93 replies to this topic

[m1tch]

Hi guys, my 1982 998 carb mini has been fine for a while, but now its developed a power issue with the engine, I have change the plugs, sorted the air filter (even run the engine with no air filter to remove all air restriction and I am still having a problem.

Basically when I accelerate in any gear its very slow, dangerously slow as in taking 5 seconds to get accross a lane of traffic if pulling out.

It then picks up okish on the midrange until between 25 and 40 where it sounds like its missfiring or running too rich (as if the choke was on) The engine isn't running that rich as I have changed all the plugs and they all seem okish, plus there is no overrun when I turn the engine off.

This lack of useable power means the top speed in most of the gears is about 25 when its missfiring or whatever the heck its doing.

I have changed the plugs, HT leads were changed when i bought the car, the ignitior was change just before I bought it. The other other time I have had this issue was when it was raining hard and it had a loss of power then.

I checked the fuel lines, it was slightly crimped against the rear bulkhead this morning, sorted that out but its still doing it, could it possibly be the mechanical fuel pump giving up and not getting the fuel to the carb?

The only other thing I have done before it was doing this was to give the whole thing a clean with carb cleaner, I also checked the movement of the piston inside the carb by pushing it gently upwards against the piston damper that had been topped up with oil, could I have bent the needle slightly causing overfueling?

Im thinking its either overfueling ie on full throttle the piston rises too fast causing bogging and missfireing as if its got a choke on, or its electrical, regarding the ignition coil breaking down at higher revs?

Could this possbily be caused from a bent needle when I cleaned the carb with carb cleaner, some muck got stuck on the needle or something?

My mini has a stage 1 kit on it, so I guess I need to change the needle, is the AAA needle that upgrade from stock?

Thanks for the help

[jaydee]

Mate have you set the right timing?

[m1tch]

Timing has been set correctly, lots of my mates are into minis, it has been double checked and its all good, Ive not had any problem before this with power issues, was running a dream until I cleaned it with carb cleaner etc it feels like a fueling issue when im drinking it as if there was no dashpot oil causing the piston to rise too quickly causing bogging etc

Edited by m1tch, 03 July 2009 - 09:39 AM.

[mars red mike]

Has the needle been removed from the damper at all?

[m1tch]

No, I havn't taken anything apart from the carb, the only think I have taken out of the carb is the piston damper, to check the oil, could it be that the oil is too thin causing the piston to rise too quickly causing bogging?

[mars red mike]

Scrap that, didnt read the post fully lol

Edited by mars red mike, 03 July 2009 - 10:16 AM.

[mars red mike]

Aha! Stage one kit fitted. Needs setting up properly I would suggest.

[jaydee]

even run the engine with no air filter to remove all air restriction

Noooooo...this will allow any crap to get into your engine..

By the way, remove dashpot and piston, check conditions of dashpot, spring and needle. Look if theres a lot of fuel around the jet that means overfuelling. Open the float chamber and see if needle valve is in good working order, maybe its misaligned.

Edited by jaydee, 03 July 2009 - 10:28 AM.

[mini_mad69]

Aha! Stage one kit fitted. Needs setting up properly I would suggest.

Even with a stage one kit the car should still run reasonably, just not too its best.


What colour are the plugs?

Put your airfilter back on, not only can it realy damage the engine, it completly mucks up all the fueling and will just make sorting the problem alot harder.

Are the plugs gapped correctly?

Is there sufficient gap at the points? or are you running electronic ignition?

Ben

[mycoolmini04]

this just mainly sounds like an ignition problem. If you have points then it may be those or it could just be that you need a new dizzy cap. The piece in the centre of my cap broke once and caused the same problem.

oli

[mars red mike]

Has it always had a stage one kit one it or is it a recent addition?

[m1tch]

even run the engine with no air filter to remove all air restriction

Noooooo...this will allow any crap to get into your engine..

By the way, remove dashpot and piston, check conditions of dashpot, spring and needle. Look if theres a lot of fuel around the jet that means overfuelling. Open the float chamber and see if needle valve is in good working order, maybe its misaligned.

Aha! Stage one kit fitted. Needs setting up properly I would suggest.

Even with a stage one kit the car should still run reasonably, just not too its best.


What colour are the plugs?

Put your airfilter back on, not only can it realy damage the engine, it completly mucks up all the fueling and will just make sorting the problem alot harder.

Are the plugs gapped correctly?

Is there sufficient gap at the points? or are you running electronic ignition?

Ben

this just mainly sounds like an ignition problem. If you have points then it may be those or it could just be that you need a new dizzy cap. The piece in the centre of my cap broke once and caused the same problem.

oli

I only ran the car without an air filter to get me back from down the road, its all been put back on don't worry

The plugs look ok, slightly darker on plugs 1 and 4, correct colour with the middle 2 plugs, I have changed for brand new plugs, pregapped etc

I am still running with points, they were adjusted a while ago, but like I said, I havn't had any issues with the car for aaaages lol

Is there a guide in how to take apart the carb? is it just those 3 screws round the dashpot to take it apart? there isn't anything that will spring up at me and for me to lose if I undo those?

Thanks for all the help what needle should a stage 1 kit have? I will be changing engine at some point, but not for a while, so this needs sorting

[m1tch]

Has it always had a stage one kit one it or is it a recent addition?

Recently fitted, its had a drop in K and N filter for a while, drove over to my mates about 100 miles away to get the maniflow exhaust and RC40 kit fitted over there, drove back a charm, there hasn't been any issues at all until I cleaned it with carb cleaner. Well, the last time I seem to have the same sort of issue was when it was tipping it down, but thats mini electrics for ya lol do you think it might be the coil? I have changed the HT leads, plugs and checked for spark, all is good, I have even tightened up the vacuum advance for the dizzy as well.

[mars red mike]

There is no 'definate' needle to go with a stage one kit as all engine setups differ slightly from each other. The only way to determine the best needle for your engine spec is to have to tuned on the rollers by someone who knows what they are doing and has the right equipment. End of.

[rendersonique]

I think that the dizzy cap sounds like the most likely cause as suggested above. Also change the rotor arm (but first check for irregular movement on the dizzy shaft!!).

Andy