BritBike Forum logo
BritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorThe Bonneville ShopBritBike Sponsor
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
ShoutChat Box
Comment Guidelines: Do post respectful and insightful comments.
Buy BritBike staff a coffee
Buy BritBike's staff a coffeeStill here since 1996 serving BritBike enthusiasts..
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Member Spotlight
johnnyrvf
johnnyrvf
Dordogne, SW France
Posts: 721
Joined: August 2006
Show All Member Profiles 
Newest Members
Psychorider, Shedengineering, Shayne Brown, Snow's Cycles, Scottboy
10858 Registered Users
Top Posters(30 Days)
franko 167
reverb 61
NickL 52
Popular Topics(Views)
1,003,127 mail-order LSR
a word from..
Forum Statistics
Forums34
Topics67,684
Posts679,548
Members10,858
Most Online14,755
May 5th, 2019
Who's Online Now
48 registered members (998John), 282 guests, and 865 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Spark plugs not sparking #783067 08/30/19 5:29 pm
Joined: Jun 2018
Posts: 15
E
eberhard Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
E
Joined: Jun 2018
Posts: 15
It is a 1970 A50. I got the bike to fire up about a month ago after it had stood for around 40 years.

Once I had the engine running the bike would ride for approximately 300 metres and then cut out. It would only start again after having stood for quite a bit. I later on noticed that the left coil got unusually hot.

I started to examine and analyse the wiring, especially to and from the coils. The battery is new. I had put in new condensers. There is a wire that goes from the ignition to the (-) on the left coil. Then there is a wire from the left coil (-) going to the right coil (-). On the left coil (+) there is one wire that goes to the one condenser and another wire that goes to the one set of points. On the right coil (+) there are also two wires, one to the condenser and one to the points.
I ran a volt test from the (-) on both coils to the engine block and got a 11.28v reading on both.

Then I removed the spark plugs to inspect the spark. There was spark, then suddenly the spark was gone. I had done nothing to the wires. During multiple turnings of the kick starter I got at one stage a faint spark on the left plug. Then the right side coil got hot. Then I switched off. I was also getting hot.

Any suggestions please. I am currently at wit’s end.

Support Your #1 BritBike Forum!

Check out British motorcycles for sale:
British Motorcycles on e-Bay UK
British motorcycles on e-Bay North America
Re: Spark plugs not sparking [Re: eberhard] #783068 08/30/19 5:40 pm
Joined: May 2013
Posts: 5,862
Allan Gill Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: May 2013
Posts: 5,862
Have you cleaned the points contact surfaces and checked your points gap?

You should have 0.015” when the points are fully open. It sounds like either the gap might be small on one side of points or maybe not opening at all. Causing the coil to get hot.

Also have you metered the primary resistance of the coil? Between the hot connection and one terminal.

Then check secondary resistance between both terminals and compare to the other coil.

Last edited by Allan Gill; 08/30/19 5:41 pm.

beerchug
Re: Spark plugs not sparking [Re: eberhard] #783080 08/30/19 7:41 pm
Joined: Jun 2018
Posts: 15
E
eberhard Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
E
Joined: Jun 2018
Posts: 15
I did those things earlier when I was still getting the engine to fire up. On the other hand I must maybe not take too much for granted and is it good to go through them again. I shall do so.

Re: Spark plugs not sparking [Re: eberhard] #783082 08/30/19 7:54 pm
Joined: Sep 2013
Posts: 2,083
Q
quinten Online Happy
BritBike Forum member
Online Happy
BritBike Forum member
Q
Joined: Sep 2013
Posts: 2,083

Was the points plate
And mechanical advance
Pulled , cleaned and lubed .. as part of the reanimation?

Your wiring is correct . ..


If the points cam is centered and the points correctly adjusted .
Each set off points is closed for 160 cam degrees ... dwell time
This means
If the ignition is left on without the bike running
.. it's almost certain that one coil will be in circuit and become warm .

.

Re: Spark plugs not sparking [Re: quinten] #783083 08/30/19 8:05 pm
Joined: Jun 2018
Posts: 15
E
eberhard Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
E
Joined: Jun 2018
Posts: 15
Originally Posted by quinten

Was the points plate
And mechanical advance
Pulled , cleaned and lubed .. as part of the reanimation? Yes and lubed as per the manual.

Your wiring is correct . .. Thank you.


If the points cam is centered and the points correctly adjusted .
Each set off points is closed for 160 cam degrees ... dwell time
This means
If the ignition is left on without the bike running
.. it's almost certain that one coil will be in circuit and become warm . Thanks for this information.

.

Re: Spark plugs not sparking [Re: eberhard] #783143 08/31/19 10:42 am
Joined: Jun 2018
Posts: 15
E
eberhard Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
E
Joined: Jun 2018
Posts: 15
Before “stripping” the bike for what may turn out to be something as stupid as a loose connection, I first did a lot of tests. I had bought new condensers, so I read up about testing condensers. I did the tests. The condensers passed the tests. I tested the battery, checked and tested the wires on the coils again – no magic troll had fiddled there during the dark night. Then I turned the engine. Still no spark. Next I retrieved the original spark plugs (from years ago I had learnt the hard way – do not simply discard replaced parts on old bikes). I cleaned them a bit with a fine wire brush, put in and turned the engine. And there was spark. Kiss me, I would not know the necromancy involved there.

I also did the following: I removed the plug caps and held the leads close to the head after I had turned the engine for that cylinder’s points to be closed. Then I repeatedly flicked the one point and there was good spark from the lead to the head. On both cylinders. Out of desperation I also put NOS leads and caps on.

During the whole process I noticed that spark intermittently jumps from the points to the housing. How/ why / what to do there?

Re: Spark plugs not sparking [Re: eberhard] #783149 08/31/19 1:24 pm
Joined: Sep 2013
Posts: 2,083
Q
quinten Online Happy
BritBike Forum member
Online Happy
BritBike Forum member
Q
Joined: Sep 2013
Posts: 2,083
Quote
During the whole process I noticed that spark intermittently jumps from the points to the housing. How/ why / what to do there?


It sounds like the condensers or their ground connection.
Do the condensers have dedicated earth wires ?

The condensers are always in circuit ... if the ignition is on .
But they are only seen in the circuit when they become the less resistive path ... as the points open .
If they are not there ... or consistantly there .
Inductive kicks in the primary , up to 400 volts , will seek another path .

Quote
The battery is new
Quote
I ran a volt test from the (-) on both coils to the engine block and got a 11.28v reading on both. 


There are not very good numbers , if the coils are the only load being pulled from the battery... what's the battery open voltage ?
It may be new , but is it charged ? ...

Re: Spark plugs not sparking [Re: eberhard] #783161 08/31/19 4:12 pm
Joined: May 2013
Posts: 5,862
Allan Gill Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: May 2013
Posts: 5,862
The voltage on a battery used with points and condensers isn’t as critical as it is on EI, as long as the battery will take a load the voltage isn’t as big an issue.

The jumping to earth could also be from high resistance in the HT circuit. Whilst the wires might be NOS, it doesn’t mean the copper isn’t oxidised. Some decent copper wire, non resistive plug caps, and decent terminals into the coil will make a big difference. You might need to clean the points faces again as there may have been some pitting from arcing.

Good find on the plugs.


beerchug
Re: Spark plugs not sparking [Re: eberhard] #783163 08/31/19 4:30 pm
Joined: Dec 2018
Posts: 43
D
Dave Martin Offline
BritBike Forum member
Offline
BritBike Forum member
D
Joined: Dec 2018
Posts: 43
I know it might be sacrilege to say this, but there is a reason why transistor / electronic ignition systems were invented, just sayin'.

Re: Spark plugs not sparking [Re: Dave Martin] #783164 08/31/19 4:48 pm
Joined: Aug 2001
Posts: 7,889
triton thrasher Online Content
BritBike Forum member
Online Content
BritBike Forum member
Joined: Aug 2001
Posts: 7,889
Originally Posted by Dave Martin
I know it might be sacrilege to say this, but there is a reason why transistor / electronic ignition systems were invented, just sayin'.


A perverse wish to have the same ignition timing on Thursday, that you had on Sunday when you set the points.


Amateur Loctite enthusiast.
Re: Spark plugs not sparking [Re: quinten] #783165 08/31/19 5:09 pm
Joined: Jun 2018
Posts: 15
E
eberhard Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
E
Joined: Jun 2018
Posts: 15
Originally Posted by quinten
Quote
During the whole process I noticed that spark intermittently jumps from the points to the housing. How/ why / what to do there?


It sounds like the condensers or their ground connection.
Do the condensers have dedicated earth wires ?

The condensers are always in circuit ... if the ignition is on .
But they are only seen in the circuit when they become the less resistive path ... as the points open .
If they are not there ... or consistantly there .
Inductive kicks in the primary , up to 400 volts , will seek another path .

Quote
The battery is new
Quote
I ran a volt test from the (-) on both coils to the engine block and got a 11.28v reading on both. 


There are not very good numbers , if the coils are the only load being pulled from the battery... what's the battery open voltage ?
It may be new , but is it charged ? ...


To that extend I cleaned the frame part where the condensers attach from any and all paint / coating as to ensure as good earth as possible. On other bikes I have experienced what a not so good earth can do to efficiency. Thank you for that information. The more I understand, the better.

I also thought about that, so I put the battery on a tickle charge.

Re: Spark plugs not sparking [Re: Allan Gill] #783166 08/31/19 5:13 pm
Joined: Jun 2018
Posts: 15
E
eberhard Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
E
Joined: Jun 2018
Posts: 15
Originally Posted by Allan Gill
The voltage on a battery used with points and condensers isn’t as critical as it is on EI, as long as the battery will take a load the voltage isn’t as big an issue.

The jumping to earth could also be from high resistance in the HT circuit. Whilst the wires might be NOS, it doesn’t mean the copper isn’t oxidised. Some decent copper wire, non resistive plug caps, and decent terminals into the coil will make a big difference. You might need to clean the points faces again as there may have been some pitting from arcing.

Good find on the plugs.


Thank you. I shall attend to that.

Re: Spark plugs not sparking [Re: Dave Martin] #783167 08/31/19 5:18 pm
Joined: Jun 2018
Posts: 15
E
eberhard Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
E
Joined: Jun 2018
Posts: 15
Originally Posted by Dave Martin
I know it might be sacrilege to say this, but there is a reason why transistor / electronic ignition systems were invented, just sayin'.


Come on now, don’t be a party pooper. laughing

Re: Spark plugs not sparking [Re: eberhard] #783169 08/31/19 5:36 pm
Joined: Jun 2018
Posts: 15
E
eberhard Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
E
Joined: Jun 2018
Posts: 15
I got the bike to fire up. I cleaned thoroughly around the points. The wire going to the one was in my opinion too close to the back housing so I bent it away. Battery charged. Condensers earthed. HT leads inspected and well connected. I used a non plastic call card and inserted it between the points and then closed the points and dragged the card out. I repeated that quite a few times. I wanted to achieve two objectives – cleaning the points of any grease / oil and getting a reading on the surfaces of the points (that which is not visible). The points were clean and the surface of the card was undamaged / unscratched and the way it pulled out also indicated a smoothness on the points’ surfaces.

I think (touch mahogany) I’ve got the engine running again. So I put the tank back on. Since I have fitted in-line filters I have a visual of fuel flowing / not flowing. I opened the fuel taps and no fuel was flowing. Well folks, that is tomorrow’s problem. Now I am drinking a beer. Thanks and sleep tight.


Moderated by  Allan Gill, Jon W. Whitley 

Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | DVD- Manuals & Parts books
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.7.3