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Idle Setting


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#1 ln1gaw

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Posted 15 May 2019 - 10:11 AM

Hi Guy's,

 

First time I've posted on this forum and I'm looking for some advice on setting the idle on my 1989 Mini Mayfair 998. It has a single HS4 carb which idles too high even though the idle screw is screwed right out so there's no more adjustment and the butterfly appears to be fully closed. The is also some slack in the throttle and choke cables and I'm unsure if the mixture screw can affect the idle speed to this extent. I've checked for air leaks and found nothing obvious. Starts fine with the choke and when the engine settles it just idles a bit too fast and there's nothing left to adjust it slower.

 

Any advice will be much appreciated.



#2 Junior Mini

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Posted 15 May 2019 - 11:40 AM

I had a similiar problem and it turned out to be the spindle bushes for the butterfly in the carb body had worn allowing additional air to be sucked in past the valve.



#3 unburntfuelinthemorning

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Posted 15 May 2019 - 12:13 PM

Hi Guy's,

 

First time I've posted on this forum...

Second time; you posted this yesterday:  http://www.theminifo...8-idle-setting/



#4 ln1gaw

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Posted 15 May 2019 - 12:34 PM

Sorry, yes this is the second time I posted as I thought the first got lost. How do I check for work butterfly bushes, would I expect to find some play in the butterfly because at the moment I can't detect any?



#5 unburntfuelinthemorning

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Posted 15 May 2019 - 01:03 PM

Try spraying WD40 at the throttle spindle bushes whilst the engine's running. 

 

It only takes minimal play to allow air to enter.  Lots of threads on the forum about it.

 

Also check that the fast idle screw is adjusted correctly and isn't still opening the throttle slightly when the choke is in.



#6 ln1gaw

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Posted 15 May 2019 - 01:53 PM

Would an air leak on the vacuum advance cause the same problem?



#7 unburntfuelinthemorning

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Posted 15 May 2019 - 02:19 PM

Any air leak between the throttle butterfly and head will effect the idle speed.



#8 hhhh

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Posted 15 May 2019 - 03:32 PM

I would say it would affect the idle speed, not create it.



#9 unburntfuelinthemorning

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Posted 15 May 2019 - 04:51 PM

I would say it would affect the idle speed, not create it.

I never get that right.






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