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Post by fickertravis on Nov 18, 2012 20:03:20 GMT -5
Stock engine, never been touched except fore dealer routine maintenance . Installed a Keihin carb with 88 jet, open filter and bolt on muffler. Took it for a ride and it was pinging passed the max on the speedo and BOOM lights out. Took it all apart and the piston slammed into the head. The piston is completely busted and the head is ruined. One of the valves broke off. Crazy... Has run fine before. Anyway, ordered new 50mm head and cylinder combo from scrappy. In very surprised that an engine could have complete catastrophic failure with such little modification. I've been running and building 2 strokes for quite a while and this its new to me. Any ideas what happened? I'm guessing an extreme lean mixture somehow? Also, what should i do to help prevent this with the install of the new top end. I'll be running a 95 main to start with the 50mm install.
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Post by teddy554 on Nov 18, 2012 20:44:49 GMT -5
you was pretty rich with a 88 main, i run 90mj on a 50mm open air filter scoot dont know if that could cause it to blow
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Post by fickertravis on Nov 18, 2012 22:12:34 GMT -5
Too rich would not cause that to happen IMO. I'm more concerned with what technically could have happened. Did the rod stretch? Was timing off? What generally causes this in most cases? Can i remove the oil pan or what would be the "oil pan" to get rid of any metal deposits?
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Post by teddy554 on Nov 18, 2012 22:57:46 GMT -5
i agree you just mention you thought you were lean and i dont think that was the case either, how big was the carb and what kind of muffler did you bolt on
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Post by jmkjr72 on Nov 18, 2012 23:03:48 GMT -5
the only way that damage would ahve anything to do with your mods is if it allowed it to over rev
if you over reved to the point of valve float that things start to come apart pistons hitting valves and all those parts boucnging around in side
had a customer with a blur 150 that the piston would slap the plug when he was beating the shit out of it and overerving it
he got lucky the 2 times it just smashed the plug
but the 2 people that asked me about buying that scoot when it was posted on craigslist i told them to not even look at it that i knew the scoot
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Post by fickertravis on Nov 18, 2012 23:14:46 GMT -5
It was revving pretty nice, but i would find it kind of crazy that a free flow muffler and a free flow intake could cause such high revs. In fact, I'm not sure how the revs could get that high in a stock setup. How would i keep it from over revving with the new kit?
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Post by fickertravis on Nov 18, 2012 23:23:08 GMT -5
The carb is a Keihin 18.5mm. The exhaust is basically aglass pack style muffler. Black canister with a straight through design. It's a nice bolt on.
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Post by fickertravis on Nov 18, 2012 23:23:34 GMT -5
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Post by fickertravis on Nov 18, 2012 23:25:36 GMT -5
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Post by fickertravis on Nov 18, 2012 23:26:20 GMT -5
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Post by teddy554 on Nov 18, 2012 23:27:51 GMT -5
now, that was a blow out
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Post by fickertravis on Nov 18, 2012 23:36:16 GMT -5
Yea, no kidding. This must be valve float
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millsc
Scoot Enthusiast
Posts: 103
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Post by millsc on Nov 19, 2012 10:44:59 GMT -5
that's a sight i pray i never see on my scoot i'd be sick
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Post by fickertravis on Nov 19, 2012 11:38:18 GMT -5
I just can't understand how this could happen to a completely stock motor. Now with the muffler, there was a cone piece that came with the muffler, but opted not to use it. Pity looked like it went in between the mid pipe and the muffler.
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Post by fickertravis on Nov 19, 2012 11:42:42 GMT -5
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