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Old 02-23-2010, 10:18 AM
BarelyAWake's Avatar
BarelyAWake BarelyAWake is offline
Motorized Bicycle Elite Member
Join Date: Jul 2009
Location: Maine
Posts: 7,212
Default Re: How to rebuild and balance these engines

I would heartily recommend a light port & polish, essentially cutting away flash and smoothing the bad casting in the intake and exhaust ports and the transfers - as well as the easier but essential matching of the intake and exhaust to their manifolds, including the gaskets themselves. Despite the relative "complexity" of a "serious" port n'polish, what I'm describing is truly easy for those with a lil patience and a touch of caution (like not cutting too much or scoring the cyl walls is all), yet the gain is usually quite pronounced.

I figure it like this - tho alla goodies you describe are indeed worthy, their effect is somewhat lessened when bolted to a motor that's not been "cleaned" in this fashion.

Examples of untouched sloppiness (click to view)

after jus' a few minutes with the ol' Dremel
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