High RPM on start-up, now not starting

uncle meat

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Did my air fuel mixture adj. a few weeks ago and had it running well. Sat for 2-3 weeks without starting, fired it up today and upon start-up the RPM's were at about 2500-3000. Shut it off and tried starting it again... loud backfire. Pulled the plugs and they were wet. Pulled the stock air box and the boots were wet. I also figured I better check the battery too, it was at 9.5v, but I had left the key on for a few minutes while I was checking things.
Charged the battery and that's as far as I got. I'm assuming the floats stuck or something, didn't get a chance to drain the bowls, will do that tomorrow after work.
BTW, 1975 650C.

Thanks, UM
 
... Sat for 2-3 weeks without starting
... I'm assuming the floats stuck or something, didn't get a chance to drain the bowls...

Yep, that was kinda my situation out here. Dang gasohol.
Gotta pull the carbs and clean them.
Fuel stabilizers reduced a lot of that.
Now running 'ethanol-free' fuel, carbs don't gum up anymore...
 
Ok, got it figured out. After cleaning the crabs really well I reassembled everything and tried to start, nothing. Charged battery, @ 12.9v, checked spark, good. Tried to start again and still nothing, so I figured it had to be a timing issue. I pulled the advance unit cover and it spun it freely with my hand... not good.
Below the advance unit I see a pin sitting there. Pulled advance unit and found where it's supposed to go, installed and reassembled.
Turned gas on, choke on, turned key, switch on and 1 kick it fired right up:thumbsup:

UM
 
It might be time for a new battery. A few min with the key on and down to 9.5 V. A load test might not be a bad idea. A weak battery is hard on the charging system.
 
... After cleaning the crabs really well ...

They like that. Very important before cooking.

... I pulled the advance unit cover and it spun it freely with my hand... not good.
Below the advance unit I see a pin sitting there. Pulled advance unit and found where it's supposed to go, installed and reassembled...

Wondering how it got there.
If it fell out while everything is assembled and tight, could be a problem.
If it fell out during servicing or assembly, then OK...
 
Yes, they shouldn't be able to fall out. There should be a retaining pin above the slot on the back of the advance unit to keep the pin in there .....

PinRetensionPeg.jpg
 
I was wondering how the pin got there myself. I had the top end rebuilt a bit ago and haven't put but 7 miles on it. I'm thinking it wasn't tightened fully and it worked loose over time. The pin on the advance plate is in place. I used a punch and hammer to tap the spanner looking nut tight, then tightened the 10mm nut at the end. I'll put a few miles on it and recheck. Is there a torque spec for that 10mm nut?
Thanks,
UM
 
The little 10mm nuts on the ends of the advance rod don't get tightened very tight, only something like 5 or 6 ft/lbs. That notched ring that retains the advance unit goes on a certain way. It has a raised ridge around the I.D. on one side. That should face out .....

AdvancePinFront.jpg
 
Don't mind those arrows on that pic. They're just pointing out how that retention pin for the locating pin shows through to the front side of the unit. Your notched ring probably won't end up positioned exactly like this once tight.
 
Whew, got my heart rate up there 5 twins. I'll run it a few miles and recheck to make sure unit is staying tight. I have to readjust my air/fuel mixture anyways, that will be perfect.

Thanks,
UM
 
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