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Approach to a T-120R Problem Humbly Requested – Bike Quits! #143384 06/23/08 12:38 am
Joined: Aug 2007
Posts: 20
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Jim Knight Offline OP
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The subject bike is a 1967 T-120R, restored by somebody (unknown to me) and with unknown miles since restoration (The speedo was broken when purchased). Conventional points ignition and AMAL Concentric carbs are fitted. Recently purchased by me, the bike has several kinks to work out, but I’ll start with the most alarming problem. After a few minutes of warming up, at about ¾ throttle under a mild load, one or both cylinders just quit. No coughing, missing, or sputtering, they just die. After a minute or so, I can get both cylinders back running and ride home. This has happened now five timers. The plugs after these run are a little sooted around the margins, but I think that richness is mainly in the idle circuit (another problem for later). The plugs also seem really hot, making me dread overheating, but I may be making this up.

Guys, I hope this rings a bell, and I need suggestions for a basic approach to it, i.e., what to check first versus second or third. I can tell you what seems okay: gas (new), air filters clean, plugs are new, points work and are properly gapped, alternator serving plenty of amps to the electrical system. The bike starts, idles fine and sounds fine when revved. I have not yet re-timed the engine (new TDC indicator is on the way), nor have I had time to adjust the valves. I haven’t looked into carb jetting because frankly, I’m need to be convinced that carburation is really the problem before I get into re-jetting. Thoughts?

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Re: Approach to a T-120R Problem Humbly Requested – Bike Quits! #143385 06/23/08 12:53 am
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Woody1911a1 Offline
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just a thought , fuel delivery . check petcock filters and the filter in the banjo fitting at the carb . float and needle . a full float bowl will get you up the road about a quarter mile .

like i said , just a thought . smile

Re: Approach to a T-120R Problem Humbly Requested – Bike Quits! #143386 06/23/08 1:19 am
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JubeePrince Offline
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Gas cap vent clear?

How hot are coils when this happens?

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: Approach to a T-120R Problem Humbly Requested – Bike Quits! #143387 06/23/08 1:33 am
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drp Offline
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Have you considered (or did you replace) the condensers? (new ones not NOS). I am running points and my Triumph runs like cr*p on old weak condensers. They usually get worse as they get hotter.

Dave

Re: Approach to a T-120R Problem Humbly Requested – Bike Quits! #143388 06/23/08 1:35 am
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Jim Knight Offline OP
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Haven't checked either one yet. Will next time out. What would you say if the coils do seem too hot?

Re: Approach to a T-120R Problem Humbly Requested – Bike Quits! #143389 06/23/08 2:01 am
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Jim Knight Offline OP
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I have not replaced the condensers but it's probably a good idea on this bike, with so many unknowns. Thanks.

Re: Approach to a T-120R Problem Humbly Requested – Bike Quits! #143390 06/23/08 4:29 am
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aceaceca Offline
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The connections to the amp meter and the guage itself. All power goes through there so if loose on the amp studs, no power. Mine did the same thing. I replaced the amp guage with a volt meter and made a really good connection of the two amp wires. Problem solved.

Re: Approach to a T-120R Problem Humbly Requested – Bike Quits! #143391 06/23/08 11:28 am
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649 Offline
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ignition switch.....


1970 tr6r dryframe
Re: Approach to a T-120R Problem Humbly Requested – Bike Quits! #143392 06/23/08 9:47 pm
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az-idea Offline
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..Sudden death at 3\4 throttle..sounds electrical..thing that sticks in mind is you say"one,or both"cylinders drop out..?..leads me towards points plate connections\condensors?..Vs furthur down line[Alt.main Gr.et cet]..but could be Head Gr.loose too..


Moderated by  John Healy 

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