RVF or VFR heads for racing?

Post by **VFRkieran** » Mon Sep 16, 2013 11:22 pm

So im going racing next year as a few will know and i have a good set of RVF heads lined up and a good refreshed set of VFR heads on the bike at the minute.

Ive heard different stories on which heads work better and would like some opinions or dyno prints to show the difference.

So from everybodys experience which will work best on the race bike? As i understand it the RVF heads have straighter intake paths to smooth the flow of air into the chamber but have a smaller diameter which could restrict outright power for better midrange, is this correct or are there more gains to be had at the top end too?

The specs of intake through to exhaust will be: full HRC F3 spec NC30 carbs, RVF cams, NC30 bottom end (because i like the gearbox) Maybe a little bit of DIY porting following the F3 manual, and a HRC kit exhaust.

So do i save the hassle of removing the heads and keep the standard NC30 ones, or fit my nice NC35 heads to possibly get a few more ponies?

As allways any advice will be hugely apreciated,
Kieran.

scooble · Post by **scooble** » Tue Sep 17, 2013 6:52 pm

I looked at the F3 manual in the docs section, but its in Japanese and the pictures are a bit crappy, does anyone have an english version with decent pictures?

Post by **Drunkn Munky** » Tue Sep 17, 2013 7:06 pm

I wouldnt run f3 spec carbs on anything but a f3 spec engine mate as its massively different, your be better off with ss/sp spec carbs.

contact yakama for the english version of the f3 manual, he's probably got some listed on ebay too.

Post by **VFRkieran** » Tue Sep 17, 2013 7:17 pm

Ooops i did mean SS/SP carbs, will just be the normal HRC spec carbs that most people use for racing. Had a bit of advice and i will just keep the RVF heads as spares incase anything goes tits up.

Still interested to hear which are considered to be the best though.

Post by **Drunkn Munky** » Tue Sep 17, 2013 7:21 pm

From what I've been told the rvf engine is the engine of choice when tuning for racing but as your entering the sub 64 class thats not going to matter really as your easily achieve that from the vfr.

Yakama · Post by **Yakama** » Tue Sep 17, 2013 7:52 pm

scooble wrote:I looked at the F3 manual in the docs section, but its in Japanese and the pictures are a bit crappy, does anyone have an english version with decent pictures?

Yup scooble I have them for sale, PM me if you are interested £30 posted, cheaper than on my ones on ebay for forum members

Post by **VFRkieran** » Tue Sep 17, 2013 8:05 pm

Yakama wrote:
scooble wrote:I looked at the F3 manual in the docs section, but its in Japanese and the pictures are a bit crappy, does anyone have an english version with decent pictures?
Yup scooble I have them for sale, PM me if you are interested £30 posted, cheaper than on my ones on ebay for forum members

Wish id have known you sold them cheaper on here when i bought one a few weeks back lol

Post by **Cammo** » Wed Sep 18, 2013 2:38 am

Mike Norman prefers the rvf heads (and bottom end) for his big hp big-bore engines: http://mngforce.typepad.com/nc450vdev/n ... st-go.html

But if your nc30 engine is in good condition I don't think it's worth pulling it apart for the sake of a couple of horsepower.

Post by **VFRkieran** » Thu Sep 19, 2013 12:01 am

No doubt the RVF has the better power when tuned then, i think the biggest restriction on top end power must be in the carbs rather than the engine.

I think i will carry on with my VFR heads and just keep my set of RVF ones as spares and use them when i need to. Shouldnt struggle to get 64bhp from my current motor which will put me in the in the class with the highest chance of getting a half decent result or two.

Post by **lukemillar** » Thu Sep 19, 2013 9:52 am

VFRkieran wrote:No doubt the RVF has the better power when tuned then, i think the biggest restriction on top end power must be in the carbs rather than the engine.

I think i will carry on with my VFR heads and just keep my set of RVF ones as spares and use them when i need to. Shouldnt struggle to get 64bhp from my current motor which will put me in the in the class with the highest chance of getting a half decent result or two.

If you're new to racing - don't get hung up on chasing HP right now. You'll be overwhelmed learning so much about riding the bike competitively that a few extra ponies here and there won't make much difference right now. After a season or two, that'll change completely though!

I did my first season and half the second on the NC30 on a completely stock engine.

RVF or VFR heads for racing?

RVF or VFR heads for racing?

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