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Old 11-08-2013, 01:31 PM
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GearNut GearNut is offline
Motorized Bicycle Elite Member
Join Date: Aug 2009
Location: San Diego, Kaliforgnia
Posts: 5,106
Default Re: what did you do to your motorized bicycle today?

Originally Posted by BonusParts View Post
Oddly enough i've noticed that at low rpm it runs great on low throttle input, but at wot it just bogs. not four stroke, bog. Not sure what to make of it. I shortened the header, but it was rainy all day so no test yet.
By bog, if it just looses power and seems to be running flat while you are riding at top speed, it is tuned too lean. It needs a larger main jet.
(Note, a highly restrictive or clogged exhaust will cause this symptom too even though the carb is tuned correctly.)
Now that said, if you whack it WOT from idle speed and then it bogs that too is a lean condition but good luck tuning it out. The carb has no accelerator pump and it cannot accommodate large throttle input changes without temporarily leaning out.
"It's a chinagirl. It's a sometimes fun little engine that often will break your heart. It's disposable.

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