BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
JWood Auction JRC Engineering dealers JWood Auction
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
Kommandokenny
Kommandokenny
McKellar,Ontario
Posts: 1,106
Joined: January 2004
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
193 registered members (1xfatboy), 1,892 guests, and 542 spiders.
Key: Admin, Global Mod, Mod
Newest Members
Ashley, HerbertG, WilliamLangton, Dubdoc, Tom Mullin
10070 Registered Users
Top Posters(30 Days)
koan58 85
Lannis 82
NickL 75
Stuart 67
Popular Topics(Views)
501,227 mail-order LSR
Forum Statistics
Forums34
Topics65,994
Posts638,641
Members10,070
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate Thread
Plug spark at startup, testing #713280
10/31/17 12:29 am
10/31/17 12:29 am
Joined: Dec 2006
Posts: 3,891
Massachusetts, U.S.A.
B
btour Offline OP
BritBike Forum member
btour  Offline OP
BritBike Forum member
B
Joined: Dec 2006
Posts: 3,891
Massachusetts, U.S.A.
T120R 71

This goes along with the hard to kick start thread.

So, the thought is that perhaps the coils are not up to snuff. I know the plug needs more juice to spark under compression. The plugs do spark when out. Bike runs fine after startup. But perhaps there is not enough when starting. If the inline led gizmo is lighting does that confirm that the plug is firing?

As I remember, the distance the spark should jump should be 3/8 inch. Is that correct? I realize that this does not confirm that plug will spark in the cylinder. It is just an indication.

I can perform both tests.


Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
Support Your #1 BritBike Forum!
Membership Type! Free
Member
Premium
Member
Premium Life
Member
Vendor
Member
Site
Sponsor
Recognition No Premium Member Premium Life member (5 years) Vendor Member Site Sponsor Membership
Post commercial threads No No No Yes Yes
Custom title No Yes Yes Yes Yes
Upload avatar & photos No Yes Yes Yes Yes
Link avatar & photos Yes Yes Yes Yes Yes
Private Message Storage: 10 100 100 100 100
Length of signatures 255 600 600 600 600
Removes this very advert island between post 1&2 No Yes Yes Yes Yes
Price Free $12.90/year $105.00 No End
$55.00/5 years
$210.00/year
($17.50/month)
Email
Click on button >>
  Premium Member Premium Life member Vendor Member Site Sponsor Membership
Re: Plug spark at startup, testing [Re: btour] #713352
10/31/17 2:23 pm
10/31/17 2:23 pm
Joined: Nov 2005
Posts: 7,271
Back on the mainland!
JubeePrince Online content

Life member
JubeePrince  Online Content

Life member
Joined: Nov 2005
Posts: 7,271
Back on the mainland!
Originally Posted by btour


As I remember, the distance the spark should jump should be 3/8 inch. Is that correct?


Not sure about 3/8", but the proper gap on a plug to run is 1/40"

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
Re: Plug spark at startup, testing [Re: btour] #713354
10/31/17 2:44 pm
10/31/17 2:44 pm
Joined: Dec 2006
Posts: 3,891
Massachusetts, U.S.A.
B
btour Offline OP
BritBike Forum member
btour  Offline OP
BritBike Forum member
B
Joined: Dec 2006
Posts: 3,891
Massachusetts, U.S.A.
Got em gapped at .025, Steve. They came out of the box set a big larger. They used to come out dead on. No change in behavior from old plugs, so I guess that was not the problem. I mean faulty plugs.

Now I am trying to determine if they are sparking in the cylinder with kick start. I did search, and confirmed that "in the air", using adjustable gap tool, the spark should travel 3/8 inch.

Thank you.


Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
Re: Plug spark at startup, testing [Re: btour] #714354
11/09/17 8:19 am
11/09/17 8:19 am
Joined: Jan 2017
Posts: 261
Pleasant Hill, California USA
T
TR7RVMan Offline
BritBike Forum member
TR7RVMan  Offline
BritBike Forum member
T
Joined: Jan 2017
Posts: 261
Pleasant Hill, California USA
Hi Bob, I don't know about the actual air gap the spark can jump.

However, On bikes running points, I've seen many Triumph spark plugs out of bike during kicking. The gap is indeed supposed to be .025". Visually the spark looks weak. Not a strong crack like on modern cars or even old cars. Yet the bikes start & run perfectly with this seemingly weak spark. If bike starts & idles, I doubt spark is the root problem.

I've never tested spark with Boyer or the like.

Don


1973 Tiger 750
Re: Plug spark at startup, testing [Re: btour] #714357
11/09/17 8:40 am
11/09/17 8:40 am
Joined: May 2007
Posts: 1,867
Christchurch NZ
R Moulding Online content
BritBike Forum member
R Moulding  Online Content
BritBike Forum member
Joined: May 2007
Posts: 1,867
Christchurch NZ

Are the coils not new ones?

Rod

Re: Plug spark at startup, testing [Re: R Moulding] #714375
11/09/17 1:40 pm
11/09/17 1:40 pm
Joined: Dec 2006
Posts: 3,891
Massachusetts, U.S.A.
B
btour Offline OP
BritBike Forum member
btour  Offline OP
BritBike Forum member
B
Joined: Dec 2006
Posts: 3,891
Massachusetts, U.S.A.
Originally Posted by R Moulding

Are the coils not new ones?

Rod


Coils are new 6 volt.


Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
Re: Plug spark at startup, testing [Re: TR7RVMan] #714504
11/10/17 3:48 pm
11/10/17 3:48 pm
Joined: Nov 2005
Posts: 7,271
Back on the mainland!
JubeePrince Online content

Life member
JubeePrince  Online Content

Life member
Joined: Nov 2005
Posts: 7,271
Back on the mainland!
Originally Posted by TR7RVMan

I've never tested spark with Boyer or the like.


Hi Don -

Just in case you ever need to: http://vintagebikemagazine.com/technical-articles/Boyer-trouble-shooting/. wink

Bob - if you can get a blue/white spark out of the plug, that should be (notice the qualifier) sufficient to fire. Yellow spark, not so much. Easy enough to check in a dimly lit area.

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
Re: Plug spark at startup, testing [Re: btour] #714511
11/10/17 4:31 pm
11/10/17 4:31 pm
Joined: Dec 2006
Posts: 3,891
Massachusetts, U.S.A.
B
btour Offline OP
BritBike Forum member
btour  Offline OP
BritBike Forum member
B
Joined: Dec 2006
Posts: 3,891
Massachusetts, U.S.A.
Steve, I get the spark when they are out of bike, but as you know it takes more when they are in compressed area.


Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.

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: 0.189s Queries: 15 (0.006s) Memory: 1.0419 MB (Peak: 1.2124 MB) Zlib disabled. Server Time: 2018-02-18 04:37:38 UTC