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Post by aeroxbud on Aug 5, 2021 14:21:04 GMT -5
Did you oil the bearing, and piston when you assembled it?
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shadees
Scoot Member
Posts: 83
Location: Denmark
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Post by shadees on Aug 5, 2021 15:04:28 GMT -5
Did you oil the bearing, and piston when you assembled it? Yes I did
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Post by aeroxbud on Aug 5, 2021 22:53:01 GMT -5
That sucks then. It didn't even really get going.
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Post by Zino on Aug 5, 2021 23:42:19 GMT -5
Wow that is terrible
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shadees
Scoot Member
Posts: 83
Location: Denmark
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Post by shadees on Aug 6, 2021 7:27:28 GMT -5
The piston will never work again.. I have used my Dremel tool with some fine sand paper on the cylinder head,, and this can be used again for sure.. Last thing is the cylinder itself.. Its only flaw is a single scratch,, but a big one.. Wonder if this will work again if I get it honed ??
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Post by geoffh on Aug 6, 2021 7:28:23 GMT -5
That is a shame, I find it surprising the kits don't,t come with a matched bearing but hey ho,my rebuild woes were always the piston pin clips,were yours still in the piston?.
Geoff, must have been typing at the same time,that gouge looks too deep to be honed out rebore and oversize rings is my guess but that's going to cost more than a replacement !
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shadees
Scoot Member
Posts: 83
Location: Denmark
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Post by shadees on Aug 6, 2021 9:39:01 GMT -5
That is a shame, I find it surprising the kits don't,t come with a matched bearing but hey ho,my rebuild woes were always the piston pin clips,were yours still in the piston?. Geoff, must have been typing at the same time,that gouge looks too deep to be honed out rebore and oversize rings is my guess but that's going to cost more than a replacement ! Infact the clips was some of what took least damage in this disaster I'll try and hone it.. The gauge looks deep,, but some of the "walls" are material from the gauge itself,, so it's not as deep as it looks
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shadees
Scoot Member
Posts: 83
Location: Denmark
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Post by shadees on Aug 6, 2021 12:28:42 GMT -5
How much spacing is normal when putting the needle bearing into the piston ?? This bearing is 13mm,, and the shortest point in the piston is 16,58mm..
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shadees
Scoot Member
Posts: 83
Location: Denmark
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Post by shadees on Aug 6, 2021 14:27:28 GMT -5
When placed in the crank rod it's a perfect fit,, and with around 2mm free space on each side.. That's normal right ?? Just trying to investigate the accident and get cleared on a few things
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Post by geoffh on Aug 7, 2021 11:02:49 GMT -5
Shadees,I have the naraku 70cc cast iron kit and ordered the piston pin bearing it has the same dimensions as yours,this clearance doubt is new to the forum,so lots of kits fitted with this brearing with no failures I can recall?.both you and Rob used an old one first so maybe that's the lesson to take from this??.
Geoff
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Post by captincvmn on Aug 8, 2021 9:06:15 GMT -5
For my Stage6 S/R kit I used a new bearing and wrist pin but it was a replacement bearing for a 50cc piston and I didn’t like how much it was able to slide side to side inside the piston. I got 1000 miles roughly on it before it grenaded. Now I have a new used Corsa cylinder and I’m using a bearing that’s originally designed for a KX65 engine. I have a 12mm pin. This bearing is wider and fits with no play inside the piston on the pin. I think I’m gonna ride around for 500 miles and then pull the cylinder and inspect it. I’ve ruined three cylinders in 2000 miles and I don’t want to keep going at that rate.
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Post by 90GTVert on Aug 8, 2021 9:08:11 GMT -5
I've used gouged cylinders before. The cylinder kit for my liquid cooled 103cc was about $400 and I had a couple of failures with it. Didn't want to toss it, so I did a quick hone with a ball hone. It ran fine. It's not ideal, but as long as you can make sure the edges of the gouge aren't sitting proud into the bore, it may be OK.
Sometimes pistons are more expensive than they should be, so it's never a bad idea to price out the piston kit and gasket/o-ring kit vs a whole cylinder kit and see if you think it's worth the cost of the piston with the now damaged parts or if you'd prefer all new stuff for the price difference.
I started not reusing pin bearings. I can't blame you for your choice, and I've done the same so many times. I can't even say for sure that I wouldn't reuse one that had no failures of any sort associated with it and I didn't have another around. I think it's a better idea to think of them basically like part of a gasket kit though. It still feels wasteful to me, but after winding up with so many damaged parts $15 for a new bearing isn't so bad.
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Post by captincvmn on Aug 8, 2021 9:12:31 GMT -5
I actually had to file my piston *slightly* to make the bearing slide in and out.
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shadees
Scoot Member
Posts: 83
Location: Denmark
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Post by shadees on Aug 8, 2021 10:03:31 GMT -5
The most annoying part of crashing this cylinderkit,, is because I have decided to sell the pink scooter.. So kinda just wanna get it in good shape,, without anymore biig costs.. In Denmark we have some stupid laws about moped class vehicles.. We have a big and small drivers license for these.. When you turn 16,, and get your moped drivers license,, and you are allowed to ride a small moped,, that can run 30kmt on the roads (when you turn 18,, are are allowed to drive them without a moped drivers license).. And then we have the big ones,, that are allowed to run 45kmt on roads.. You need to be 18 years old and have a proper drivers license to run these.. Just to clear out the stupity in this.. When a kid turns 16,, he can get his (or hers) tractor license,, and legally drive a tractor on the road with like 50 tons heavy equipment.. But he can only ride a small moped I have a friend that has this Aprilia Rally liquid cooled with white plates.. Meaning it's registered as big moped.. And these are FUN,, since you can get the really big bores on these guys,, and with liquid cooling.. It's gonna be my precioussssss But first I need some money to start the new project,, and the bink beast are supposed to help me with that - Frederik
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Post by 190mech on Aug 8, 2021 16:11:38 GMT -5
I agree the cylinder should run OK if it has no burrs protruding into the bore..Top end bearing should have little space inside the piston,with 2mm side play each side,the bearing WILL walk over and cause severe sideloading, failure is just seconds away!The old Spanish motorcycles used hardened steel shims on each side of the rod bearing to keep a close fit..
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