Piston Port Two Strokes in GP-250/350

Piston port air-cooled 2-stroke GP bikes should race according to capacity as they did when they were new. It would increase the GP grids and would be historically accurate.

 

Fred,
If you listen carefully,you will hear the sound of a riding crop on a dead equine.
Tom

 

fred could you give an example of what you talking about for us mentally chaling...challlenn... ch..retards!

 

Hmmm, in practice it means my TD-3 and/or DS-7 (250 Yamaha piston port 2-strokes) could run against Chris Marshall's Ducati 250 (or Kellehers Aermacchi 250) rather than 350s and bigger bikes.

 

a td against a duc 250 single or my 250 single? george taylors td makes about 55-60 rwhp. a ds7 can make over 50. ducs and buls are making 30-35hp. a well developed ds7 can smoke the 350 class. duc 350 with a butt load of money thrown at them may hit 40hp. if these bikes(ds7) are allowed in 250gp i dont believe entries will go up at all. im not wasting time and money against those odds and i doubt if ducati dudes will. i would just race the bul in ahrma and my rz in wera. i believe lyn garland has a ds about ready for 350gp, i think he will walk away from the 350's down the straights for sure.
in ahrma 350gp roger swartout runs a kaw a1, i remember seeing him pull away from 350 singles with ease. roger admits his bike is very mild, he raise th ex about 2mm a little more intake timing etc. i think the ds has more potential.
td's raced against 350 singles back in the day. kevin cameron and kawasaki tried in vain to beat the td's with the big horn single. just didnt work. the yamaha were to strong. dam yamahas.
oops.....except mine

 

u bin reedin agin ain't u

 

gee, can I run my 750 in v-2 because it's about the same speed buffs 350?

 

It depends on the time period you want to define your race class. A TD3 is a generation ahead of Duc singles, or 2stroke singles like Scott's Bul 250. I'm afraid putting newer GP bikes in might do more to run people out of WERA 250 GP than to bring people in. Besides, there's no reason a DS-7 can't keep up in 350GP as it stands.

 

Well, it was a good try on my part anyway. But I think some people are optimistic when they say that some people are getting 60HP out of a TD-3. At start up when the motor is cold you are lucky if you are getting the factory claim of 48HP, which was very optimistic. And that 48 HP is at 10-11K RPM with very little HP below 9K. At mid race it is probably not putting out more than 42-43 HP.

 

Hey Guys, I had to put my two cents worth in on this one. As I understand it, the reason vintage racing exists is because during a certain time period the jap 2-strokes began to put the british/italian and even jap 4 strokes out of the games. A whole class of motorcycles were rendered USELESS !! I do have a decent running Duc BUT is is also one that has had buckets of money, time, developement, crashes, blown engines, etc. etc. thrown at it. If , by a simple rule change , history was to repeat itself, why have we worked so hard to try to reach the top with what we have ? To relegate it to the back of the garage or basement under a tarp because it's not competitive -- AGAIN !! As Scott put it, I believe a lot more bikes would fall away from the grids than would be replaced. Nothing against the 2 strokes ( some of the finest, nicest racers I know ride them !! ) but I DO NOT want to have to ride one to be competitive. Neither can I afford a replica 7R. Television or back to dirt-tracking ?????

 

I have a fairly good DS7 running 350 and 500 GP that has probably never passed a 350 Duc on Road A's back straight.In fact I have been passed by several 250 Ducs.
Of course none of them have a problem passing me in the turns either
I think it's time to write the VRC about a spec DS7 class.For all three of us,assuming of course that Lyn gets his done
Tom

 

Tom, I hope my comments were NOT taken as an affront to the DS 7s. They weren't !! If one of y'all kicks my butt with a DS , shame on me !! Now, back to my comments before . It's just that when I see a movement beginning that could spread to other classes, it's best to step up and voice your pros or cons then ( and reasons for !! ) instead of after the fact ! It's no secret that a 2 strk , CC to CC , will make more hp than a 4 strk. That's why they're performance indexed ie: 250 2 strk vs 350 4 strk, etc. etc. When numbers of cylinders begin adding up, it becomes even more critical. I'm just trying ( SELFISHLY !!!! ) to avoid having a 350 cc 2 strk twin end up beside me on the grid because it's also a 350 !! I've had to race against the replica 7rs ( NOT vintage in my eyes ! ) MV triples and most everything thing else in Ianuccis' arsenal. Unless we can all afford to open our own museum of one-of 250,000.00 factory racebikes, we need to concentrate on racing what we have in the fairest way possible. Rules are rules. We play by them, we die by them !!! On to the GNF !! Let's have some fun !!!!! Steve

 

The point Tom is making is that today's worked on 350 Ducatis have more motor than DS-7s. I would pass a Ducati 350 (on my DS-7) at about turn three at VIR only to have the Ducati blow by me on the front straight before the finish line every lap. I actually crashed out on the DS-7 trying to pass the Ducati on turn one hoping it would last till the end of the race, as passing on turn three didn't make it. The TD-3 would fare no better, the only difference is the dry clutch and chrome bores which only make it a little harder to seize.

It's a safety issue!!!

 

DS7 dudes. if you can make 40hp you can outrun most duc 350,s.
fred-at daytona george taylor(TD) is able to pass some rd250's that make over 50 dyno'd hp. my under standing is he has spent time developing his bike.
buff harsh kicks my butt at talladega on his honda 350 when im riding an rz that has 20 hp on him. if chris marshall is riding a duc 250 and beats a ds7 it wouldnt suprize me, hes a fast rider. if the yamaha had as much money and r&d thrown at it im sure it would blow the ducs away.
a ds can make more than 40hp shirley....i mean surley.

 

From the Daytona radar speed's on AHRMA's site ( I know, not a dyno, but a pretty good yardstick) a fast 350 Norton thumper went 113mph ( the Ducs were slower that particular year) and G Taylor's TD3 went 123mph. I won't repeat everythng that's on there, but if you look at the site, you'll see the trend...

 

250 class

I would like to weigh in on this subject. I can understand that the era when the 2-strokes ended the competitive 4-stokes in the 250 class should not be repeated. If the recreation of an era is one of the criteria for classes (and I think it should). Why are 2-strokes so left out.. The TD3 and TZ250 were benchmark bikes. In today’s short vintage sprints I am not sure how much of a benefit that the water cooling is. Virtually any of the Yamaha 250 racing twins can be developed to exceed 50 and even 55 HP. The difficulty is riding them and reliability. Properly done and with some effort I have no doubt they would dominate the balance of the 250gp class and render many bikes non-competitive.


As the years go by I would like to see us attempt to re-index certain bikes. The issue currently for the TD3 and TZ’s is pistons. No one runs a water cooled 250 (no real class that one would be competitive in) and most of the TD3/TA250’s that are run are converted to a CR125 or other substitute piston with a bit of machine work.

There is rumor that Yamaha is going to make a run of TD/TZ250 pistons for the 70 series bikes. I think it is premature to create a new “formula 250 GP 2-stroke” class but I think an eye should be kept open to that possibility.

I enjoy the open exchange of information here and the fact that with WERA we have the opportunity to participate and contribute in the development of our racing organization and classes, even when I don’t agree ( a rare thing) with the result.

 

Bob, I share your affinity for the RD's and TZ's, but I don't think the superbike classes indicate a loathing of 2 strokes by AHRMA. Rather, they are trying to attract entry level riders on 4 strokes who would otherwise be frightened away by the death-grip the Yamaha smokers have on the Formula 250 and Formula 500 classes. And that death-grip is historically correct, but the diesels are very attractive to those who aren't into jet-swapping, so I can see the need for them to have a class.
As for WERA 250GP, or any other performance-indexed set of rules, some historical fudging is neccessary because we do not recreate only one year of history but rather a short period. In WERA GP, we're simulating the earlier years prior to the early '70's 2stroke domination. If the cutoff date were 1972, then it would be expected that 2 strokes would be the dominant machines. Instead, it's pre-1969, with indexing to help even the playing field.
To me, it would be more logical to add early TZ's to V2, rather than 250 GP, since V2 goes up to 1974. Also, the drum-only rule in V2 seems like an anachronism, since there were discs on common street bikes by the cutoff time. just my $.02

 

Well put Carl. I'm under the impression that just about any class that allows bikes made after 1969 will be dominated by any 2-stroke of that time frame. But of course you could always allow the diesels a 2X displacement advantage (it's only fair... 2 strokes have twice the number of power strokes of a 4-stroke with the same number of cylinders spinning at the same rpm).

 

Let me fill in a little modern Vintage history.In 1994 I won the V1 WERA class on my 43HP CB350,in '95,"Rocket"Ron Kaufman kicked my ass up and down the East coast on the Tom Keating-owned,Chris Bernstein-built DS7/250.Ron was a featherweight,skilled rider.I could keep up with him on most places on the track,but was left in the dust on the straights in particular.My expert opinion places his bike around the same power as mine,42-44HP,a formidable bike for the V1 class.If your DS7 is getting passed by 250 Ducatis' (the fastest in WERA making around 30HP on their best day)you either need to get a new tuner or accept that you don't know how to build a fast bike.Running a built DS7 in GP350 would destroy the rest of the field,V1 seems about right for classifying the bike.
There was one Ohio DS7 rider who whined so much to WERA Vntage about how slow his bike was in V1 that a completely ambiguous ruling was introduced to allow "certain" DS7s into a slower class.
Let's leave the GP classes as"four-stroke"dominant,to avoid reenacting the historic death of four-strokes by the two-stroke.
For anyone who wasn't watching,last GNF Chris Marshall finally got the Gianinni TZ250 (F?)jetted right,and completely walked me on the straights while I was riding my 56HP RD400.F-500? My gut reaction is no-way,but I'd have to think about that one.
As the rules have been fine-tuned and shuffled in the last few years,there has been a trend separating the four-strokes from the two-strokes.I can't say whether this is good or bad.On one respect many people would like to see larger grids,should we combine classes,say,V2,F-RD,GP-500 into one class?Sure,the first few races may have a grid of 18 riders,but a lot of those riders may get pissed off and stop racing because their"XYZ"bike is not competetive because of the rules(of course,MY XYZ is the best it can be,and,uh,that fast guy MUST be cheating,right?I know for a fact that NO XYZ can go faster!)Or, should we split every class until there are two bikes in each class,everyone should be happy,the worst they may do is get a second! Racing teaches us all about our egos and how accepting we are to humility.Humility to accept that there is always someone who can ride faster that us,and that a bike can always be made to go faster.The trick is to keep trying and have FUN along the way.

 

Yea! In light of this, V1 should be my bump-up class with the XS!!