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Recommended single carb setup for Mini K 1100
https://www.ausmini.com/forums/viewtopic.php?f=5&t=97077
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Author:  makes [ Sun Apr 08, 2018 1:01 pm ]
Post subject:  Recommended single carb setup for Mini K 1100

Hi Mini Community,

I have a 1969 Mini K1100 that currently has extractors, maniflow twinbox exhaust (1.75") and twin SU carbs (1.25 inch) fitted.

It generally runs very well but unfortunately I have had a few problems with the carb setup
1. Seems to be running a bit rich.
2. Ongoing issues with fuel overflow/leakage from float system. I have fitted rebuild kit once already to both carbs that fixed for a while but has come back for some reason.
3. Fuel economy seems much lower than I would expect.

I am currently thinking of reverting to the simpler standard single carb setup. I have searched online etc. but have found conflicting advice & information. Most of the available info seems to be on boosting performance but my main priorities are reliability, low maintenance and economy without affecting everyday driving too much.

My questions are;
1. What would have been the standard carb & needle fitted to Mini K originally (not mentioned in workshop manual).. I suspect from forum messages here was a single 1.25" carb ?
2. I have heard that later HIF carbs are an improvement (mainly because fuel float is at bottom of main carb body) ?. Would a HIF38 or HIF44 from UK with an appropriate needle work perhaps ?
3. I was planning to stick with SU but there's a Weber 32/36 down-draft kit available for Moke & Mini, would that be worth considering for simplicity & other advantages they claim ?
https://www.lynxauto.com.au/mini-850-12 ... rsion.html
https://www.minimania.com/part/P4-004/C ... ir-Cleaner

Would appreciate any suggestions.

Thanks, Makes

Author:  timmy201 [ Sun Apr 08, 2018 3:01 pm ]
Post subject:  Re: Recommended single carb setup for Mini K 1100

The K did have an HS2 (1 1/4") carb standard.

Another option is the single HS4 (1 1/2"). They were used on later 998 engines, mini-matics, Morris 1100S and other 1275 engines.

My 998 has an HS4 carb with a performance kit similar to what you have now. I used the supplied AAU needle and it works perfectly, and has good safe AFR and it pretty good on fuel (7-8L/100km)
http://www.minispares.com/product/Class ... STN17.aspx

Author:  simon k [ Sun Apr 08, 2018 8:27 pm ]
Post subject:  Re: Recommended single carb setup for Mini K 1100

makes wrote:
2. I have heard that later HIF carbs are an improvement (mainly because fuel float is at bottom of main carb body) ?. Would a HIF38 or HIF44 from UK with an appropriate needle work perhaps ?


this ^^ HIF44

Author:  9YaTaH [ Mon Apr 09, 2018 7:56 am ]
Post subject:  Re: Recommended single carb setup for Mini K 1100

Makes, I don't know where in Oz you are...but why not consider getting the issues sorted out by tuning company?

If you are keen to spend some dollars on the machine then lift the head and get it flowed etc

I have heard that there were problems with the HIFs over the earlier HSs...so do some reading on the subject maybe...

Author:  makes [ Wed Apr 11, 2018 9:27 pm ]
Post subject:  Re: Recommended single carb setup for Mini K 1100

Hi Guys, Many thanks for your suggestions, they are very helpful. I will research and consider these options further. Cheers, Makes

Author:  1071 S [ Fri Apr 13, 2018 7:40 pm ]
Post subject:  Re: Recommended single carb setup for Mini K 1100

HS4 (1 1/2") SU on a 2nd hand Metro manifold worked fine on my Daughter's slightly warmed 1100 (295 head, Peco extractor ......and a few other bibs and bobs..

If you can't find a Metro manifold then MiniSpares make a replica...

But there's no reason your twins shouldn't work properly... Mine haven't needed a tweek in almost 10 years.

There really is no alternative to a proper dyno setup done by someone who knows what they're doing... Trial and error is very expensive at $20 odd a needle. But you don't need an expert to set the needle valve properly ... what sort of fuel pump do you have?? SU's don't like much over a couple of psi..

Cheers, Ian

Author:  michaelb [ Wed Apr 18, 2018 7:36 pm ]
Post subject:  Re: Recommended single carb setup for Mini K 1100

I have single 1 1/2” on two of my minis with 1100,s.
Extractors, modified head and 266 cam and setup on dyno is critical to achieving proper running and respectable power.
Dyno is not cheap but essential when trying to sort out any running issues.
And yes there are mini friendly or SU friendly dyno operators out there.

Where are you?

Author:  Goldbrocade_62 [ Sat Apr 21, 2018 8:15 pm ]
Post subject:  Re: Recommended single carb setup for Mini K 1100

makes wrote:
Hi Mini Community,

I have a 1969 Mini K1100 that currently has extractors, maniflow twinbox exhaust (1.75") and twin SU carbs (1.25 inch) fitted.

It generally runs very well but unfortunately I have had a few problems with the carb setup
1. Seems to be running a bit rich.
2. Ongoing issues with fuel overflow/leakage from float system. I have fitted rebuild kit once already to both carbs that fixed for a while but has come back for some reason.
3. Fuel economy seems much lower than I would expect.

I am currently thinking of reverting to the simpler standard single carb setup. I have searched online etc. but have found conflicting advice & information. Most of the available info seems to be on boosting performance but my main priorities are reliability, low maintenance and economy without affecting everyday driving too much.

My questions are;
1. What would have been the standard carb & needle fitted to Mini K originally (not mentioned in workshop manual).. I suspect from forum messages here was a single 1.25" carb ?
2. I have heard that later HIF carbs are an improvement (mainly because fuel float is at bottom of main carb body) ?. Would a HIF38 or HIF44 from UK with an appropriate needle work perhaps ?
3. I was planning to stick with SU but there's a Weber 32/36 down-draft kit available for Moke & Mini, would that be worth considering for simplicity & other advantages they claim ?
https://www.lynxauto.com.au/mini-850-12 ... rsion.html
https://www.minimania.com/part/P4-004/C ... ir-Cleaner

Would appreciate any suggestions.

Thanks, Makes

Any su can haveoverflow issues check float heights I would look at what a 1100 sprite would have as a needle and spring set up would be close I would assume

Author:  carbon [ Mon Apr 23, 2018 3:06 am ]
Post subject:  Re: Recommended single carb setup for Mini K 1100

I had problems with my twin SUs flooding couple of years back, I fitted an in-line fuel filter just before the carbs and have not had any problems since. I think it was specs of rust from the tank stopping the needle valve from sealing, and that was using viton tipped type.

Author:  makes [ Sat May 05, 2018 12:37 pm ]
Post subject:  Re: Recommended single carb setup for Mini K 1100

Hi Guys, thanks for your ideas and suggestions. I will try fitting a fuel filter immediately before the carbs. A proper dyno tune & carb setup sounds like the best long-term solution to find best fuel mixture. I am located on the Gold Coast QLD. Thanks.

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