Norton running problems

I have a 850 commando to which I had a Mikuni carby fitted about the same time they stopped supplying leaded petrol here in Western Australia, Since then I have had nothing but trouble, once the bike is started I need to pull away at once or turn the choke of and keep the revs up, in traffic it is murder as the plugs Foul up giving the indication that it is running rich. Making any adjustment to the carby and we get the jump jump effect as I call it and indication that it is running weak. On longish runs where the rpm is over 4000 Rpm its good until the next time you come to start it.
The bike is fitted with Boyer ignition and I don’t think this helps.
I have been using B.P Ultimate.
Any advice would be welcome.

[/img]

trident
when you say (when we adjust it) just what are you adjusting? the carb will basicly have 5 circuits to set #1 main jet ( over 3/4 throttle)#2 needle (1/4 to 3/4 throttle) #3 slide cutaway (off idle to 1/4 throttle) #4 pilot jet ( idle ) #5 idle mixture screw to fine tune from pilot jet. this is just an approxamation but should give you an idea where to look other just the needle and main where some people think will work magic.

bill

Problems running Norton

Hi Bill
Thanks for your advice, I can see that I have to go a lot further into this, the adjustments I have made have been a combination with the pilot jet and the needle. Fortunately a friend has offered to lend me a tuning manual for my model carby.
Maybe I will learn somthing.

running problems.

I had problems with the "jump jump" thing you describes as well/fouling plugs, bike went fine with the throttle wider open. It also had a Boyer fitted. I bought new Amals, same problem - nothing seemed to help. The bike had good compression, little or no oil consumption. Everything seemed OK - it just wouldnt run properly and it drove me mad.

In an act of desperation, I bought some Bosch Super 4 plugs (4 electrodes). It was like getting a new motor, litterally. Adjusting the carburettor settings now also worked as pr the book.

I know this most likely just cures the symptoms - maybe not the problem, but boy it felt (and still feels) good. Since then I have done 2000 miles without missing a beat. Plugs are brown and clean. I even tried going back to the standard plugs - same problems. Just dont ask me why...

Personally, I don't think the Boyer is causing problems. But....check the wiring, especially those crimped connectors, they can drive you insane until you solder them all.
If I was a betting man, I would think that perhaps the needle is no longer as "true" as it once was, and I would start by blowing out the pilot and making sure all orfices are unplugged, clean, and tidy.
On the carb.
Cleanliness is next to Godliness as they say.
I have seen the same symptoms from a Mikuni with a dirty pilot.
Mikuni, never Qantas.