NF5 Pistons & Rings

This is the place to talk about Two-Stroke road race machines from Honda.
User avatar
RC45
Posts: 207
Joined: Wed Nov 18, 2015 12:31 am
Location: YZR Wannabe - Houston, TX
Contact:

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?
3MA track refugee
YZR500 OW81 rep
NS400 track refugee
TZ500V track refugee
1RK Silhouette TZ535
2KM
NF5

abond
Posts: 152
Joined: Wed Oct 12, 2016 9:49 pm

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.
BRS Racing #61
VRRA Competition Coordinator

trev45
Posts: 166
Joined: Mon Jan 11, 2016 10:18 pm

Re: NF5 Pistons & Rings

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

PM sent too David

Cheers Trev

User avatar
RC45
Posts: 207
Joined: Wed Nov 18, 2015 12:31 am
Location: YZR Wannabe - Houston, TX
Contact:

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?
3MA track refugee
YZR500 OW81 rep
NS400 track refugee
TZ500V track refugee
1RK Silhouette TZ535
2KM
NF5

trev45
Posts: 166
Joined: Mon Jan 11, 2016 10:18 pm

Re: NF5 Pistons & Rings

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

Clearance

2 thou cast piston
3 thou billet piston

Cheers trev

User avatar
RC45
Posts: 207
Joined: Wed Nov 18, 2015 12:31 am
Location: YZR Wannabe - Houston, TX
Contact:

Re: NF5 Pistons & Rings

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

Thank you sir.

Much appreciated.
3MA track refugee
YZR500 OW81 rep
NS400 track refugee
TZ500V track refugee
1RK Silhouette TZ535
2KM
NF5

parillaguy
Posts: 21
Joined: Thu Sep 17, 2015 1:21 am

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

lesviffer750
Posts: 38
Joined: Mon Dec 28, 2015 5:15 pm

Re: NF5 Pistons & Rings

Postby lesviffer750 » Sun Oct 22, 2017 8:46 pm

Agree with parillaguy, never seen sizes on HRC pistons, mind you i have only ever used genuine ones in my nf5, i do know that for 92 honda modified the pistons for the last year of nf5's, the skirt is slightly longer to help stabilise the piston, i have two of these later ones installed at the moment, plus two in a spare motor.

User avatar
RC45
Posts: 207
Joined: Wed Nov 18, 2015 12:31 am
Location: YZR Wannabe - Houston, TX
Contact:

Re: NF5 Pistons & Rings

Postby RC45 » Tue Oct 24, 2017 3:03 am

I hear you guys, but just wanted to make these piston crown marks did not mean anything regarding being part of matched sets or 'A' or 'B' pistons.

I have 2 sets of new HRC pistons and 1 spare set with the spare barrels.

Image
Image
Image
Image
Image
Image
3MA track refugee
YZR500 OW81 rep
NS400 track refugee
TZ500V track refugee
1RK Silhouette TZ535
2KM
NF5

lesviffer750
Posts: 38
Joined: Mon Dec 28, 2015 5:15 pm

Re: NF5 Pistons & Rings

Postby lesviffer750 » Tue Oct 24, 2017 6:43 pm

Strangely enough the NSR250 road machine, which the nf5 engine was designed on, uses 3 different size barrels and pistons ie, A barrel= B piston, B barrel= no mark piston and C barrel= D piston, although this is not realy critical in my opinion, in the hey day of F3 racing in Asia the top riders would mix and match barrels and pistons on their NSR's depending on the type of circuit. Not sure if a lot of people are aware, but, a proper factory F3 nsr is stuffed with a lot of nf5 parts.


Return to “HondaTalk”

Who is online

Users browsing this forum: No registered users and 1 guest