BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
JRC Engineering dealers
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons, "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Member Spotlight
Jeff23
Jeff23
Connecticut
Posts: 51
Joined: January 2009
Show All Member Profiles 
Shout Box
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Who's Online Now
20 registered members (Alan_nc), 202 guests, and 387 spiders.
Key: Admin, Global Mod, Mod
Newest Members
Gtommy, Stew Dempsey, JoeBrown, Bart223, Duckster
10175 Registered Users
Top Posters(30 Days)
Lannis 102
reverb 89
koan58 68
Stuart 66
L.A.B. 54
Popular Topics(Views)
554,066 mail-order LSR
Forum Statistics
Forums34
Topics66,604
Posts645,479
Members10,175
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate Thread
bench testing a magneto? #92318
05/16/06 4:23 am
05/16/06 4:23 am
Joined: May 2004
Posts: 181
Portland OR
Z
zgears Offline OP
BritBike Forum member
zgears  Offline OP
BritBike Forum member
Z
Joined: May 2004
Posts: 181
Portland OR
ive got my bike together, and its timed right. but, i cant get it to fire. any one know anything about bench testing a magneto. how do i know if its hot enough? im geting a orange spark not a blue one.


53 thunderbird
Support Your #1 BritBike Forum!

Check out British motorcycles for sale:
British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Check out British motorcycles for sale:
British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Re: bench testing a magneto? #92319
05/16/06 7:57 am
05/16/06 7:57 am
Joined: Oct 2003
Posts: 3,564
Emsworth, sunny south of Engla...
D
dave jones Offline
BritBike Forum member
dave jones  Offline
BritBike Forum member
D
Joined: Oct 2003
Posts: 3,564
Emsworth, sunny south of Engla...
My B31's magneto would make a blue spark if I spun it with my fingers when off the bike. I would try checking the condenser, the pickup and copper slip ring (clean with methylated spirits)and clean/ gap the points. Make sure you have the right kind of plug cap for a mag. Try removing it and check the spark from the end of the wire. Also try changing the wire. You may find that some simple things will make a big difference.

Re: bench testing a magneto? #92320
05/16/06 10:14 am
05/16/06 10:14 am
Joined: Jan 2005
Posts: 429
New York
gs750 Offline
BritBike Forum member
gs750  Offline
BritBike Forum member
Joined: Jan 2005
Posts: 429
New York
Quote:
......I would try checking the condenser, the pickup and copper slip ring (clean with methylated spirits)
That would be denatured alcohol over here.


1971 Triumph T100C
1974 Honda XL350
1982 Suzuki GS750T
2000 Honda VFR800FI
Re: bench testing a magneto? #92321
05/16/06 12:24 pm
05/16/06 12:24 pm
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
RF Whatley Offline
BritBike Forum member
RF Whatley  Offline
BritBike Forum member
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
Take a good sparkplug and rip off the "strap" over to the center, so that you have a center electrode with a 3/16" spark gap in any direction. Your mag should be able to jump that gap with only a quick 1/4 turn by hand. And the spark should be bright blue.

bigt


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

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
Re: bench testing a magneto? #92322
05/16/06 4:50 pm
05/16/06 4:50 pm
Joined: Mar 2005
Posts: 10,087
Boston, Massachusetts
J
John Healy Offline

BritBike Forum member
John Healy  Offline

BritBike Forum member
J
Joined: Mar 2005
Posts: 10,087
Boston, Massachusetts
Bench testing a magneto, without proper equipment, is typically anecdotal.

Although Richard's test is sort of reassuring it is not a fair test. It will not tell you about the condition of the condensor or the condition of the insullation of the armature's secondary windings. It will also not tell you about the condition of the magnet.

That said, it will give you a good idea if the bike will start or not. It will not tell you what will happen after the bike warms up and you are miles from home.
;2c:
john


Re: bench testing a magneto? #92323
05/16/06 5:01 pm
05/16/06 5:01 pm
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
RF Whatley Offline
BritBike Forum member
RF Whatley  Offline
BritBike Forum member
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
Quote:
Originally posted by John Healy:
Bench testing a magneto, without proper equipment, is typically anecdotal.
John, although I respect your knowledge, experience and great wisdom, this time, however, I have to respectfully disagree. Bench testing a magneto is really more like urinating into the wind. You get this nice warm feeling all over, but in the end you've probably not even done so much as to impress your friends.

laughing


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

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
Re: bench testing a magneto? #92324
05/17/06 1:10 am
05/17/06 1:10 am
Joined: Mar 2005
Posts: 82
B
beagleplex Offline
BritBike Forum member
beagleplex  Offline
BritBike Forum member
B
Joined: Mar 2005
Posts: 82
Well, let's say we DO have the right equipment. What temperature would the mag have to be to perform the "Heat Soak Test".

Re: bench testing a magneto? #92325
05/17/06 11:05 pm
05/17/06 11:05 pm
Joined: Mar 2005
Posts: 10,087
Boston, Massachusetts
J
John Healy Offline

BritBike Forum member
John Healy  Offline

BritBike Forum member
J
Joined: Mar 2005
Posts: 10,087
Boston, Massachusetts
www.srm-engineering.com/MagDynoElectrical.pdf?img

Although SRM uses typical engine operating temperature, I would suggest operating temperature, plus 50% as a safety factor. There are days in August where the temperature of the motor will get at least 50% higher in traffic than it typically runs the rest of the year


Re: bench testing a magneto? #92326
05/18/06 5:46 am
05/18/06 5:46 am
Joined: Mar 2005
Posts: 82
B
beagleplex Offline
BritBike Forum member
beagleplex  Offline
BritBike Forum member
B
Joined: Mar 2005
Posts: 82
Thanks John, SRM really have a slick site these days! Those magmaster machines must be thin on the ground even in the UK....

Re: bench testing a magneto? #92327
05/18/06 1:07 pm
05/18/06 1:07 pm
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
RF Whatley Offline
BritBike Forum member
RF Whatley  Offline
BritBike Forum member
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
Gosh, I feel so inadequate! Maybe I should come out with a full-color brochure on our shop's Lucas mag tester. laughing


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

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
Re: bench testing a magneto? #92328
05/18/06 7:29 pm
05/18/06 7:29 pm
Joined: Mar 2005
Posts: 82
B
beagleplex Offline
BritBike Forum member
beagleplex  Offline
BritBike Forum member
B
Joined: Mar 2005
Posts: 82
It would be great to see a photo of a Lucas brand mag tester. Do you think they actually built it or relabelled a third-party machine? Some photos of your workplace are far overdue!

I replaced a condenser in my Goldie years ago that had a Mica condenser in its KNR1 racing mag. Lucas actually made a conversion kit that had the paper and tinfoil condenser , two little brass posts and all the other little bits to fit the smaller competition (KNC1) style cond. into the racing armature. I tested that mag clamped in a bench vise spun with a 3/8" butterfly impact and one of those Briggs and Stratton clamp on spark testers. Snap snap snap and good to go...maybe it took a few tries though, smile come to think of it. I bought that kit from a guy named Jim Hunter in Los Angeles who was selling out his bike shop. What a great guy! Oops, talking beezers on the Triumph board!

Re: bench testing a magneto? #92329
05/19/06 2:13 am
05/19/06 2:13 am
Joined: May 2004
Posts: 181
Portland OR
Z
zgears Offline OP
BritBike Forum member
zgears  Offline OP
BritBike Forum member
Z
Joined: May 2004
Posts: 181
Portland OR
Thanks for the info. i just had my mag rebuilt by Waren Wheeler in Ont. Canada. ive had good results from him in the past, but it looks like this mag is still weak. i dont think he has SRM's Wonder Mag Tester 9000 . maybe ill send it back. or, is there some one in the states that restores mags?


53 thunderbird
Re: bench testing a magneto? #92330
05/19/06 2:49 am
05/19/06 2:49 am
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
RF Whatley Offline
BritBike Forum member
RF Whatley  Offline
BritBike Forum member
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
The shop I work at does. Call 770-867-1676, 9-9EST, 7 days a week. Can't beat those hours!


bigt


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

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
Re: bench testing a magneto? #92331
05/23/06 2:38 am
05/23/06 2:38 am
Joined: May 2004
Posts: 181
Portland OR
Z
zgears Offline OP
BritBike Forum member
zgears  Offline OP
BritBike Forum member
Z
Joined: May 2004
Posts: 181
Portland OR
i just got some more mags, there missing some parts. do you think i should send them too? or should i try to locate the parts?


53 thunderbird
Re: bench testing a magneto? #92332
05/23/06 3:13 am
05/23/06 3:13 am
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
RF Whatley Offline
BritBike Forum member
RF Whatley  Offline
BritBike Forum member
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
Send the armatures. You can keep the busted bodies.

bigt


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

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
Re: bench testing a magneto? #92333
02/28/07 8:17 am
02/28/07 8:17 am
Joined: Feb 2007
Posts: 8
Carlsbad, California
M
magmark Offline
BritBike Forum
magmark  Offline
BritBike Forum
M
Joined: Feb 2007
Posts: 8
Carlsbad, California
If you want to bench test a magneto - say the common K2F - all you need is a drill motor, a small engine spark gap tester - set at "S/E" (small engine or about 1/4" gap) from a lawnmower shop, a piece of rubber tubing, a short piece of metal rod and two small hose clamps. Use the rubber tubing to connect the metal rod to the threaded end of the mag drive shaft, clamped to each with a hose clamp. Turn it with your drill motor, counter-clockwise unless it is a Vincent mag, then turn it clockwise. Ground the other spark lead to the body of the mag when testing. Don't hold onto the mag with your bare hands. Clamp it in a padded vise. This wider gap simulates firing in a dirty combustion chamber and is really only showing you that the mag is capable of putting out a spark - cold, not under operating temperature. It is a fair start and easily done. More of an insulation check than anything else!

magmark

Re: bench testing a magneto? #92334
02/28/07 12:59 pm
02/28/07 12:59 pm
Joined: Jan 2007
Posts: 180
Sydney
AussieOn81Bonne Offline
BritBike Forum member
AussieOn81Bonne  Offline
BritBike Forum member
Joined: Jan 2007
Posts: 180
Sydney
Hey Z,

Try Benchtesting it with a sledgehammer (or even a murderer) i could not wait to ct the maggie off of my baby - nothing but hassle.

Seriously - i have heard of testing with a drill before and i think that Mark might be right on the mark so to speak.

Parko


Once was blind but now can see
81 T140E
50's T'Bird
Re: bench testing a magneto? #92335
02/28/07 5:34 pm
02/28/07 5:34 pm
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
RF Whatley Offline
BritBike Forum member
RF Whatley  Offline
BritBike Forum member
Joined: Oct 2003
Posts: 11,168
North Georgia, USA
Quote:
Originally posted by beagleplex:
It would be great to see a photo of a LUCAS brand mag tester. Some photos of your workplace are far overdue!
I actually considered posting a couple of photos every week of what happens at the shop where I play on weekends. A couple of weeks ago I walked in on "Mr Bones" himself, Dave Aldana busily rebuilding a B50 flat track engine. One week we had 2 Vincents in for electrical service. Two weeks ago the boss was building up 3 Tiger Cubs for AHRMA trials. Last week he was preping his 2 Manx Nortons and his roadracing 650cc Norton for Daytona. It just seems like there's always something going on there.

And, so as not to steal the thread, on the "off days" we build mags and generators. laughing


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

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
Re: bench testing a magneto? #92336
03/05/07 4:26 am
03/05/07 4:26 am
Joined: Oct 2002
Posts: 547
minnesota
J
joe a. Offline
BritBike Forum member
joe a.  Offline
BritBike Forum member
J
Joined: Oct 2002
Posts: 547
minnesota
bench testing by spinning with your hand is as good as spinning with a drill maybe even better as it should spark fine if quickly spun by hand with it's drive gear...neither is a proper test as previously stated it just shows it sparking but can't detect faults at temp,under actual cyl press,vibration,etc. it will spark with a bad secondary or bad condensor with these tests but you need to put the mag under adverse conditions to see if it is truely working properly.i usually do several static tests and then heat soak and run it on my test stand at speed for a sufficent time...but as i had said before if you are questioning your mag it probably is due for an overhaul as most are quite old and in need of help.cotact me if you want it tested properly....joe @ v-cycle


Moderated by  John Healy 


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.6.1.1
(Release build 20180111)
Page Time: 0.151s Queries: 14 (0.040s) Memory: 1.1344 MB (Peak: 1.4015 MB) Zlib disabled. Server Time: 2018-04-26 09:18:04 UTC