20 replies to this topic

[supermotolee]

sorry to bring this up as i read all this chat about hiff this and su that and i dont know what ones people are talking about...
i have a standard 998 one with the float on the side fitted to my 998 and it runs ok but its a bit rough at idle probably mixture/cleaning ect (running engine on floor :grin: ) and i also have an all in one style carb :erm: no external float chamber that has a 1 1/2 inch bore i understand the hiff44's have 13/4 inch bore so what do i have and will it work ok with my 998 stage one engine? its just now i've cleaned it and checked its all ok i'd like to use it
if you need pics i may be able to get them up but the carbs not marked or i'm not looking in the right place
thanks all

[Guess-Works.com]

The one on you engine is an HS4, S for Side and 4 for 1/8's of an inch over one inch so 1.1/2"...

The other is either an HIF4, IF for Intergrated Float and 4 as before or HIF38, 38 being 38mm ( the EU has something to answer for there ! ) or 1.1/2"...

Yes they will swap, but not sure if it's wise to use the HIF on a std cast manifold as there will be two studs missing.. should be ok, but there are 4 stud holes for a reason!

[supermotolee]

thanks that clears it up a bit!!! i have an ally manifold and lcb to replace the origional stuff when the engine goes in the car and i'l fit the other 2 studs too now all i need is a suitable k&n are the copies worth bothering with or are the propper k&n filters the best?
thanks

[998dave]

As above, your one with the bit on the side is an HS4 carb, and the other one probably an HIF38.
They are the same size internal bore, almost... HS4 is 1.5 inches = 38.1 mm diameter so in theory has a larger throat and larger capacity then the HIF38, but you won't notice as the HIF is also more modern, it's a matter of personal preference.

Finally SU - both of them are SU carbs! )

Dave

[miniman5]

on a 998 you want a HIF38, i just brough one for mine acutaly, thats one and a half inch 'all in one' type HIF stands for High Intergral Float, the floats inside it. ive been told this wont give you any performance gain(unless you put a bigger needle in it), but it will give me better fuel econemy and better responce.

[Jammy]

ive been told this wont give you any performance gain(unless you put a bigger needle in it).

Not true anyway, putting a bigger needle would not give you any performance gains either. Each needle is specific to an engine, if you don't have the correct one then the mixture won't be correct and your engine won't perform to its potential.

The HIF carbs solved the problem with of the HS carbs being starved of fuel when going round right hand corners because the float was on the side.

[miniman5]

Not true anyway

guesworks says otherwise

[Guess-Works.com]

Does he ????

[miniman5]

yea you said over msn the other day

[Purple Tom]

I think Miniman5 might mean a different profile needle, as fitting a 'bigger' needle would actually cause it to run leaner, causing all sorts of problems (not to mention poor performance).

[supermotolee]

right thats cool i am a bike mechanic so i understand about how the needles and profiles work it was just what carb is what, as i couldnt see any markings.
i'm goning to use the hif carb its about 1 1/2 inches in bore and i'm fitting a full 2" system and lcb probably with a k&n filter i tried that win su program but couldnt get it to load on my computer anyone know what needle would be a good start? or just get it running and take it to a rolling road ?
got a play mini style big bore side exit back box i'm excited to hear it run for the first time all rigged up
cheers everyone

[Guess-Works.com]

If your going to run an LCB, and an Alloy inlet and a high flow air filter ( such as a K&N ) then you're pretty much at stage one, where the favourites are AAA and AAB needles.. the AAB provides a little more richness in the upper half of the rev range, I generally use AAA's as a good starting point on 998's with stg1's

[supermotolee]

right thanks for that i'l see what i can find. yeah i'm pretty much there with the stage 1 kit i just fitted one to my girlfriends mini that came with an aau needle how does that compare the the aaa?
thanks

[Dan]

Well, the needle from a stage 1 kit is normally optimised for a 1.75" exhaust. You'll need something slightly different if you use the 2" and the LCB as it's not so good for a Mini, especially a 998. So I would start with the AAA as it's a little leaner and then the rolling road can always file it to get it richer, whereas thay can't make it any leaner. Just don't rag the engine if you suspect it is running lean.

But having said that all the stage 1 kit's are different, so try asking one of the larger suppliers (Minispares or Minisport, don't ask someone like Huddersfield who just don't have the budget to develop these things properly) what they supply with their kits that do come with 2" exhausts.

Or try phoning MLM in kent and asking AC Dodd what he suggests. He is a real top quality A series tuner and an expert with SU needle profiles.

[Sprocket]

Yes they will swap, but not sure if it's wise to use the HIF on a std cast manifold as there will be two studs missing.. should be ok, but there are 4 stud holes for a reason!

Thats wierd, because the 94 mayfair we had, had only two diagonal bolts on th HIF38