Pistons

[Jamboy]

Is it true that NC35 pistons are lighter than NC30 ones?
Just wondered if there would be any benefit changing them over to 35 ones and has anyone done this already and noticed a change in performance?

[reverse cylinder jim]

Is it true that NC35 pistons are lighter than NC30 ones?
Just wondered if there would be any benefit changing them over to 35 ones and has anyone done this already and noticed a change in performance?

Think they are higher compression than the nc30 ones, dont know if they are any lighter as ive not weight mine yet. Not sure about if they offer any real gains but everyone seems to be running them on race bikes etc so i will be running them in my new engine.

[lukemillar]

I was looking at an old thread on here (think it was for a 57mm piston group buy or something?)

Anyway, Mike Norman had listed the weights of both stock NC30 and NC35 pistons + HRC NC30 as well as some other aftermarket brands. I'm pretty sure the weight difference between the NC30 and 35 is negligible

[lukemillar]

Found the info:

JE 444cc: 147.6g
OE VFR: 133.4g
OE RVF: 133.3g
REC 57mm: 127.6g
CP 57mm: 119.5g
Cosworth: 118.0g
HRC 55mm: 117.2g

Mike Norman
G-Force Engine Development

[ciweed_xest7]

May i know, can we use VFR NC 30 piston for RVF 400 NC 35? is it just the same piston or need reboring work to the block? please anyone?

[skinnydog0_0]

Yer you can use 30 pistons in a 35 no need to rebore. 35 pistons i believe give a higher compresson ratio so are the piston of choice if you have to replace them.

[Cammo]

35 pistons i believe give a higher compresson ratio so are the piston of choice if you have to replace them.

I've heard this numerous times on the forum but I'm not sure that it's correct. I guess only the engine builders will know.

They are a newer, slightly altered design. The nc30 pistons are no longer available, have been discontinued.

[skinnydog0_0]

35 pistons i believe give a higher compresson ratio so are the piston of choice if you have to replace them.

They are a newer, slightly altered design. The nc30 pistons are no longer available, have been discontinued.

I guess thats why they are the piston of choice

[scooble]

can someone confirm whether the NC35 pistons are the same of higher CR than the NC30 ones. From what I've read elsewhere, their weight is about the same too, is this also correct?
Is there any advantage in fitting NC35 pistons in an NC30 engine?

[Neosophist]

can someone confirm whether the NC35 pistons are the same of higher CR than the NC30 ones. From what I've read elsewhere, their weight is about the same too, is this also correct?
Is there any advantage in fitting NC35 pistons in an NC30 engine?

the weights are listed in this thread! 0.1g difference.

NC30 pistons are NLA, but if your thinking of doing it just for the crack of it then there isn't any reason to make special effort.

Regarding piston design difference.

Honda stated in their RVF press release that the RVF piston achieved on average 3% weight reduction over a standard VFR400 piston, it also has less reistance than the VFR piston.

This should help throttle response slightly as their is less friction in the bores.. but dont' forget the RVF also combined this with different carbs, intake design and smaller valves to increase turblance and velocity of air. and a lighter flywheel.

Something was also changed in the exhaust piston hole by 0.5mm to reduce audiable slap

You can read about the piston design changes here as well as all of the other press info on the RVF in the Honda RVF400 factbook

http://www.honda.co.jp/factbook/motor/R ... 0/005.html

I believe compression ratio was the same