The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Bill ss on 18.09. 2014 15:05

Title: plugs
Post by: Bill ss on 18.09. 2014 15:05
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  *smile*
Title: Re: plugs
Post by: Greybeard on 18.09. 2014 15:13
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.
Title: Re: plugs
Post by: Bill ss on 18.09. 2014 17:51
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.
Title: Re: plugs
Post by: Triton Thrasher on 18.09. 2014 18:04
Renew the needle jet.
Title: Re: plugs
Post by: beezermacc on 23.09. 2014 00:02
Pickup brushes?
Title: Re: plugs
Post by: muskrat on 23.09. 2014 05:17
Yep all of the above. The A7's especially the SS loves to rev. Should do 60mph in third easy.
Cheers
Title: Re: plugs
Post by: Angus on 23.09. 2014 19:27
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  *smile* *loveit* *clap* *yeah*

Opps back on topic check and nice light brown plugs
Title: Re: plugs
Post by: Bill ss on 30.09. 2014 19:42
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. *conf*
Title: Re: plugs
Post by: muskrat on 30.09. 2014 21:50
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
Title: Re: plugs
Post by: duTch on 30.09. 2014 22:25

Quote
 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.... *ex*

  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.. )


Title: Re: plugs
Post by: Bill ss on 01.10. 2014 17:33
 Thanks for your replys  guys. *wink2*
Title: Re: plugs
Post by: Gerry on 25.10. 2014 05:44
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
Title: Re: plugs
Post by: muskrat on 25.10. 2014 11:14
B7ES for alloy head B7HS for iron head. If plugs are sooty try B6.
Cheers
Title: Re: plugs
Post by: Terryb on 25.10. 2014 19:25
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.
Title: Re: plugs
Post by: BSA_54A10 on 26.10. 2014 21:47
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.
Title: Re: plugs
Post by: Greybeard on 27.10. 2014 08:30
Modern fuel is not petrol.
I'm not sure UK petrol is as bad as yours but I use octane booster; seems to be good stuff.

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.

I also turn the petrol off to stop the engine.
Title: Re: plugs
Post by: The Artful Bodger on 27.10. 2014 10:29
I was never happy with the running of my Huntmaster (iron head A10 engine) despite using a fuel additive. I then found, fairly locally, a garage selling 4 star (leaded petrol) and was truly impressed with the change of the bike half a mile down the road, no more pinking, smoother running with more "get up and go". But............. at £1.99.9 a litre ouch!
  I ran several tanks of 4 star and couldn't bear the thought of going back to unleaded, but cried each time I filled up. I did some research and came across "Millers Oil VSP VSPe Power Plus" around £20 to treat 500 litres of petrol. I also have a real bee in my bonnet about ethanol so have been using super unleaded which is often ethanol free, you need to check your local suppliers and this varies depending on the make and even your geographical area. It's easy enough to test for ethanol using a measured amount of water in a container (jar, test tube etc.) and adding petrol to this, shake well and firstly see if the fuel goes cloudy with suspended water in it. Then leave it to settle out and see if the water amount has increased, ethanol is suspended in petrol but mixes with the water making the water level increase. By the by, ethanol can be removed from petrol by this method.
  A chance fill up of my GS 850 with BP Ultimate made a noticeable difference to her running, almost the same as the 4 star in the Ariel, has led me to now only buy from BP. I took the plunge and filled the Ariel with BP Ultimate, added the Millers and she's running as sweet as with the 4 star, it also cured the ache in my wallet.
 I feel you have a problem beyond just the petrol you're using which hopefully you'll get to the bottom of. But ethanol petrol is a destroyer of classic vehicles and needs to be avoided at all costs, I'm very happy at having found a combination of fuel and additive which really works for my bikes.
  Millers claim this additive (they do several) is also a protection against ethanol as well as an octane booster and lead replacement, I still prefer to go belt and braces and buy ethanol free petrol in the first place.
Colin
 
 
Title: Re: plugs
Post by: Greybeard on 27.10. 2014 13:10
Millers Oil VSP VSPe Power Plus" around £20 to treat 500 litres of petrol.
Millers claim this additive (they do several) is also a protection against ethanol as well as an octane booster and lead replacement.
Good write-up; thanks. I've ordered a 500ml bottle of that jollop from Ebay, (£20, post free).