Engine Stutter Solved (Interesting Discovery) - Triumph Forum: Triumph Rat Motorcycle Forums
» Main Menu

Discussion Forums
 » Twins
 » Tiger
 » General
 » RAT

Features
 » Blogs

Motorcycle.com Links

Contribute
 » Photo

Motorcycle Forums
» Insurance
» Sponsors
» Our Partners
»ATV Reviews
»Motorcycle Games

Twins Technical Talk Technical Talk for Hinckley Triumph Twins: Bonneville, T100, Speedmaster, America, Thruxton, and Scrambler.

Reply
 
LinkBack Thread Tools Display Modes
Old 07-27-2010, 05:49 PM   #1 (permalink)
Senior Member
Powerbike
Main Motorcycle: 2009 Thruxton
 
Join Date: Feb 2009
Location: Johannesburg, South Africa
Posts: 329
Engine Stutter Solved (Interesting Discovery)

For the past few months I've been experiencing stuttering from my 2009 EFI Thruxton under certain conditions. Through trial and observation I concluded that the problem is most probably due to a weak spark. The observations leading to this conclusion were:

-Stutter coincided with rich fuel mixtures, especially with sudden acceleration and fast increasing rpm's (sudden hard acceleration in low gears from low speed).

-It was also worse when the engine was cold and still on richer warm-up mixtures.

-Using higher octane fuel made the stutter worse.

All this suggested a weak spark struggling to ignite rich (or higher octane) mixtures.

So last night I decided to quickly check the basics around the coil in the hope of confirming my suspicions. Everything checked out OK except for the resistance between the coil core (HT ground) and the bike frame, I got about 1.5Ω when it should be very close to 0. So that confirmed the weak spark theory and just left finding the culprit.

Almost all bikes I've owned have just had the coil bolted via a bracket to the frame, thus grounding it. While simple and elegant this is a far from ideal setup, the brackets are usually steel and thus painted, not an ideal contact surface for electrical conductance. It's for this very reason that some people run a ground wire directly from the coil to the battery, claiming improved engine response.

Triumph's setup is even worse, I was amazed to find that the coil bracket is grounded to the frame via a little tab at the front merely touching the frame. The tab is slightly spring loaded against the frame by the flex in the bracket. That's it! The tiny contact area was, of course, rusted on my bike as well, explaining much, especially why the bike also tended to misfire more in the rain...

So, a short wire shunt was quickly constructed and firmly bolted between the coil core and the frame. Et voilą, resistance down to zero, and I'm happy to report the stutter is gone, and the bike running better than ever.

I wonder how many of the bikes stalling in the rain is also due to this poor coil grounding...???
Grubscrew is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 07-27-2010, 06:04 PM   #2 (permalink)
Senior Member
Formula Extreme
Main Motorcycle: 2010 Speedmaster
 
Lonerider60's Avatar
 
Join Date: Apr 2010
Location: Gaylord, MI
Posts: 637
Other Motorcycle: 2008 FZ1
Thanks for your persistance and input on this issue. When I get to doing a valve clearance check and have the tank off, I'm ging to do a check of my own coils and their grounding.
__________________
Riding for the pure enjoyment of two wheels.
Lonerider60 is offline   Reply With Quote Quick reply to this message
Old 07-27-2010, 06:08 PM   #3 (permalink)
Senior Member
World SuperBike
Main Motorcycle: 2008 Thrux
 
NorthernThrux's Avatar
 
Join Date: Mar 2008
Location: London, ON Canada
Posts: 1,893
Other Motorcycle: 2010 Speed Triple
Interesting indeed. Probably the best thing is to run a wire to the battery negative. Is the coil in the EFIs the same as the one in the carbed versions, in which case I wonder how many of the previous wet running and other problems blamed on the pickup coil might have actually been this silly little issue.

EDIT: My Nology case is plastic. It can't be grounded. Duh.
__________________
2008 Thrux. 1087 TPUSA motor. SOLD
2010 Speed Triple. SOLD

Last edited by NorthernThrux; 07-27-2010 at 06:41 PM. Reason: I'm a bozo
NorthernThrux is offline   Reply With Quote Quick reply to this message
Old 07-27-2010, 06:12 PM   #4 (permalink)
Super Moderator
Site Supporter
Nova
Main Motorcycle: Custom 955 Speed-Tona
 
DEcosse's Avatar
 
Join Date: Feb 2005
Location: Pleasanton CA
Posts: 16,907
I'm sorry, but most respectfully, I think you are seeing a placebo effect.
The case of the coil is not electrically part of the system;
The primary has positive power and the 'ground' is switched by the ECM;
The HT output of course is obvious and its return path is via engine ground and ultimately to the same grounding point as the ECM which completes the circuit.
Indeed many coils have plastic cases (have no direct experience of what the Thruxton one is: but from your report would believe you that it is metal - however irrelevant)
- as in point demonstrated by Northern Thrux example in post above.
The 'grounding wire to the can' mod is urban legend across multiple motorcycle sites - but it has no basis of fact in its actual operation and does absolutely nothing.

What your described stutter/surging problem really points to is actually a lean mixture as opposed to rich - this is very typical throughout all the Triumph range in attempt to meet emissions standards.
DEcosse is offline   Reply With Quote Quick reply to this message
Old 07-27-2010, 06:50 PM   #5 (permalink)
Senior Member
Grand Prix 500
 
Join Date: Jul 2007
Posts: 124
I think Decosse might well be right but I must say that the wiring diagram dosnt help (at least mine) as it do's not show the spark plug thus the high tension earth via the spark plug?
fredflinstone is offline   Reply With Quote Quick reply to this message
Old 07-27-2010, 11:15 PM   #6 (permalink)
Senior Member
Formula Extreme
Main Motorcycle: 2013 Street Triple
 
Fuzzy's Avatar
 
Join Date: Sep 2009
Location: Little Chute, WI
Posts: 585
Other Motorcycle: '68 TR6R TT Special clone
He got it working right, and that sure as hell beats walking home!
__________________
"I am living as I please"
Fuzzy is offline   Reply With Quote Quick reply to this message
Old 07-28-2010, 12:14 PM   #7 (permalink)
Senior Member
SOTP Vintage Series
Main Motorcycle: 03 T100
 
mikeinva's Avatar
 
Join Date: Mar 2007
Location: richmond va
Posts: 7,861
decosse is right if the wires are hooked up it will fire hanging in the air.
__________________
Why do I feel young on my bike
mikeinva is online now   Reply With Quote Quick reply to this message
Old 07-28-2010, 01:38 PM   #8 (permalink)
Senior Member
Powerbike
Main Motorcycle: 2009 Thruxton
 
Join Date: Feb 2009
Location: Johannesburg, South Africa
Posts: 329
Nope, you guys are dead wrong about this. No placebo effect at all, with the ground wire disconnected, it misfires/stutters seriously, to the point of almost stalling, no way that's in my head. Connect the wire, stuttering is gone. Pity you guys are so far away, I could demonstrate it quite easily for you.

Yes, the housing is made of plastic, but look closely and you will clearly see the metal core of the secondary windings sticking out at both ends. The coil is in fact bolted down via the core ends. Why would Triumph have endeavored to ground the coil core if it's of absolutely no consequence?

All the above is fact boys, theorize over it as much as you like or call me a liar if you must. It's just a 10cm piece of wire that takes 3 minutes to fit. Certainly worth a try for anyone experiencing similar symptoms to mine, wouldn't you agree?
Grubscrew is offline   Reply With Quote Quick reply to this message
Old 07-28-2010, 01:56 PM   #9 (permalink)
Lifetime Premium
Site Supporter
Legend
Main Motorcycle: 2009 Bonneville SE
 
Forchetto's Avatar
 
Join Date: Jun 2009
Location: Asturias, Spain
Posts: 14,313
Other Motorcycle: Yamaha XV1100
Extra Motorcycle: Qingqi QM200GY-BA
I think guys here are assuming the coils fitted to EFI models are the same familiar all-plastic encapsulated ones from either Gill, PVL, Nology, etc

Our coils are entirely different, Japanese, made by TEC, model MB-10

The fixings are entirely different and although I haven't had the opportunity of having a close look at it, I certainly will now...

I still can't see why grounding the laminated core makes a difference as the primary and secondary windings are isolated from it (I think). With some single-ended coils this has to be done via the fixing bolts, but with our double-ended ones the secondary is isolated from the core.

Last edited by Forchetto; 07-28-2010 at 01:58 PM.
Forchetto is offline   Reply With Quote Quick reply to this message
Old 07-28-2010, 02:49 PM   #10 (permalink)
Senior Member
Powerbike
Main Motorcycle: 2009 Thruxton
 
Join Date: Feb 2009
Location: Johannesburg, South Africa
Posts: 329
Forchetto, it is not uncommon for the primary and secondary windings to be completely isolated from one another within the coil and thus NOT sharing a common ground. When this is the case, the secondary windings are often grounded to the core. I suspect this is most likely the case with our Tec coils, hence why Triumph bothered to ground the core (albeit poorly), and hence why my grounding exercise solved my misfire.

From the experts:
"Conventional canister or can style coils used with older distributor ignition systems usually have a common primary and secondary ground connection. High energy coils may use a similar design or have isolated primary and secondary windings. DIS coils may have isolated primary and secondary windings (typical of the waste spark systems), or a common primary circuit with an isolated secondary circuit. COP and CNP coils usually have a common primary and secondary ground junction."

"The metal core in a ignition coil could be part of the circuit and is the common or return or ground."

I should have checked this while I had the coil out... I will most certainly do so next time, when I fit my newly constructed (and highly conductive) aluminium coil bracket.

Last edited by Grubscrew; 07-28-2010 at 02:52 PM.
Grubscrew is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Triumph Forum: Triumph Rat Motorcycle Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter your valid email address, that can receive an automated confirmation message. Otherwise, you won't be able to gain full access.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Stutter and Check Engine light jwolfe9 Speed Triple Forum 6 04-24-2010 05:45 PM
Interesting Twin engine tech sheet... Jon Hardcastle Biker Hang-Out 5 06-30-2009 01:00 AM
new wiring discovery jdirt1 Twins Technical Talk 2 01-16-2009 04:42 AM
Amazing Discovery... cafetbird Hinckley Classic Triples 14 12-06-2007 03:22 AM
Unpleasant discovery about myself.... Copper Twins Talk 31 01-14-2006 11:30 AM

Powered by vBadvanced CMPS v3.2.2

All times are GMT -4. The time now is 08:13 AM.



Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Motorcycle News, Videos and Reviews
Honda Grom Forum Harley Davidson Forum Honda 600RR Kawasaki Forum Yamaha R6 Forum Yamaha FZ-09 Forum
1199 Panigale Forum Roadglide Forum Honda CBR1000 Forum Vulcan Forum Yamaha R1 Forum Yamaha R3 Forum
Ducati Monster Forum Harley Forums Honda CBR250R Forum ZX10R Forum Star Raider Forum Yamaha Viking Forum
Suzuki GSXR Forum V-Rod Forums Honda Shadow Forum Kawasaki Motorcycle Forum Star Warrior Forum KTM Duke 390 Forum
SV650 Forum BMW S1000RR Forum Honda Fury Forum Kawasaki Versys Forum Drag Racing Forum Ducati 899 Panigale Forum
Suzuki V-Strom BMW K1600 Triumph Forum Victory Forums Sportbikes BMW NineT Forum
Volusia Forum BMW F800 Forum Triumph 675 Forum MV Agusta Forum HD Street Forum Suzuki GW250 Forum
Yamaha Motorcycles Victory Gunner Forum Honda Vultus Forum HD LiveWire Forum Ninja H2 Forum Ducati Scrambler Forum

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.