Scored barrel?

[impulse1985m]

If my Aprilia RS125 barrel is slightly scored by the exhaust from a shattered piston ring then would that be okay to just put a new piston and rings in and maybe loose a bit of compression which I'm not fussed about.

Ste

[Kickstart]

Hi

That would depend on how deep the score is, but quite possibly you will loose too much compression for the engine to run.

As a guide my old Futura scored the barrel when a ring snapped. The score was around 0.5mm deep, and just a touch wider than that, with one ring still OK. The engine would not run like that.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[impulse1985m]

The score is just above the exhaust port and is very minute. I have a new piston and set of rings ready to put in now, would that be a wise idea?


Ste

[Kickstart]

Hi

Without seeing it, I cannot really say. However if it has gone through the plating then I would say it needs replating / replacing. The alloy under the plating will wear very quickly.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[impulse1985m]

Roughly how much will that cost?

Ste

[Kickstart]

Hi

Not sure. A new barrel is something like £250 the last time I asked (could be more or less now), while replating it will be around £100.

For new engine parts go to Peter Knight on 0176 141 4106. For the replating there are a few people around, such as PJ Engineering in Wolvo.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[impulse1985m]

Im just getting some pics of inside the barrel now, hold on 2 ticks.

[impulse1985m]

My camera's not good enough to get a sharp closeup. What about getting the barrel re-bored? Is that worth doing?

Ste

[Kickstart]

Hi

The standard barrel is plated and cannot be rebored. There is just a thin layer of "chrome" over the alloy of the barrel. If you rebored it you would remove all the "chrome". Also if you rebored it you would need a matching larger piston.

However some people can bore the barrels out and insert a cast iron liner. This costs about the same as replating, but does mean that you can rebore the barrel. I am afraid my only experience of this was not a good one so it is not something I would try myself.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[impulse1985m]

Who would I need to contact to replate the engine?

[Kickstart]

Hi

I think there are 3 or 4 places in the UK that can replate barrels. PJ Engineering (www.prox.co.uk) is one, another in Lancourt Ltd who are on 01934 612226 I think. Most other places just send it to one of the limited number who can actually do the job.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[impulse1985m]

When they replate it, do they fill and score with the plating?

[Kickstart]

Hi

I believe that they remove the old plating and weld in the score to fill it, machine it to specification and then replate it.

I would suggest that you take the barrel to a place you trust to get a 2nd opinion before sending it off if you are in any doubt as to whether it is required.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[impulse1985m]

Okay, thank you for your help again. I will contact PJ tommorow and get their oppinion.

Cheers, Ste.

[Kickstart]

Hi

Good luck, hope you get away without needing to repair it!

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing