Archived Posts

[Admin]

FYI, I checked out Ralph Hudson's TR500 and he's using a KR164 on rear and a KR124A on front.

I'm thinking of going to this combo to get some more ground clearance. On of the problems I'm having is grounding out the chambers when cornering, especially on the right side. This certainly limits the lean angle, 'cause when hard parts start touching the ground.....

[Admin]

FYI, I checked out Ralph Hudson's TR500 and he's using a KR164 on rear and a KR124A on front.

I had thought about those as well. You may have changed my mind. I do believe that Dave Crussel used those on the H1R as well.

[Admin]

I guess Dunlop is the favored tire of vintage road racing? Any other brands worth considering? Avon, Bridgestone, Metzler?

Jim

[Admin]

Avon would be the other choice. Bad thing about Avons is that they are not current in their racing compounds and after about 5 racing weekends they can go away from you without notice. Even though the tread still looks good.

[Admin]

Dave Crussel does run the KR124A front / KR164 rear, but he also runs WM4 front and WM5 rear rims.

[Admin]

Dave Crussel does run the KR124A front / KR164 rear, but he also runs WM4 front and WM5 rear rims.

10.3.5 FORMULA VINTAGE: Includes 500 Premier, Formula 750, Sportsman 750 and Formula 500. Also includes Honda CB550 four-cylinders.
NOTE: If you have a machine you believe would fit into this class but is not listed, submit an eligibility request form found on page 95.
103.6 REQUIREMENTS AND MODIFICATIONS FOR FORMULA 125/250/500
a) All machines must be no-compromise Grand Prix racers (i.e., clip-on or low, narrow handlebars; no lighting equipment or related brackets, except that factory-welded brackets may be retained if desired; no starting mechanisms; no street equipment of any kind, including brackets).
b) All machines must be equipped with racing exhaust systems; silencers are required on two-strokes and encouraged on others.
c) Any drum brakes (front or rear) of the period are permitted.
d) One front rigid-mounted steel disc brake may be used on F-125 and F-250 machines, and two front rigid-mounted steel discs on F-500 machines. Calipers must be period type with a maximum of two pistons. Late-model alloy types are prohibited.
e) Rims—Formula 500: Wheel rim diameter must be at least 18 inches and not exceed WM3 (2.15 inches) front and WM5 (3.00 inches) rear. Formula 250: Wheel rim diameter must be at least 18 inches and not exceed WM3 (2.15 inches) front and WM4.5 (2.75 inches) rear. Formula 125: Wheel rim width must not exceed WM3 (2.15 inches) front and rear.
f) Honda four-cylinder machines may use Keihin CR Special carburetors in all Formula classes. Maximum 26mm for CB350/400 fours in Formula 250 and Formula 500.

According to the above if he is running a WM4 front than it is illegal.

[Admin]

My mistake, must be WM3 front and WM5 rear for Dave.

[Admin]

I invite views to the contrary, but I think bracing a swing arm on a T500 is not time or money well spent. I weigh in at a svelt 270lbs fresh outta the shower, probably more when I put on a brain bucket and two or three cows worth of leather. I followed Muzza's guide for building a T500 and have found it to track like it is on rails. Krash rode it a couple of years ago and I believe he found the same thing.

Come to think of it, I don't know anyone that has braced the swingarm. This might matter if the bike was going to produce 100+ hp but admittedly T500's probably produce less than that (more like 98.7hp, right ).

PS and before Jim gets all over me for it, yes, I will post a pic of the race bike shortly.

[Admin]

I invite views to the contrary, but I think bracing a swing arm on a T500 is not time or money well spent. I weigh in at a svelt 270lbs fresh outta the shower, probably more when I put on a brain bucket and two or three cows worth of leather. I followed Muzza's guide for building a T500 and have found it to track like it is on rails. Krash rode it a couple of years ago and I believe he found the same thing.

Come to think of it, I don't know anyone that has braced the swingarm. This might matter if the bike was going to produce 100+ hp but admittedly T500's probably produce less than that (more like 98.7hp, right ).

PS and before Jim gets all over me for it, yes, I will post a pic of the race bike shortly.

I had a 71T500 that would "rearsteer" if you got on the rear brake firmly in a corner,I believe that was caused by swingarm flex,but coulda' been the crappy Goodyear Eagles that were on it.

[Admin]

I invite views to the contrary, but I think bracing a swing arm on a T500 is not time or money well spent. I weigh in at a svelt 270lbs fresh outta the shower, probably more when I put on a brain bucket and two or three cows worth of leather. I followed Muzza's guide for building a T500 and have found it to track like it is on rails. Krash rode it a couple of years ago and I believe he found the same thing.

Come to think of it, I don't know anyone that has braced the swingarm. This might matter if the bike was going to produce 100+ hp but admittedly T500's probably produce less than that (more like 98.7hp, right ).

PS and before Jim gets all over me for it, yes, I will post a pic of the race bike shortly.

But reading through Muzza's race prep guide, he recommends both shortening AND bracing the swing-arm with angle iron.... I don't remember if you shortened your swing-arm or not? I'd imagine a shortened swing-arm would be at least a little stiffer?

As for the pics... I'll believe them when I see them! (after all you have had almost 12 hours since you posted - next you'll be telling me you had work or something!)

Jim

[Admin]

ive always run 2.15 (wm3) on rear and 1.85 (wm2 on front for all my T500 and TR500 racers..
the factory Tr500's ran the same..
I also have doubts that you would even fit a wm4 or 5 in a standard 500 swingarm without having to run a narrower than standard tyre width to prevent the chain/swingarm rubbing ..

I sorta cant understand why you would go any wider than that on a 60 to 70 hp bike? you are only sacrificing corner speed and handling by using a wider tyre.. I seriously doubt you will have traction problems!

Idealy Wm2's on front and back would work great on a mildy tuned 500..

[Admin]

Finally got a spare moment to get out to the garage and take some pics.
For starters.

The bike started as a 1972 and I put a GT500 engine into it after getting frustrated with the points. I had a set of twisted rearsets from a Katana lying around so I modified them up for rearsets. The chambers were made by a fellow in our VRRA group, and the seat is a H2R knockoff. The tank from an RD350LC. Some of the neat stuff that I'm proud of is the oil tank in the seat hump and the way the bracing lines up with the tank.
Presently I have an electrical gremlin that needs to be exorcized.

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[Admin]

Very nice I like.

[Admin]

Looks good Mowgli!

How about a list of specs?

Jim

[Admin]

Hey Shannon,

What tyres (both size and brand) do you like for your racers? Interesting thoughts on the rim sizes....

Jim