Hi all, I have just bought an NC30 VFR400 race bike which I am in the process of rebuilding. I have a couple of questions I hope you can help me out with.

I've stripped the bike down to do full chassis re-build, and it is a very neat little thing. It has the 17" rear wheel conversion, braided brake lines, twin 2-into-1 pipes, all superfluous electrics removed, carby tray with open carbs. The suspension has been re-worked judging by the alternative springs fitted.

The frame is light and well built, but I can't believe how heavy that ProArm is. Is there a regular way of lightening it? I figure you must be able to do something with the rear brake assembly, considering I don't use the back brake at all when racing. I could machine the disc thinner. Is there anything that other people have already done?

This bike has a 17" wheel fitted. I read posts that say you should change the links to RC35 to retain the geometry. How can I tell if my links have been changed? What are the standard dimensions? Are there any ride height adjusters available?

Actually, I just checked the overall diameter of the 17" and 18" wheels, and with the tyres that are on them, they are the same, so there isn't a geometry change. The 17" has a Bridgestone 165/630 (630mm outside diameter) slick, and the 18" has a 150/60 treaded Michelin.

The front engine mounts were broken off the cylinder head, which apparently is a fairly common problem, so it's off to the welder to get them fixed. Judging by the coolant leaking from the exhaust joints, the front head gasket is blown, so I have to take the head off anyway.

Hopefully, this project won't take too long (famous last words )

Good luck!

Broken mounts is classic signs of a good crash.

How much time and money do you have to throw at it?

If you want light light then ditch the pro-arm and fit a traditional arm. I've seen a few 30s running traditional swining arms, also elimates a lot of wheel issues.

From memory they were

I think its RCV4 on here that has a traditional swinger in his NC30 race bike.

Lasse's race bike has an SP2 swinger in it.

Broken head mounts = just get another head, far easier. The race bike I built had broken head mounts, turns out that the frame mounts were also buggered. New frame...

Thanks for the replies.

I suspected a normal swingarm would be lighter. But a large part of the character of the NC30 is the ProArm, so I'd like to keep it. I think I'll fit a lighter disc and replace some of the big bolts with something lighter.

There don't seem to be any replacement heads available at a good price, or any price, in Australia at the moment. I'm getting the head welded up by an aluminium welder who specialises in castings, mag wheels etc. for $80. I have to remove the valves and seals as he pre-heats the head and he doesn't want to damage the valve parts.

Who knows what's happened to the frame in its previous life as a race bike? If is hasn't been down the road, they weren't trying! I'm going to check the frame for straightness, but it looks undamaged. There are no dents or scrapes on the frame, so that's a good initial indication.

be careful with the valve seals, they are pricey if you need to replace them.

Good advice, I'll be careful with the valve stem seals.

i might be incorrect but im sure they have to be replaced if you remove them from the head? Current prices from Honda are about £9 a seal and a little less from CMSNL and david silvers, at those sort of prices its probably going to be cheaper buying a good second hand head from abroad.

There are weight saving options for the pro arm swinger but it doesn't come cheap, custom hangers for mini ISR and brembo calipers can be had, and then you have lightweight axles which are super rare but not unobtainable.

If you weigh it up against to have a conventional swinger properly fitted and setup there's probably not going to be a lot of difference price wise, id like to know how the 2 compare weight wise though, has anyone ever weighed a pro arm and all the gubbins?

Power Sports Plus in usa have valve stem seals for $6.00 ea and head gaskets for $26.00 ea, I am waiting for confirmation of availability. Postage varies with price would be about $20.00 for purchase up to $60.00, worth considering.