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My Eternal Project, or the Scooter That Refuses to Live. Any Ideas?

4330 Views 59 Replies 11 Participants Last post by  Unkle Krusty
And the scooter is dead for a third time now...I’m running out of things to replace.

If you’ve not been following my CF Moto saga, here’s a recap:

First Revival

Acquired in November from a fellow Gambler 500 team member. I replaced the battery, the carburetor, and learned the starter solenoid was installed backwards by a previous owner. It sat for roughly two years without running and I made a gamble that I can make the old fuel burn again. While I was successful in that, I made two critical errors:

1. I didn’t replace the fuel filter.

2. I rode it every day for a month, not really ever allowing it to get to running temperatures.

Despite that, the scooter was good for 75mph, impressive acceleration, and it all around it ran absolutely perfectly. I felt I had myself a good score and with actual fresh fuel I’d probably even break 80mph. I proceeded to daily it for a month, taking it everywhere.

Fixing my Original Mistake

I made sure I ran all the bad fuel out of the tank and made sure the tank wasn’t rusty. Then I filled it with good fuel.

I then replaced all the fuel lines, the fuel filter, and the carburetor. I then installed a pod filter. I also closed off the crankcase vent to the airbox. Instead, the crank vents out into the outside. The original problem with not being able to start after getting hot remained, but at least I was no longer fouling my air filter and carb with particulate matter (air filter material) and oil. Top speed was about 40. Figured I would get more speed from restricting the pod filter, but first I really wanted to address the problem with not being able to restart with a warm engine.

Take Three

I decided to replace basically everything else I didn’t touch. I took the panels off and replaced the air filter so I can ditch the pod filter and go back to the factory setup (I still have the crank venting to the outside, though) and not have to jet the carb. Then I replaced any old vacuum lines that remained. All this work resulted in no change. It does cold starts well, but introduce any heat and it’s dead. The engine tries to fire, but it just won’t.

You can get it to start on starting fluid, and then it will go on to run like it’s misfiring and it’ll die as soon as you stop moving...then fail to start again.

Only thing I haven’t replaced is the spark plug (because the bloody thing has a spark plug that requires a bigger socket than the one I have for my smarts), but I fear it’ll be a waste of time.

Is there anything else I’m missing or do you think the spark plug will be my magic bullet?

This was supposed to be an easy project, but it certainly has taught me a lot about motorcycle/scooter repair! If the spark plug doesn’t fix it I’ll probably get rid of it. I’m just not sure how much I would be able to trust it at that point..And I'd hate to do that because when this thing was running well it was an awesome way to get around. 75mph top speed and everything.

For a TL;DR - here’s everything I replaced:

- Battery
- Fuel Lines
- Vacuum Lines
- Carburetor (built in electric choke)(2 times)
- Air Filter
- Fuel Filter
- Oil
- Fuel

Only thing I can think to replace now is little sparky..
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How does the gas tank vent?
Maybe it's blocked and forming a vacuum? When it wont start or runs like **** remove the gas cap and see if it works better then.
Is there a fuel pump that could be bad or is it gravity feed? Check flow?
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I'm not sure how to troubleshoot a vacuum fuel pump system.. how does that even work? How does it start? The fact that you can get it started with fluid has me wondering...

To check the vent can you just leave the cap loose for a test?

Fuel pump is vacuum based. When I replaced the vacuum lines and fuel lines I went almost clear with everything so I can see it all in action. IIRC, the tank vents through the petrol cap, which I'll probably give a good clean to make sure it isn't blocked.
You have me laughing at an old memory, I was helping a friend ( 30+ years ago) work on his broken down Alfa-Romeo spyder and he told me that the problem was that I was cursing at it in English, it needed to be addressed in proper fluent Italian profanity or it would never work , he then gave me a demonstration :)

Have you tried cursing at it in Mandarin?

I was troubleshooting a re-occurring, random, pneumatic fault on a Heidelberg press at work a few months ago. I tossed a few choice words in German at it...and it hasn't happened since.. (knocks on wood)
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Congratulations, I knew you'd figure it out!
It's always fun to get to the bottom of something that had me stumped!
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