NF5 Pistons & Rings

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RC45
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Re: NF5 Pistons & Rings

Postby RC45 » Tue Oct 03, 2017 12:30 pm

And here is a followup - what marking on my barrels denotes A, B or C spec piston usage?

The casting marks on my RS250 are 12217B on the front cylinder and 12107A on the rear cylinder.

Does this mean 1 uses an A and the other a B piston??

Is this normal or perhaps a little tuning trick from back in the day when this bike was bashing fairings in the Japanese 250 race series?
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abond
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Re: NF5 Pistons & Rings

Postby abond » Tue Oct 03, 2017 7:09 pm

If they've been bored and re-coated the marking may or may not be accurate. Best to just check with a bore gauge.
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trev45
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Re: NF5 Pistons & Rings

Postby trev45 » Tue Oct 03, 2017 9:54 pm

PM sent too David

Cheers Trev

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RC45
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Re: NF5 Pistons & Rings

Postby RC45 » Tue Oct 03, 2017 10:28 pm

abond wrote:If they've been bored and re-coated the marking may or may not be accurate. Best to just check with a bore gauge.


Is there a chart of what bore size range is appropriate for specific piston types?
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trev45
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Re: NF5 Pistons & Rings

Postby trev45 » Sun Oct 15, 2017 4:22 am

Clearance

2 thou cast piston
3 thou billet piston

Cheers trev

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Re: NF5 Pistons & Rings

Postby RC45 » Wed Oct 18, 2017 1:23 am

Thank you sir.

Much appreciated.
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parillaguy
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Re: NF5 Pistons & Rings

Postby parillaguy » Sun Oct 22, 2017 2:43 pm

Just to be clear...I have never seen a RS125 or RS250 piston from HRC with a 'size' on them. You get one piston in the box. As for NF4 VS NF5 pistons. I still have some of both and they are not the same. The dome profiles are a bit different. Will they interchange? YES! I run NF4 HRC pistons in my RS250. HRC did sell different NX4 and NX5 pistons but stopped selling NX5 pistons and supplied NX4 when you wanted a NX5 RS250 piston. parillaguy


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