20 replies to this topic

[seamistgreen]

Yes, thankyou Dklawson and Carbon, the butterfly valves are the correct way and no gap when closed.

now im not entirely sure what nicklouse means when they are not connected correctly. i.e. linkages? cables?  twin probs 01.jpg   84.23K   22 downloads

The float bowl gaskets are new, thank you James for raising that point, the other gaskets are also new.

I have now discovered something new. I put a different set of plugs on ( cleaned and gaps set). It started well, and ran better for about a minute, before gradually becoming rougher. So the plugs are getting fowled up, and lots of black soot. rechecked the compression, and an even 120 on all cylinders.

HMMMM.....the mind boggles.

Edited by seamistgreen, 18 October 2015 - 09:37 AM.

[Dusky]

Could be as easy as a wrong plug or wrong timing if the mixture and needle are right. What needle do you run?

[seamistgreen]

Could be as easy as a wrong plug or wrong timing if the mixture and needle are right. What needle do you run?

( m) needles and (red ) springs. my next task is to check valve clearances.

[Dusky]

 

Could be as easy as a wrong plug or wrong timing if the mixture and needle are right. What needle do you run?

( m) needles and (red ) springs. my next task is to check valve clearances.

 

Well, M needles are standard for a 1275 cooper S. Does your engine have the cooper S cam toghether with the big valve head?

 

What spark plug heat range do you run? NGK6 will be a good start here I suppose

[seamistgreen]

 

 

Could be as easy as a wrong plug or wrong timing if the mixture and needle are right. What needle do you run?

( m) needles and (red ) springs. my next task is to check valve clearances.

 

Well, M needles are standard for a 1275 cooper S. Does your engine have the cooper S cam toghether with the big valve head?

 

What spark plug heat range do you run? NGK6 will be a good start here I suppose

 

Gday Dusky, the motor is an A+ series 1275, 1989 vintage, big valve head. thats all I know unfortunately. bought it second hand. running standard ngk plugs, will check specifications on plugs.

[dklawson]

The float bowl gaskets are new, thank you James for raising that point, the other gaskets are also new.

 

I put a different set of plugs on ( cleaned and gaps set). It started well, and ran better for about a minute, before gradually becoming rougher. So the plugs are getting fowled up, and lots of black soot. 

 

Float bowl gaskets on H and HS series carbs are not critical for carb performance.  Their job is only to keep fuel from sloshing out of the bowls during cornering.  On HIF carbs the gaskets are on the bottom of the bowl and are critical for preventing leaks.

 

The sooty plugs suggests a few potential problems.  

Your mixture needles could be way too rich, or

Your mixture adjustments of the needle could be WAY off.

Additionally (and very important) is that the float valve in the bowl could be out of adjustment.  If you remove the float bowl lid, look for the bowl to be 1/2 to 2/3 full of fuel.  Any higher than that is too much and can result in overfueling.