42 replies to this topic

[007xico]

Hello,

 

I have another thread, where i explained how unlucky i been, when comes to mechanics.

 

Basically i got a refurb hs4 carb and a new cone filter , only reason was to look prettier. As the car failed on MOT because emissions , i asked the garage if they could fit it and tune it up , they did but the car wouldn't run properly. After i took it back three times, they got someone from outside (friend of them) that races minis and sets them up.

 

In the end was told: "with our friend help , we set it up as best we could but still isn't ok, the needle in both carbs are not the right one for the new filter, the new filter lets in too much air".

 

With the previous carb the carb would start most of time without opening the air, now is all over the place, need to open all the way and if i push it down, will die. After lots of research , i do know how to set it up but could never get it to the right mixture setting.

 

Any thoughts on this?

[chrissyb007]

U need it rolling road tuned so they setup correct needle etc. will be worth it

[coopdog]

Yep +1 on the rolling road

[Carlos W]

We're the carbs rebuilt before fitting?

[007xico]

We're the carbs rebuilt before fitting?

I got it from eBay, cleaned and rebuild.

[007xico]

Yep +1 on the rolling road

Don't know of any rolling road, close to me.

But shouldn't the car at least run ok? Obviously not 100% but at least not cutting out. 

Probably will give the old carb a clean and put it back as it was .

[ChopperHarris]

If you want to check if it really is the filter, put some gaffa tape over about 30% of it...is it better?
Is the filmter a recognised make?
Some used for bikes are too free flowing and we either mask off or spray with a heavier oil...not a perfect solution but will get you mixture appro correct till you find the correct answer/mixture

[David128]

Have you checked for air leaks at manifold?

[timmy850]

What needle is in the new carb? Did you keep your old needle, or did you use the one that came with the new carb?

Edited by timmy850, 21 November 2015 - 05:14 PM.

[007xico]

Have you checked for air leaks at manifold?

 

 

What needle is in the new carb? Did you keep your old needle, or did you use the one that came with the new carb?

I will check for leaks and i believe the mechanic hasn't installed a gasket carb to manifold, also carb to filter there is only the the rubber seal, should i put the gasket too.

 

Needle on both is AAC i believe, tried both needles already. If i take it to a rolling road , how do i know what needle to buy ? Should i change the jet ?

[007xico]

 

[cal844]

An AAC needle is quite rich!

[1984mini25]

We're the carbs rebuilt before fitting?

 

If you look in his other thread the carb was cleaned, painted and fitted with new gaskets...

[007xico]

 

We're the carbs rebuilt before fitting?

 

If you look in his other thread the carb was cleaned, painted and fitted with new gaskets...

 

It wasn't the one i had but one i got from eBay , already painted and new gaskets.

 

I am stuck, mechanic doesn't seem to resolve my situation.

What i learned from it is that a carb should be clean, gaskets fitted, springs moving freely, oil in dashpot and adjust the mixture at the back. Screw down to make mixture richer or up weaker. Got a new vacuum pipe too.

When changing to a cone air filter, a new needle should be fitted but still don't know what needle and a rolling road is recommended.

 

I might just give the old one a clean without taking it apart, new needle in floating bowl, new gaskets all around and the original filter.

It's a shame because i really wanted a cleaner look in the engine bay.

[timmy850]

The needle sounds like a good starting point - it is the standard needle for a 998 with a waxstat jet. http://www.minispare...es/CUD1002.aspx

 

Winding the jet to change the mixture changes the mixture throughout the entire power range. This is not the best way to tune the needle. 

 

The needles all have different diameters at lengths along the needle. As the needle rises higher, it lets in more fuel from the jet. As the diagram below shows, the thick end changes the idle/low speed mixture and the middle is the cruise mixture, and the bottom is the top speed mixture. A good tune will have the correct shaped needle to have the correct mixture right throughout the power range. A good tuner will measure the air/fuel ratio over the power band and either select a new needle to match that, or shape the existing needle to suit.

http://www.sw-em.com... dimensions.JPG