Rule change submissions close 1 March 2016 - be in to win.

[TZ350]

If I have this right. The first pic is of a Honda MX bike that competes in FIM sanctioned, MX bike races. So therefore a competition Bike/engine.

The second pic is of a Ducati Monster 1. A road bike. Which may have competed at club level events or even a one make series. However this is still a Non Competition Bike/engine.

Yes, exactly right, there are factory specific race bikes and factory road bikes. We are allowed to use anything made by the factory for non competition use, which usually means road use. Some exceptions exist, piston and ignition to name two, are open and can come from anything.

There are specific capacity limits for Bucket racers but that does not stop someone using parts from a bigger capacity road bike engine or any non competition motorcycle engine and modifying them in all sorts of ways so long as the final engine capacity is within the Bucket rules.

The majority of Bucket bikes are basically standard FXR150's and a great deal of good racing is done with them. There are only a crazy few who go all out in the tuning stakes, I am not sure it does them any good and you do not have to go there to have a good time with Buckets, unless you want to of course.

PS, Hp on its own is over rated, it is the complete bike and rider package that makes a winning formula.

[timg]

Hp on its own is over rated, it is the complete bike and rider package that makes a winning formula.

But for folks like me with bugger all talent HP sure helps!

[seymour14]

But for folks like me with bugger all talent HP sure helps!

HP in the South Island is beneficial.

But us Northies are all Torque...

Torque is the most useful tool on a Kart track.

[F5 Dave]

Its the most useful tool on KB.

[timg]

HP in the South Island is beneficial.

But us Northies are all talk...

Talk is the most useful tool on a Kart track.

Fixed it for ya

[TZ350]

Naturally my interest is the 24mm carb equivalent rule and how it should be measured and should it be updated to specifically include EFI or done away with all together. Rule change submissions close 1st March. Input on the 24mm rule or any Bucket racing rule for that matter that interests others would be welcome.

Nothing hidden, the very 1st post on this thread declared my interest.

To me a "total inlet orifice area of 452mm2" looks a better definition than "24mm carb equivalent".

The very 2nd post shows the direction of my thinking.

Here is the rub When you have two people both who coincidently have air cooled bikes both suggesting the 24mm carb restriction is utterly irrelevant anyway. Why is it so irrelevant that it must be removed?

The rub is that people get involved with what interests them.

There shall be no restriction on the make, type or design of carburettor, ignition, exhaust, piston, cam, valve springs.

So Cams are open, pistons are open, ignitions are open, carbs are open, etc.

So ""no restriction on make or design of carburettor"" no restriction on make, that is me, as I am the maker or design, my own design of high flow venturi insert carburettors. I make these from other manufactures carburettor bodies. So total, totally legal, they also make the 24 thing ineffective as a restriction. Also there is the dawning of the 2T EFI throttle body thing becoming a reality.

With MNZ's hopelessly confused clarification. I wanted to see if we could formulate a better way of defining "equivalent to a single 24mm carb" without changing the original thrust of the rule, which was basically, all air through an equivalent 24mm hole.

I am not fussed, keep the rule, change the rule or level the playing field carburetor wise by doing away with the rule.

In hindsight and experience I think it has always been an ineffective rule. But the only way I will lose anything is if the 24mm rule is dropped. The rules may be simpler but I will have lost all of the perceived benefit I may have gained from my hard work.

That is the real rub.

[speedpro]

From a long way away and having plenty of time to consider this discussion, I can honestly say that I see this as a way of allowing the "restriction" to be located seperate from the carburetor. The adantages are obvious. For example a "restrictor" could be placed at the inlet of an airbox which in turn feeds a large carb mounted on the engine with obvious advantages of packaging and throttle control.
I don't think the rule is broken despite the difficulty and confusion trying to be made of it. I think the issues have been created to justify a rule update which would allow changes as described above.
I'd be happy to delete the rule as long as the 125cc engines were banned at the same time. It does seem that the increase to 125cc 2Ts was a mistake

[jasonu]

[QUOTE=TZ350;1130948582]

I am not fussed, keep the rule, change the rule or level the playing field carburetor wise by doing away with the rule.

In hindsight and experience I think it has always been an ineffective rule. QUOTE]

Because of the rule the playing field is mostly level. What is the most HP a 100cc 2t water cooled motor has made? 25ish HP? The top 150cc 4t's? 27ish hp? I see reports of all types of F4 machinery doing the winning.
Maybe if you 125cc 2t guys aimed a bit lower HP wise your motors would be a bit less stressed, would make a bit less heat and might last long enough to do a bit of winning.

The rule has done its job exactly as intended. It made eligible a new type of motor into a failing class while limiting those new motors enough so as not to immediately over power the existing machinery.

[TZ350]

Because of the rule the playing field is mostly level. What is the most HP a 100cc 2t water cooled motor has made? 25ish HP?

Maybe if you 125cc 2t guys aimed a bit lower HP wise your motors would be a bit less stressed, would make a bit less heat and might last long enough to do a bit of winning.

Best I have personally seen from 100cc 2T is 30hp, the graph has been posted on this thread.

""Maybe if you 125cc 2t guys aimed a bit lower HP wise your motors would be a bit less stressed"" agreed and that has been the point of a lot of this discussion, that air cooled 125 2T's are limited by their cooling system.

As you're post pointed out, a 125 2T air cooled engine can make 30hp too but they are more thermally limited than they are limited by the supposed 24mm carb restriction.

Also a bigger carb won't make an air cooled 125 2T run cooler, 30hp of air drawn through a 24 or 34 or 44mm carb is still 30hp worth of waste heat to get rid of. There is no extra air going through the the motor, 30hp is 30hp, if there was extra air then it would be 30+hp.

[jasonu]

Also a bigger carb won't make an air cooled 125 2T run cooler, 30hp of air drawn through a 24 or 34 or 44mm carb is still 30hp worth of waste heat to get rid of. There is no extra air going through the the motor, 30hp is 30hp, if there was extra air then it would be 30+hp.

More fuel/oil must also mean more air (if there wasn't more air it would be running rich) which in turn would add to the amount of cooling.

[TZ350]

More fuel/oil must also mean more air (if there wasn't more air it would be running rich) which in turn would add to the amount of cooling.

It could be made to run rich whatever size carburetor you use.

30hp = 30hp = 30hp = the same amount of air/fuel and waste heat regardless of the size of carburetor the 30hp worth of air was inducted through by the engine.

[TZ350]

But that's the kicker if it is truly irrelevant why the need to get rid of it,

There is no "need" unless you want to start tiding up the rules. 1st of March, two weeks time is the dead line for this year, that's the "need".

[seymour14]

There is no "need" unless you want to start tiding up the rules. 1st of March, two weeks time is the dead line for this year, that's the "need".

Well I propose that Water-cooled 2ts go back to 104cc, the tried and true capacity, and we all go on our merry way...

Crisis and arms race averted, Doomsday Clock gets put back to 11am.

[jasonu]

There is no "need" unless you want to start tiding up the rules. 1st of March, two weeks time is the dead line for this year, that's the "need".

What you are proposing is more than a 'tidy up'. Getting rid of the 24mm carb rule is a significant change that, by your admission will change the way you go about building a 125cc 2T air cooled motor.

[seymour14]

What you are proposing is more than a 'tidy up'. Getting rid of the 24mm carb rule is a significant change that, by your admission will change the way you go about building a 125cc 2T air cooled motor.

Someone needs to fill me in with history. Have the air cooled 2ts been successful in the past? Or more to the point, too successful?

If not, the suspicion is they may do well on big tracks, but as Regan says, you roll the dice on the smaller ones. Thermal conductivity plays a big part, but whether the rule changes or not, it will be fun to play around with more and see what can be achieved within whatever rules apply to it. Our dyno runs look promising with a 24mm carb, but reality says that the bike still needs to finish a race...

As to water-cooled 2ts, they are already proven successful, it would be sad to make them the only bikes worth while having (buying). I would be proposing to the whole team to buy up 110cc engines if the rules stay as they are.