help diagnosing a rough idle?

[Ruffus]

@hawk, as said some pics from a non drop forged Kymco LIKE 125 crank. As far I can see there is, as mentioned, a conn. rod holds/keeps it together. From marks it has been machined after completing, so I assume its heatshrunk together. No welding marks to be seen.
The likelyhood to turn is given, but IMO not very high.This motor was a complete piston/ cylinder wreck, and those bearings are still in good order, so I would exclude a bearing fault on your ride.
Btw, this 4-slot special nut on the generator side is LEFT HAND threaded.

@scooterfan, you might be on a good track too.
Forgot to mention in my carburator issue that, when I replaced my vacuum lines with silicone hoses, I had an intermitting surging.

It came out, those silicone vacuum hoses were after a while not airtight anymore. Became a pudding-like consistency. Got a patch which softened in contact with oil and fuel.
Changed them to simple black rubber fuel lines, new clamps on it and vacuum was established again.

[Iahawk]

thanks for all the replies, guys.

Scooterfan - I pulled my carb twice and completely disassembled, cleaned all passages with a spray can of carb cleaner and replaced pilot and main jet.  I 'think' I have it perfectly cleaned but I can always do it again. I thought I did a thorough job of checking for any air or intake leaks. I replaced my intake manifold O ring..and checked for leaks using both starter fluid and propane gas (from a small cylinder) sprayed around all connections...no change in idle with any of these (and I didn't blow myself up, either, which was a win!)

Ruffus - thanks for pictures of the crank..that's likely my exact crank as the 163cc motor is a bored out Kymco 125cc.

I can always redo my vacuum lines and clean carb for a winter project. I hadn't heard of silicone vacuum line issues (I don't believe mine did that as the problem existed before I changed my vacuum lines to silicone and persisted after)

I watched a GY6 crankshaft replacement video on youtube and the person made a point of pointing out the left hand thread you're referencing..important point!

So I guess the simplest explanation is usually the correct one...which would be carb or intake or vacuum leaks. All things that can keep me busy during the off season.

I appreciate everyone's input.

[JJJoseph]

submerge everything except the needle and seat spring in white vinegar for about 24 [hours].

Vinegar is corrosive, so use sparingly. I've always used toluene, an excellent, non-destructive carb-cleaner solvent.  You can buy it in auto-parts stores as "carb cleaner", but also cheaper as "lacquer thinner" in Home Depot, occasionally mixed with acetone.  Either works well for soaking carb components.

[Iahawk]

thanks, JJJ, looks like a serious carb cleaning is in my future.

[stuo]

Maybe it's just the gas going bad. How about riding it until the tank is empty and see how it idles with a fresh tank of fuel?

[Iahawk]

Stuo - thanks for the suggestion but I've run multiple tanks of gas through the scoot this season. I always use ethanol free gas with stabil marine added and I've even been dosing it with techron this season in hopes of cleaning something in the carb that I may had missed.  I also added a fuel filter this year (did not have one, previously).

I've put 650 +/- miles on the scoot this season.