air,gas,vaccum problem? By hafaharley (Read 565 times)

[hafaharley]

Hello, I have a Schwinn newport 150cc. It starts fine, idles fine, but bogs down and turns off at high speed? any ideas

[richardthescooter2]

I'd check your vacuum lines and intake clamps for leaks and air filter, mine was choke yesterday after I has adjusted a/f ratio screw, turned out to be my air filter soaked with rain water.

[hafaharley]

Yes I have gone thru the lines cant seem to locate any problems. I can rev up the engine w/no bogging down sounds great. but when I run it at a constant high speed it will bog down and quit. Thank you for your post

[richardthescooter2]

When it does this the next time pay attention when it boggs, back off throttle 1/8 or 1/4, if it surges forward your lean, if it settles down or recovers itself it too rich.

[Alleyoop]

Q1.
When you say you run it at constant speed, is that at Wide Open Throttle or 3/4 or Half or at any throttle position but constant?

It is running LEAN and starved for fuel but to determine where the problem may be have to know the answer to Q1.

Do you have any mods on the scoot? Free Flow Filter, different muffler etc..?

Could be several things,
1. The Fuel Filter is partially clogged.
2. Vacuum line going to your Fuel Pump or Petcock may be leaking
3. You have a crack on the INTAKE MANIFOLD and it widens as it gets hot.
4. The Float is set to high in the carb bowl and the level of fuel drops below the jet because it cannot keep up.
5. The carb is running lean at the top end and you may need a bigger main jet.
6. If you haven't adjusted the Fuel Ratio Mixture and the temps have dropped quite a bit you could try Richening the FUEL RATIO Mixture screw. Give it 1 turn COUNTER CLOCKWISE and see if that HELPS. When the temps drop the motor needs more fuel when temps get hot they need less fuel.
Alleyoop

[hafaharley]

Ok thank you I start trying everything mentioned and get back to you