6 replies to this topic

[luismx123]

Heyo,

Last weekend I swapped needle in my HS4 carb to something that was more "recommended" and tuned it with a colourtune kit, and whilst the fuel burns better (consistent throughout), I have lost some torque/performance whilst accelerating...

The engine stats.
998, stage 1 kit, k&n cone filter, stubstack below air filter (tested for 5% more airflow by cannot remember who exactly but was a legit source),123 ignition dizzy.

 

Needle before: AAU. 

Using the colourtune, it was slightly rich at idle and too lean higher up. Slight leaning during acceleration.

I had to richen the mixture as it would stutter hard whilst accelerating if the mixture was set to an ideal burn at idle.

New Needle: ABD (stage 1 rich)
Using colourtune to check, clean burn throughout the whole range. Slight leaning during acceleration.

Seemed to burn perfectly along the whole range, no flat spot, but seemingly less kick than the AAU.

Next needle to test: AAA
Will see on the weekend how that goes.

 

I chose to get an AAA and ABD needle as i know minispares advises using an ABD on an open style cone filtered stage 1 kit, and the AAA as that seems to be the "standard" stage 1 needle being sold. 
 

Is it normal to lose performance like this or am I just crazy?
Ive heard from a friend who does vw golf tuning that leaning out during acceleration increases performance so not sure how that applies for a mini :/

[creakyjaws5533]

Surely the best needle would be the one that came with the stage 1 kit? The manufacturers spend a lot of money developing kits

[ACDodd]

Stop wasting your time, have it measured properly using a gas analyser or a wide band reader. Fueling adjustments can then be made by carefully polishing the needle to give you what the engine actually needs. Can be done on a rolling road although competent operators seem to be rather thin on the ground nowadays.

I will be at the Rivera run on the may day bank holiday weekend doing just this!

Ac

[petey81]

Ac ???

[cal844]

You can get it set by an MOT centre emissions machine.

Drive the same stretch of road whilst you tweak it. If you do change the needle check it on the emissions machine.

You can also change the oil in the dashpot for a heavier weight oil, my minis use 20/50 engine oil, if I switch to anything lighter or heavier it will cause the engine to struggle. With a little fettling and note taking(So you know what you've changed)

[luismx123]

Surely the best needle would be the one that came with the stage 1 kit? The manufacturers spend a lot of money developing kits

well yes, but minispares themselves have said the delivered AAU needle is for closed plastic housing air filters. Hence why I went richer as there is more air in the system, and simon himself posted that they advise an ABD for open cone filters.

 

 

Stop wasting your time, have it measured properly using a gas analyser or a wide band reader. Fueling adjustments can then be made by carefully polishing the needle to give you what the engine actually needs. Can be done on a rolling road although competent operators seem to be rather thin on the ground nowadays.

I will be at the Rivera run on the may day bank holiday weekend doing just this!

Ac

 

id definitely love to take you upon that offer but i live in central Austria, where the next mini guy is 200km away, and i have never heard of anyone having a rolling road here in austria, let alone the 2 mini specialists who i have been to that do not have a rolling road in their garages :/. This is the reason for my colourtune purchase and asking around. Its my only possibility to get close enough to something "good". 

 

You can get it set by an MOT centre emissions machine.

Drive the same stretch of road whilst you tweak it. If you do change the needle check it on the emissions machine.

You can also change the oil in the dashpot for a heavier weight oil, my minis use 20/50 engine oil, if I switch to anything lighter or heavier it will cause the engine to struggle. With a little fettling and note taking(So you know what you've changed)

 

What would i be looking for with the emissions test? They surely wont know how to tune the mini according to the emissions so if i find someone to let me use their machine id have to know what im doing first

I have been testing with different oils. Got some SU oil, 10w40 (like calverst advises), 20w50 and some ATF oil. Been trying with ATF at the moment just to make sure I only change one variable at a time. Still need to test the 10w40 and SU oils once i have the needle setup well. 
Regarding the writing down aspect, makes sense. I sort of remember "ah ABD needle was turned down 2 1/6th of the nut leaner from the AAU, but never noted it properly. 
Dont get me wrong guys, my mini drives well and pulls good, I was just wondering why a leaner mixture from a leaner needle would give me more ummppphhh than one that burns better along the entire rev range...

Thanks for the answers though. Still interested what you have to say!

[hhhh]

I'm sceptical of the leaner burn increases acceleration claim unless it's too rich to begin with. In general, for greater power, a richer mix approaching 12.5:1 is required. Maybe VW Golfs have overactive accelerator pumps that need to be compensated for?