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2 Stroke Bicycle Engines & Kits 2 stroke engine kits need careful installation and setup, find out how from our professionals here!

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  #1  
Old 12-30-2016, 03:35 PM
Earbiter Earbiter is offline
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Default I... blew it up. Rebuild?

Towards the end of last summer while riding home from work, bike was running great, then when i was coming to a stop the engine just died.
After i started going again, i tried to start it back up, it struggled but finally started. But now the exhuast was very loud and had a serious lack of power.
I finally got a chance to dig into it, found one of the piston retainer clips had broken and made it's way into the cylinder, where it dug two large gashes into the cyl wall and the piston skirt.
Found no evidence of bottom end damage, or the clip.

I know there are top end rebuild kits, but will this be ok? Or should i just replace the whole damn thing?
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  #2  
Old 12-30-2016, 04:04 PM
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Kioshk Kioshk is offline
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Default Re: I... blew it up. Rebuild?

Are you sure it was caused by a retainer-clip? I'm sure you verified that one was missing when you removed the piston. I ask that since the indentation-damage to your cylinder looks a lot like the indentation of a needle from the upper needle-bearing. Check that bearing too to make sure it's still in one piece.

That said, it's easy to rebuild the top-end; you'll just need to make sure you clean out the bottom-end properly. I usually remove the entire engine, fill the bottom-end with gasoline, and slosh it around by cranking the flywheel. Dump out the waste and repeat a few times. This should clean out any offending particles there. You'll need a new cylinder, piston, rings, and gaskets: lower and head. You may need a new needle-bearing.
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Old 12-30-2016, 04:50 PM
Earbiter Earbiter is offline
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Default Re: I... blew it up. Rebuild?

Ya im sure, i was planning on getting this kit http://www.ebay.com/itm/191550568760,
i know it's cheap but it's all i can afford right now.
Just wanted to know if it would be ok. Ty.
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Old 12-30-2016, 04:56 PM
Earbiter Earbiter is offline
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Default Re: I... blew it up. Rebuild?

Sorry if i misspoke regarding the clip being gone, i have them both but one is clearly broken. What i meant was it wasn't in the bottom end. I'm guessing it got thrown out the exhaust. I'll prolly have to clean the pipe to make sure it's not floating around in there.
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Old 12-30-2016, 06:53 PM
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ultralight01 ultralight01 is offline
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Default Re: I... blew it up. Rebuild?

You could buy a new engine for $30 more, or a $50 49cc pocket bike engine. I have no knowledge of how to fix two strokers, but I'm sorry this happened.
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Old 12-30-2016, 07:11 PM
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MotorBicycleRacing MotorBicycleRacing is offline
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Exclamation Re: I... blew it up. Rebuild?

Quote:
Originally Posted by Earbiter View Post

I know there are top end rebuild kits, but will this be ok? Or should i just replace the whole damn thing?
There are 2 kinds of 47 mm / 66cc pistons.

Your piston is a high wrist pin hole for a Skyhawk type motor.

The ebay piston "photo" is a low type for a PK 80 type motor.
Whether that is the correct pic is anyones guess?

If that piece of the clip is in your bottom end you will destroy
your new top end.

I don't like those double clips, the single arm ones don't fail like that.

Last edited by MotorBicycleRacing; 12-30-2016 at 07:20 PM.
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  #7  
Old 12-30-2016, 08:38 PM
crassius crassius is online now
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Default Re: I... blew it up. Rebuild?

motors are cheap, when parts become chunks, why take a chance on trashing a new top end if an old chunk appears after the rebuild

if it were a cleanly seized piston or suchlike, that would be different
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Old 12-30-2016, 10:04 PM
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Kioshk Kioshk is offline
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Default Re: I... blew it up. Rebuild?

That's a decent replacement, but as MBR advises: verify the piston size.
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Old 01-01-2017, 08:06 AM
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cannonball2 cannonball2 is offline
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Default Re: I... blew it up. Rebuild?

You can buy the complete basic engine in the $75 range shipped if you search around on eBay. Problem I have had with parts was not always getting exactly what was listed.

Just be sure if you go for a replacement that the intake\exhaust spacings are the same
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  #10  
Old 01-01-2017, 09:45 PM
Earbiter Earbiter is offline
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Default Re: I... blew it up. Rebuild?

Good advice all ty, i think i will just buy a new engine, and keep the old one for parts or something.
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