anybody had experience whith bike carbs fitted to 7 port head? any information wanted,ie,sizing,brand,from which bike,linkages,where to buy, filters,has 2 /40mm webers at the moment but having a bit of grief with tuning [seems to be transition problem] hard to find good weber tuner in melb

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16v, twin cam, 'a'series, cooper S replica,3x dcoe webers,Around 200 HP and heaps of torque

What type of 7 port

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A proper mini redlines at 13 500 rpm

I'd say go for it. I don't run a 7 port head but I run a set of bike carbs on my ute and they work well. I find them pretty easy to adjust once you understand all of the circuits. I've never tried tuning a weber before so I can't make direct comparisons between the two.

If you do go for it though, I'd recommend at least a Gunson Colortune for tuning them individually at idle. I also have a wideband AFR gauge which helps me during the rest of the range.

Also, pay a lot of attention to mounting the carbs at the same angle they are mounted on the bike.

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"In two years time your car will be like a lady's clothes, out of date, my car will still be in fashion when I am dead" - Sir Alec speaking to Pininfarina

What size engine have you got?

I know that most bike carbs have a fair bit of adjustment before you have to start changing jets etc so they might be a good idea. I've not done it personally but I do run 4x KeiHin CV Carbs on my Honda powered Mini, but these are actually a matched set of carbs off a Gen 1 MS1 Mugen Civic, so technically not bike carbs.

For ease of sourcing, you probably want the most common set of 4 carbs you can find. From my looking around when I was looking at putting some on a race engine, Honda CBR600/700 carbs or Yamaha R6 carbs were the easiest to find. My carby guy at the time told me to look for 400-450 carbs to use on a 3000cc 6 cylinder. I'm guessing if you're a running a 1275+ you'd be looking for something smaller again to put you in the right area. I couldn't even tell you if there is a 4cyl bike smaller than 450 that run individual carbs, but I reckon they would probably be a Jap Import and hard to find. This being the case you'd probably have to go for the 600 carbs which I guess would mean rejetting etc, and I think you'd probably find yourself in the same position you are in at the moment. Once again, I have no actual experience here, this is just speculation from what information I was given when looking into it.

What settings are you running on your 40DCOE's at the moment? Chokes, aux venturis, idle, mains, air correctors, emulsion tubes, pumps, float level? I'm not very well versed in Webers but when I ran into trouble tuning mine, there were some very helpful and knowledgeable people on here who helped me get through it. Myself or someone else may be able to help?

Cheers,
Keels.

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-Wasabi
1972 Clubman - Daily Driver
1962 850 - EW1 Powered

motor first rebore so 1310?, its a pierce head larger valves and cleanup around throats, as for jetting details don,t know offhand but will look soon.engine is in rear of mini,so,a bit difficult to remove jets to see,got a bloke fddling at the moment,he has improved it alot ,he said ,and i agree seems to go well until around 4000 rpm then seems a bit flat

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16v, twin cam, 'a'series, cooper S replica,3x dcoe webers,Around 200 HP and heaps of torque

Put an A/F ratio meter on it, it's probably going lean.
A member here put a Mikuni (designed for H/D) on his 1412 Mini, I had to drill the main jet out because he couldn't buy the size it needed.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Hi i'm moding this ones to try on my 7 port project, velocity stacks were created by me not part of the original setup.

https://www.facebook.com/media/set/?set ... 172&type=3


Regards from Portugal
Diogo

I agree with Doc, sounds like it might be lean on the main circuit. That or the chokes may be too small restricting the air flow. I think for your setup 32mm chokes would be appropriate. It's hard to tell without being there. When it goes "flat" does it feel like the power sort of tapers off or more like it's hit a wall? Does it still run well when it's lacking power or does it cough and carry on?

Diogo, some very nice work there. Are they Yamaha R6 carburettors? I also really like the ITB setup on the 1460cc...

Cheers,
Keels.

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-Wasabi
1972 Clubman - Daily Driver
1962 850 - EW1 Powered

was coughing and back firing through carb, since fixed ,doesn,t hit a wall sort fades away, seems flat ,like its all torque little HP,about to pick it up from carb bloke,we,ll see,he recons it,s going really good.the more i read the more i,m convinced it,s progression hole problem

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16v, twin cam, 'a'series, cooper S replica,3x dcoe webers,Around 200 HP and heaps of torque

Hi, very thanks, i do my best

The carbs are 40mm GSXR 1100 they are the Mikuni BST40, those carbs was the base to evolute for the well known Mikuni RS.

On the ITB´s, i made an adapting flange to fit them on my K1200 head conversion, but they require many mods, they are not a direct fitment.

Diogo