Excellent choice for vintage racing IMO

[bitzz]

I've built numerous vintage racers from street bikes and I agree that you should start with a "beater"... if you're going to be serious about the venture. Serious as in trying to win races.
If you're SERIOUSLY building a racer. all you're going to use of the original bike is the VIN, the frame and big chunks of the motor, everything else is going to be replaced and everything that is not replaced will be FULLY refurbished.
"Serious" vintage racers are in the minority of the field

[GregT]

Rich I'll agree with your clarification. If there is a decent bike with superficial damage and lower price, that makes sense.
A tweaked frame or shock damaged engine, walk away.
The adjective "beater" means junk to to me.

A tweaked frame shouldn't put you off. You're automatically going to check it for straight anyway - and straighten it - before bracing it....aren't you ?

Last year I went through a Hyabusa roadrace sidecar engine which had been crashed. Put sideways into a shipping container barrier when the brakes failed.
Crack test everything, check everything for straight. It'd hit so hard the crank thrust bearings had been indented. Bent selectors where the pilot had tried changing down...Now rebuilt and running well again. Don't give away a potentially good engine for the sake of possible crash damage.

[Buffalo Bill]

Still looks like a person would save a lot of work and worry, starting with a clean low mileage bike.
Certainly I would be saving a lot of money and time beginning with a bike like the GS650 I posted.

As for "cutting up a beautiful bike", can anybody say this Yamaha XJ550 Seca was uglied up for racing?
I took this photo in June 2016, and you can all see he earned the #1v number plate for winning the 2015 national championship.

[RichDesmond]

it's only nice because he hasn't crashed it yet.

[Nessism]

That Yamaha has been heavily modified. Things I can see are a different swingarm, exhaust system, different brake discs, brake lines, carbs, pods, shocks, seat, oil cooler added, rear set pegs, custom paint job, and (no doubt) many more that are not visible. A better question might be: what hasn't been modified? You think that motor hasn't been cracked open and optimized too? I seriously doubt it. So imagine buying the 650E and taking it completely apart and throwing away 2/3's of the parts. What's the point in that?

[Buffalo Bill]

All bikes are nice until they're crashed. So worry about that mint 650E, maybe the new owner will lowside it, then spray bomb it black? Force ASE bolts into it, because he lost the metric bolts? Snap off all the exhaust studs, then…well the potential fk-ups are endless.
Ed I understand your values.
PS: Start a debate thread about the need to preserve or restore bikes in the condition they came from the factory, and all that means in detail.

[GregT]

All bikes are nice until they're crashed. So worry about that mint 650E, maybe the new owner will lowside it, then spray bomb it black? Force ASE bolts into it, because he lost the metric bolts? Snap off all the exhaust studs, then…well the potential fk-ups are endless.
Ed I understand your values.
PS: Start a debate thread about the need to preserve or restore bikes in the condition they came from the factory, and all that means in detail.

Both points of view are valid - but where ir's a bike produced and sold in big numbers, I see no point in worrying about preserving a good one. There's always a better one out there.
In terms of preserving bikes in factory condition, the race regs current around the world don't encourage that. Modifications are encouraged in the name of safety....Some of this I agree with, some I don't. I'd like to see some of the very high power post classic superbikes ridden on the tyres they used in the day....That would be very entertaining.
Here in NZ we have an anomaly applying to the pre63 class - Manx Nortons etc - modifications are not encouraged, they're pretty strict.
But history here is that due to lack of parts and distance from the factory, if something broke, it got modified or changed. An unmodified factory race bike was a vary rare beast. Now they're all looking like they just came out of the factory. A lot of the interest in this period has been lost IMO.

You can't make everyone happy. My local Classic/vintage club is very successful because it caters for everything. Ancient to 1990's. Bums on seats and bikes on track means a club stays alive and flourishing.

[limeex2]

Would that be up against KZ650's? What other models can be run? I ran against some KZ's back in the day that would bump up to the 750 class and they could be made to be very competitive and were bullet proof. Part of the fun of vintage racing, for me anyways, is they still look fairly stock. The production classes I used to run were a blast. All you could change was brake pads and lines, handlebars, shocks, gearing, jetting. Maybe more people would try it if they had some classes like this. Naked bikes? I would have no problem carving one up a vintage bike. Not a sought after or very valuable model of any brand.

[Buffalo Bill]

AHRMA is the only vintage racing club that's visited my home track, as far as I know.
They have many more classes, but these are where you find the GS and similar bikes.
There are more rule details like: Kawasaki GPz550, 1981 only.