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#375008 - 05/24/11 3:42 pm Triumph T120 R eats fuses  
Joined: May 2011
Posts: 11
Triumph Thaiger Offline
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Triumph Thaiger  Offline
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Joined: May 2011
Posts: 11
Phuket, Thailand
Hello all
I'm new to this forum.
I am the proud and happy owner of a mongrel 1971(engine)/1972(frame)Triumph Tiger 650 which I bought some 29 years ago. Recently she has developed a problem which I can't make sense of though. About a year ago a "friend" borrowed the bike. It's true what they say : there are three things in life you should never lend out : your wife, your chainsaw and your motorbike. In any case, he crashed it into a local motorbike- with- side car- noodle shop of the type that any of you who has ever visited Thailand will be familiar with.
(Un)fortunately he was not hurt ( nor was the noodle man) and the bike was fine after replacing the front fork stanchions. However ever since the event( and it is definitely since then) some times, but not always and ONLY just after start up (can be cold or warm start but more often warm start)she blows the fuse. She never blows a fuse whilst underway. Other a massive short I can't think of any scenario that causes a 35 amp fuse to blow but all electrics (I only have the bare neccessities ( horn, lights, brake lights) are fine.Battery is in excellent nick( I know how to test a battery ), generator is standard, ignition is a Boyer Mk I,she has a zener diode, wiring was re done by myself two years ago and I can't find any (obvious) shorts. Any solution some of you might have for me will cause immense grief to my local supplier of fuses but great joy to me. .
Best regards from sunny Thailand

Maxim Jurgens


Single carbed Triumph T120 R 1971/72 mongrel
BSA M20 Sunday Morning Blast Weapon 1939 (under construction)
Moto Guzzi V7 Special 1971
Moto Guzzi V50/65 track bike
Dnepr MT 16 with side car
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#375032 - 05/24/11 5:26 pm Re: Triumph T120 R eats fuses [Re: Triumph Thaiger]  
Joined: Oct 2003
Posts: 11,108
RF Whatley Online content
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RF Whatley  Online Content
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Joined: Oct 2003
Posts: 11,108
North Georgia, USA
Maxim -
Welcome aboard!

Here are some tips on finding the short.

Replace the fuse with an ammeter. The meter will "peg" at max when you get the short. BUT you may also have a situation where you are "shorting" to ground, but not simply pulling enough current to blow the fuse. The ammeter will also detect this.

Connect the ammeter and start wiggling the harness. These type shorts are usually the harness rubbing against a sharp metal edge that has cut into the harness and thereby making intermittent shorts at certain vibration ranges. On a 1971 this is 1) usually around the battery box, and 2) anywhere you have those original metal cable ties. ALWAYS replace the metal cable ties with modern plastic versions.

Your situation tells us that the short is on the powered side of the ignition switch. That is, it is in the wiring to a device that is turned OFF when the key is OFF. That rules out the charging circuit. It leaves the ignition and lighting circuits.

Often times you can segregate the functions of the harness (charging, ignition, lighting) by disconnecting discrete items like the horn, headlamp or brake light switch while you wiggle the harness.

Also, on stock 1971 and 72's there is a huge bundle of connectors above the horn that cannot be over looked. Since it is out of sight this area does not get much maintenance. These can be connected wrong. Within that bundle, the Red/White electric starter wire for instance needs to be insulated or it will short whenever the button is pushed.


As you can see it can take some detailed one-on-one time with your bike to find the issue, but the work is not hard if you will follow a logical path of thinking. Therein lies the biggest problem for most people, who want to jump from investigating the front axle to searching the tail lamp bulb. You have to have a logical search sequence. Since the power to create a short starts at the battery, I suggest you start at the battery and work toward each device. This process is detailed RIGHT HERE.

Hope this helps! bigt


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

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
#375038 - 05/24/11 5:40 pm Re: Triumph T120 R eats fuses [Re: Triumph Thaiger]  
Joined: Sep 2007
Posts: 1,562
Roadwarrior Offline
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El Dorado, California
Maxim, firstly, welcome to the forum. If your running standard gear, multiple fuse pops are generally caused by a sudden short caused by vibration. Not sure what advise to give except to really go through the wiring looking for any potential short. I assume it is not when you turn on the headlight, or step on the brake pedal. Do the fuses blow while you are kick starting the bike? Could be the sudden jolt to everything. I would carefully check all of the wiring inside the headlight bucket, and also the wiring for the horn and kill switch. I had a faulty connection to the horn on one of my bikes that kept blowing fuses. I finally realized the horn was loosely mounted and contacted the frame at the electrical connection when I hit a large bump. Also, I have never run a Boyer with a Zener and rectifier. I have always swapped those out for a Podtronics power box. Good luck.


Bob


73 Triumph T140 Main Ride
70 Bonnie
67 BSA West Coast Hornet

56 Chevy

Who are the brain police?



#375043 - 05/24/11 6:11 pm Re: Triumph T120 R eats fuses [Re: Triumph Thaiger]  
Joined: Dec 2006
Posts: 3,742
btour Online content
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btour  Online Content
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Massachusetts, U.S.A.
The horn sounds likely if from the accident.

Also check the battery is not hitting the seat pan. Was he a heavy friend?

And I bet the rubber bumpers for the seat are missing. After starting you woul land on the seat. That would do it.

Last edited by btour; 05/24/11 6:15 pm.

Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
#375048 - 05/24/11 7:33 pm Re: Triumph T120 R eats fuses [Re: Triumph Thaiger]  
Joined: Jun 2007
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DPO Offline
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DPO  Offline
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Douglasville (Atlanta) Georgia
Fuse?


If you love it, let it go. If it comes back, you've highsided!"

1971 Triumph T120
2005 Triumph "America"
1976 BMW R90/6
#375067 - 05/24/11 8:30 pm Re: Triumph T120 R eats fuses [Re: Triumph Thaiger]  
Joined: Mar 2005
Posts: 9,964
John Healy Online content
John Healy  Online Content



Joined: Mar 2005
Posts: 9,964
Boston, Massachusetts
REplace the fuse with a tail lamp bulb, or something similar. The fact that it lights with the ignition and lighting switches turned off indicates that you have a short. Disconnect things, and or wiggle things, until the bulb goes out. When it goes out you have found your short.


#375118 - 05/25/11 1:38 am Re: Triumph T120 R eats fuses [Re: Triumph Thaiger]  
Joined: Jun 2010
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MikeinBiddeford Offline
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Maine
I hate intermittent electrical problems. Some times I wish they would just go out with a puff of smoke and some charred insulation.

I'm going to take a shot in the dark here. Are you using the choke lever on warm start ups as well as cold? I know there is no electrical connection on the cable, but as RFWhatly says, it could be bundled with some wires that have chaffed their way through.

I had problems with blown fuses on my '71. They went away when I got rid of the Zeiner diode and installed a Podtronics. It may have been a coincidence, but I don't miss the diode.


Please do not believe anything I write. I am a hack but I like to guess the right answers.
#375146 - 05/25/11 7:20 am Re: Triumph T120 R eats fuses [Re: Triumph Thaiger]  
Joined: Oct 2004
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Tiger Offline
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Tiger  Offline
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Melbourne Australia
All for fixing stuff rather than replacing but the original harness may be getting a wee bit ratty after 40 odd yrs ?

The harness on my TR6 was sourced ex British Spares in NZ about 7 yrs back and has been trouble free, easy to install if you cut the old harness off just short of where it plugs into various components so colour coded wire stubs remain.

Then lay the new harness out and temporarily tape it to the frame, this helps as for instance brake light cables obviously do not belong in the headlight shell etc.

Not related to your present issue but if you do rewire replace the "glass" fuze and fuze holder with the blade type and run lots of extra earths [grounds].


1969 TR6R
7.62 x 51 is not a maths puzzle.
#375166 - 05/25/11 12:47 pm Re: Triumph T120 R eats fuses [Re: Tiger]  
Joined: Jan 2008
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JBMorris Online content
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JBMorris  Online Content
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Farmington,Connecticut,USA
Originally Posted By: MJ
that causes a 35 amp fuse to blow but all electrics (I only have the bare neccessities ( horn, lights, brake lights) are


Don't forget that a 35 amp fuse is the "Factory" designation and should be replaced with a 20 amp one.
This issue has been discussed more than once on this forum.
Good Luck

Last edited by Brien Morrissey; 05/25/11 12:50 pm.

1978 Bonneville T140V PX
#375205 - 05/25/11 3:53 pm Re: Triumph T120 R eats fuses [Re: Triumph Thaiger]  
Joined: Mar 2005
Posts: 9,964
John Healy Online content
John Healy  Online Content



Joined: Mar 2005
Posts: 9,964
Boston, Massachusetts
Don't forget that the 35 amp specified by the factory is an ENGLISH standard. The same rated fuse in the US is sold as 17 amp.

There is two different ways of rating fuses and putting a 35 amp US fuse in the bike will allow the wiring harness to melt before the fuse blows.


#375215 - 05/25/11 4:37 pm Re: Triumph T120 R eats fuses [Re: Triumph Thaiger]  
Joined: Dec 2006
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btour Online content
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btour  Online Content
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Massachusetts, U.S.A.
I am glad you guys said something about that. I noticed it but did not comment.


Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
#375872 - 05/28/11 6:46 am Re: Triumph T120 R eats fuses [Re: Triumph Thaiger]  
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RetroRod Offline
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RetroRod  Offline
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QLD, Australia
I say chaps, when will we see a revised wiring harness that moves us on from the single point of failure single fuse, to something with a 1/2 doz separate circuits to fuse.

Then that shorted instrument lamp won't leave us high, dry and handsome, looking for the problem on a wet,cold and windy night,10 miles from home. Well, carry a hot wire kit just to be on the safe side!! RR


'72 Bonneville
"He who praises you for what you lack wishes to take from you what you have." - Don Juan Manuel
#375930 - 05/28/11 3:10 pm Re: Triumph T120 R eats fuses [Re: RetroRod]  
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shel Online content
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shel  Online Content
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ohio
Originally Posted By: RetroRod

Then that shorted instrument lamp won't leave us high, dry and handsome, looking for the problem on a wet,cold and windy night,10 miles from home.


That was my thinking when I wired my Trident. I'll most likely do the same to the Bonneville some day.


When given the choice between two evils I picked the one I haven't tried before

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