in the first box. Got to move some shit around to get to the other boxes. Shed is a little full at the moment.:niceone:

[tigertim20]

Only a gn and 2 xl ones in the first box. Got to move some shit around to get to the other boxes. Shed is a little full at the moment.:niceone:

ha I now that problem, 3 bikes and an mx5 of a friends currently occupying most of my garage!

[unstuck]

ha I now that problem, 3 bikes and an mx5 of a friends currently occupying most of my garage!

Im trying to talk her indoors to let me build a bigger shed, but apparently we need carpets and paint and shit, what do they know aye.:weird:

[ac3_snow]

yep - left hand side was easy. apart from my flywheel getting wrecked. sigh. one of the magnets is in pieces, literally. surprised it was running at all.

dont suppose anyone has a mudbug enine sitting around with a flywheel they could be encouraged to part with?

Let me know if unstuck doesn't find one for you. There will be one in the garage I can send down if need be.

[MarlinHemi]

What did it end up being i have a very similar problem?

[tigertim20]

left hand side main seal.

wasn't hard to sort out. seal cost a couple of bucks.

[Mirkie]

What you've already looked for - a vacuum leak. Check mains seals...left side will leak air, right side will suck gearbox oil.

Where are the main seals?

[Mirkie]

Got a mudbug thats idling funny - hanging idle.
usually starts and idles fine.
sometimes starts and idles high, but wont come down. giving the throttle a quick sometimes brings it back down - but only sometimes.
usually starts fine, then when you rev it, the idle stays up high where you revved it to.

Have checked for vacuum leak - couldnt find one.

Have removed and cleaned / lubed throttle cable - not the issue.

what else should I look at?


I’ve got the same issues. Let me know if you suss it and I’ll do the same. I’ve spent hours on it !
Cheers Mirkie