Interchangeability of carbs and carb rubbers for oil-cooled engines

[Wee Man]

I've got 40mm carbs and rubbers. What measurements do you need? 

[Dezza]

1 hour ago, Wee Man said:

I've got 40mm carbs and rubbers. What measurements do you need? 

Internal diameters of the rubbers and ods of the carb inlet stubs please!

[fatblokeonbandit]

1100G shfty carbs and 750 teapot  rubbers..

 

Edited November 15, 2019 by fatblokeonbandit

[Captain Chaos]

worth mentioning that the 2nd generation GSX-F (the Baboon arse) has different carbs and rubbers than the first generation (the Teapot). Baboon arse is from 1998.

 

 

[baldrick]

not trying to complicate matters, but would it be an idea to put jetting settings up, for the commonly asked questions ?

I fully realise there is no substitute for dyno time, im more thinking "ballpark figures" for the usual suspects,

i.e.what size pilot, main jetting, needle clip etc for my gsxr  with a race pipe and k&ns, for like 36's 38's 40's etc.

Or am I opening up a minefield here?

[Captain Chaos]

1 minute ago, baldrick said:

Or am I opening up a minefield here?

yes.

Jetting is also dependant on climate, altitude, fuel quality...

[baldrick]

I did say "ball park".

Given that probably 90% of members are around sea level , using unleaded etc.

Edited November 15, 2019 by baldrick

[Wee Man]

40mm carbs and rubbers 

 

[SiBag]

14 hours ago, Dezza said:

Anyone with a set of 750 teapot carbs/rubbers? It would be good to confirm the sizes as being able to use 750 teapot rubbers to mount 36mm CVs from another model as this will widen the available choices for those sourcing 2nd hand parts.

I've got a short stroke teapot motor in the garage with rubbers on it.

I'll have a measure over the weekend if it helps.

[Dezza]

8 hours ago, SiBag said:

I've got a short stroke teapot motor in the garage with rubbers on it.

I'll have a measure over the weekend if it helps.

Yes, please! Many thanks Simon.

[Dezza]

8 hours ago, Wee Man said:

40mm carbs and rubbers 

 

Interesting! Seems to me that the rubbers from a GSXR 1100 M or N will be too big to accommodate other carbs, including RS 40s.

[Dezza]

12 hours ago, fatblokeonbandit said:

1100G shfty carbs and 750 teapot  rubbers..

 

1100G shaft drive thingy? With the oil cooled engine I assume? I forgot these so that is 2 birds with one stone as now we have the 750 teapot measurements too.

[fatblokeonbandit]

6 hours ago, Dezza said:

1100G shaft drive thingy? With the oil cooled engine I assume? I forgot these so that is 2 birds with one stone as now we have the 750 teapot measurements too.

But as captain chaos said the late ones are different, I haven't any idea which ones I had early or late model,??

[dupersunc]

Fcr41s use the bst38mm carb rubbers.

There are different length bst36 rubbers. Mk1 bandit runners are approx 5mm longer than 750j/k and mk1 teapot rubbers. this is an issue if you want to run the stock airbox.

[Dezza]

3 hours ago, dupersunc said:

Fcr41s use the bst38mm carb rubbers.

There are different length bst36 rubbers. Mk1 bandit runners are approx 5mm longer than 750j/k and mk1 teapot rubbers. this is an issue if you want to run the stock airbox.

Yes, this is a good point. I noticed using the rubbers from a 750L brought my carb bank a little closer to the head so they are likely shorter than the Blandit 1200 rubbers I had on it before. Maybe 750 slingshrt rubbers are just shorter than those for larger / earlier engines?

[bluedog59]

I would think the short rubbers may be a handy way of reducing the inlet tract tuned length for higher revving engines given that the only other way ( given the same basic cylinder head casing ) would be to shorten the carb/airbox rubbers which could make more problems than it solves.*

* Theory and I've had beer.

[Lachie04]

Long stroke 98+ teapot rubbers

Only uses two types  1 for #1&2  and 1 for #3&4

The Post 98 model teapot has 36 mm carbs and the spacing of the carbs is Roughly 82-86-82

and they are 5mm longer than the Dot head rubbers

they will not take RS carbs as the spacing is all wrong even though the carbs would fit the rubbers

suffice it to say and most of you would know BSt 36's are not all the same internally or externally

 

Yes short stroke teapot will take RS flat slides

 

 

Edited November 18, 2019 by Lachie04

[Dezza]

15 hours ago, Lachie04 said:

Long stroke 98+ teapot rubbers

Only uses two types  1 for #1&2  and 1 for #3&4

The Post 98 model teapot has 36 mm carbs and the spacing of the carbs is Roughly 82-86-82

and they are 5mm longer than the Dot head rubbers

they will not take RS carbs as the spacing is all wrong even though the carbs would fit the rubbers

suffice it to say and most of you would know BSt 36's are not all the same internally or externally

 

Yes short stroke teapot will take RS flat slides

 

 

No teapot had carbs bigger than 36mm (rubbers have an id of ~40mm) so I am guessing you are using other rubbers to mount those RSs, which will have inlet spigot ods of either 42mm (RS 34,36,38) or 44mm (RS40). Unless the rubbers have been enlarged by sanding that is. I have some RS38s and they aren't going to fit in a set of unmodified BST 36 rubbers in a million years.

[Lachie04]

3 hours ago, Dezza said:

No teapot had carbs bigger than 36mm (rubbers have an id of ~40mm) so I am guessing you are using other rubbers to mount those RSs, which will have inlet spigot ods of either 42mm (RS 34,36,38) or 44mm (RS40). Unless the rubbers have been enlarged by sanding that is. I have some RS38s and they aren't going to fit in a set of unmodified BST 36 rubbers in a million years.

Are you holding your tongue to the left like the manual says?

But seriously

whoriginal rubbers

Whoriginal carbs

And they are original as I rebuilt them slide guides, little pilot rubbers and all (so good for another 30K)

Correct RS have 42mm OD 

And those are 38's in the pic

42 out  vs 42 in

30yr old rubbers little bit of heat gun some red rubber grease and plop straight in no mods

Oh BTW 

98+ teapots are BSR carbs which I remembered about 1/2 hr after last post

Edited November 19, 2019 by Lachie04
added pic

[Lachie04]

On 11/14/2019 at 9:18 AM, fatblokeonbandit said:

80 - 85 - 80 ....???

 

 

 

Those look the same as the 98+ teapot rubbers

Edited November 19, 2019 by Lachie04

[Dezza]

If the teapot 98+ rubbers are the same as FBOB's B12 MK, which seems logical as both bikes have BSR36mm carbs, how come a set of RS38s spaced 77-93-77 go straight on? Are the B12mk2/teapot 98+ head castings different so the inlet ports are spaced differently?  Maybe these BSR rubbers are 'chamfered' on the inner edges as RS 38s do not go into B12 mk1 rubbers or the like.

Edited November 19, 2019 by Dezza

[Ted M]

4 hours ago, Dezza said:

If the teapot 98+ rubbers are the same as FBOB's B12 MK, which seems logical as both bikes have BSR36mm carbs, how come a set of RS38s spaced 77-93-77 go straight on? Are the B12mk2/teapot 98+ head castings different so the inlet ports are spaced differently?  Maybe these BSR rubbers are 'chamfered' on the inner edges as RS 38s do not go into B12 mk1 rubbers or the like.

@DezzaII've got a B12 mk 1 engine and head with Mk2 rubbers and carbs I'll get my ruler out tonight and post up the spacing and check to see if the BSRs are chamfered. Great post too lots of good info 

[Ted M]

Here you go mk 2 B12 carbs. I can’t see any Chamfer on the carbs. 

[Dezza]

Thanks Ted. Your set up confirms that the MK2 carbs and rubbers can be transferred to a MK1 head as a complete unit. What I cannot understand is if the 98+ teapot carbs and rubbers are the same as MK2 Blandit items, how using the 98+ rubbers enables the mounting of a set of 77-93-77 RSs on a 750 dot head, unless the 98+ teapot heads have a unique casting with different inlet port spacings.

 

Also, Ted, what is the od of the MK2 inlet stubs on the BSR36 carbs? I cannot quite make it out from the pics

[Lachie04]

@Dezza

The Flat slides did not go on the 98+ teapot rubbers, as far as I know, you can only alter the internal spacing of RS Carbs between 2-3 to 85mm not the outer pairs but I have never played with them that way

 

Edited November 20, 2019 by Lachie04