tuning

[mixerman]

Dear All.
I am having problems with the carb tuning the engine runs rough and it kicks out black smoke, the tuning nut at the bottom of the carb if i turn it in either direction it makes no diffence anybody any ideas
thanks phil



1960 minor
su carb
h2

[brixtonmorris]

is the choke cable stuck?, or has it jumped out of its tube on the carb, causing the choke to be on, so adjusting the nut wont make any differance
you should not be able to see the brass jet near the tuning nut if the choke is off.

[johnm]

Assuming the choke is not inadvertantly pulled, then the first thing to check is that the piston and jet aren't sticking.

Remove the dashpot (three screws) and make sure the jet isn't sticking and then make sure the dashpot and piston are nice and clean and the damper topped up with oil and it should adjust unless it's got the wrong needle and/or jet.

[bmcecosse]

Sounds like the jet is stuck down at least slightly - either held down by the choke - or just stuck ! Could also be the float chamber/fuel inlet valve sticking causing petrol to flood in. Is the pump ticking away like mad - or just an ocassional tick ?

[mixerman]

thanks for you replies as far as i know the choke is not sticking the float chamber is fine , how do i check a sticking inlet valve? fuel pump is ticking now and again if it is a sticking needle or jet what can i do take the carb offand take it to a carb man or can i do it my self
thanks phil

[Handy]

thanks for you replies as far as i know the choke is not sticking the float chamber is fine , how do i check a sticking inlet valve? fuel pump is ticking now and again if it is a sticking needle or jet what can i do take the carb offand take it to a carb man or can i do it my self
thanks phil

Hi,
You can buy a service kit from ESM.I fitted one last weekend and set everything up properly.I now have a smooth and stable tickover and smoother acceleration.
I have had problems with the jet sticking slightly in the past. I stripped it and cleaned the components.
If you're going to remove your carb, it's wise to fit a service kit anyway.It shouldn't take you much longer than one hour.
Make sure that you leave a small amount of slack in your choke cable!

Ian

[bmcecosse]

Try just blasting the jet assembly with wd40 - and working the choke back and forth - do this many times - better if someone else works the choke and you can watch. Also -there must be a wee spring there to pull the jet up - has it maybe rusted/fallen off ?

[mixerman]

I have stripped the carb down put it back togheter jet and needle are fine when i start it is still rough and when u rev it it cuts out straight away i have tested the fuel pump it is fine can any one help me before i go mad and smash it up
thanks phil

[ColinP]

Phil,

At the risk of "teaching granny to suck eggs"...

Assuming that the carb is fine, then the mixture is too rich, or one of the cylinders isn't firing properly.

have you tried:

Running the engine with the air filter off the carb?

checking that all the breather tubes (rubber) are clear? (I'm told that some of the latest 1098's had a complicated breather arrangement - didn't always help)

disconnecting the plug leads in turn to see i there's a drop in the engine speed?

oops - nearly forgot - check the size hole in the air filter breather pipe - I once drove a moggie with a large hole - it sucked up oil from the rocker cover into the air filter ..

luck,

Colin

[brixtonmorris]

sounds like butterfly valve and piston are not working together.
is the light spring in the dashpot, does the dash pot have light oil (3in 1), not engine oil in it.
if that dont work, i can send you a used working carb for a fiver.
do you know about the little button under the piston/ dashpot ,on the carb, that on tick over when you press it the engine should stall.
have you tried it. does the engine stall?

[Onne]

should it stall? I knew it was a way of checking your mixture, so if it stalls, the mixture is set allright?

[mixerman]

sounds like butterfly valve and piston are not working together.
is the light spring in the dashpot, does the dash pot have light oil (3in 1), not engine oil in it.
if that dont work, i can send you a used working carb for a fiver.
do you know about the little button under the piston/ dashpot ,on the carb, that on tick over when you press it the engine should stall.
have you tried it. does the engine stall?

the spring is ok i have put 3/1 oil in dashpot i have pressed the button when it manges to run with no effect i come to the conclusion the carb is faulty but saying that the hs2 carb is that simple what can go wrong?
phil

[mixerman]

Phil,

At the risk of "teaching granny to suck eggs"...

Assuming that the carb is fine, then the mixture is too rich, or one of the cylinders isn't firing properly.

have you tried:

Running the engine with the air filter off the carb?

checking that all the breather tubes (rubber) are clear? (I'm told that some of the latest 1098's had a complicated breather arrangement - didn't always help)

disconnecting the plug leads in turn to see i there's a drop in the engine speed?

oops - nearly forgot - check the size hole in the air filter breather pipe - I once drove a moggie with a large hole - it sucked up oil from the rocker cover into the air filter ..

luck,

Colin

colin i have done all what u say before i think the carb is faulty until i get a spare one and put it on i cannot rule it out a kind man has offerd me a spare one 4 a fiver so i going 4 that i have sent him a post but he has not replied yet
thanks phil

[mixerman]

sounds like butterfly valve and piston are not working together.
is the light spring in the dashpot, does the dash pot have light oil (3in 1), not engine oil in it.
if that dont work, i can send you a used working carb for a fiver.
do you know about the little button under the piston/ dashpot ,on the carb, that on tick over when you press it the engine should stall.
have you tried it. does the engine stall?

the spring is ok i have put 3/1 oil in dashpot i have pressed the button when it manges to run with no effect i come to the conclusion the carb is faulty but saying that the hs2 carb is that simple what can go wrong?
phil

hi i have just a timing check with a bulb and the fuel pump is clicking away about every 30 sec but if the enghine not running where is the fuel going so i have took the top of the bowl and the bowl is full to the top that cant be right can it as ive been told the fuel level in the bowl is very inportant were sould the level be
hope u can help phil

[Willie]

With regard to the 'button' which is properly called the 'piston
lifting pin'. with the engine at normal operating temperature and
ticking over you should gently take up the free play on this pin and
then lift it a further 32nd of an inch. The tickover should briefly
increase and then revert to the original. If the tickover rises and
stays faster then the mixture is too RICH (the mixture nut needs to
go UP one flat at a time). If the tickover slows or the engine stalls
then the mixture is too WEAK and the mixture nut needs to go DOWN
one flat at a time

[bmcecosse]

Sounds like the piston is not rising/falling as it should. Does it fall with a nice 'clunk' ? Have you had the needle out of the piston ? It must be put back in with the shoulder flush with the base of the piston. Also on early carbs the jet needs to be centered - read your Haynes to see how. Are you sure the plug leads are on in the correct order ? 2134 is the correct order. Pump giving odd tick every 30 seconds is fine - and the float level only rose because you lifted the top and allowed the fuel in the pipe to run in.

[Cam]

Just as a note, 2134 is indeed the correct order, but you might see it written as 1342 in books/manuals as it is conventional to reference plug number 1 first. 4213 and 3421 are also correct.

[mixerman]

Sounds like the piston is not rising/falling as it should. Does it fall with a nice 'clunk' ? Have you had the needle out of the piston ? It must be put back in with the shoulder flush with the base of the piston. Also o­n early carbs the jet needs to be centered - read your Haynes to see how. Are you sure the plug leads are o­n in the correct order ? 2134 is the correct order. Pump giving odd tick every 30 seconds is fine - and the float level o­nly rose because you lifted the top and allowed the fuel in the pipe to run in.

Hi every thing u have said i have done the piston is falling with a nice clunk the needle is right and the needle/jet are centred timing is right new plugs points condenser i cannot what else i can do <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; phil

[bmcecosse]

Better get the engine compression tested - could be head gasket blown.

[brixtonmorris]

bmcecosse may have somthing here