My Dad bought his grandkids a cherry 120 XCR at an auction. (still has all factory grease on the carb linkages.)

I've changed the gas in the tank, confirmed the oil level is approx mid-way when cold, gotten my 9 year old to start it, it starts really well, pulled the needle-pointed jet out of the carb to inspect it (it's really sharp), set up the throttle linkage so the throttle safety cut-out switch works properly, and can't seem to get a reliable idle without the choke being out.
I've moves the governor spring to the various positions - found that the slow position will barely allow it to engage the clutch... I have the spring on the hot-rod position at the moment.

I've read the previous multi-page thread about the trouble 'Sledporn had last year, and then pulled out the needle shaped jet to see if the tip was distorted (it's in perfect shape). I spun it all the way back in till gently seated and backed it out 1-1/2 turns (I'm at approx 800' ASL) and still have the surging idle when I push in (dis-engage) the choke. It will idle well, albeit slightly fast with the choke out halfway - but it's on the verge of engaging the clutch.

I know my little guy will become bored with this machine quickly, but I'd like to have it running absolutely perfect prior to doing any mods to it.

There is no governor bypass or anything on it yet - just the flimsy little governor spring the I believe is OEM

where should I look - I haven't taken the carb off yet (It's not friendly to get at to remove.) Nor have I confirmed that the governor shaft and arm are in the right relationship - hust guessing that they are so far.

Help!?

Run some Seafoam thru carb, chances are it's varnished up. It's a little awkward to pull carb but very easy to drop carb bowl.

something is dirty its running lean, dissassembly the entire carb and make sure all the passages are clear
dan

It took me 3 times removing the carburator and cleaning it........must be a partical of sludge ordirt. Get some carburator cleaner, dismantel the carb and let it soak in a bucket for 20 minutes. Re-assemble and adjust. Be sure your valves are properly adjusted as well.

Sorry - I guess I should have replied - problem got solved.

It seems that since the throttle cable attaches to the governor lever rather than the carb butterfly, the sled would idle, pick up speed - governor fly-balls would compensate and drop the rev's - governor fly-balls would compensate and raise the revs, etc. the governor assy was trying to compensate for inconsistant fuel delivery by continually swinging the governor arm with changing rpm's which in turn, kept moving the throttle arm going to the carb. This was why it kept surging, or as I called it "hunting".

the solution was to thoroughly clean the carb - and I mean thoroughly.

It runs like a top now, it's a bit too small for my 9 near old, but since he doesn't know any better he's happy. I'm trying to convince my 4-1/2 year old that he should try it too, but he's still pretty scared.