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Old 04-27-2013, 05:13 PM
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bairdco bairdco is offline
a guy who makes cool bikes
Join Date: Aug 2009
Location: living the dream in southern california
Posts: 6,258
Default Re: Top Speed, 80cc Chinese motor? what is the record?

ha... blew up the engine. phone was fine.

i was riding down the pacific coast highway in newport beach with the wind at my back, and about 5 feet behind a pickup truck.

the speed limit is 55, but everyone does closer to 70, and the stoplights are far apart.

the guy i was drafting knew i was there and kept slowly speeding up to see how fast i could go.

my phone was in the sleeve pocket of my gas station jacket so it picks up the gps satelites for the speedo ap i was using, and it saves the top speed.

my motor made a loud bang, and since i was in a full tuck, i was looking at it. a small fireball came out of the head, it blew my exhaust pipe off, and grenaded inside.

luckily my back wheel didn't seize up. the motor tried to seize, but the momentum just broke apart the piston instead, so i could roll off into the bike lane.

the guy in the truck came back and said his speedo had me at 65, but my phone said 62. he said his neighbor has a bike that's lucky to get up to 30mph.

i collected my pipe off the side of the road and pedaled home.

after i pulled it apart, the top of the head studs were bent and stripped, my piston was pretty much missing except for the part connected to the rod, the exhaust threads were completely stripped in the jug (i was using bolts instead of studs,) the plug gap was smashed closed, and the cylinder lining looked like grey, melted slag, and the head's combustion chamber looked like it was hit with buckshot.

what i think happened was the rod stretched, just enough to slam the piston into the head, and all the other damage followed after.

the head was from a harley aermacchi m50, and i had to modify the squish band so the piston wouldn't hit. it had a buttload of compression but worked great for 8 months of everyday use.

modified, these motors can easily run 9k or more rpms.

the bike is the silver 1940's colson on my profile page. i ended up selling that bike with a stock-ish engine for a bunch of money
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