14 replies to this topic

[foggy]

Hi all, have been driving my mini happily for the last week after it's MOT. has been running well, however yesterday i noticed that occasionally when i either ease off the throttle (but not completely let off) and same when i ease on the throttle from the engine running on idle. it kind of stutters. but then is fine when more throttle is applied.

 

I was thinking could it be to do with the dash pot oil? either the grade or quantity thats in there? possibly causing the pot to rise and fall to quickly?

 

I am running a 998 twin hs2 carb engine with LCB maniflow exhaust system, with an electronic dizzy for those who don't know.

 

Thoughts welcome. :)

[Nick Warwick]

Possbily or it could be your timing is slightyl out. Both worth checking but add the dashpot oil first.

[foggy]

Forgot to mention.it is generally worse when the engine is cold.

[Carlos W]

Did they adjust the mixture to get it through the emissions?

 

I think it's running slightly lean

[foggy]

No, however he did say it was running a bit lean and i could afforfd to richen it up.

i have opened the jets up a bit, but have no way of determining how much i have done it by and if its running the correct mixture. so maybe i should open them up a bit more?

Edited by foggy, 26 June 2014 - 12:48 PM.

[Yoda]

There is your answer then. You need to balance the twins. Make sure you have the mixtures the same on both, ( use a colourtune to get fairly close ) I use a 2 colourtune at home, one in cyl 1 and the other in cyl 4. once you have the mixtures equal on a fast idle, then you set the idle screws by using a small piece of hose. Stuff on end in yer lugole and the other end at the throat of each carb one at a time. You will hear a different pitched hiss. balance the carbs at idle using the idle adjuster untill both carbs hiss the same. then adjust each carb exactly the same to bring your idle to what you require. This is real simple to do and gets you pretty close to perfect tune. then if you want to improve on that, a rolling road session is required. All this info is on the Burlen website. Google it and have a read.

 

As long as your carbs are in good condition, they will stay in tune for a long time. dont beleive people who say that you cant keep em  in tune, they have either only had worn out twins or dont know how to tune them in the first place.

[foggy]

Thanks for that. i use the hose and listen technique so am familiar with that.

the colourtune test sounds like its what i need to do. Are they pricey to buy?

Cheers

[Yoda]

cant remember, i have had mine for over 30 years LOL

[KernowCooper]

Use the lifting pins to lift the slides, engine stalls or falters = weak - engine revs up and stays there = to rich- engine revs slightly and settles back to where it was = correct

[Dusky]

Use the lifting pins to lift the slides, engine stalls or falters = weak - engine revs up and stays there = to rich- engine revs slightly and settles back to where it was = correct

And what is the CO when it is correct?

[foggy]

Lifting pins?

[KernowCooper]

Most HS2s have lifting pins or all the ones I've seen

Attached Files

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[foggy]

Hmmm.mine doesn't have those. I'm borrowing a colour tune off a friend. Will let you know how that goes.

Edited by foggy, 27 June 2014 - 05:39 AM.

[KernowCooper]

Then use a small screwdriver to lift the slides slightly with the elbows removed if you have any and set the mixture that way/

[foggy]

I used a colour tune on them.but it was showing that there could be wear in the needle.and after adjustment it was doing the same stuttering.so i will be taking a look when i get a chance. Tempted just to take it to Slark who is very close to me.