MC-54-250B poor acceleration By turtle8 (Read 1,079 times)

[turtle8]

I finally took some test rides today and the acceleration is very slow below 3,000rpm. It didn't look like the variator was operating properly, so I took if off for inspection. All of my slider were out of position and pretty much toast. I installed the old rollers and there was no improvement in acceleration. What size belt should I be running? It doesn't seem to be going up and down the pulleys as far as it should.

Note: The engine idle has a pronounced lope to it and a minor pop sound from the exhaust at low rpm. I enriched the mixture some, but that didn't fix the popping sound. After the subsequent test ride, I could smell that the mix was rich.

Above 3,000rpm the acceleration is OK and there is a little bit of vibration that I am not too keen on.

What kind of insight do you ScooterDocs have for me this time?

[kz1000st]

I know it's a pain but I would start playing with the idle mixture screw. It plays a big part in the running below 3,000. Also check your manifold and hoses. Popping is usually an air leak.

[turtle8]

Idle mixture screw is the small brass screw on the bottom of the carb, right?

Also, I have what sounds like a loose brick inside my muffler.

[turtle8]

I need to amend my original observation notes. I've fiddled with the mixture with no significant changes in engine operation. I could not detect any air leaks. The sound I am getting while on the center stand, and revved to 2,000 rpm is a slight dieseling sound. Low speed acceleration is still poor; I'd called it bogged down.

As I stated in another thread of mine, the rear wheel still spins at a good clip while idling on the center stand. My new clutch from ScrappyDog didn't fix that problem.

[Cruiser]

It sounds like the engine is lugging at low speeds. Since you mentioned the rear wheel spins while on the center-stand and you have already replaced the clutch assembly, it still sounds like a variator problem. Have you tried running the engine without the variator assembly? See if the sound goes away and if the response with no load is good.

It really seems like a variator weight is out of the track.

[ce]

Open the diaphragm and raise the clip to lower the needle, that will slow down the flow of fuel through the main jet.

[turtle8]

TA-DA! It is fixed!

I ran the engine without the variator, and the engine ran perfectly. I then cleaned out the variator, reinstalled the Dr. Pulley Sliders and carefully put the assembly on the shaft (without the backing cover). I went for test drive, and the runs great.

The problem was with the rollers/sliders were getting out of position when I put the variator on the scooter.

Now I have a 250cc scooter that I paid $300 for, and put about $300 worth of parts and misc supplies in. I feel good.

[jalat]

\o/ Sound like we have a winner \o/

[turtle8]

Thank you very much Cruiser and all who provided their input and expertise.

-Michael

[Cruiser]

Your welcome, Michael. It's great to hear that you are one happy scootist. ;D