50cc chinese pit bit

[racerbugg]

I know it not a scoot, but this being one of the best forums for a reliable answer, though Id ask you guys first. Heres the problem
feels like needle is too lean. So I of course moved it up, and down, and tried a spacer from my dremel kit. Did't work and can't find jets for it. And of course the honda shop didnt want to even help because its a z50 clone and not a honda.
Ordered a bbr kehien. Same problem. No matter how I jet it.And yes it has fresh fuel.
The problem being really bad hesitation from idle. Crack the throttle and it dies. If you feather it to where the clutch engages then its fine after that. But hard for my son to learn to ride a bike like that. I can't do a compression test as my tester doesnt have an adapter that fits that size plug. I can fire it up by hand but I also bench press 300 lbs for reps so I'm a bit stronger then most.
I like the bike and so does my son , just want it to run a bit better. Any ideas?

[hit88]

i'v got some of these engines i build them for racing what do ya need? i think i can help ya out........thanks....hit88

[racerbugg]

i want it to run properly. I have looked for air leaks around the intake with brake cleaner.(while running)
and i can jet a bike , well a 2stroke anyways this thing is getting me a bit PO'D

[90GTVert]

Can you get any improvement by changing mixture screw settings?

[Fox]

Have you checked the valve clearances?

It's gotta be just like this:

[racerbugg]

almost no difference in performance aside from idle quality for air screw adjustment, and valve clearances are checked(my thought too)

[90GTVert]

You probably would have noticed doing valves, but had it been apart so maybe cam timing could be off? It's pretty normal for a single cylinder 4T w/no accelerator pump or w/o a CV carb to bog under quick throttle, but you shouldn't have to baby it. If it's idling pretty low now, perhaps try upping idle speed? I know you've played with jetting on 2 carbs already, but something quick to help see if it still could be fuel related would be to try revving with no filter and to try revving while covering or partially covering the mouth of the carb. If it'll work any of those ways, you still have a jetting issue to work out or if it needs to be choked it could still have a leak somewhere you haven't found. I will say though that my old pitbike engines were really bad about extremely high idle with air leaks compared to the other small engines I've messed with. Maybe I just had worse air leaks on those though? lol

[Fox]

Did it ever run right or did you buy it second hand with this issue already?

[racerbugg]

I got it second hand and unused. It's an07 sdg and was sitting pretty much since new. The tits were still on the tires. I've tried with / without air filter partially covering the mouth of the carb, differt carp of course and does yhr same no matter what. The valve timing was spot on and I can't find any leaks. I have sufficient fuel flow as well. Contimplating selliing and going back to a 2stroke ( ktm)