11 replies to this topic

[MurphyShaw]

Hi everyone,

 

Recently I have replaced the exhaust system on my mk1 998 with an rc40 system and performance extractors, as well as a 'k and n' filter set up on the carb. 

 

Prior to the replacement, my idle speed was within 'normal' spec, around 600. However now the idle is around 1300-1400. I have completely loosened the idle adjustment screw and the fast idle adjustment.  I have also fiddled around with the mixture nut below the (HS2) carb and the engine still idles high. 

 

Any ideas? 

 

Thank you!

[NZMini1275]

Could be an air leak on the inlet manifold

[imack]

As above, sounds like an air leak

[paul748]

You will need to do a bit more than fiddling with the mixture nut on the carb.

Have you changed the needle? If not, this is your problem. You have increased the air flow in and out of the engine so you will need the correct needle to get the mixture right.

Paul

[ukcooper]

get the right gasket there's two .- non ported head and ported head 

 

replace ya manifold gasket needs to be  spotless it needs to be and yes I said that twice as it needs to be spotless.

 

make sure theres no leaks on ya system.

 

then get it rolling roaded as you changed the mixture  and it needs a new needle , you change anything to do with fuling it needs to be reset by a rolling road …. full stop or start by loads of needles and guessing try a a aaa for a start but will be rich and drink petrol, needles are about a tenner each, cheaper to get it rolling roaded, then don't mess with it till ya wont pay for another r/road 

 

did not realise you was non uk try these, sorry

 

 http://www.winsu.co.uk/index.html ya have pay for this one tis ok but takes a few says get back to you , tis worth it I think and he's a good lad

 

 

http://www.mintylamb.co.uk/suneedle/   free but have fun 

Edited by ukcooper, 27 July 2019 - 02:00 PM.

[MurphyShaw]

Thank you!

 

Can anyone help with what type of needle I might need? 

[paul748]

Hi

Without a rolling road and CO analyser it's a bit trial and error.

But Minispares sell a full stage one tuning kit and they include a AAU needle which is good enough to get it running.

You could try that, they are available off the ebay for around 12 UK pounds.

Paul

[jonjosar]

Hi MurphyShaw,

It does sound a bit like an air leak. If you havent already done this,try taking a tin of wd40 or similar and spray it around all the gaskets, inlet to head, carb to inlet, brake servo banjo bolt (if fitted) and listen for a change in the engine revs. If they rise, then its drawing the fluid into the mixture.

There are a couple of things you might also need to consider.

As the OP said, have you changed the manifold gasket?

What sort of inlet manifold have you fitted - If you have cut the old inlet/exhaust cast type as some do, then the casting joint can come very close to where its cut?

Make sure that the flanges where the new inlet and exhaust meet are the same thickness as with having only one stud and the thick washer to tighten both can be a problem.

The needle will definitely need looked at and the car properly tuned and set up.

I,m in the middle of the same problem and have had to look at all of the above. Unfortunately, i dont have the bench mark of knowing that the car was ok before i started as mine is a complete rebuild. 

[MurphyShaw]

Thanks Paul748, ill look at one of those.

 

 

Jonjosar, thanks for your reply. Ill try the wd40 and then go from there

[MurphyShaw]

Hi guys!

 

I tried the wd40 around the manifold and it doesn't seem to be increasing the engine revs so i guess i can rule any significant air leak out at this stage.

 

I bought a AAU carb needle thinking it would be a quick swap without reading in to spring vs fixed. Is AAU only for spring? i read somewhere that you can modify the spring needle to become fixed by taking of the collar off, is this possible??

 

If not, what would be the best needle to for a stage 1 kit (rc40+k&n etc) for the fixed needle type?

 

Thanks again guys

[luismx123]

Hi guys!

 

I tried the wd40 around the manifold and it doesn't seem to be increasing the engine revs so i guess i can rule any significant air leak out at this stage.

 

I bought a AAU carb needle thinking it would be a quick swap without reading in to spring vs fixed. Is AAU only for spring? i read somewhere that you can modify the spring needle to become fixed by taking of the collar off, is this possible??

 

If not, what would be the best needle to for a stage 1 kit (rc40+k&n etc) for the fixed needle type?

 

Thanks again guys

 

Ive tried AAA, AAU and AAB needles. All ran ok. There isnt much difference between them. The AAU was slightly lean, the AAB was so so but i found the AAA ran best on my 998 with stage 1 kit, (rc40,k&n etc) and a stub stack under the filter which aids in airflow. This is why i went with a needle that lets more gas in, as the increase in airflow would lean out the mixture enough. I use a gunson colourtune to check my settings, but many experienced mini guys have had a pass by on it. Its always either 1/6th turn too rich or too lean - according to them and their experience. Close enough I'd say

p.s i have an HS4

Edited by luismx123, 14 August 2019 - 02:41 PM.

[MurphyShaw]

Ok thank you,

 

Im running a hs2 for some reason, the guy before me had it on. It has a fixed needle. What would i run with that? or is it worth just upgrading to the hs4?