? Rich Running

[Angus]

I hate gearboxes and Carbs.
Firstly I have to admit that I did not even look at the plugs on the A7 (to SS spec) last year she was running great and when I last did check them there were a nice chocolate brown.
I have not changed anything, well not true the oil for the same as I always use, and she appears to have developed a fault. She runs fine under load but when shutting down, going downhill or cruising she appears to be eight stroking. The plugs are black and covered in soot.
One more time I have not changed anything well again not true I changed the plugs after the first time and she ran fine for about 50 miles and then cough cough splutter splutter, accelerate pulls fine, shut down cough cough splutter splutter.
No smoke out the back so not burning oil. What could it be I will try another brand of petrol (but again I have always got my fuel from the same place). I have always used premium unleaded with Castrol Valvemaster Lead Replacement.
Suggestions please
 

[Triton Thrasher]

Try a new needle jet, unless it's already pretty new.

[muskrat]

G'day Angus.
I agree with TT. A new needle and jet would be my 1st job, along with checking the float height.
Cheers

[Angus]

Thanks guys
Brand new carb just over 4 years ago or 5000 (4900 very good running) miles still worth a new needle jet and float height ?
I was think perhaps the pilot circuit maybe blocked but it ticks over fine.

Problem is once I start to pull it apart then I really have changed something

[Triton Thrasher]

The needle jet is fairly cheap.  The needle doesn't really wear much.

The sudden onset of richness is odd.  Have you raised the needle by a notch, perhaps inadvertently?

Fitted a fibre washer under the Monobloc float needle screw-in thing on top of the float chamber?  Fitted the float upside-down?

[muskrat]

G'day Angus.
Could it be something from left field like the choke slide not all the way up or even a broken cable? Or even lefter field like you forgot which way the choke lever goes (oldtimers creeping in).
Cheers.

OFF TOPIC
ps I see you have a model 7, one of those won best British at my clubs show last weekend.

[Angus]

G'day Guys

TT I have not touched anything in the carb as she was running so well, and I dont do Carbs.
Musky thanks will check that.

This is time to take stuff apart and give is all a clean and blow through

Off topic I have also always hated gearboxes only ever played with one successfully, the model 7 is currently enhancing that hatred, but they are a pretty bike.

[Angus]

Sorry people, I work in IT and I have searched honest and I know I have read a thread on float/fuel height on a mono block carb, not the plastic cover I thought there was a way with a pipe or am I imagining it. Just want to be prepared before I start pulling it apart to do all the checks. a link will be great  .

Editied
Found it, well not here on another site a pipe of the pilot jet then measure the fuel to the pip on the float cover (right in the middle of the cover just below the right leg of the M for Amal).

[mugwump]

Check main jet has not worked loose.

[Butch (cb)]

Check main jet has not worked loose.

+1

[Angus]

Carb off cleaned checked and put back on level checked. started it and took it for a ride  just the same.
Re-drain the petrol and put it in the notrun, that is running and slowly proving its unreliability (gearbox now) and it starts to show the same symptoms.
buy normal unleaded petrol from another brand and dont add any additives, a couple of splutters for a few miles them back on song. Back to riding with lots of smiles, I have not even checked the plugs I am so happy 

[Greybeard]

...buy normal unleaded petrol from another brand and dont add any additives, a couple of splutters for a few miles them back on song. Back to riding with lots of smiles...

That's great Angus. 

PS. Are you going to the BSAOC Open Day again this year? I may just ride over for the day(s)

[Angus]

Off topic

I want to go if I ride I will come for the Sunday and will stay at the travel lodge as a bit far for a there and back in one day (not by ozzy and USA standards), otherwise I may drive 

[Angus]

Dam and blast, its back with a vengeance. Actually stopped last night then started again and stopped limped home. get home plugs covered in black soot 

She needs a good service as done lots of miles this year (well for me anyway) so off with seat and as she had a full tank decide to drain it, pull off pipes and put on both taps and nothing, not a drip. Blow through and get a mouth full back and flows fine. Now could that be the source of my problem, could a blocked tap cause a rich running appearance. Regard less need to clean fuel tank of crud.

[Butch (cb)]

Hmmmm. As per a different thread, mine came home on the back of a rope the other week. The problem very clearly seemed to be fuel starvation on mine – I didn’t even pull the plugs to look. Found what I take to be some kind of rubber gland had swollen up in my lever type taps. I’ve re-established flow – drilled one out a bit, replaced the worst one with a brass lever type which simply works on a taper (I think). Not bothered to attempt a restart since though.

Not sure why fuel starvation would make the plugs sooty.