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Old 01-26-2016, 03:34 PM
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sbest sbest is offline
Motorized Bicycle Elite Member
Join Date: Nov 2015
Location: Nova Scotia
Posts: 249
Default Re: Bogging at top end

Originally Posted by Mouse View Post
Cdi brand new spark plug connection good ran cleaner in fuel compensated with more oil
Then that is not 30:1 any more, unless it was 50:1 to start with.

You cannot "compensate with more oil" for anything. It just messes everything up.

So, symptom = wavering bog at WOT (wide open throttle).
You need compression, fuel, spark and timing to run, so:

Compression? Any good?

Fuel? Got enough? Pull line off carb and check flow. Does it pour out or trickle?

Mixture? Warm it up and put a new spark plug in.
Run it WOT for a few minutes, shut it off, clutch and coast to a stop.
Pull the plug and have a look at the base of the electrode insulator, way down deep inside the threaded shell. Is it black, brown, tan, light grey or white? If it is black you are too rich. If it is white or light grey you are too lean. Jetting issue.

Spark? Put it on a center stand or upside down (good luck with the tank!). Pull the plug conneted alongside the motor. Crank the pedals in the lowest range and watch the spark (I didn't say it would be easy). Is it yellow and snaps or is it blue and quiet? If it is blue, replace the plug first, then go further.

Timing? Timing lights don't work well on these motors so best to check the mechanical integrity of the magnet and coil and electrical connections.

This should be a good start.

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