High rpms = 4 stroking

[Mac]

Hi Norm,
I an Mac (Bill McEnery), Pretty new to MB but certainly not mech stuff. I checked out your home page, my vote is gearhead!! I really like the Home built AC. I'm certified A&P and a whole lotta other stuff.
A question for you if I may. I just built 2 "80cc" Zoom kits on schwinn riversides, I cant seem to get the motors to pull past 1/2 throttle, they just flatten out. I adj the needle, seems to run the best on the top grove. These are the stock carbs that come with the kit, I did take them apart to check for FOD etc... No problems noted but There is no jet size stamp. What do I need? a smaller jet? Where can I get them and if you could, let me know the size

Info: Amsoil Syn. 24:1, reg unleaded, NGK B7HS, new Plug wire, stock aircleaner.

If you could steer me in the right direction I would really appreciate it

Mac

 

[Norman]

Mac I sent you a PM hope that info will help.

 

[Mac]

Norm,
Received your PM. That was the post that I thought I lost.

Thanks a bunch!

Mac

 

[HighCycleNM]

if i put de c clip in the first or second position? (at the moment is on the 4th trace)

The full throttle, the needle should have no effect at all- it's all the main jet at full throttle.

 

[Jonathonh]

Four stroking is cause by an over rich condition.

Your jet is too big.

What if the engine starts to do it all of a sudden after years of riding? Changed the plug and leaned it out but mine still doesnt scream like used to. Note the exhaust is cut off and its ported. Did real good in the cooler months.

 

[Jonathonh]

The full throttle, the needle should have no effect at all- it's all the main jet at full throttle.

You think the carb is partially clogged? (Nothing has changed on the motor)