best carb for 1098..

[samuria]

a friend of my mate has a box full of su carbs..
he said i could take my pick
what should i look for
he said there is a hs4?????

[bmcecosse]

Well grab it! An HIF38 would be very slightly better, but an HS4 is fine.

[Biggles1957]

Agreed!

[Boris64]

All other things being equal, what will the differences be over a standard carb on a 1098 engine as photo?

Thanks

Pete[frame][/frame]

[bmcecosse]

The carb will appear slightly larger in the photo.......

[Boris64]

touchee

and what about performance, is it worth the effort?

Pete

[bmcecosse]

OF COURSE it will be better - but you really need to look for an alloy inlet manifold for it, to get the best. However - you can either use a later Mini manifold, or open up the hole in the manifold you have. Are the fixing holes vertical - or at 2 o'clock?

[Boris64]

Bmc,

Assuming you mean carb to manifold fixing, then vertical as photo.

What's the significance of this?

Pete[frame][/frame]

[don58van]

What's the significance of this?

The significance is that you won't be able to use your existing manifold to mount the HIF38 or 44.

If you happened to have a manifold with the angled mounting studs (2 and 8 o'clock), you could use it.

Cheers
Don

[Boris64]

Don,

Thanks for the advice.

I have got hold of a 2nd hand HIF38 (which needs rebuilding) on a mini manifold, so will see what options there are for exhaust manifolds.

Any advice on air filter?

So much for originality

Samurai - apologies, I assume you're doing the same thing but I have completely hi-jacked your thread, sorry

Pete

[samuria]

yes but its all good info....

[Boris64]

Samuria,

Thanks, if your happy then I'll keep adding questions to this post.

Pete

[samuria]

Samuria,

Thanks, if your happy then I'll keep adding questions to this post.

Pete

fire away pete

[Boris64]

In that case,

is it realistic to 'splice' the mini alloy inlet manifold into the existing cast exhaust set up?

If so how?

or

is there an exhaust only manifold that will link to the existing exhaust?

Thanks in advance.

Pete

[bmcecosse]

The answer is - you can use the alloy manifold with the existing exhaust manifold, and it works very well like that. No 'splicing' - you just cut the old inlet section off - when you cut, make sure you are well towards the inlet side, so no chance of cutting in to the exhaust - then simply grind down the cut face on the exhaust until there is room for the inlet when it's all on the head - WITHOUT the inlet touching the exhaust.... I use a K&N taper cone filter, but it's noisy... Some use Marina/Maestro/Princess filters - if you can find one...... DO NOT use a 'pancake' filter.....

[Boris64]

Bmc,

That's terrific thanks, hopefully everything I need to know

I guess there'll be a few brackets to make for accelerator/choke cable etc. but otherwise should be ok.

Thanks.

Pete

[bmcecosse]

Probably need a longer acc cable - so get a nice nylon lined new one (and a spare..) in stock. The choke cable can usually be persuaded to fit - or easily extended.

[Boris64]

That's terrific thanks.

Pete

[Boris64]

I think I'm making progress and whilst 'no-one' was looking used the other 'workshop' to clean the hif38 carb as the photos.

All looks to be in good condition so other than the few paper gaskets I have not replaced anything.

I cut off the bracket and stud for the mini/metro? air filter as it's of no use for the proposed/recommended k&n.

I drilled a hole by the dash pot to accommodate the bicycle fitting for the choke cable as this will allow better routing than alongside the throttle cable. Must let my son know about his bike I also elongated the hole for the throttle cable fitting to get a straight route to the linkage.

The inlet manifold needs the fitting for the servo vac pipe and has a location for the dizzy advance. The latter appears to be cast solid for drilling but I will be using the connection on the carb unless anyone suggests otherwise.

The current needle is ADP - as I have a standard 1098 and standard exhaust will this be ok? I'm looking for max impact from my hard work.

Also, given all the quality/accuracy of the carb machining why are the butterfly screws so rough and intrusive? Is it worth just cutting these shorter?

Thanks

Pete[frame][/frame][frame][/frame][frame][frame][/frame]

[bmcecosse]

One of Vizards major mods is to trim off the screws and Loctite them in - and to 'knife edge' the leading edge of the butterfly -indeed in extremis he trims one half of the shaft down ....... However on an otherwise standard engine this won't be worth while. Just try the ADP needle and see how it goes.