Britbike forum

Classic British Spares Klempf British PartsBaxter Cycle BritBike Sponsor SteadfastCyclesSRM Engineering Lucas Classic Motorcycle Industrial tec supply Hepolite Pistons The Bonneville ShopLowbrow Customs

Upgrade your membership to: Premium Membership | Gold Membership | Life Membership | Vendor Membership | Site Sponsor Membership
Member Spotlight
Myles Raymond
Myles Raymond
Glasgow, Scotland
Posts: 173
Joined: August 2001
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Top Posters(30 Days)
quinten 89
Rohan 66
Top Likes Received (30 Days)
quinten 13
Newest Members
vanGinneke, Gearhard, yornocT120R, robert wilby, Jonah A
11,839 Registered Users
Who's Online Now
0 members (), 29 guests, and 73 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Page 1 of 2 1 2
#851617 06/14/21 10:52 pm
Joined: Oct 2012
Posts: 5,897
Likes: 148
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 5,897
Likes: 148
I have been riding around a bit on the A10 project bike... Runs perfect ...except...after about 20 minutes the engine starts to misfires badly on both cylinders. This occurs at 3500 rpm regardless of throttle position or engine load. Below 3500 rpm it runs great and idles nicely. Fiddling with the Manual advance does not clear the problem.The inductive electronic tach needle goes nuts when it misfires. engaging the cold start makes no difference...
The plugs look ok, no signs of obvious carb problems...
The K2F magneto was fully rebuilt, rewinding etc by a man i have used in the past. It came with a test report..
Non resistor NGK iridium plugs, solid core wires with non resistor terminals and so on...
I am going to change the plugs and check the points tomorrow...
Anyone have a mag act up like this?


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
British motorcycles on eBay
Joined: Jun 2019
Posts: 142
Likes: 4
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Jun 2019
Posts: 142
Likes: 4
That sounds like a heat related problem to me. My first guess would be ignition coil but I wouldn't rule out a capacitor either. How long did your guy run the magneto on the test stand?

Disclaimer: My experience is primarily with aircraft magnetos and less with bikes.

Joined: Oct 2012
Posts: 5,897
Likes: 148
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 5,897
Likes: 148
Originally Posted by mondtster
That sounds like a heat related problem to me. My first guess would be ignition coil but I wouldn't rule out a capacitor either. How long did your guy run the magneto on the test stand?

Disclaimer: My experience is primarily with aircraft magnetos and less with bikes.
One hour and supposedly in a heated situation..


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Jan 2014
Posts: 1,604
Likes: 175
N
Britbike forum member
Offline
Britbike forum member
N
Joined: Jan 2014
Posts: 1,604
Likes: 175
Capacitor packing up.

1 member likes this: RF Whatley
Joined: Nov 2011
Posts: 7,285
Likes: 428
Britbike forum member
Offline
Britbike forum member
Joined: Nov 2011
Posts: 7,285
Likes: 428
Originally Posted by Hillbilly bike
after about 20 minutes the engine starts to misfires badly on both cylinders. This occurs at 3500 rpm regardless of throttle position or engine load. Below 3500 rpm it runs great and idles nicely.
Rather than the capacitor, it sounds like when it gets hot the insulation is giving up at higher rpm (i.e. higher voltage).

1 member likes this: gREgg-K
Joined: Apr 2015
Posts: 1,438
Likes: 49
D
Britbike forum member
Offline
Britbike forum member
D
Joined: Apr 2015
Posts: 1,438
Likes: 49
I would use freeze spray and see if the fault clears.

Dibnah #851652 06/15/21 11:09 am
Joined: Oct 2012
Posts: 5,897
Likes: 148
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 5,897
Likes: 148
Originally Posted by Dibnah
I would use freeze spray and see if the fault clears.
No need to, it runs fine after a few hour cool down.....
It goes back to the shop....


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Jun 2014
Posts: 242
Likes: 6
B
Britbike forum member
Offline
Britbike forum member
B
Joined: Jun 2014
Posts: 242
Likes: 6
About the only times the magneto's on my old A10's ever gave me grief it was usually due to one of the carbon brushes not making a good contact with the armature , In your case of both cylinders misfiring i'd unscrew the main earthing brush > It's the slot headed screw next to the identification tag "as can be seen in Magnetoman's Avatar" .. Check it's clean and also that the spring still "Springs" , Next thing is try cleaning the brass armature it runs on - i used to use a small screwdriver with a thin strip of clean rag looped over the end of it & poke it into the hole while slowly turning the engine over , Be aware this can sometimes give you a shock ? .. One other thing to check is the ignition kill wire that's connected between the centre of the points cover and the kill switch .. Is it cracked or rubbed bare anywhere along it's length and so earthing itself out ?.

Remember the faster the mag spins - the bigger the spark ,
At 3500 rpm the energy produced inside your magneto might just be high enough to find it's own rout down to earth

Bodie #851740 06/16/21 3:27 pm
Joined: Nov 2011
Posts: 7,285
Likes: 428
Britbike forum member
Offline
Britbike forum member
Joined: Nov 2011
Posts: 7,285
Likes: 428
Originally Posted by Bodie
the ignition kill wire that's connected between the centre of the points cover and the kill switch
It's definitely worth the time to disconnect the wire at the magneto and do a quick test. The only way that could be a problem is if there is a crack in the wire, or an internal issue with the switch, in combination with a resonance at that rpm. Although that's unlikely, it's not impossible, and it's faster to do the test than to remove the magneto.

Since the magneto was rebuilt, the two most likely suspects are the condenser and the coil. However, the symptoms are inconsistent with condenser failure, so my money is on the internal wiring.

Joined: Oct 2012
Posts: 5,897
Likes: 148
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 5,897
Likes: 148
I shipped the magneto to the rebuilder this morning....I built the bike from a pile of parts,everything electrical is new and the wiring is hand fabricated...I did check the obvious, points, pickups, kill switch I even checked the resistance of the spark plugs.On the first longer ride when the ignition acted up I returned, pressed the kill button but the engine keep running. I had previously rerouted the wire, got distracted and forgot to put it on the terminal....


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Feb 2021
Posts: 2
W
Novice poster
Offline
Novice poster
W
Joined: Feb 2021
Posts: 2
Hillbilly I am curious you had mentioned you are using "Non resistor NGK iridium plugs" . I also run a mag on my bike and when I was trying to source out new plugs for my machine I looked into the Iridiums but I was told by all the suppliers that Iridium plugs do not come in a non resistor version. Can you clairify this for me please, are your plugs in fact Non Resistor and an Iridium?...........thanks wayne

Joined: Oct 2012
Posts: 5,897
Likes: 148
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 5,897
Likes: 148
Originally Posted by waynelbergman
Hillbilly I am curious you had mentioned you are using "Non resistor NGK iridium plugs" . I also run a mag on my bike and when I was trying to source out new plugs for my machine I looked into the Iridiums but I was told by all the suppliers that Iridium plugs do not come in a non resistor version. Can you clairify this for me please, are your plugs in fact Non Resistor and an Iridium?...........thanks wayne
I bought 1/2 dozen new old stock off ebay for $15..B7EV...A common plug for 2 strokes..


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Oct 2003
Posts: 11,294
Likes: 35
R
Britbike forum member
Offline
Britbike forum member
R
Joined: Oct 2003
Posts: 11,294
Likes: 35
Originally Posted by waynelbergman
I was trying to source out new plugs for my machine I looked into the Iridiums but I was told by all the suppliers that Iridium plugs do not come in a non resistor version.
True.

NGK no longer produces non-resistor spark plugs. If you want to keep running B7ES plugs, then you had better run down to the auto parts store now and buy a box or 2. Soon all that will be available will be BR7ES, with the "R" denoting an internal resistor demanded by automobiles.

thumbsup


Don't hide 'em, Ride 'em !!

RF Whatley
NE Georgia, USA
Joined: Aug 2012
Posts: 1,066
Likes: 70
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2012
Posts: 1,066
Likes: 70
Originally Posted by mondtster
That sounds like a heat related problem to me. My first guess would be ignition coil but I wouldn't rule out a capacitor either. How long did your guy run the magneto on the test stand?

Disclaimer: My experience is primarily with aircraft magnetos and less with bikes.
No ignition coils on magneto bikes.


Bill
1974 Norton Commando
1966 Lightning
1965 Lightning Rocket
1966 Norton Atlas
1967 Norton Atlas
1948 Panhead
Joined: Aug 2012
Posts: 1,066
Likes: 70
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2012
Posts: 1,066
Likes: 70
Originally Posted by Hillbilly bike
I have been riding around a bit on the A10 project bike... Runs perfect ...except...after about 20 minutes the engine starts to misfires badly on both cylinders. This occurs at 3500 rpm regardless of throttle position or engine load. Below 3500 rpm it runs great and idles nicely. Fiddling with the Manual advance does not clear the problem.The inductive electronic tach needle goes nuts when it misfires. engaging the cold start makes no difference...
The plugs look ok, no signs of obvious carb problems...
The K2F magneto was fully rebuilt, rewinding etc by a man i have used in the past. It came with a test report..
Non resistor NGK iridium plugs, solid core wires with non resistor terminals and so on...
I am going to change the plugs and check the points tomorrow...
Anyone have a mag act up like this?
What gap on plugs? Too wide a gap with magneto is bad. Thinking .016" is good


Bill
1974 Norton Commando
1966 Lightning
1965 Lightning Rocket
1966 Norton Atlas
1967 Norton Atlas
1948 Panhead
Beach #852962 07/03/21 4:31 pm
Joined: Nov 2011
Posts: 7,285
Likes: 428
Britbike forum member
Offline
Britbike forum member
Joined: Nov 2011
Posts: 7,285
Likes: 428
Originally Posted by Beach
No ignition coils on magneto bikes.
This comes as shocking news to me.

1 member likes this: Beach
Joined: Feb 2008
Posts: 5,729
Likes: 289
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2008
Posts: 5,729
Likes: 289
If there were you might have to change your name to Coilman!

Joined: Oct 2012
Posts: 5,897
Likes: 148
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 5,897
Likes: 148
Vintage US bikes with Morse type magnetos have separate coils......Isn't the Lucas armature a coil.....Plug gaps? .018 with the non resistor Iridium... in the past I never had issues with .022 using conventional plugs...


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Feb 2008
Posts: 5,729
Likes: 289
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2008
Posts: 5,729
Likes: 289
Over the years I have always used 20 thou for plug gap with magneto and 25 thou for coil ignition.
Never had a plug gap problem using those gaps.
Had plenty of other problems but that as they say is another story!

Joined: Sep 2013
Posts: 3,338
Likes: 142
Q
Britbike forum member
Offline
Britbike forum member
Q
Joined: Sep 2013
Posts: 3,338
Likes: 142
A Magneto Armature is a coil , or 2 coils , which is normally known in AC parlance as a Transformer .
... so if anyone wants to be known as Transformer-Man , i think the name is still open .

Joined: Oct 2012
Posts: 5,897
Likes: 148
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 5,897
Likes: 148
Back on topic for a minute..The man who reconditioned the mag says one pick up brush was hanging up. He ran if for an hour with no problems. Last I head he was setting up a elevated temperature test....The mag man is supposed to be one of the best....
But...big changes have occurred, stay tuned to this channel for the latest updates...


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Oct 2003
Posts: 11,294
Likes: 35
R
Britbike forum member
Offline
Britbike forum member
R
Joined: Oct 2003
Posts: 11,294
Likes: 35
This is why you need a magneto armature tester. You can "run" the armature on the bench at varying speeds, look for insulation breakdown, and swap out the capacitor while it's breaking down.

[Linked Image from i.imgur.com]

The machine doesn't lie.


Don't hide 'em, Ride 'em !!

RF Whatley
NE Georgia, USA
1 member likes this: Gordon Gray
Joined: Oct 2012
Posts: 5,897
Likes: 148
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 5,897
Likes: 148
I bet you know the magneto rebuilder by name and know he has all the equipment...


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Nov 2011
Posts: 7,285
Likes: 428
Britbike forum member
Offline
Britbike forum member
Joined: Nov 2011
Posts: 7,285
Likes: 428
To put in a, ahem, plug for magnetos, the one for my Ariel sat totally neglected on the shelf for nearly three years, but the bike started on the first kick once the bike was back together. Try that with a battery ignition system.

1 member likes this: Beach
Joined: Oct 2012
Posts: 5,897
Likes: 148
knuckle head
OP Offline
knuckle head
Joined: Oct 2012
Posts: 5,897
Likes: 148
The double engine racer I built has sat in my rider's pub since It's last race on July 25 2018. it has a onboard lithium iron battery that has not been charged since July 2018...with Pete Suchawreck from this site as a witness, I pressed the starter button , the Harley starter motor turned over two high compression Triumph engines with Pazon Smartfire ignitions with no problem. The engines started so quickly we both jumped back....The bar patrons also were startled, some beer was spilled, lol. I had no idea a lithium battery could hold a charge so long.
But a magneto can still fire some engines after dozens of years...


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
1 member likes this: NickL
Page 1 of 2 1 2

Moderated by  Jon W. Whitley 

Link Copied to Clipboard
Job CycleBritish Cycle SupplyMorries PlaceKlempf British PartsPodtronicVintage MagazineBSA Unit SinglesBritBike SponsorBritish Tools & FastenersBritBike SponsorBritBike Sponsor






© 1996-2021 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5