plugs

[Bill ss]

I took the a7 ss for a run today well i wanted to,she started first kick i let her tickover while i put my lid on,set off and she starts misfiring,i pulled over to check that the choke was off, it was so i set off again but only running on one cylinder i gave her a bit of gas and she kicked in on two anyway i took her home and pulled the plugs they where both dry and black,allso the exhaust is black and oily.

I have searched the forum and i can't find any answers,     so help 

[Greybeard]

I recently had something like this. In the end I decided that I'd been pottering around town too much and the plugs were sooty so I took her out for good long run: this cleared the cobwebs out and she runs lovely again.

[Bill ss]

Thinking about it that could be it,it's been off the road for 30 years and i'm treating like it's a rebuild,i've only done 8 miles on it all very slow ,only got into forth gear once then back down to third.

I might need to get it on the road and up to running temperature.

[Triton Thrasher]

Renew the needle jet.

[beezermacc]

Pickup brushes?

[muskrat]

Yep all of the above. The A7's especially the SS loves to rev. Should do 60mph in third easy.
Cheers

[Angus]

I know I know we should be to old for this but gave A7 (built to SS spec) a bit of welly today 60 in second, 80 in third shut down at an indicated 90, that should clear out the cobwebs a bit 

Opps back on topic check and nice light brown plugs

[Bill ss]

I found time to give the A7  a run out again,i took her down some quiet country lanes while she was missfireing, and nearly got wiped out by a Range Rover, i came around a bend and he was overtaking a line of cars,i had to ride in the gutter while jamming my brakes on,anyway back to the bike.

I got onto the local 60MPH road and pushed her upto 50MPH she was running on two cylinders ,i did about three miles and did a shoulder check and there was quite a bit of blue smoke coming out of her so i turned off at the next turning and stopped,i gave her a quick rev and the exhaust was clear so i carried on with my ride.

Just to add when i stopped the tickover was a bit lumpy,i had the feeling that she would stall if i left her on tickover,i made my way back home no more smoke by the way,  when she had cooled down i checked the plugs,they were still sooty and the exhaust was still damp.
The plugs in the bike are NGK B7ES  in the manual it says they should be NGK B77EC  how important is it to have the correct plugs? according to the manual she is running rich so my thoughts are to check the air screw before i start delving into the carburettor.

She had a 40 mile run so graybeards tip did'nt cure her but it was fun trying it.

                All advice welcome.

[muskrat]

Sounds like she's too rich or sucking oil down the valve guides, but first I'd go with beezermacc and Triton Thrasher
A worn needle will give a rich mixture and dirty pickups/slip ring will give a misfire.
Cheers

[duTch]

 came around a bend and he was overtaking a line of cars,i had to ride in the gutter

Times like that, you need a spare couple of plugs in case you lose one through his windscreen....

  mine started having similar symptoms after I dropped the needle a notch the other week, more pronounced at start up, gets better after warmed up, but sometimes runs a bit erratic at standstill, I'm thinking to run slightly hotter plugs (previously changed from BP7ES to B7ES,which I haven't looked at yet...!)
  Not sure what B77EC are, but manufacturers do change their product codes (as discovered when I was looking for a Bosch plug for my chainsaw.. )

[Bill ss]

 Thanks for your replys  guys.

[Gerry]

Hi Bill, With regards to the B77EC, I couldn't find any and the shop checked with NGK and they had no record of such a plug, I think it is a typo in the workshop manual as mine says the same!! Cheers Gerry

[muskrat]

B7ES for alloy head B7HS for iron head. If plugs are sooty try B6.
Cheers

[Terryb]

I would also check the tappets. My SS was producing sooty plugs, more so on the offside than the near after renewing the tappet adjusters. Once I got the tappet clearance right, she ran beautifully with the light brown plugs on both pots.

[BSA_54A10]

Modern fuel is not petrol.
Generally you need to go 1 grade hotter with the plugs.
modern fuel which is not petrol seem to have a lot of heavy oil that does not burn ( which is why you have an afterburner fitted to your car ).
this crud will deposit onto your plugs and give no end of grief and can only be burned off.
I had one plug that burned or better than 15 minutes there was so much crud deposited deep down on the insulator.
The other big thing is to run the carby dry at the end of your ride or at any stop where the engine is liable to cool right down.
As the fuel runs out the engine burns lean for a short while which is also a lot hotter so it burns the crap off the plugs.

Sedate riding makes this a lot worse so as the boys have said, pop in a new needle & needle valve, these were standard tune up items when the bike was transport and are still standard tune up items now the bike is a toy . Then take it out and give it some revs, particularly from cold.
Avoid at all costs leaving a cold motor idling becausae you will end up with deposits on the plugs and will be back at square one again.

Now days I get fully kitted up before I start the bike and don't even think of top gear for the first 15- 20 minutes if not longer on a cold engine.
At the end of the day it is close the fuel taps and let the engine run dry.

This slight alteration to my old riding habits has again returned my BSA's to the reliable rides that they used to be.
Prior to this I was forever changing plugs and at one time would not leave the garage without at least two spare sets and was perpetually changing plugs come time 3 in one day. Having adopted the above regeime I have been running the same plug for better than 4 years.
The one exception to this was allowing the engine to be in over run for too long without retarding the spark.
So if you are an "old school" BSA rider and a heavy user of engine breaking on a bike with manual timing you also need to remember to retard the spark if you are going to be on over run, particularly if the engine is cold. I backed off on a long sweeping bend in top gear about 1/2 after lunch stop. About 1/2 way through the bend I opened the throttle and ,,,, nothing motor stone dead. Got it back home , popped in a new plug and started first kick.