My 1975/93 Mini Sprite just arrived from England and it has a idling probelm. When I start it the choke seems to kick in and raises the idle. I press/kick the accelerator pedal to release the choke at it works for a few minutes, then the idle goes up again. I am not a mechinc, and could use any help I can get. Thanks

 

I am totaly new at this, but can tell you what I've learned in the last few weeks on our 74/90 something. By the year I'm guessing you have the SPI (single port injection) It turns out there is very little you can do because its computer controlled. There is a screw on the backside of the throttle linkage (on the throttle body) that you can adjust some. The solution I found was on the underside of the air filter housing there are a couble of vacuum hoses, disconnect and plug the red one. This helped my idle out alot. Other than that ckeck fo r vacuume leaks and maybe clean out the throttle body just to make sure nothing is sticking.

Nik

 

I don't think I have SPI. The car is carburated. But I will check the the vacuum and clean the linkage around the carb. thanks

 

I too am new... but my '77 had the same problem. Two things to look at... I had to pay for this... I am not a mechanic so please just use this to think [FONT=Wingdings][/FONT]
On the bottom of your carburetor a round cylinder is coming out of the bottom. Inside that is a needle I’m not sure what “needle” this is but mine had gotten off to one side. Sometimes the idle would go up because the needle was not settling in the bottom. The shop here had a tool to align this. (I am so new to this I don’t know if this was BS but if it helps you then good…?) Second. On the flap inside the carburetor there is a small spring mounted pin type of thing. What this does is when you let off the gas and that flap shuts… the suction pulls this little needle till the spring over powers the suction. The man at the shop said to close it permanently. JBWeld it… is what he did for me. Since I got it back it stays at a perfect hum. Also I had the electronic ignition put on… WOW. It fits inside the distributor and with no points the 1098 I have runs like a new motor. I hope this helps. Please keep in mind I paid for someone to help me with this and I don’t know too much yet.

 

Reminds me of a thread I was involved in a lil' while back. And now, after spending several hundred dollars because of bad advice here....I now know that the basics are still a good starting place.

Number 1 - never worry about or screw with the carb until you are 110 percent sure the ignition is absolutely correct. To screw with the carb when the ignition is wrong is wasting money.

Number 1.5 - vacume leaks are typically bad.....find and fix.

(my idle was very high else everything got ruff. Fixing a vc' leak improved this significantly....figuring out my timing mark was off, resulting in crap timing settings made up the other half.)

Number 2 - if you have an HIF series SU ... it is a sealed unit. You need to drill out a plug to screw with the mixture.... Meaning, it is highly unlikely the basic mix is bad. Look for something else. Bad jet? Possible... But real tuning of these beasts beyond idle means swapping needles, not turning screws...or GF JB weld

Number 2.5 - plug color remains an excellent indicator.

Number 3 - the number of people who understand how a manual choke works is on par with the number of WW2 vets.... you shouldn't need to kick the accl to release a manual choke.....an 'automatic choke' maybe.....

Google or MiniMania will lead you to several excellent sources of information about carbs & choke in general and SU in particular. Or search here, I've lain many a link.

(and p.s. .... I can start my 1275 on a warm day w/out the choke. Correct procedure according to a collector with 8 Healy's whom I've consulted - associated with a shop specializing in classic restoration and race prep. His comment on listenening to the engine "you want to mess with this?")

 

I think it is just the linkage sticking. When I put the pedal down it sticks and i can put my toe under it and pull it back, then it revs lower. I will try spraying sub lube on the linkage to see if that fixes the problem. Thaks everyone for the help.

 

Consistent with the start simple theorum

MiniMania has throttle cables. It is a pretty easy run... I replace throttle and choke and was amazed at the improvement. I ended up shortening the choke about 6 inches tho....made for a cleaner run and it actually moves easier.