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Old 01-22-2015, 08:59 AM
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Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: Top Speed, 80cc Chinese motor? what is the record?

Originally Posted by bairdco View Post
quick note on opti2. i love the stuff on my street bikes. i run them hard all day without worries. .

but racing with it was a different story. i blew pistons apart on a regular basis. on the street, you hear noises and you stop. the bike gets a break at lights, traffic, or parked at the liquor store.

on the track? a ten lap race at the grange gokart track is roughly 15 miles of full throttle, over revving torture, usually in hot weather. if my exhaust falls off i don't stop. if it makes grinding noises, i push it harder. the only thing that matters is crossing the finish line. if a brand new, fully modded engine makes it till the end of the day, it's a success, no matter what place i finish.

one race i crossed the finish line, shut the bike off in the pits, and it was seized when i tried to start it again. just melted the piston to the jug.

i run klotz oil at 20:1 now and the same engine's made it thru three races so far.
Do you run your engines on the lean side?

I use the Opti2 @ 100:1 and I've done many rides for up to 25 miles one way running wot most of the way at speeds of upper 30's to mid 40's depending on the bike and mine never show signs of serious overheating and I've had not oil related failures.

Now i do understand that my engines arent turning 10,000 rpms either and if they were I'd probably have a melt down also.

The fear on running my engines so hard for so long is why I started adding some Maxima 927 Castor to the mix, I thought a little extra protection cant hurt for sure.

Ya know while typing this out i just realized that I have had one failure that could be due to overheating... so I guess this part of the post will be an edit of what I said about not having an oil related failure.

The engine I built up to get me over that 50mph hump ended up trashing the tension in the rings and that engine lost almost all compression, piston looks fine and cylinder looked fine but compression very low, this engine wasn't running lean best I could tell either, good plug color.

One of you math wiz'es can probably tell me what rpms I was running.

24" rear wheel, 30T sprocket, maximum speed reading on GPS 52.0 Mph

Tires were 24x1.75 not sure of the actual circ.

So I guess now that I think about it I have had what could be said to be an oil related failure with opti2...shrug....

None of my other bikes run the rpm's this one was turning at those speeds.

maybe i'm learning something here about what I should consider as far as mix for any engine I get to turn the high rpms' from now on...????
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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