96 Thunderbird Carb or Electrical Problems

Jerrydef

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96 Triumph Thunderbird Cruiser 900
I have a 96 Thunderbird 900 Cruiser. Due to health concerns the Bike sat for about 18 months. But it had a Stabilizer in the Fuel Tank and I had run the Engine with the Petcock OFF until it stopped think I had run all the Fuel out of the Carbs. When I went back to ride it again I bought a New Battery and it started but would not idle unless I was at 1/2 Choke or more. I took the Carbs off and cleaned out the Float Bowls and cleaned the Jets as the Idle Jets were clogged. It ran better but would not run correctly and barely at all unless at 1/2 Choke. I pulled the Carbs again and took to a local Triumph Dealer and paid them to disassemble the Carbs, Clean, and reset to Factory Specs. It now Idles great but under acceration it seems to run intermittently on 2 cylinders, then 3, then 2, then 3. Do you think I still have Carb problems or do you think it could be Spark Plug Wires or a Coil going bad? Thanks for your help!!!
 

Silli

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Sounds more electrical than fuel. Any chance of rats having got to the wiring during the layoff? Spider webs causing earth shorts?

Check it out as follows.

Remove and insulate no 1 plug lead. Ride. Does it run ok on the two remaining cylinders? Replace plug lead.

Repeat for leads 2 and 3.

If the answer to the question is "yes" for all three tests, it is not the electrics.

If the answer to the question is no, then the cylinder from which the lead has been disconnected in that phase of the test is the one with the fault.

Good luck.
 

Jerrydef

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I forgot to mention I did Empty the old Fuel from the Tank before I put the Carbs back on after I took them apart the first time when it did NOT run correctly.

Thanks for the tip on Isolating the cause........ When you say to "Insulate #1 Plug Lead, and so forth; are you saying to disconnect the Lead from the Coil and just leave the Coil empty, or to pull Lead from the Plug and let hang or find a way to Ground? Sorry, I work well with things I can see and have some problems in understanding things Electrical items that I cannot see. I can do most anything if I have full instructions but do not want to mess anything up by doing it wrong!!!

I guess I am still confused as if ONE of the Carbs is still clogged, it will run on only ONE cylinder with your test and also on only ONE if a bad Coil. What makes some of this so difficult is the riding as it has a Sidecar attached which does put it under more of a load than just the Bike.

I have been able to get the sequence of pulling the Tank and the Carbs down pretty good, and after some trial and error have been able to pull the Center Plug with some effort. All the Plugs look good so I cleaned and re-gapped to 0.034. But like I said, it idles great but runs on 2 or 3 cylinders intermittently under acceleration, and even crusing.

Thanks to any and all for your help and thoughts!!!

Jerrydef
 

The Seeker

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I don't know your bike in particular, but is there a fuel filter? When you drained the tank if old fuel, did you drain it via the fuel line feed to the carbs? Did that flow well? Also...on my Trophy 1200, Triumph put tiny plastic fuel filters right where each fuel line went into the carb body. One of those could be clogged.

Fuel tanks must also vent even when the cap is closed. A clogged vent could prevent enough flow of fuel at over idle. Usually the vent is in the cap or the cap's closing mechanism. You can rule that out by riding with the cap ajar and seeing if that cures it.

To do the above, I would pull the sparkplug cap off of the sparkplug to isolate each cylinder and leave the coil end in place.
 

Silli

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Seeker is right...... just pull off the plug cap.....
 
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