just a quick note for those with SU's pumping the throttle does nothing except make you feel better, they don't have accelorator pumps so all your doing is openimng the throttle butterflies, cold start with SU's rely on the choke.

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Roundies and Clubbies(except vans) are both ugly that is why I have Midas and a van
1293 Mini Midas Bronze,1275 Clubman van

i just finished reading that whole thread and was just about to say the same thing..

pumping the throttle on a SU does nothing.. flaps the little butterfly around and thats it..

webers(most other carbs actually) have a lil diaphram which squirts some petrol in when you pump it..
no point on an SU

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Expert in training

JAM

Not a common twin SU issue I would be looking else where like the distributer.

Was it totally rebuilt, is it the right one for the car or modified or from another car entirely, whats the shaft like, have you put in another distributer and tried that?

steve

Hi,
Had the same problem on my twins. The choke cable would pull in and out no problem(inside the cabin). The car after numerous attempts to fire,would finally fire then run on two, then three and finally four cylinders as it warmed up. By chance I checked the choke and linkage whilst a friend engaged the choke cable from inside the cabin. Whilst the choke cable was working fine inside the car, under the bonnet- one choke was sliding up and down, the other side was stuck. After fixing the ceased side, the car starts with the choke on after 2 or 3 turns.
Thanks

Is the timing too far advanced? hence kicking back?

Pumping SU does nothing!

When mine was too advanced (only by a degree or two) it would be a bitch to start. Always kicked back after a few spins. When i retarded it, hey presto! started every time but it went like a pile of loose bolts... It didn't like it so retarded. So I used the Dr Mini trick to start the car, I installed an ignition kill switch. I am now at least 5-6 degrees more advanced and it runs great, much more power. This is how I start my car with a dellorto:

Pump pedal 6-8 times, pull choke, turn they key for 3-4 seconds, flip the switch and way we go. Starts first time everytime.

This might not be the answer for you but I thought I'd bring it up as it puzzled me for ages why my car was hard to start. It was all about timing. I am pretty sure JAM would run good if not better on more advance so maybe installing a kill switch could be the answer?

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Lillee - 1969 Morris Mini K

My 1100 with twin carbs starts first time everytime. Even when it is -7 it starts first time, that is what I want when it is my daily drive to work car.

Make sure the choke works.
It should not be hard to pull. (Tip, Push the accelerator down when you pull the choke out, it takes the load off the throttle cam on the choke)

If it is starting on one or two cylinders and then the others chime in later it sounds like a spark plug problem.

I never had any issues starting NAV. not even when it was -9 in Canberra, and yes NAV was out in it as I forgot to put him to bed.
Check the gap in the plugs/points and double check the timing.
Has the cam been played with i.e. advanced?
Also the tappet clearance has it been checked since firing him up?
Lastly what fuel you using? NAV is a bit harder to start on regular than premium or optimax

Barney's main problem is the twin HS4 choke linkage doesn't seem to be allowing full choke..
Make sure yours does, also that the fast idle screws do actually give you one when choke is on.

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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.

I had trouble getting mine started today and i had read this post so after trying another few time i did the hot water trick and started right away.
Nice tip GT.
unit

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Cooper S Mk 2

ok,,,seems to be a lack of choke problem,,,very common with choke cables being very old & dry inside,,,,a little lube on both the cable inner & the carb jets as well should have it all sweet agin

& on the pumping the throttle pedal thing, just for those who don`t know & for those who think they know--->

Pumping the throttle on a """NORMAL""" cars carby (not injection ones) will actually squirt some raw juice into the chambers,,,SU carbs don`t have a squirt mechanism, so in effect, what some people have said about pumping will do nothing is """SORT OF""" right,,,HOWEVER!!!!!!!!!!,,,when you`re trying to start a mini without choke, then absolutely no throttle at all for the first few attempts will help draw fuel up with very little air, therfore giving as rich a mixture as possible without choke,,,but after the first few kicks, then it is benificial to actually pump the pedal ever so slightly as it will "OPen/Shut/Open?shut/Open/Shut the butterfly, which in turn adds fuel, then a tiny bit of air, then fuel, then a tiny bit of air & as it starts to actually fire up, then you can actually keep pumping the throttle every so small amounts tho & it will help fire it to life because every time you back off, it will draw fuel in & effectively "Pump" the carb

if you don`t understand what i`m saying here or you disblelieve me, then try it, but hardly touch the throttle when you do it, just a slight touch then off, slight touch then off etc, don`t open up the carb much at all , if you understand?

anyways, just thought i`d add that little bit of usless trivia to all those interested,,,some """KNOW""" what they`re talking about with the theory, but others """KNOW""" what happens in Practice

yeah, ok,,,i`m getting cheeky no,,,i`ll shut up & go to bed

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Thats one of the first things i was told by my mini mechanic i reckon...
"why the fiddle sticks are you pumping the accelerator?"
"i dunno... get the fuel in there, easier to start?"
"not on an SU carby you dickhead"

aww shucks

I think mine was a combo of:

1. Mixture too LEAN

2. Not enough choke

Sorted it last night I believe

Thanks all for the feedback!

Glad you didn't get rid of the twins.. I'm not liking all these negative feelings towards the twin su's everyone seems to have! Mine were fine, and are now even finer after I re-kitted them. They love me and I love them and we sing songs together.

Yeah Matt, I found exactly that when I was running a tired & cranky 998 with no choke cable.

First try with no throttle. It may kick over. Then do some tiny pumps as it cranks. That usually worked. Never thought about why, even though I knew SUs don't have a "tromp it pump".

If it was really cranky, I used to have to get out, pop the bonnent and wedge a rock or stick in under the carby to hold the choke on. Lazy I know, should have just gotten a choke cable settup.

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"Life is not like a box of chocolates... it's more like a jar of jalapenos. Whatever you do today, may burn your arse tomorrow."

glad you got it sorted twin SU's are blamed for a lot of problems that are really caused by bad setup and unfortunatley a lot of so called mechanics have no idea how an single Su works let alone multiple carb steup work, allways good to find someone that is BMC/Leyland trained as they are about the only mechanics who have been trained on SU carbs. As ythe doc said make sure your fast idle screw/cams are adjusted correctly and the choke is lowering the the jet fully and then its just a matter of pull choke and hit starter, you only have to touch the throttle if you setup is wrong, seems I need to explain to our friend from up north as he seems to neglect the fast idle setup ( I can be cheeky to )

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Roundies and Clubbies(except vans) are both ugly that is why I have Midas and a van
1293 Mini Midas Bronze,1275 Clubman van