Hey Mongo...

Check the graph on this thing - looks pretty racer friendly.

http://www.ekartingnews.com/viewtopic.php?t=75382&sid=5e96ec5cadfd9f5c6be28a1d952cf22f

 

That chart shows 105 HP for the 68MM bore and 4mm stroked crank which = 421cc. I know for a fact that the 421 engine in my chassis that Charles is using is not putting down 105 HP. It's built correctly, has great carbs attached and decent pipes. I question that dyno accuracy. We know all dynos are different. My seat of the pants dyno tells me the 421 I rode is in the low to mid 80's range. I've ridden enough bikes to feel I'm pretty close with that estimate. I've poured all over the internet and guys make wild claims all the time. IMO, most of it is BS. I know what I've ridden and that is reality. I'll gladly let you take my 396 hybrid out. It uses a 66MM bore Cheetah Cub cylinder and 4mm stroked crank. Balanced crank and Hinson clutch. 38mm carbs, V-Force 3 reeds.

 

Just saying - the rulebook should be about what COULD be done, not about what HAS been done.

 

I agree with that. The beauty of the aftermarket stuff is the wide variety of porting options and engine sizes. Different bore sizes, stock stroke, 4mm stroked, 7mm stroked, etc. You can really design an engine around your riding style and application. IMO, that is cool. Since WERA has no clause for excluding aftermarket cylinders it's really just about buying the size you want for the class you intend to run in. Some could argue that the Cheetah Cub cylinders are a step backwards in technology from OEM RZ cylinders since they are non-powervalve.

 

Precisely the point. How would a RZ350 fare against a properly race built RZ500 engine in a Spondon type frame with good suspension and 17" slicks (all allowed under the current rules)?

 

I think quite well, actually - the 500 motor is not the best design, and weighs a great deal. The 500 starts out over 100lbs heavier than the 350... I'd take lightweight and 80hp over heavy and 95hp anyday. A 125 only makes 40hp, yet laps faster than any of them.

 

So why isn't everyone riding the Honda RS125 noted in the rules?

The Kawi triples are not the best design and heavy as well but Crussell and I seem to win a few races on them.

 

I dunno - I think at one time they WERE the best design (the TZ750 was sort of cheating, IMHO).

Nixon certainly seemed to do just fine with them.

 

Fixed it for you Joe, I mean really, RZ Racer or Wine Slut, this is Mark after all...

Mark is gifted in many ways, blowing up racing motors is but one.

 

Thanks Bob....It has been a while since I killed one, but that's one of the reasons I'm going back to the RZ.... they always held up to my "style" of riding better than the rd's.

Joe-
Yes porting isn't cheap...never was. I'm just saying that there are plenty of cyls and plenty of tuners (SCR, the "other" Gary, RZ's Unlimited to name a few) to do good work, so the "Cheeta/Cub/Athena cyls are the only option for RZ racers" line isn't really valid. If (or WHEN as Bob so kindly pointed out...) I damage my cyls badly enough that they need replacement, I'm sure I'll be looking for the new stuff. It is better than the stock stuff. If/when that happens, I'll be more than happy to run V5/V6lw.

I'm fine with it whatever the rules are. I'm just glad to be racing an RZ again! It just seems kind of logical the way it is right now. All of this is moot anyhow, because if Jim ever gets that H2 sorted out, 70cc's extra displacement wont matter. That thing will definitely "go to 11" if ya know what I mean...

 

EDIT:

Well Sean beat me to it but here it is anyway... Come on lets at least try and keep some integrity in the process

Having read this thread (together with other recently written information ) one would have to question if accuracy is even included in the intent..

The way this arguement is being presented is as if the displacement is a manditiory componant of the alternative cylinders. Joe even poses his questions and statements as if the larger than legal displacement is all that is available.

This is not a case of "I have to run this big because that is all that is available", you can order the cylinders configured for stock stroke and ANY bore from 64mm.
This feels so much like either "this is what I have already built" ( I won't editorialize on that) or "This is the trick setup everyone with Banshee's is running or selling"

If I am not mistaken I believe Mark and others will have the choice of aftermarket cylinders@ 66mm, I believe that the actual legal bore limit @ 54mm stroke is 66.4mm.

If you think the RZ500 has an advantage BUILD ONE..... I have not seen one win the championship or dominate the class in the 12 years I have been around WERA Vintage. If I am not mistaken the class was won this year by an aircooled 425cc twin shock RD400 that bumped up to the class from F-500.

BTW I believe there is a class for 400CC+ RZ's it is called V5 (if I am not mistaken on the displacement limit there)

I really have a hard time understanding the argument that increasing the cost of building a competative bike for a class will somehow increase participation when it will also obsolete many of the bikes intended for the class.

I believe the 373cc limit is imposed based on TZ twins running a single 750cc cylinder which is a 66.4 mm bore.

 

Sean,
My post #24 states you can buy the aftermarket stuff in whatever configuration you want depending on the class you choose to run. I haven't asked for a larger RZ displacement in F-2 stroke. I offered a compromise option for the people who wanted 450cc versus the people who said leave it alone. If I were to build an engine for the class I would still go after market and use a Cheetah Cub kit. I know they sell one off the shelf at 360cc and I'm pretty sure they would build a 372cc version with only about 3 or 4 week lead time.

Enough said already IMO. I'll leave this to the rest of you folks now. I just wanted to point out to people out there that options do exist and you don't need an inside track to a porting wizard.

 

Damn right!

Mr Jolly and Shit!

 

Well, since part of my written request (petition) for some changes in Form 2-Stroke included this issue (larger capacity RZ motors), I guess this is the answer to that issue; I didn't know rule change requests were done now on the BBS, it's okay, I just didn't know that and would have handled it here.

So, I might as well ask for clarification on the other issues presented:

1. The TZ750 in V-5: twin shock only as it stands now, request made for inclusion of mono-shock frame. Disposition?

2. The RG500 in Form 2-Stroke: included some years ago, then it simply vanished from the eligible bike list. Unless I was blind, dumb, and deaf, I don't recall any RG500's showing up to win any regional or national championships at least not since 2001; there never were any articulated reasons for excluding this particular bike, and I do not remember any known ruling on it. I doubt if we will see any genuine old school Formula 1 RG's (XR14-XR72) on the grid, so we are discussing the street version, and there probably would be few of those if any. But I could buy one, prepare it, and come out in this class. Disposition?

3. Not included in my petition was another bike, a 1984/1985 EMC-Rotax 250cc (2-Stroke) in a Harris alloy frame that I owned many years ago. I have the opportunity to buy it back from the owner, it has sat almost untouched. Form 2-Stroke?

Regards,
Charles R.

 

Fascinating reading. It clarifies a lot of the events of the last year for me both on and off the track.

Best of luck to everyone next year participating in Formula 2 Stroke.

 

Because I sold mine back in 2002 :down:

 

Don't forget - liquid cooling is a fad.....