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Old 02-03-2015, 02:59 PM
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mapbike mapbike is offline
Motorized Bicycle Elite Member
Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: Curious about the engine, :question:

Those transfers look good boxcar, looks like the jug has the rectangular ports instead of the small cat-eye looking ports.

I still need to make the video I spoke of making that shows ports in relation to the piston when its at BDC, I made one but it didn't turn out like I wanted and it was just to dang long.

Your pics give a good view of how much the transfers are opened at BDC of the piston, this is something I was curious about since out of all the new jugs i have only two of them will open the ports that much at BDC of either the 40mm stroke GenIV lower or the GT5 lower I have, I'm starting to see now more than ever that all china girl cylinders aren't made even close to equal, it's looking to me that most of the run of the mill cylinders available on-line have small transfers and they are to low, some of mine are only opened half way at BDC one either the 40mm stroke engine or the 38mm stroke engine, a couple of them open just barely over half way.

I'm becoming to realize now why the performance between different engines can be so different, even though they both may have basically the same mods.

Seems that maybe the engines with the lower smaller transfers are good for lower RPM set ups that are built to have good low end and a little mid range power that will get a bike geared right into the mid 30mph range, but even with all the other correct mods those engines just wont ever accomplish mid to upper 40mph speeds.

looks like you may have a good one there boxcar, if that engine is silky smooth like you say and because it has such good looking ports, I'm gonna say you have an engine there that has some good potential for a mid to upper 40 mph cruiser with the right gearing, carb tune and exhaust.

Thanks for sharing the pix boxcar.
I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!
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