1st time post here, need some help please.

Our Badger will idle what seems to be normal then it will
surge in rpm's. If we then punch the throttle that will
normally bring the rpm's back down. The bike runs
ok when we are riding, just the idle problem. The idle problem
is unpredictable and is annoying and dangerous when
it surges in gear.

Thus far I have taken the carb off and apart and cleaned
it up put it back together, same surging idle.

Any help in direction to proceed with this repair is appreciated.

Thanks,
Glen

 

Spray some carb cleaner around the carb/intake and see if the rpm's change.
Sounds like it could be a air leak.

 

Tried the carb spray around the intake areas, good idea but
did not change the idle speed.

Saying Eradic may have been a misnomer - the machine will idle
and then on its own adjust its idle high. Almost like the choke
kicked on (it didn't). It then stays high until we punch the
throttle once and then goes back to a normal idle speed. It then
repeats the above in a couple minutes.

So far carb taken apart and cleaned, brand new plug, checked
for intake leaks. Seems like it should be an easy fix to no avail.

Any ideas from past experiences?

Glen

 

From suggestions I screwed in the carb mixture screw
all the way in, it idles much better now. seems to have
stopped the creeping idle.

However, I have to wonder why this has to be screwed in
100% to idle and run properly, not normal i do not think. I also
took out the screw and looked at the tapered end and seems
to look ok, no scoring or burrs. Seems to still smell rich
idling.

Wondering if anyone has input on whether the mixture screw
s/b replace or just dont' worry and be happy.

 

This manual
6789438-Yamaha_Badger_80_Service_Manual_Repair_1985-1988_Yfm80.pdf
is for a 86 moto 4 80 but it as the same carb as yours.

That is actually the air screw on this carb so screwing it in actually gives the engine more fuel.
Perhaps you have some partial plugging in the pilot jet and air screw area of the carb or perhaps your float level is too high causing it to run rich at a idle.
Ken

 

The Badger has been doing just ok at idle. It likes to stall once
in a while and of course it is always at the most unoportune time.

I have to agree with the pilot jet being the problem which I will get after in the next week or so.

Appreciate the link. Will post after the carb rebuild as to how it is
dooing.

Happy off-roading until then.

Glen

 

I've had the exact same problem, have had two mechanics work on it, I've messed with it several hours lubricating the throttle linkage, etc, finally took it to the dealer today and they're going to install a kit in the carb,,,,I think its a design weakness but I'm hoping they can fix it.

 

Hey Greenh - We recieved the new mixture screw awhile ago
and installed it. Made enough of a diferance to bring the idle
where it should be. It still is not the greatest and it will
still creep up in RPM's once in a while but a flick of the thumb
brings it back to where it should be. So it is reasonable and
at least safe now. Would like it better. Would like to hear
how your rebuild goes.

G

 

Will do, hope to have it back sometime next week.

 

Got a call from dealership, they wanted to order new carb, intake, etc with estimated repair cost of $550 or so,,,I picked it up and brought it home,,,,I guess I'm done with it,,,,may part it out.