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Motorized Bicycle Trouble Shooting Use this area to post problems that may arise, if you could use some help in figuring out what is wrong with your engine and what needs to be done to achieve top performance.

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  #1  
Old 09-19-2016, 02:16 PM
crassius crassius is offline
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Default got a bad one here

a while back I had a guy with bike that sat several months - wouldn't start

decided motor full of fuel and got it started with lots of smoking, but it had sat so long with fuel in it that it took over 20miles to get it up to full speed and even then it was weak uphill - assumed gas had evaporated from fuel in motor to leave gummy mess down there that would slowly clear up over time, and it did after a few months

now I have one worse - got it started and fuel was so dried out inside that I get no smoke, and it needs half throttle to idle, but finally catches on and over-revs

checked everything else (seals, gaskets) - replaced muffler carb CDI Intake manifold spark plug just in case - good compression at 125lb

hoping that if I can keep it running it might clear up, but wonder if I'm missing something

never seen one this bad

any ideas of something I might have missed?
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Old 09-19-2016, 09:40 PM
Slogger Slogger is offline
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Default Re: got a bad one here

I'm going with a mondo air leak at the case split.
Filled with gas and left to sit for months maybe the gasket has gone away between the case halves.
I'd check the torque on all the case bolts. If they seem loose that would be a clue.
That's all I got.. It is weird.
Good luck, Mr Crass!
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Old 09-19-2016, 11:59 PM
crassius crassius is offline
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Default Re: got a bad one here

hit them all with impact driver a couple days ago (even the three under the clutch) - yesterday I taped a white paper towel to bottom of motor in case gasket had a gap in it that tightening wouldn't fix - came out clean

beginning to think "it's dead Jim"
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Old 09-20-2016, 10:24 AM
Slogger Slogger is offline
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Default Re: got a bad one here

??????????
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Old 09-23-2016, 11:11 AM
curtisfox curtisfox is offline
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Default Re: got a bad one here

Have you tried sea-foam in the gas, it really helps to desalted the varnish and crud.........Curt
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Old 09-23-2016, 12:26 PM
crassius crassius is offline
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Default Re: got a bad one here

no, didn't try that - had a day of DR apts, then a day of rain - will try to get it going again today, then maybe just give up on that motor
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Old 09-23-2016, 01:26 PM
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bairdco bairdco is offline
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Default Re: got a bad one here

Have you taken it apart? Piston top and head might be carbonized, rings might be stuck, etc.

Every old motor I've had, I'll pull the top end and clean it up, replace the gaskets, and rewire it before I even try to start it.
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Old 09-23-2016, 01:55 PM
crassius crassius is offline
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Default Re: got a bad one here

it was a new motor half a year ago before it sat - did look inside and all looked good (tho very wet).

One difficulty with a repair shop is to keep from charging more for labor than a new part would cost.
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Old 11-12-2016, 04:15 PM
crassius crassius is offline
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Default Re: got a bad one here

got another POS like above

same thing in that everything looks good & good compression, but it sat for many months

ran so weak I could barely keep it running 3 or 4 times a day for a couple days, and now is starting to get a bit smoother with more power

been thinking evaporated fuel in bottom of these leaving tarry substance in bottom that interferes with new fuel, but cleaned motor very well to see if any residue shows up outside where case gasket or base gasket may have deteriorated from sitting dry

still clean so far, but I'll post if it turns out that these gaskets fail from sitting
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Old 11-12-2016, 04:34 PM
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Agreen Agreen is offline
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Default Re: got a bad one here

For troubleshooting purposes, I like to use a refillable spray can with gas/oil mix. If it runs while spraying in to the carb, it's a carb issue. At the very least, you can get it running for long enough with that to help free things up.

http://www.ebay.com/itm/like/1522136...&ul_noapp=true
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