Bonneville Daydream

Generally, as for which is more aerodynamic, I'd guess the JPN because it's fairing is wider and likely a bit taller too. The rider has to fit behind the fairing for it to do any good. Most road racing fairings are for pro riders who typically are the size of chimps.

Grandpaul - thanks for sharing that. I never ran at Bonneville but I have spectated there and it's a magical mind bending unforgettable experience.

grandpaul said:

Production Racer would be a far better idea than the extremely overweight JPN.

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I don't think the PR is actually legal for the class (at least with SCTA). The requirement is that 500 of them have to have been produced and for sale to the general public through dealers. Norton made far less than 500 PRs. With AMA, the wording is a little fuzzier, as quoted here:

"A “production motorcycle class” is as “produced by a recognized manufacturer," and the public must be able to purchase a minimum of 500 frames through retail dealers. Production class motorcycles shall not be modified from original equipment at time of manufacture. e.g., frame, forks, gas and oil tanks, seat, front and rear lighting, fenders, wheels, brakes, air intake box and (unmodified) exhaust system. They shall also contain the engine that they were originally produced with. Driveline method/type must remain stock (i.e. belt drive must remain belt drive)."

With either group, you might get away with running a PR in the Production class, or you might not. It would depend a lot on how knowledgeable the tech guys are, and whether anyone protested. You could claim that the PR was just another Commando model (true), but I don't know if that would fly. I'd get a reading from the tech guys (in writing) before starting in that direction.

Ken

Since there were only 200 JPNs built, the PR stands a bit better chance.

FOR SURE the public could purchase more than 500 frames!

You got it right, GP, it is an experience you'll never forget. And seriously addictive. I was there in 2008, but just as a spectator. Don't remember if we got to chat or not.

This was my last successful attempt at Bonneville, in 2006. After that it was just abortive attempts with the streamliner and a fun, but unsuccessful, attempt with this bike and a 920 on nitrous..



I did manage to get the class record at 126.461 mph, but it didn't last very long. In 2008 Tom Mellor bumped it up to 180.317 mph with his very streamlined Triumph triple. It would take a much more serious aero design (and a lot of horsepower!) to get near that on a 750 Commando.

grandpaul said:

Since there were only 200 JPNs built, the PR stands a bit better chance.

FOR SURE the public could purchase more than 500 frames!

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I didn't realize so few JPNs were built. I think the total number of PRs built has also been reported as somewhere around 200, or maybe a little less.

I think that means that neither one is legal with SCTA, but maybe with AMA. Someone would probably have to try it to find out for sure.

Ken

Interesting stuff guys. Is there some kind of ‘eligibility officer’ as we have for classic racing here in the U.K.?

It’s a hell of a risk to build a bike and get all the way there just to be sent back home!

You could take your lawyer with you, and sue the organiser for your costs and mental anguish, if the rules are misleading.

Fast Eddie said:

Interesting stuff guys. Is there some kind of ‘eligibility officer’ as we have for classic racing here in the U.K.?

It’s a hell of a risk to build a bike and get all the way there just to be sent back home!

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With SCTA there's a Chief Motorcycle Inspector, the chair of the Motorcycle Technical Committee, and a Motorcycle Rules Committee. If I were unsure of the meaning of any of the rules, I'd contact them. I'm sure there are similar officials one could contact for questions about AMA eligibility.

The rules are actually pretty well stated in the rule books, but if you're deliberately pushing the limits on something like the definition of a Production bike, it would be wise to enquire first. About the only question that's been raised here is whether the PR or JPN could be run in the production class. I'm pretty sure not, but I'm sure you could get a determination before starting to build one. In my experience, the tech inspectors are much more interested in safety issues, and unless there's a blatant attempt to run in the wrong class, they don't usually worry about that. The problem comes when you set a record and someone protests. That's mostly when eligibility issues come up.

If you seriously want to try to build a PR for the 750 class, let me know, and I'll take it up with the technical guys at the next club meeting (SCTA is composed of a collection of clubs).

Ken

Thanx, Ken. It will be very helpful to clarify that. The same would hold for the 8-valve Triumph TSS, there were only 238 built.

I thought about the TSS as well GP, that would be a strong contender.

But they were 1982-83 whereas the production 750class is pre 1082 isn’t it? So I think they’re out on date alone.

For some bikes, actual number produced may be difficult to prove. The TSS is one of those cases, I’m pretty sure the figure was closer to 400 in total (maybe 238 into USA?) but there are different opinions out there and factory records aren’t as clear as we’d expect today.

Fast Eddie said:

I thought about the TSS as well GP, that would be a strong contender.

But they were 1982-83 whereas the production 750class is pre 1082 isn’t it? So I think they’re out on date alone.

For some bikes, actual number produced may be difficult to prove. The TSS is one of those cases, I’m pretty sure the figure was closer to 400 in total (maybe 238 into USA?) but there are different opinions out there and factory records aren’t as clear as we’d expect today.

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The difference between SCTA and AMA classes can be a little confusing here. Both have Production classes, with no date limitations. Only AMA has the Production Classic classes. The rules are the same, except the Classic classes are limited to bikes produced prior to 1981. The problem with the classic classes, at least for us Commando fans, is that we would be competing against a bunch of more modern designs, i.e. four cylinder DOHC engines, 750 2-stroke triples, desmos, etc. As soon as someone gets serious with one of those, the record will be out of reach for us. That's the reason I like running in the pushrod classes. At least I'm only competing with other pushrod engines. AMA and SCTA both have separate Pushrod classes in most categories, but AMA does not have a separate pushrod category in the Classic classes.

On the other hand, if you just want the experience of running at Bonneville, the AMA event (Bonneville Motorcycle Speed Trials) has their "Run Watcha Brung" category, where you pay a fee and make a run just for time. You get an official timing slip, but are not competing in any classes. The fee is much cheaper than running for a record, and the tech requirements are simpler. Go to https://bonnevillespeedtrials.com/ for more info.

Ken

Is that what started out as the BUB event, Ken? That's what it was in '08.

grandpaul said:

Is that what started out as the BUB event, Ken? That's what it was in '08.

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Yep, that's it. A few years back Dennis Manning, who started the BUB meets, turned them over to his wife Delvina to run, and she changed the name from BUB to the Bonneville Motorcycle Nationals.

Ken

Ah, good. I set the inaugural class record in Prod/Hvy.