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scored cylinder


tomarnold
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With all this crappy weather I finally got round to decoking my motor and servicing the carb.

I was pleasantly surprised to find how easy these jobs were, but unpleasantly surprised by the two scores in the cylinder wall. The piston looks unmarked. My motor (Rad Arrow with Raket 120) has been running absolutely fine, but I'm wondering if I should get this sorted? I'm not experienced in the internals of engines - I've always serviced my own motorbikes and cars, but never messed about with cylinders and pistons before. A new cylinder from Radne is about £250 which seems a bit steep, and I'm not sure it's necessary considering how well the motor was running. Is it expensive (or indeed possible) to have the cylinder replated? Would you just take it to your local motorbike shop?

For the time being I have put it all back together so it's ready for when the weather clears up, but I need to know if I ought to be sorting out this cylinder scoring issue.

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There are only two companies in the Uk who carry out the plating.

http://www.poetonaptec.co.uk. I have used these before. Very good. They dress and chamfer the port windows nicely. Which should be about 1mm @ 45degrees.

http://www.langcourt.com Also get good reports from bike forums.

They will both deal direct with you.

Just remember to strip ALL steel fittings from the barrel, as the acid used to strip old coating will eat away completely.

If you are replacing the piston. Send that with barrel so that they can size the bore correctly to allow for thermal expansion.

Always check the port chamfers when the barrel is returned. Otherwise it could end up snagging a ring and buggering the barrel completely!!

A diamond file is about the only thing that will dress the plating.

Any ally smeared on the barrel (from seized piston) can easily be removed with 1200 wet/dry and lots of water.

As stated, if you can feel the scratches with fingernail, ideally its re-plate time.

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