52 Mk 11 the start

[RMS eng]

Good Point.............

check the old rules, when the rule was set for a 125 air cooled 2 stroke to have a 24mm carb,not 28mm with a spacer?,the four stroke rule was set at 140 or 145cc,and you could have 2,3 4, cylinders and water cooling ect ,i think that part of the rule has been from the start

[Buckets4Me]

check the old rules, when the rule was set for a 125 air cooled 2 stroke to have a 24mm carb,not 28mm with a spacer?,the four stroke rule was set at 140 or 145cc,and you could have 2,3 4, cylinders and water cooling ect ,i think that part of the rule has been from the start

carburation equivalent is not a 24mm motobike carb so it dose beg to ask what they ment

you could have a 24mm hole and tip the petrol in from a bucket

[TZ350]

2003 is the oldest rule book I could find and it talks about "carburation equivalent", carburation not carburettor.

So it looks to me they were leaving it open for any kind of fuel/air control system including kart carbs, fuel injection, automotive or even home made or modified carbs.

"carburation equivalent" are the key words...........

[speedpro]

The whole debate is over where it's measured. If a larger carb is modified so it now has a piece that has a cross-sectional area equivalent to a 24mm circle then it complies with the rules as written. The 24mm restrictor has to be part of the carb to meet the rules. There is nothing in the rules that says where the measurement is made, unlike karts. The idea of where the measurement was to be made may have been there but was not written in the rules. Personally I don't see a need to update the rules, though check with me after Taupo on that. I look on what TZ has done as a cunning idea to get around a restriction.

[TZ350]

carburation equivalent is not a 24mm motobike carb

Agreed................ I think the rule was carefull to not exclude any kind of carb/fuelling option.

[speedpro]

2003 is the oldest rule book I could find and it talks about "carburation equivalent", carburation not carburettor.

So it looks to me they were leaving it open for any kind of fuel/air control system including kart carbs, fuel injection, automotive or even home made or modified carbs.

"carburation equivalent" are the key words...........

Selective quote there.

It actually says carburation equivalent "to a single 24mm carburetor". It's not talking about a fuel injection throttle body the equivalent size of a 24mm carburetor, it's talking about a carburetor system, say two very small carbs, that have a area equal to or smaller than a single 24mm carb.

I always thought of the wording as a way to stop guys running something like two 22mm carbs

[TZ350]

Selective quote here.

It actually says carburation equivalent "to a single 24mm carburetor".

Yes...... I stand corrected ........ on the quote thing.

[Yow Ling]

Selective quote there.

It actually says carburation equivalent "to a single 24mm carburetor". It's not talking about a fuel injection throttle body the equivalent size of a 24mm carburetor, it's talking about a carburetor system, say two very small carbs, that have a area equal to or smaller than a single 24mm carb.

I always thought of the wording as a way to stop guys running something like two 22mm carbs

So if you fitted a EFI system, there is no venturi necessary you could have a slide or butterfly how do you measure it as carburetion equivelent?do you allow for the butterfly shaft? it could get pretty messy
if you put a 24mm restrictor in the system as is pretty standard practice in most other motorsport the problem is solved and tzs system is legal.

[Buckets4Me]

Selective quote there.

It actually says carburation equivalent "to a single 24mm carburetor".

so realy you are only allowed a single 24mm carburetor then and nothing but a 24mm carburetor maby a 22mm carb bored out to 24mm. or a 28mm sleaved down to 24mm ?(with the sleave taperd so it flowes better


so why not just a 24mm carburetor and not the equivalant (and what is equivalant anyway?) what about fuel injection with a 24mm butterfly ? that would be deamed equivalant wouldn't it ? (new cbr125's)



shut up anyway Mr Green we are only trying to catch up to you

[Buckets4Me]

Selective quote there.

. It's not talking about a fuel injection throttle body the equivalent size of a 24mm carburetor,

I always read it as it was


why make it equivalant to a 24mm carb instead of say just a 24mm carb?

[Yow Ling]

I always read it as it was


why make it equivalant to a 24mm carb instead of say just a 24mm carb?

because the then awesome T125 stinger had 2 carbs that exceeded the 24 mm equivelent. (maybe true, only the bucket historians will know)

[Henk]

So that you could run two 17mm carbs if you felt so inclined? 452 mm2 split over both cylinders of a twin to give same area as a 24.

[Buckets4Me]

because the then awesome T125 stinger had 2 carbs that exceeded the 24 mm equivelent. (maybe true, only the bucket historians will know)

I guess that would make sense as if it had 2 carbs you would want to be able to run 2 carbs again but a single 24mm carb makes it hard

[speedpro]

It was written to stop smart asses using two 24mm carbs. There was buckets round with 2 carbs at the time. I know of one that had a carb on the rotary valve and one on a crankcase reed on the same engine. If we had just said "24mm carb restriction" then you have to use a 24mm carb, but as many as you like.
The rule was a bit unfortunate for the 125 twins but the one I've seen ran just fine with some copper plumbing fittings and a single 24mm carb.

[F5 Dave]

because the then awesome T125 stinger had 2 carbs that exceeded the 24 mm equivelent. (maybe true, only the bucket historians will know)

Well the Stinger was fitted with Amal carbs in some markets, but they are queer downdraught units. Must finish mine (roadbike).