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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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If you DO end up giving up, make sure the scooter goes out in style. Maybe burn it or something.

+1 on the valve adjustment - very important.

Where is the fuel tank on that scooter? The vacuum fuel pump probably uses a diaphragm inside which tend to stiffen up when exposed to ethanol - seen it a bunch of times with those types of pump.

Are you able to post a close-up photo of the engine/pump area?
I know some folks who do the Gambler events - they actually used their retired service van for it last time to retire it.
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If you're able, pull the cover off of the magneto area and pull the bolt out which holds the rotor on. Look carefully and see if there is any evidence the flywheel key has sheared and rotor moved its position.
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Hog: It's a designed weak point for a lot of smaller engines. If the engine meets a sudden stop (engine stalled abruptly, whatever..) the inertia of the flywheel can actually snap the crankshaft. Companies will use softer (even aluminum) flywheel keys to prevent this.

Honestly after doing a bit more research it may or may not have it - I'm really not "up" on these smaller scooters.

Understood MM, sometimes it makes sense to just cut your losses and move on.
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Lots of respect for the Cub - I think it's the world's most produced motorcycle. Good for you!
Victory! Congratulations!

The valve adjustment is interesting. Older CB450 twins can be adjusted the same way due to the torsion spring system they use. I wonder if your scooter is similar.
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