small nick in my barrel/ snapped piston ring/ shredded parts

[benandthe]

I've managed to snap my piston ring thanks to bits of metal....

Basically I was going uphill on my 70cc scooter at about 60mph and the gudgeon pin decided to get sharp, shred the gudgeon pin and spit bits of metal all around my crank and up my ports into the head/piston: https://i1222.photobucket.com/albums/dd482/Ben_Piranha_Lewis/DSC01911.jpg

Not the best moment of my life, seeing as I was on the isle of wight scooter rally.. lol

Luckily there is only very minimal damage to the barrel :

https://i1222.photobucket.com/albums/dd482/Ben_Piranha_Lewis/SAM_0175.jpg

Any ideas/ suggestions on removing the nick?
Just, carefully, get a bremmel drill on there?
Can't really port it out anymore as it's already massively ported, it's the "Stage 6 Racing 70cc" kit.
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Sold: NRG 50cc, SR125cc, CBR125cc, Mito MK 1 125cc, Speedfight 50cc, Stomp 125cc, cbr125cc, NRG 172cc, CBF 125cc, Zip 70cc, stomp 140cc
Current: CB500 (waiting on DAS)

[Dr. Quack]

If it’s a chrome bore it's a re-chrome.
If it's a cast bore it's a re-sleeve.

I'm sure there will be a re-bore kit knocking around for you scooter.
If you go for this don't forget to up-jet the carburettor.

Looks like you cay a whole new top end. (It will be a lot cheaper this way)
https://www.ebay.co.uk/itm/piaggio-nrg-polini-70cc-big-bore-kit-/270799353880?pt=UK_Motorcycle_Parts&hash=item3f0ce63818

[MickC]

You may also have to consider splitting the engine cases to make sure nothing has been left inside, last thing you want to do is rebuild the top end and then have some poxy piece of metal screw everything up again.
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Previous: CG125,XS250 (converted to 400),Z250A, GPZ550, Norton Commando, XS500, 78 Laverda Jota, GPZ1100,Harris bonneville, XV750 (mono shock),TR1

[Pete.]

[benandthe]

[benandthe]

[benandthe]

[Dr. Quack]

[Dr. Quack]

Two stroke barrels wear down the exhaust port side so place the pistion in and check for piston slap before deciding weather or not you will get away with a re-hone and an oversized piston kit.

[Pete.]

[benandthe]

Really don't know why people argue on my threads. lol

Anyhow, it's fixed and running like a dream again now, got a mate to carefully port it a little and the nick is gone now, the excess coking on the head is due to me not pre-mixing at the right ratio and having too much oil in there, so it's making a mess.

These Stage 6 kits are notorious for needing a new piston ever 3000 miles or so. oh well.
____________________
Sold: NRG 50cc, SR125cc, CBR125cc, Mito MK 1 125cc, Speedfight 50cc, Stomp 125cc, cbr125cc, NRG 172cc, CBF 125cc, Zip 70cc, stomp 140cc
Current: CB500 (waiting on DAS)

[Dr. Quack]

With forums you have to sift out the good scraps from the garbage.
With a cheap re-hone you can fit a 10th miil over sized piston kit, your your piston kits go up by say .25 then you can't.
This is realy cutting corners. I would go for the new top end if I was you.

Like i say 2 stroke barrels wear down the exhaust port side so place the pistion in and check for piston slap.

The decision will be yours young warrior.

[benandthe]

It's all good and well so far, went in for a quick dyno run at my mates shop, kicking out a lovely 10.4bhp, run on a moped dyno not a full bike dyno so it's much more accurate, all factors like air pressure and temperate and sea level elevation taken in.

He had a look at the piston and the barrel and said no issues, but the kit is designed for sprinting rather than long distance riding really.
____________________
Sold: NRG 50cc, SR125cc, CBR125cc, Mito MK 1 125cc, Speedfight 50cc, Stomp 125cc, cbr125cc, NRG 172cc, CBF 125cc, Zip 70cc, stomp 140cc
Current: CB500 (waiting on DAS)

[Pete.]

[benandthe]

[Im-a-Ridah]

[benandthe]

I was thinking about cutting out a section between the footwell and the front of the bike, behind the wheel, and having some kind of tubing going through from the front onto the head/engine. not sure how or what it would be made of, would also be wanting to fibreglass over it to make it look better.

Oh well, it works now and I don't normally ride her that far.
It's good for now.
____________________
Sold: NRG 50cc, SR125cc, CBR125cc, Mito MK 1 125cc, Speedfight 50cc, Stomp 125cc, cbr125cc, NRG 172cc, CBF 125cc, Zip 70cc, stomp 140cc
Current: CB500 (waiting on DAS)