5 replies to this topic

[Mr. Bridger]

Model: 998 Mini Checkmate

Year: 1990

I've already got a stage one kit. If I were to buy a different carb (or twin carbs) what should I go for? As far as I know, I've currently got a single HS4. Would twin HS2s be the best option? Or a single HIF38? Or something else entirely?

The John Cooper kit that you could buy with the Checkmate came with twin HS2s so I quite like the idea of that, but what's going to give me the best performance?

Thanks.

[Pooky]

I tried twin HS2's. Lost power on the Dyno with them compared to my old HS4. Although Gerald said there was an air leak in them somewhere

Unless you're desperately seeking the period look of twins then a HS4 or HIF38 would be best. Never used a HIF38 myself as I'm more than happy keeping it simple with my HS4.

If you're after performance your time and effort could go into better things than carb mods but have you considered Vizard-ing your current carb? Narrowing the throttle butterfly spindle, cut off the butterfly screws, knife edge the butterfly, file an angle on the first edge of the carb piston, K&N filter with ram pipe blah blah blah

Twins are also pretty expensive even in half decent condition, you're looking £100+ for a pair that won't need rebuilding. That money could be spent on a new cylinder head or numerous other mods that will get you more power

Edited by Pooky, 26 May 2010 - 04:19 PM.

[GreenMini17]

Yeah, its suprising how having the correct ram pipe makes such a difference. You can gain 2hp just from having the right ram pipe on there! Amazing.

[Mr. Bridger]

I got focused on carbs because I was looking at the brochure for the Checkmate and the Cooper kit that could come with it. It says that, with the Cooper kit, the 0-60 time is reduced to 12.6 seconds from 16.5 seconds. The kit only has twin HS2s, a performance exhaust and a 'polished flowed cylinder head' (it doesn't say which one, although someone on here said it was from Janspeed).

I know the general recommendation is to go for new rockers/cam/head after a stage one, but they all seem far more complicated than the carb. My plan was to get the best carb and then look into heads.

Second hand twin carbs are also surprisingly cheap, although it does look like you'd have to rebuild most of them.

So should I ignore the carb for now, other than making sure mine is in top condition?

Edited by Mr. Bridger, 26 May 2010 - 04:55 PM.

[blacktulip]

hif38 every time. the performance is good plus you dont get fuel starvation on hard cornering.

[lrostoke]

The kit only has twin HS2s, a performance exhaust and a 'polished flowed cylinder head' (it doesn't say which one, although someone on here said it was from Janspeed).

The valves are also bigger, bro in law had the kit fitted to his, unfortunately he got it with 100,000 miles on the clock so not at its best.
On removing the head it looked like mice had been eating the valve seats.
We've since fitted a 2nd hand engine which is now bored to plus 40 thou and gone to HIF38. One day soon though we are planning on seeing if the "Cooper" head can be resurrected.