What size is a 24mm carb?

[TZ350]

Someone on the FXR150 site sought a clarification from MNZ ( http://www.fxr150.co.nz/forum/showthread.php?1068-104cc-carb-size&p=13141#post13141 ) re, "where is a carb measured".

There seems to be some confusion as the posters interpretation of MNZ's reply indicated that MNZ regarded the carb size is measured at the very end of the carb where it is largest.

The only carb manufacturer I know of that does that is Lectron. There is no real industry rule but the convention followed by every other manufacturer I know of, sizes their carb at the venturi just behind the slide where it is smallest.

I have registered on the FXR150 site so I could ask that the original question put to MNZ and their written reply, could be posted.

Anyway what is the size of a 24mm carb or its equivalent?

And where does MNZ's 24mm equivalent rule come into this???

[Motu]

CV carbs is where the confusion is. Slide carbs are measured at the flange or mounting...CV carbs are always bigger, and some (Japs) measure at the flange because it sounds bigger, and everyone wants a bigger carb. Others (EG Bing) measure at the bridge where it is narrowest.

[TZ350]

(Japs) measure at the flange because it sounds bigger, and everyone wants a bigger carb. Others (EG Bing) measure at the bridge where it is narrowest.

It would be great to see some carburettor industry literature on where their carb size is measured.

[Grumph]

CV carbs is where the confusion is. Slide carbs are measured at the flange or mounting...CV carbs are always bigger, and some (Japs) measure at the flange because it sounds bigger, and everyone wants a bigger carb. Others (EG Bing) measure at the bridge where it is narrowest.

Where it's measured is irrelevant IMO - the rule says "equivalent to a single 24mm carburettor" i read that as, in the case of a single carb, somewhere within the confines of the carb body it has a bore of no more than 24mm.

I'd point out that for years Mikuni made slide carbs with oval throats. The sizing was the equivalent area of the oval...But invariably the engine side was a larger bore. VM30's were 33mm on the inlet stub, VM26's were 28mm....Then the VM29 flatslides on GSXR750's had a 29mm offset entry but past that, in fact from the front of the slide, they are 33mm clear bore...

If the rule sinply said - All entry air must pass through a hole no larger than 24mm dia, The intent would be clear as would enforcement.

[Motu]

Find a carb with a stamped size, measure it, find another, measure it. Soon you will have a data base and know everything you need to know.

[Grumph]

Find a carb with a stamped size, measure it, find another, measure it. Soon you will have a data base and know everything you need to know.

It would be nice to think that whoever answered the question at MNZ had that much experience...But I've never found that to be true sadly...

[TZ350]

If that definition is accepted as is, then most of ESE's work on taper bored carbs is illegal.

I was worried about that for a moment. But in our flow bench testing we found a much larger carb with a 24mm venture at the engine end flowed a lot more air than a plain 24mm venture by itself. Our conclusion was that the larger carb bore acted like a flow straightener so there was less disruption at the face of the 24mm venture.

So if I have to, to meet the new MNZ interpretation I would simply get a 24mm OKO and bore it out to 32mm all the way to the last mm or two. The last part would be moulded into an aerofoil leading edge shape with just a smidgen of the original 24mm bore left for the convergent part of the venture.

That way the carb would measure 24mm right at the engine end to satisfy MNZ's interpretation of how to measure a carb and the divergent part of the venture could be formed by the rubber carb mount and inlet tract. Our flow bench tests showed that this 24mm configuration in a 32 carb passed an air volume similar to a std 30mm carb.

Easy Peasy and anyone could do it.

318912318913

These are pictures of a 28mm carb with a 24mm insert but the idea is basically the same. Simply cut the venture insert off at the end of the carb. The insert measures 24mm there and that makes the carb by definition MNZ legal. And the longer off cut part of the venture insert is glued into the rubber carb mount to form part of the inlet tract.

Actually this whole thing has got me interested in carbs again because you can flow a shit load of air through a large carb with a 24mm venture at the end. We even did this with a carb that was originally 38mm. It ran Ok too but using it brought me into conflict with people who thought that clever thinking and engineering in Buckets was somehow cheating.

318914318915

Husaburg now owns the mighty 38.

Because reversion takes place at significant cross section changes, using a venture insert in a larger carb could effectively shorten the inlet tract to the length of the venture insert itself, this could be very useful.

[TZ350]

Where it's measured is irrelevant IMO - the rule says "equivalent to a single 24mm carburettor" i read that as, in the case of a single carb, somewhere within the confines of the carb body it has a bore of no more than 24mm.

It is how I see it too.

[jasonu]

Someone on the FXR150 site sought a clarification from MNZ ( http://www.fxr150.co.nz/forum/showthread.php?1068-104cc-carb-size&p=13141#post13141 ) re, "where is a carb measured".

There seems to be some confusion as the posters interpretation of MNZ's reply indicated that MNZ regarded the carb size is measured at the very end of the carb where it is largest.

The only carb manufacturer I know of that does that is Lectron. There is no real industry rule but the convention followed by every other manufacturer I know of, sizes their carb at the venturi just behind the slide where it is smallest.

I have registered on the FXR150 site so I could ask that the original question put to MNZ and their written reply, could be posted.

Anyway what is the size of a 24mm carb or its equivalent?

And where does MNZ's 24mm equivalent rule come into this???

Mate as you should already know MNZ does not give one fuck about Buckets (except for the large amounts of cash the class generates). They are only interested in 'real bike' racing. The MNZ will not reply with any useful information or clarification.

[richban]

Where it's measured is irrelevant IMO - the rule says "equivalent to a single 24mm carburettor" i read that as, in the case of a single carb, somewhere within the confines of the carb body it has a bore of no more than 24mm.

I second that..........

[cotswold]

Easy Peasy and anyone could do it.

318912318913

These are pictures of a 28mm carb with a 24mm insert but the idea is basically the same. Simply cut the venture insert off at the end of the carb. The insert measures 24mm there and that makes the carb by definition MNZ legal. And the longer off cut part of the venture insert is glued into the rubber carb mount to form part of the inlet tract.

Actually this whole thing has got me interested in carbs again because you can flow a shit load of air through a large carb with a 24mm venture at the end. We even did this with a carb that was originally 38mm. It ran Ok too but using it brought me into conflict with people who thought that clever thinking and engineering in Buckets was somehow cheating.


Some of the lads in the UK's freetech 50 series use a 28pwk with a venturi as they reckon it speeds up the air flow, damned if I can find the post now but if I do I'll put it here

[Grumph]

Mate as you should already know MNZ does not give one fuck about Buckets (except for the large amounts of cash the class generates). They are only interested in 'real bike' racing. The MNZ will not reply with any useful information or clarification.

Very true - but in this case they have responded. And their answer is contrary to how the rule has been viewed and interpreted for some years...
Either they withdraw the answer or clarify it.

[seymour14]

Might be time they give us a minimum length that the 24mm diameter must be before it gets to the inlet manifold. That would solve all conjecture.

This is now scary shit to me, as the carb on our GPR125 is a straight 24mm...:shifty:

[richban]

Might be time they give us a minimum length that the 24mm diameter must be before it gets to the inlet manifold. That would solve all conjecture.

This is now scary shit to me, as the carb on our GPR125 is a straight 24mm...:shifty:

Lets just say its 24mm held for 2mm. Job done. Don't be scared its only a carb. Lets say we have a PWK style carb. After hours of flow beach work and then hours of dyno work the best combination of fueling v flow will be found for a particular engine.

Not many people will be doing that work will they? And if its rob, he will publish the work for all to see. So not really a big deal me thinks.

Lectron will make you a 24mm carb if you want. They are a carb manufacture! Maybe a 24mm HV carb from them would the ticket. Could be 28mm at the spigot 24mm at the slide and big on bell mouth. Completely legal as they are a carb manufacture :shifty:

[AllanB]

I can't believe this is not clearly defined in the rules - mind you no being so clear leave it open to modifying as above which is also good for development.

Me - I agree - provided there is a point within the carbs physical inlet makeup that measures 24 mm it's 'legal'.

[Yow Ling]

I can't believe this is not clearly defined in the rules - mind you no being so clear leave it open to modifying as above which is also good for development.

Me - I agree - provided there is a point within the carbs physical inlet makeup that measures 24 mm it's 'legal'.

thats wide enough to drive a bus through, the measurment should be square mm, which is what the "equivelent" alludes to equivelent of 24mm carburettor is 452mm2, I like the idea of it bieng measured within the carb body.

Actually a definition of a carb is also important, in this age of efi

[Grumph]

thats wide enough to drive a bus through, the measurment should be square mm, which is what the "equivelent" alludes to equivelent of 24mm carburettor is 452mm2, I like the idea of it bieng measured within the carb body.

Actually a definition of a carb is also important, in this age of efi

That last is true and relevant. I also like the idea of quoting it in mm2.
my earlier idea of passing the intake air through a 24mm hole, while easy to police, is open to the use of heimholz resonators attatched to big carbs...
Don't know if that's a good idea or not.

[richban]

That last is true and relevant. I also like the idea of quoting it in mm2.
my earlier idea of passing the intake air through a 24mm hole, while easy to police, is open to the use of heimholz resonators attatched to big carbs...
Don't know if that's a good idea or not.

The pass through a 24mm hole is so easy to police. Why make it hard? Really what is a good reason to make it anymore difficult than that?

[Yow Ling]

The pass through a 24mm hole is so easy to police. Why make it hard? Really what is a good reason to make it anymore difficult than that?

It depends where the hole is, if it just feeds the airbox it is the same as 2 x 24mm carb equivelent, also some carbs are not round , like nsr carbs

[Grumph]

The pass through a 24mm hole is so easy to police. Why make it hard? Really what is a good reason to make it anymore difficult than that?

Slow down - i'd simply suggested that all intake air had to pass through a 24mm hole - i didn't specify it had to be part of the carb(s)
This could conceivably mean a big airbox with forward facing entry using a venturi with a 24mm bore...which may not be the best way to restrict a 125....

i'm still in favour of wording it so that at some point in the carb body the passage may not be bigger than 452mm2 (assuming mike's maths are correct)
i see no point in specifying that this has to be for so long a distance. You may well be ruling out a usable carb by doing this, some pumpers have a very short venturi.

[richban]

Man I get bored easy these days.... Carb rules are dum. Lets just build open 50cc F5 bikes.

[TZ350]

318933

30mm vis 24 in a back to back test. Red line = 24mm carb Blue line = 30mm carb, not much difference.

So 24 or 30 the power was pretty much the same.

So what are we really trying to achieve with a 24mm carb restriction for 2T's that are over 104cc. Remember this carb restriction also applies to those 100cc builders that have taken the easy no de stroke option and are using the oversize (107cc MB100) KT100 pistons.

All this restriction talk is about carbs, EFI is not mentioned in the rules, so does that mean throttle bodies are open? ... :devil2:

If we have to have a restriction then I favor the "all inducted air has to pass through a 452mm2 orifice at some point" approach.

That gives you a restriction but leaves the door open to unrestricted innovation which is one of the attractive features of Bucket Racing.

[richban]

318933So what are we really trying to achieve with a 24mm carb restriction for 2T's that are over 104cc.

I think its to give the 4 strokes a small chance at keeping up.

[speedpro]

It's funny, originally the idea was to restrict the 125cc engines to the carb that they were mostly fitted with by the manufacturer, that being a 24mm carb. I worded it that way to stop clever buggars using more than one. Things have moved on of course. Nobody considered fitting a suitably sized venturi to a larger carb, until Rob came along. I still think it's more or less worded OK and also that the 24mm has to be part of the carb, not somewhere else on the intake system.

I think the rules are clear that you can use any size fuel injection throttle body you like. After all it does not mention them anywhere in the rules. Technically you also have to run a 24mm carb, because it does say that in the rules. It doesn't say "if you have a carb" it must be a certain size. It says bikes running a certain engine are restricted to carburation equivalent to a single 24mm carb. There's a restriction there.

[TZ350]

318933

So what are we really trying to achieve with a 24mm carb restriction for 2T's that are over 104cc.
I think its to give the 4 strokes a small chance at keeping up.

............. :laugh: true, but I am still waiting to hear of a 2T winning the BOB.

[TZ350]

I think the rules are clear that you can use any size fuel injection throttle body you like. After all it does not mention them anywhere in the rules. Technically you also have to run a 24mm carb, because it does say that in the rules.

:scratch:Hmmmm now EFI is a reality, does this mandatory 24mm carb actually have to work?

318936

At 30 rwhp Speedpros unrestricted 100 Blue line betters my 125 in the dyno stakes. It is something anyone could do if they applied themselves like Speedpro has.

Things have moved on, EFI is a reality. So what do we really want to achieve here. And do we still need an induction restriction at all? Or should all 2T's be restricted to 24mm's? probably.

[cotswold]

Man I get bored easy these days.... Carb rules are dum. Lets just build open 50cc F5 bikes.

Richban for president 😎

[jasonu]

I think its to give the 4 strokes a small chance at keeping up.

Nope. It was to offset the 25cc advantage they had over the current for the day 100cc watercooled motors.

[FastFred]

Nope. It was to offset the 25cc advantage they had over the current for the day 100cc watercooled motors.

Now that 100's are allowed to go out to 110cc on re bore, is the restriction still relevant.

A 100cc water cooled motor already has an enormous advantage over air cooled engines, maybe to be fair, the water coolers should be restricted to 24mm and the air cooled engines unrestricted. Now that would be more balanced.

[richban]

110cc on re bore, is the restriction still relevant..


Re bore is short for – replace bore – right :innocent:

[jasonu]

Now that 100's are allowed to go out to 110cc on re bore, is the restriction still relevant.

A 100cc water cooled motor already has an enormous advantage over air cooled engines, maybe to be fair, the water coolers should be restricted to 24mm and the air cooled engines unrestricted. Now that would be more balanced.

110cc on rebore is only 4cc more than they had so from what I have read that is more to do with ease of obtaining pistons rather than a power advantage.

TZ, Green and probably others have proven you can make 30 or more HP from an air cooled 125 with a 24mm carb. As soon as they figure out how to get them to hold together, and I am sure they will, they will hold the advantage over the 100cc 2t water coolers and likely the 150cc 4t's as well.

It sounds like you have a 125cc 2t...

[FastFred]

318936

At 30 rwhp Speedpros unrestricted 100 Blue line betters my 125 in the dyno stakes.


TZ, Green and probably others have proven you can make 30 or more HP from an air cooled 125 with a 24mm carb.

No, they are both good engine builders but it looks like Green has shown that his water cooled 100 can better TZ's air cooled 125.

To be fair it looks like it is the water cooled 100's that should be restricted, not the air cooled 125's.

Just logically following the evidence.

[Grumph]

To be fair it looks like it is the water cooled 100's that should be restricted, not the air cooled 125's. Just logically following the evidence.

The equivalency thing has been fluid for years with no one type holding an advantage for very long - except on the big tracks where until the watercooled 100's get sorted fourstrokes will continue to rule.
Given any new motors being brought out which are bucket legal are 4 strokes, things could change again - or maybe not...

[TALLIS]

I think the restricted carb rule for 125cc a/c should be dropped, the difference in power will be marginal and they still need to be reliable to be competitive. Just a thought.

[TZ350]

.... they still need to be reliable to be competitive ....

Yes and that is probably the greatest restriction on an aircooled 2T engine.


I think the restricted carb rule for 125cc a/c should be dropped.

Me too, as there is no useful evidence that shows its necessary or effective in its purpose.

But if we are going to have it, it would be good to have a consensus about how its interpreted.

The common convention has been that carburetors are sized on their choke size and/or flow/min with slide carburetors measured at the narrowest point in the venture, this is usually just behind the slide. It is the usual thing Mikuni, Delorto, Kehien to name a few do this but it is not a rule and not every manufacturer does that, Lectron is an example. Pumper carbs are commonly sized at the venture, Tillotson is an example.

And CV carbs with their variable venture are measured at the flange. Maybe MNZ were thinking of them when they issued their clarification. Because its not the way most of the current manufactures make slide carbs, so if MNZ's rule clarification was applied as is, it would make a lot of the 24mm carburetors from the major manufacturers illegal.

It would be good to have some sort of consensus about how we want to apply "the equivalent to a single 24mm carburetor rule".

[richban]

The common convention has been that carburetors are sized on their choke size and/or flow/min with slide carburetors measured at the narrowest point in the venture, this is usually just behind the slide. It is the usual thing Mikuni, Delorto, Kehien to name a few but it is not a rule and not every manufacturer does that, Lectron is an example. Pumper carbs are commonly sized at the venture, Tillotson is an example. And CV carbs with their variable venture are measured at the flange.

It would be good to have some sort of consensus about how we want to apply the current 24mm equivalent rule.



All you need to do is ring all the carb manufactures you mentioned and ask them how they measure there carbs. Easy! Then put it in a document and send it to MNZ for them to include into the rules. :msn-wink:

Really though asking for consensus is a big fat waste of time. There are to many personal agendas to get past. And this site is no true representation of the racers. If you go searching for all the clarifications for all the rules you are limiting yourself more and more. Build race blow up then build again. At the moment the biggest issue is reliability.

[mr bucketracer]

24mm is 24mm , not that hard realy lol

[kel]

Really though asking for consensus is a big fat waste of time. There are to many personal agendas to get past. And this site is no true representation of the racers. If you go searching for all the clarifications for all the rules you are limiting yourself more and more. Build race blow up then build again. At the moment the biggest issue is reliability.
Summed up beautifully!

[speedpro]

Really though asking for consensus is a big fat waste of time. There are to many personal agendas to get past. And this site is no true representation of the racers. If you go searching for all the clarifications for all the rules you are limiting yourself more and more. Build race blow up then build again. At the moment the biggest issue is reliability.

Absolutely correct. Any bucket engine built to the edge of what's allowed under the rules will be a winner with the correct rider on board. The horsepower is there to be had. Most blowups aren't related to the power but rather the tune or a mechanical limitation of the base engine. FXR rods and TS crank bearings for example. MBs of course have no weak spot and I just blow them up now and again so everyone else doesn't feel too inferior.

[seymour14]

Absolutely correct. Any bucket engine built to the edge of what's allowed under the rules will be a winner with the correct rider on board. The horsepower is there to be had. Most blowups aren't related to the power but rather the tune or a mechanical limitation of the base engine. FXR rods and TS crank bearings for example. MBs of course have no weak spot and I just blow them up now and again so everyone else doesn't feel too inferior.

And KR's are an unknown quantity.

But not for much longer...:yeah:

[Pumba]

And KR's are an unknown quantity.

But not for much longer...:yeah:

I thought that had already been blown up twice? (or parked up before it did blow up is maybe more correct:devil2:)

[seymour14]

I thought that had already been blown up twice? (or parked up before it did blow up is maybe more correct:devil2:)

Third times the charm...:cool:

[TZ350]

Someone on the FXR150 site sought a clarification from MNZ ( http://www.fxr150.co.nz/forum/showthread.php?1068-104cc-carb-size&p=13141#post13141 ) re, "where is a carb measured".



If you go searching for all the clarifications for all the rules you are limiting yourself more and more. Build race blow up then build again. At the moment the biggest issue is reliability.

Agreed, and I didn't ask for this clarification, just needed to get a feel for how others saw it. Happy to go along with the consensus if there is one.

[TZ350]

here is the original answer from mnz.

Chapter 24 has been changed to chapter 16 in the latest version of the MoMS. So it becomes 16.2 now. That rule does not specify whether it's at the venturi or the bore size but the usual convention when specifying carburetor size is to measure the inner bore diameter on the exit side of the carburetor.

I have understood the convention a little differently but have not been able to find anything current on the net that shows how credible carburetor sources see it.

I cut my motorcycle racing teeth in the days when Amal carb specs said "Choke Bores Measured Behind Throttle Valves" and this is the convention I grew up with.

318955


On the face of it the MNS clarification of measuring the carb at the exit side (because a carb is larger there) looks like it makes the Mikuni Kiehin and other common manufactures 24mm carburetors illegal for us to use, I am sure that wasn't the intention so there must be something I have missed or maybe "exit side" is MNZ's way of saying "behind throttle valve????.

In the end, the interpretation of the rule is whatever MNZ wants to say it is, and that is Ok..... Kiwi-azz, thanks for posting their reply.

[kel]

In the end, the interpretation of the rule is whatever MNZ wants to say it is, and that is Ok

The correct answer from MNZ is exactly as per the first part of the reply i.e. "That rule does not specify whether it's at the venturi or the bore size" end of story. Besides "usual convention" doesn't fit with buckets :Punk:.

[Grumph]

The correct answer from MNZ is exactly as per the first part of the reply i.e. "That rule does not specify whether it's at the venturi or the bore size" end of story. Besides "usual convention" doesn't fit with buckets :Punk:.

Exactly so. What MNZ and the original questioner have to realise is that what is in the rule book IS the rule. It can be varied (but the intent can't be changed) by meeting supp regs. Any clarification from MNZ is merely how someone at MNZ sees the rule - IT IS NOT A RULE.
The rule book as it stands is what we work to, not anonymous suggestions.

The only ways to define it absolutely are to either change it with a remit or protest someone and have it defined by the process of protest, appeal, judgement.
I see no reason to do either.

[Hilleye]

Exactly so. What MNZ and the original questioner have to realise is that what is in the rule book IS the rule. It can be varied (but the intent can't be changed) by meeting supp regs. Any clarification from MNZ is merely how someone at MNZ sees the rule - IT IS NOT A RULE.
The rule book as it stands is what we work to, not anonymous suggestions.

The only ways to define it absolutely are to either change it with a remit or protest someone and have it defined by the process of protest, appeal, judgement.
I see no reason to do either.

I would definitely agree with Grumph and Kel.

I'm assuming that MNZ rules operate in a similar fashion to laws. If so, then Westminster Law principles would apply (what all NZ law is based on). That is, unless it is expressly forbidden, it is allowed. In this case if you can show somehow that a carb meets the 24mm restriction through any interpretation of the rule (i.e. somewhere in the carb body measures no more than 24mm in this case) then it is legal. This would be especially easy if it is how one or more carb manufacturers determine the size of their carbs already, which would therefore constitute a standard convention within industry. i.e. you're following industry standard practice when measuring carb size, not making up your own. Bored out carbs with a venturi, might be on the fringes, but still they're not expressly forbidden, therefore they're legal, especially if they started out as a standard 24mm carb.

The only time this would change is by precedent, which would be when MNZ actually makes a formal ruling regarding a specific location that the measurement has to be taken from or how long the 24mm restriction within a carb needs to be. In the MNZ case this would probably take the form of a supplementary regulation regarding the 24mm carb restriction. In this case it seems like all that's been given is the opinion of an MNZ official, which I wouldn't think constitutes a ruling and hence wouldn't constitute a precedent/supplementary regulation on which to base future determinations of carb legality on.

Therefore, going forward I'd say nothing has changed. If it's not explicitly stated in the rules as being illegal, it's legal. And, the MNZ opinion on the 24mm carb restriction counts for almost nothing until it becomes a supplementary regulation.

[TZ350]

Bored out carbs with a venturi, might be on the fringes, but still they're not expressly forbidden, therefore they're legal.

Yes, agreed, and they should be legal too. Buckets has always been about making the best of what you have, or can beg, borrow or steal, it would be a pity to see restrictions introduced with the purpose of limiting innovation.


... unless it is expressly forbidden, it is allowed. In this case if you can show somehow that a carb meets the 24mm restriction through any interpretation of the rule i.e. somewhere in the carb body measures no more than 24mm ... then it is legal.

Makes sense. You should be able to do anything you like to a carb so long as it has a 24mm equivalent hole in it some place that all the wind passes through.

[jasonu]

. You should be able to do anything you like to a carb so long as it has a 24mm equivalent hole in it some place that all the wind passes through.

That was part of the original intent of the rule.

[Grumph]

I would definitely agree with Grumph and Kel.

I'm assuming that MNZ rules operate in a similar fashion to laws. If so, then Westminster Law principles would apply (what all NZ law is based on). That is, unless it is expressly forbidden, it is allowed.

The only time this would change is by precedent, which would be when MNZ actually makes a formal ruling regarding a specific location that the measurement has to be taken from or how long the 24mm restriction within a carb needs to be. In the MNZ case this would probably take the form of a supplementary regulation regarding the 24mm carb restriction. In this case it seems like all that's been given is the opinion of an MNZ official, which I wouldn't think constitutes a ruling and hence wouldn't constitute a precedent/supplementary regulation on which to base future determinations of carb legality on.

Therefore, going forward I'd say nothing has changed. If it's not explicitly stated in the rules as being illegal, it's legal. And, the MNZ opinion on the 24mm carb restriction counts for almost nothing until it becomes a supplementary regulation.

Similar to westminister law, yes. But in no case except a protest committee can MNZ actually make a formal ruling on a machine spec question once the rule is in the book. The executive can I believe introduce an interim rule to cover any major point which arises - but that is subject to scrutiny at the next AGM.A couple of seasons back the 250 prod mess arose because as i understand it, they (or individuals inside MNZ) tried to make a set of ad hoc regs over ride the book. Couldn't be done and as expected ( by me anyway)the protest committees upheld the regs in the book. Supplementary regs usually apply only to one meeting - or very rarely to a defined series. By definition they are extras put there for a specific reason eg a local class for a street race. They have a defined life too and must be reapplied for if they are to be used again.
Be thankful we're not subject to the same regime as kartsport - there's a specific instruction "if it's not mentioned as allowed, it's forbidden"

[F5 Dave]

Ahh, - `Wife` rules.

[TZ350]

- there's a specific instruction "if it's not mentioned as allowed, it's forbidden"


Ahh, - `Wife` rules.

So true ...... :yes:

[TZ350]

The common convention has been that carburetors are sized on their choke size with slide carburetors that is measured at the narrowest point in the venture, and this is just behind the slide.

319183

Ok for what its worth, I finally found a reputable manufacturer who specifies where their carb is measured

[jasonu]

319183

Ok for what its worth, I finally found a reputable manufacturer who specifies where their carb is measured

You could use one of those on your bucket...:niceone:

[TZ350]

You could use one of those on your bucket...:niceone:

AMAL

319184

I did think about it, and they are available new too:- http://amalcarb.co.uk/t-t-series/10tt9.html

[husaberg]

You could use one of those on your bucket...:niceone:

i know its a joke but size for size a RN Amal will actually flow more air than the best Mikuni or Keihin smoothbore.
As they don't have a pesky needle hanging in the middle of the throat to interupt the flow.:msn-wink:
The TT was a better carb on two strokes as the GP2 doesn't have a proper pilot cuircuit.
With the remote float they can also operate at any level of downdraft.
I don't think Rob needs any prompting to use some more pom bits remember he used to use a morris carb on the spliter intake:spanking:
Then a holden one on his ex atac.

[Grumph]

I wouldn't count too much on every type of Amal advertised being available. The mob making them are developing a reputation. It would appear that while starting with a hiss and a roar, they're running out of money and production is spasmodic....
Talk to the people with Concentric orders backed up for months and no delivery in sight.

[TZ350]

319185 $1,200 NZD all credit cards accepted.


I don't think Rob needs any prompting to use some more pom bits remember he used to use a morris carb on the spliter intake:spanking:
Then a holden one on his ex atac.

Clever thinking and adapting what you can find, is what I love about Buckets.