16 replies to this topic

[mattrsa]

Hi All 

 

After a bit of confirmation. 

 

I have recently got my mini back on the road. It is a 998 with a stage one kit including needle. I have noticed that when Im driving that when I'm driving once the car has warmed up that when I accelerate hard that there is some hesitation (flat spots). This is not the case if I drive like a granny. These symtoms are not present when I pull the choke out. This of course seems to suggest under fueling (running lean). Correct?

 

My plan this weekend is to have a bit of a play with the carb mixture screw. Before I do I'm just wondering how much adjustment (turns) it has on it. How many turns should I give it to begin with?

 

I know I should book it in for a rolling road session ideally but I don't won't to spend the money on that as I plan to install a rebuilt 1275 at the end of the summer. 

 

thanks in advance. 

[nicklouse]

First question. Which kit and what needle.

 

setting the seat height has little to do with the running. It is more the tick over mixture.

[coopertaz]

could also be lack of dashpot oil, you should also get red spring for dashpot with kit. if not fit this or even a yellow one this will help

[Ol timer]

I had a similar problem to this...thought it was running lean. adjusted the carbie. changed dash pot oil and a new spring. seemed to work for a bit then did the same. I checked the mixture using a gunson Air fuel spark plug kit as well as a gastester. everything seemed to be ok. it actually ended up being the distributor cap.

Edited by Ol timer, 04 April 2022 - 07:54 PM.

[Chris1275gt]

If you’ve not got 20/50 engine oil in the dash pot put it in.

Attached Files

•  4C95E232-1EE7-4E82-89AF-BA9A691659D1.jpeg   237.5K   26 downloads

Edited by Chris1275gt, 04 April 2022 - 07:32 PM.

[mattrsa]

thanks for all the replies 

 

I think the needle is a AAU I think from the stage 1 kit from mini sport. 

Yes the dashpot should have oil and I think I used this oil (https://www.minispar...|Back to search) 

 

I did think initially it might be the dizzy but as I said when I run the carb with the choke partially or fully open it does not have the reported issues

[mattrsa]

thank Chris. that is a very useful chart

[nicklouse]

thanks for all the replies 

 

I think the needle is a AAU I think from the stage 1 kit from mini sport. 

Yes the dashpot should have oil and I think I used this oil (https://www.minispar...|Back to search) 

 

I did think initially it might be the dizzy but as I said when I run the carb with the choke partially or fully open it does not have the reported issues

It seems that many people have issues with (or have had) issues with that kit. It seems the needle in the MiniSpares kit was a better option. But this may now be old news.

[mattrsa]

I did actaully remove the needle and refit the orginal and that made the issue even worse. 

will take the dashpot off and replace the oil and see if that helps. 

 

will report back

[Chris1275gt]

thanks for all the replies 
 
I think the needle is a AAU I think from the stage 1 kit from mini sport. 

Yes the dashpot should have oil and I think I used this oil (https://www.minispar...|Back to search) 
 
I did think initially it might be the dizzy but as I said when I run the carb with the choke partially or fully open it does not have the reported issues

Take that out of the dash pot and put the 20w 50 oil in and it should be ok. I had the same problem and it cured my flat spot. The lighter su oil allows the piston to rise too quickly letting too much air through while the petrol flow is a couple of seconds behind hence the flat spot.

[coopertaz]

stage one we always used to run AAV needle

[cal844]

stage one we always used to run AAV needle

On a 998 I ran an AAV, on a 1275 (HIF carb) I use an AAU

Edited by cal844, 06 April 2022 - 07:30 PM.

[Steam]

stage one we always used to run AAV needle

On a 998 I ran an AAV, on a 1275 (HIF carb) I use an AAU

The AAA was always the goto for 1275 stage one.

[mattrsa]

Quick update: 

I replaced the oil in the car with 20w50 and it it slightly better but there is still some hesitation on hard accelleration. THis is resolve by pulling the choke a 5th of the way. Anything more than that the car bogs down (too much fuel?)

I think I might have to just bite the bullet and get it booked in on a rolling road. 

[Ethel]

It could be ignition. A richer mixture improves conductivity in the plug gap so weaker sparks can jump the gap. 

 

The first part of the choke (until it contacts the fast idle screw) only increases idle speed. Unless you're pulling it more than that you're not making it any richer. This brings up something else to look at: a worn throttle spindle leaking air, or any air leak engine side of the throttle.

 

A rolling road session could be a waste of money if one of these faults means they can't set the tune properly.