Motorcycle carb help, stumble and stall out.

[Joe Bob]

I have a Dellorto single side draft carb. Specifically a PHGB 19mm on a two stroke motor. I have the manual but nothing discuses trouble shooting. I'd like to get some direction prior to a rebuild.

The bike sat for awhile and would not start. I figured bad gas. Dumped the fuel, blew out the bowl and jet. There was crud in both. New fuel and it starts and will idle.

However, it will not accelerate and then stalls out and refuses to restart until it sits a bit. Manual choke doesn't change anything. Fuel delivery is good, I put a clear line on the petcock and it drained with a full stream. "I" should be so lucky.

I posted on a small motor MC forum but no response after two days.

Any ideas?

[Gogar]

Does the diaphragm look ok?

[KFC911]

Maybe run some Berryman's B-12 or similar through it?

[LakeCleElum]

U have crap in the tiny passages for the idle circuit and the pilot jet. Remove your idle mixture screw/spring and your pilot jet. Do the main jet while in there. Use spray carb cleaner and compressed air. A strand of soft copper wire as a last resort, wire can damage the passage.

Your main jet may (or may not) screw into a nozzle the has maybe six or eight tiny holes, those holes and be plugged also, less likely.

Call if you want. U have my number. Good luck sir.

[Dansvan]

or...

Is the sparkplug wet? If it will idle logic says the idle/pilot circuit is ok. If the carb is over fueling the motor, it wont accept more fuel by opening the throttle. If engaging the choke changes nothing it may be because too much fuel is present already. Letting it cool down after it dies allows fuel in the crankcase to evaporate and eventually dry out enough to re-start. But a quick peek at the spark plug on a 2 stroke reveals all. I'd suspect a piece of crud holding the needle off the seat allowing fuel level to get to high.

[Joe Bob]

The plug is new, it was an oem acceptable replacement. The old plug lost it's electrode and a bore scope didn't find it in the cylinder. The new plug looks normal for an oil burning gas mix.

[Joe Bob]

[Brando]

I agree with Bob. It may be time to pull the carb, disassemble it, and soak it in a gallon of carb cleaner from O'Reilly's to break up the gunk. Then assemble with new seals and ensure the float is in good shape. Inspect all the parts. Who knows when it was rebuilt (if ever) and how well it was cared for before you got it.

[pdxfj]

Forget the carb dip..

Find a 20% off coupon for Harbor Freight and get their large ultrasonic cleaner. Fill with water and some aluminum safe cleaner, turn on the heater, disassemble carb. Once the cleaner is up to temp, toss everything in and run for about 30-40 minutes.

Remove, rinse and reassemble.

The ultrasonic cleaner will do a 1000x better job at cleaning than the chem dip..

[dlockhart]

Originally Posted by pdxfj

Forget the carb dip..

Find a 20% off coupon for Harbor Freight and get their large ultrasonic cleaner. Fill with water and some aluminum safe cleaner, turn on the heater, disassemble carb. Once the cleaner is up to temp, toss everything in and run for about 30-40 minutes.

Remove, rinse and reassemble.

The ultrasonic cleaner will do a 1000x better job at cleaning than the chem dip..

This.

I have had to clean several carbs this spring. I used a 50/50 mix water and simple green.

When done use carb cleaner and blast the passages to make sure they really are clear. I had some weird crystalline growth on the emulsion tube on one of my brothers SV650 race bikes. That set of carbs took a few spins through the ultrasonic to clean up.