RVF or VFR heads for racing?

[28hodge]

Luke speaks the truth, I’ve just finished my first half season with Bemsee in Sub64.

I'd done 5 trackdays (4 of which were at Oulton) before entering my first race, I'd used racechrono on the trackdays and my best time was a 2.18. My first race at Oulton was with wirral100 at the end of Apr. After the weekend I'd taken 4 seconds off best, despite conditions being worse than they had been for the trackdays.

I entered Bemsee’s Oulton round at the end of May early June, and took another 7 seconds off my previous best. So after just 4 races I went from 2.18 to 2.07 laps, making zero changes to the bike. Thats an 11 second improvement over no more than 40 laps if you take qualifying into account, that’s over 1min 15sec improvement over a 7 lap race distance (more than half a lap most of the time)

Do not worry about trying to get everything out of the bike power wise, you’d be a lot better off concentrating on making sure the bike runs 100% and it does this 100% of the time, it’s very frustrating for example your on for a really good result and making good progress through the field and probably heading for your best result to date only for the earth cable to come loose and the bike stop on lap 4 of a 7 lap race (ask me how I know this)

A. Your losing expensive track time
B. Your losing a good result
C. Your eroding a bit of confidence in your bike which isn’t good.

For the first two years the biggest limiting factor will be your riding and not the bikes performance. I can 100% guarantee that someone doing laptimes 5 secs or more better than mine could get on my bike and still do them laptimes give or take.

When i decide that the bike is beginning to hold me back I will look at weight and handling before power as I think (certainly in sub 64) this is where biggest gains will be had.

As long as your bike isn’t a total dog and only giving mid 50’s on a dyno it’ll be fine.

Are you going to race with Bemsee next year, the provisional calendar is out and looks good,I’ll be doing the northern rounds again, so Oulton Donington Cadwell and Silverstone, and need to go and do Brands GP as well despite it being over 6hrs away!!

If you need any help or anything from someone who was where you were last year drop me a PM and I’ll do my best to help.

[VFRkieran]

Thanks for the help guys all the info is really useful and definatly been taken on board, ive decided that im not going to be buying any more fancy pants bits until i actually need them, apart from a set of PFM cast iron discs as ive wanted some for ages :D

I cant beleve how much you knocked off the laptimes at oulton mate impressed with that, my goal is to take 10-12 seconds off the best time i did at Cadwell at the trackday back in august, its made me realise that i dont need to go spending loads of cash to get more power or worrying about this and that right now, just need to focus on getting out there and actually racing the bike.

The actual bike is sound and im more than happy with it, i know its been put together properly and nothings fallen off in the 3500km since i rebuilt it so i must be doing something right, only thing thats niggling in the back of my mind is a little puff of blue smoke when changing down for mansfield at cadwell, however its not causing a noticeable drop in oil level and i think i may have been a little heavy handed shifting down for the turn.

Yea i will be going with Bemsee and maybe EMRA, just trying to cram in as much as possible for the least possible outlay, Cadwell, Brands and Mallory are the 3 im looking to enter but that may change depending on how much cash i can save over winter whilst doing my driving test and buying a van.

So thanks again and its time for me to get a move on as my Car theory test is in 45 mins, wish me luck!

[scooble]

I had a bit of an up and down season on a KR1 (long story),
however, I have an NC30 as a road bike, but when I got it, I had to do a complete engine strip as the head was leaking oil.
Whilst the engine was out, I re-cut the valve seats and removed some of the nasty casting flashes, lumps, bumps and sharp corners with a dremel, and put it all back together with new stem seals, RVF pistons and rings as well as a 3/4 Yamamoto system (which I wrapped as far as the 2:1 sections)....still loud though!
I have also accumulated a few spares from here and there, such as a complete spare engine as well as a set of RVF cams, so I'd be interested to hear how the NC30 head RVF cams combo works.
By all accounts, the lift is the same, but the duration is longer, so the Volumetric Efficiency should be better, and if optimised with the correct jetting, should in theory be an advantage.

I'll probably get my jetting set up on the dyno as is, then I might try bunging the RVF cams in (should be possible with the engine in frame) and see how that does on the dyno

[iron chef]

Are you racing a 400 next season then scooble?

[scooble]

I'll still try and campaign the KR1 if I can get some good power from it, I have a few options to try. I'll do some mods to the NC over the winter months like adding a ZX636 front end and a 5" VFR750 rear wheel (simply because I cant stop myself fiddling), and whether I race it or not, the mods I think will still make it a better road bike.
....trouble is, it simply doesnt go ring a ding a ding

[lukemillar]

If you need any help or anything from someone who was where you were last year drop me a PM and I’ll do my best to help.

DItto from me. I may in in NZ but have been racing for 5 years now (2.5 on the NC30) so am happy to help anyway I can.

I think the main piece of advice I would give would be to always make sure you enjoy yourself. That was the main reason I switched from Supersport to Post Classics and I haven't regretted it one bit!

[VFRkieran]

@ scooble not sure if you have seen my build thread but last winter i stripped and rebuilt the heads with new stem seals, re ground valve seats, and a bit of polishing to the chamber, didnt dremel the inlets as i couldnt get hold of one as funds where a bit tight, im in a much better position this year cash wise but dont have as much time.

On the subject of RVF cams they are also much lighter allowing the engine to rev up quicker, the bike felt so much more powerful compared to before the rebuild but i also fitted a full system, rejetted and checked the valve clearances so im not sure how much of that was down to the camshafts alone. Still havent had it on the Dyno to see what BHP its producing but maybe this week seeing as the weathers good i may get a chance to ride over.

Thanks again Luke, i may be in contact shortly had a little chat with Mark about racing in general the other day so hopefully im heading in the right direction from following his advice. I do hope i can allways enjoy myself when doing it ive still got a long way to go and a few long evenings in the garage prepping the bike. I have also read your race thread a good few times and found it very useful, have a couple of ideas of where i want to go with the bike if i get into it seriously and a good few are taken straight from your thread.

Oh i passed my car theory test this afternoon so i am one step closer to getting my van, watch this space...

[Cammo]

I'm not convinced that the rvf cams are responsible for much of a power increase, but the design is better suited to high rpm running.

Enjoy yourself on the track Kieran, sounds like you're going to have a ball. I went through it all a few years ago now, had plenty of fun, some big scares at high speed, but now want to do it again...

[CMSMJ1]

We all want to do it again Cammo...

My advice - get out and get it done and then worry about the rest of it.

[scooble]

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.

What is the SS/SP spec carbs anyway?