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Which carby(ies) for a warm 998?
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Author:  Ian Davy(oz) [ Thu Oct 08, 2009 8:12 am ]
Post subject:  Which carby(ies) for a warm 998?

Hi All,

Being new to Mini's I have a question.

I'm planning on putting a warmed up 998 into my newly acquired 850 and was wondering if I should use twin 1-1/2 SU's, or a 1-3/4 SU (either from my collection at home) or something else?

Ian

Author:  ryan [ Thu Oct 08, 2009 8:21 am ]
Post subject: 

I would be putting on a 1.5" or twin 1.25"

Author:  TheMiniMan [ Thu Oct 08, 2009 8:55 am ]
Post subject: 

Most "STD" 998cc mini engines run a single 1&1/5 carb,,,,, sooooo,,, seeing that each piston (998cc divided x 4) only sees one carb of 1&1/2" hole,,, then twin 1&1/2 carbs fitted will be the same in that respect, ---> just the manifold is a great improvment in design with far less restriction, better flow & more even distribution of mixture across all 4 cyls

so ,,, There`s absolutely nothing wrong with fitting twin 1&1/2s onto it , it will go very well if tuned correctly to suit

Author:  gafmo [ Thu Oct 08, 2009 11:24 am ]
Post subject: 

If you have it use it. The twins will work just nicely as Miniman has said. I have a warm 1098 (Similar to a 998) and it has a HIF44.
I am at present building a Nice warm 998 and it will be getting a 1 1/2 SU
If you wanted to you could put a 40 Dellorto also.

Any of the these carbs will work well if correctly set up with the correct (SU) Needles or jets etc with the dellorto

Author:  david rosenthal [ Thu Oct 08, 2009 2:35 pm ]
Post subject: 

Now I will up-set the apple cart. :D
Put a pair of Kei-Hin carbys off a jap bike.honda,kwaka,
You can get a set of 38mm, 40mm,42mm or 45mm quads from a bike wrecker fairly cheap. Just set them up as twins[use all the std linkages with a longer connecting shaft]
These carbys are very good[Matt is starting to love them ] and as he said they are a cross between a SU and a Weber. They have separate idle mixture, low speed/accelator fuel supply and when you open them up flat out they just feed fuel via needle like SU.
They are simple to fit to a manifold as the have a rubber connector off the carby. This stops fuel airation in the float bowl.
They other advantage is that if you get a set off a honda cbr 600 or bigger , the carbs can run at a angle of 25 deg upto 40 deg with-out up-setting the float level

Author:  lil-ute [ Thu Oct 08, 2009 7:07 pm ]
Post subject: 

david rosenthal wrote:
Now I will up-set the apple cart. :D
Put a pair of Kei-Hin carbys off a jap bike.honda,kwaka,
You can get a set of 38mm, 40mm,42mm or 45mm quads from a bike wrecker fairly cheap. Just set them up as twins[use all the std linkages with a longer connecting shaft]
These carbys are very good[Matt is starting to love them ] and as he said they are a cross between a SU and a Weber. They have separate idle mixture, low speed/accelator fuel supply and when you open them up flat out they just feed fuel via needle like SU.
They are simple to fit to a manifold as the have a rubber connector off the carby. This stops fuel airation in the float bowl.
They other advantage is that if you get a set off a honda cbr 600 or bigger , the carbs can run at a angle of 25 deg upto 40 deg with-out up-setting the float level

can these carbies be ran on a 1380

Author:  david rosenthal [ Fri Oct 09, 2009 12:14 am ]
Post subject: 

Lil-ute, get a couple of 42 or 45 carbys [ie 1 5/8, 1 3/4] they were fitted as quads on BIG jap bikes. honda cbr F4 600, 900, and 1100 all ran 42's and the later 1100's ran 45's. The little tricks and set-ups take a bit of working out ,but once they are set-up they are a good all round road carby.
The ultimate would be some CR slide throttle carbys, but they cost BIG bucks, but that's all the race bikes use.

Author:  mattsmadmini [ Fri Oct 09, 2009 11:01 am ]
Post subject: 

Ive got a pair of Kei Hin carbs sitting in my garage, i think they work out to be around twin 1.5"s.... just have to be bothered to make a bloody manifold for them.... and yes, eventually they will find there way onto a 998...

Author:  MG Rocket [ Fri Oct 09, 2009 4:27 pm ]
Post subject: 

david rosenthal wrote:
Now I will up-set the apple cart. :D
Put a pair of Kei-Hin carbys off a jap bike.honda,kwaka,..........
They are simple to fit to a manifold as the have a rubber connector off the carby. This stops fuel airation in the float bowl.

David, can these be hard mounted to a manifold on an "A" series without
the aeration or is there still too much vibration?...I'm just thinking that bikes
seems to have a finer more intense vibration at full stick.

Author:  mattsmadmini [ Fri Oct 09, 2009 4:35 pm ]
Post subject: 

David has been walking me through making a manifold for these carbs Rockie, basically the same as it would be on a bike nice long intake pipes (as long as possible) alloy or similar then use some "go fast" silicon hose to mount the carbs to mani....

my thought is how to keep the carbs "in place" maybe strengthen the mani?

David will obviously have more knowledge than myself in these matters... just thought id "put it out there"

:P

Author:  Phat Kat [ Fri Oct 09, 2009 7:50 pm ]
Post subject: 

I keep seeing those Kei Hin carbies come up... Gotta say,,, sounds like a pretty good Idea... :D

I was just whinging at BALLISTIC the other day that there isn't much of a choice as far as SU carby savvey dyno tuners go... Being a newer and currently more popular carby, I'm gana stick my neck out and say that there would possibly be way more people around that can set them up propperly on the dyno, and being Japanese, well its arguably better than German! :lol: Plus parts would be way easier to get cos they are still in production, probably cheaper too...

I was just about to start a thread to try and get a Carby fight-I mean discussion going about who reckons what carby is good for what.. you know hear peoples findings... and stuff ups :lol: Mainly just to get some food for the old thinker, usually people come out with all kinds of whacky ideas, sometimes stuff you haven't heard of :D But I think I'm gana play with one of those next,

Cool idea :D

Author:  gafmo [ Fri Oct 09, 2009 8:21 pm ]
Post subject: 

Love it. Keep the idea flowing

Author:  sgc [ Fri Oct 09, 2009 9:54 pm ]
Post subject: 

Phat Kat wrote:
and being Japanese, well its arguably better than German!


German? SU's are English ;)

Author:  74snail [ Fri Oct 09, 2009 9:57 pm ]
Post subject: 

sgc wrote:
Phat Kat wrote:
and being Japanese, well its arguably better than German!


German? SU's are English ;)



Yeah but when you burn your hand on the manifold adjusting settings , all the swearing sounds German to me



.

Author:  david rosenthal [ Fri Oct 09, 2009 10:14 pm ]
Post subject: 

sgc wrote:
Phat Kat wrote:
and being Japanese, well its arguably better than German!


German? SU's are English ;)

As pommy as you could ever get. First designed in 1905 by George skinner. He went into probuction in 1907 with his two brothers and called the company, SKINNER UNOIN, hence the abriviation SU.

OK back to the jap stuff. The bike carbys have a rubber connection piece. This rubber is very hard. To get the carbs on/off you have to use a heat gun and warm the rubber up, but once they are on with a hose type clamp they are good.
Talk to Mad Matt and see how he did his on the baby bimmer. simple ,cheap be works a treat.Just put your mind to the exersise, nothing is impossible

For most if not all the "A" series cast iron wheezer heads I would say that two 38,or 42mm carbs would be good enough. As Matt and I have found with the t/c heads then quads are flat out feeding the engine. Matt is running quad 45's and he just keeps giving them more fuel and the engine just keeps pulling more revs. It will eventually go bang, I know from my engines that they will only take so much, but I am a butcher and when it goes bang then I know the limits

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