Hey Mongo...

Well charles, I think I'm going to be your guinea pig. I've got an RZ350 with a bone stock motor and Toomey's that I plan on bringing to a few rounds this year. Just need to finish safety wiring and slap on a new set of Avon's and see what happens.

I realize that I'll be sucking lot's of blue smoke from everybody passing, but I just love to ride the thing and I'm not a good enough tuner to screw with it too much.

Please give a wave when your passing #115!

 

Welcome! Well, it won't be me that'll be passing you in Form 2-Stroke, but count on it by some of the fast guys in that class, regardless of what you've done to the bike. Fast is fast, and past is past...Tell some of your friends to get them an RZ and come on out! Oh and I don't deal with guinea pigs, only large Hampsters.

 

Exactly.......

Sean,
What makes it confusing is there isn't a displacement limit, just a bore specification. Other rules certainly don't exclude stroking, porting, after market cylinders, etc.... so the possibilities are endless. The bore spec only makes sense if it says you have to use stock stroke, and it doesn't. Anywhere......

Personally I like what Charles and Joe have suggested, without looking back to be specific, but something around 400 to allow the RZ to have a chance on the straights with the triplesand 500's. I have a lot of time and money in my stock cylinders and will run them this year, but I'd like the option to put aftermarket cyls on in the future with reasonable limitations. We need some clarification in the rules, and you've got a good feel for how a given bike indexes in against the rest of the class. Just put it in writing and put us out of our misery.......

I've been saying all year I'm tired of racing against myself, kind of hard to improve that way....I am for whatever it takes to get full grids.....

 

Bro Chuck,
Thank you for your vote of approval, however, I need Mongo's, not yours. As far as chains and whirly bits, The XL, as with the Ascot, is blessed not only with a cam chain but also has a counterbalancer which is driven by a chain, both of which have manual adjusters and springs and such. I realize that you are fascinated with such things as reed valves( little flappy things, right?), rotary exhaust valves (they make cool noises when they cycle) and oil pumps, but none of them are driven by chains, so you don't understand them and they only get adjusted when you need to rebuild after the latest seizure.

Your pal,
Ken

PS. any advice on chambers to get my Sears Allstate ready for Formula 500?

K

 

Bro Ken:

Okay so I jabbed at you a bit, but I have always voted for counterbalanced chain driven cams that are MANUALLY ADJUSTED, just so you know. And, further, just to accomodate illuminati such as you, I have totally removed the power valves on my ride! But this is all wasted effort- the real concern should be focused on your Sears Allstate (Puch) 'Twingle.' I can give you assistance to produce sufficient tire-shredding power and heart-stopping acceleration to reduce you to a bag of nerves!. But none of this will do you any good at all, Ken, if you are reluctant to rid yourself of the obsessive-compulsive disorders associated with driving diesels in motorcycle races. Do not, repeat, do not, engage with your 'Twingle' until you have reached some accord with your inner self.

Your true pal,

Charles

 

check your math.......

The actual displacement at 65.5mm (0.060" over) and 54mm stroke is 363.91 cc's.

 

:wow:

 

You guys don't think I actually got out a calculator did you? (I DID say "approximately"...)

 

Yes...yes we did.

The devil is in the details.

 

Everything on my 1982 Kaw. was available and being raced in 82. Except for the tires. I think Vintage racing should be more like that.

Should we allow water cooled, four strokes. They will last longer so racing will be cheaper. Where does it end? Maybe when you go to aftermarket heads or Cyl. You should move up a class.

You probably could talk someone into Vintage racing if he thought he could buy an old bike and modify it's original parts and be competitive.

Instead you could sell them on the idea that if they buy a bike then get different heads, cyl, crank, and some race glass you could do well. Most of those parts weren't around when the bike was built. It wont be vintage but some of the parts are old.

The first TZ700's were the twin shock. I think the one I was on was only a 700. The 750 mono came later.



Sam Williams #47 SCVR

 

So, Sam, are you saying that vintage bikes should all be OEM spec or they're not vintage eligible? You mention the old TZ750 (which originally was 694cc), well, since day one with those bikes, tuners and riders were making modifications or trying to get aftermarket parts to make the TZ faster and last longer. Same thing with all of the TZ's and the Yams that preceeded them...change is the only thing that is permanent.

 

I would like to see the bikes the way they were raced in that period. That is just my preference.

I think period correct mods are fine. On my bike a 82 ELR replica the factory raced them with six piston brakes at times but they are not legal with WERA or AHRMA. Someone along time ago that went against the sprit of Vintage.

A Superbike class may be a little different than a Formula class but should still try to conform to period correct changes.

I love the old TZ 700's I just didn't like ridding it. The Mono was a much better bike.

 

This is not intended to “parse” the rules, just looking at what the rules actually state


“Formula 2-Stroke
This is a Vintage Formula class where hybrids up to 1985 are permitted. Alloy race frame of the perimeter type may be used as these were available in the period, but twin spar (“Delta Box”) frames are prohibited.
Among the eligible Formula 2-Stroke machines are the following: Honda RS 125 (steel frame only); Kawasaki H2, H2R; Suzuki RG250, and GT750; Yamaha RZ350, RZ500, TZ250, and TZ350. Specialty frames, such as Harris, Nikko-Baker and Spondon, are permitted.
Component Specifications
Major components are the engine and frame. Successive year models of the marque are eligible provided that major components are essentially unaltered (like design). Hybrids (a motorcycle comprised of mixed origin or composition) are permitted, provided that the design and operating principle was in use prior to the cutoff date. We will allow specific modifications, as appropriate, for disabled riders on a case by case basis, considering bike and class specifications, i.e. use of air shifters for disabled riders in superbike spec classes.
Updating and backdating is permitted within the category dates. Components of later date may be used provided the design and operating principles of the component is essentially unaltered.”
From the “Engine” section:
“Cylinders may be bored to a maximum of .080” singles, .060” twins, and .040” three and more cylinders from the class limit.”


After reading the rules for F-2stroke, given there is not a specific “class displacement limit” it would seem to be that each bike is limited by its original displacement. Based on this I am not sure I see where an RZ or a TZ is legal above 366.81cc’s and depending on how you read the rules the max may be 364.18cc’s

FWIW the .060 overbore limit = 1.524mm

Nowhere in the F-2stroke rules is a bore of 66.XX specified for an RZ or a TZ
If the intent of the rules is for the bore limit to be based on the stock 64mm bore +.060 it would appear an RZ has a limit of 65.524mm / 364.18cc’s If it is based on a true 350cc displacement @ 64.236mm + .060” then it would be 65.76mm / 366.81cc’s

Here are some calculations based on bore/stock stroke calculations:

AHRMA formula
Bore X Bore X .7854 X # cylinders / 1000 = CC's
Bore Stroke multiplier # cylidners Displacement

Stock 350 Bore
64 54 0.7854 2 347.44

Pi formula stoke bore
64 54 2 347.43

Bore @ actual 350cc's
64.236 54 0.7854 2 350.00


Maximum bore FROM STOCK "350" 64mm bore
65.524 54 0.7854 2 364.18


Maximum bore FROM A TRUE 350cc 64.236mm bore
65.76 54 0.7854 2 366.81


Displacement @ bore
66 54 0.7854 2 369.49
66.25 54 0.7854 2 372.29
66.4 54 0.7854 2 373.98
66.5 54 0.7854 2 375.11

 

Bob, I left out several passages and the treatise on displacement calculations as you can see...and this, also is not intended to 'parse' the rules (although some could see it that way...interpretation, you know, is a personal thing)...you say there is no "specific class displacement limit" but I read, in the very same 'Engine' section you quote from, the following: "Any machine with a dispalcement (sic) limit following it in the class rules cannot use these overbores, the listed displacement is absolute." Is that not what is written? Therefore, to use one example, the class eligible RZ500 is limited to 500 cc and no overbores allowed. Correctomundo? So, for certain bikes listed with a displacment limit, there can be no overbores allowed...all of those calculations in vain. BUTT, I'm all for rewriting some of the rules to make things better for everyone. What d'ya think?

 

Why don't you save a lot of time and calculations and just ask WERA to ban aftermarket cylinders on any bike in the class? That seems to be the intent of this thread and it would make the rules unambiguous for a change.

And while you're at it please take up the subject of both my H1 and H2 cylinders that have been converted to use reed valves.

You're on a roll and probably have an opportunity to remove both of those bikes from the grid as well.

 

Sam:

Sure, that's a real treat, seeing the old 'Superbikes' as they were raced back in the day...Wes Cooley, Eddie Lawson, Wayne Rainey, Kevin Schwantz style machines...much like I'd love to see old school Suzuki TR500's & RG500's, all of the TZ series of bikes, Kawi triples and make sure we get all of those KR750's out too, throw in half-a-dozen MV triples, Triumph Slippery Sams, Norton Manxes, maybe six or seven Patons, Gileras, and the Laverda V-8's sitting around gathering dust...Sam, it would be great, but it ain't gonna happen anytime soon. We may get a rare treat once in a while, but those bikes and their maintenance costs are far above what the average guy can afford.

 

For what?? Are they over the cc limit?

 

Charles, I am not sure I that section the same way you do. The overbore rule provides “maintenance” bores. To be interpreted as follows:

Example,
F-500 allows any bike entered to be a maximum of 500cc’s regardless of original displacement (other than specific exceptions such as allowed for the GS450 and SR500 etc.) Any motor in the class is allowed overbore in addition to the class limit.

For a full 500cc twin it is bore @ 500cc’s + .060” / 1.525mm per cylinder
For a 500cc triple it is bore @ 500cc’s +.040 / 1.016mm per cylinder
Applying the specific displacement rule the SR500 is limited to an absolute displacement of 540cc’s and the GS450 @ 550cc’s absolute displacement limit with no maintenance over bores.

If F-2stroke the bikes are identified by their model designations, in the case of the RZ’s this includes 350 and 500, I believe these bikes are entitled to the maintenance bores under the rules. The RZ350 would be legal @ 350cc’s plus .060” / 1.525mm per cylinder and the RZ500 @ 500cc’s + .040” / 1.016mm per cylinder

:up: