The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: peter on 27.03. 2011 16:20

Title: Spark Plug Color
Post by: peter on 27.03. 2011 16:20
In my BSA Gold Flash Jg.1954 the left spark plug is always brown, and the right spark plug is always sooty and black. The bike runs quite well. Do I have to change something anyway.
Peter
Title: Re: Spark Plug Color
Post by: lawnmowerman on 27.03. 2011 17:39
Hi Peter

A carb bias spacer may help - angle it towards the brown plug and it may even things up. I think they are available from Draganfly - or possibly Cake St classics. Maybe an idea to fit new plugs after so you can see the colour change.

Jim
Title: Re: Spark Plug Color
Post by: muskrat on 27.03. 2011 19:46
G'day Peter,
                brown is good, black is either oil or fuel. Get a mate to follow you on a ride and report any smoke from the right pipe. Blue is oil, black is fuel. Black, try Jim's fix. Blue is rings or valve guide. Check compression then add 1cc of oil down plug hole and test again. If comp goes up rings are sus. Another quick fix is to use a hotter plug in the right pot, B7ES in left and B6ES in right.
Test and report back.
Cheers
Title: Re: Spark Plug Color
Post by: BSA_54A10 on 28.03. 2011 12:59
Also check carefully the timing.
Some of the cam rings are not exactly 180 deg and a slightly out of time spark can also give you sooty plugs
Title: Re: Spark Plug Color
Post by: beezalex on 29.03. 2011 19:09
Judging mixture by the color of the top of the plug went out the window with modern fuels and the removal of tetraethyl lead.  That said, if your plug has dry soot at the top of the insulator, it's way too rich, if it's greasy soot you're burning oil. You should have neither.

If you really want to figure out your mixture by reading plugs, you need to look at the base of the insulator.   You can either do this by exposing the entire insulator by cutting the threaded portion of the plug off or getting a plug reader (really and otoscope).  The following links will help you interpret what you see:
http://www.strappe.com/plugs.html
http://www.mindsciencemotorsports.com/graphics/PLUG%20TECH.htm
http://hondaspree.net/wiki/index.php5?title=Carb_-_Lean/Rich_Tutorial
Title: Re: Spark Plug Color
Post by: peter on 29.03. 2011 21:55
Thank you for your advice, I will try out some advice.
If the problem is solved, I will answer
Thank you all, Peter
Title: Re: Spark Plug Color
Post by: renos-a10 on 30.03. 2011 08:10
Good morning Peter,

I have the same problem and i check timing first.The problem is solved.
So check your timing.
Good luck
Renos
Title: Re: Spark Plug Color
Post by: peter on 08.04. 2011 19:30
1.Compression is well
2. a mate followed me he havent seen  smoke from the right pipe.
a new Problem, if I drive very slowly so I have  misfire in the pipe,  I think I have to ckeck the timing.
Peter