T140E hard to start cold without starting fluid - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 16 (permalink) Old 04-28-2019, 09:36 PM Thread Starter
Grand Prix 125
Main Motorcycle: 1979 Triumph Bonneville
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T140E hard to start cold without starting fluid

Hello all,

I'm excited to say that after 36 years in hibernation, my 1979 T140E Bonnie came to life this afternoon!! Yay!

I just installed a Pazon EI system, rebuilt the carbs, changed all the fluids, new battery, plugs and plug wires, and with a small shot of starter fluid VIOLA!! It came to life on the second kick!

After warming it up gently, I set the timing and adjusted the MKII Amal carbs. It idles quite nicely around 800-900 rpm, though the left cylinder does seem to be burning a little richer than the right. (as evidenced by more smoky exhaust only from that side)

After shutting off the engine and letting it sit for a few minutes, it starts immediately on the first kick without any issues.

Unfortunately, if I let it sit for 30 min and try to start it (using the cold start plungers on each carb and cracking the throttle about 1/3 open), I get absolutely nothing. Hit a short blast of starting fluid in either cylinder again and it starts immediately.

Questions for the group:
  1. Any ideas why cold starting is so hard without starter fluid? I don't want to continue needing it as its hard on an engine. I've seen a few docs outlining how to ream out the pilot jet on the carbs which I didn't do when I put in the rebuild kit. Wondering if that might be a problem for cold starts when the pilot circuit might be most needed for supplying initial fuel for ignition?
  2. Any thoughts on how to even out the left cylinder that has a bit of a smoky exhaust?


Thanks in advance for your help to a newbie!

Tony

TJ

Last edited by tjsei; 04-28-2019 at 09:39 PM.
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post #2 of 16 (permalink) Old 04-29-2019, 07:21 AM
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Mods need to put this in the right forum VVC.


I think your cold start isn't working...sounds like you are not getting the fuel flow for a cold start. You say you rebuilt the carbies, what work did this entail? What parts did you replace? If you replaced the plungers, did you know that there are 2 versions?

The left cylinder smoking is probably a separate issue, do a compression test on it when the motor is warm, but could be valve guides?

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post #3 of 16 (permalink) Old 04-29-2019, 11:35 AM Thread Starter
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Thanks for the reply Trident.

In my case, rebuilding the carbs simply meant disassembly, soaking in carb cleaner, replacing all gaskets and o-rings, installing Stay-Up floats and viton needle valves, and blowing out the orifices with compressed air. I did not change any of the needles, jets, or sleeves.

For reassembling, I set the pilot air screws and 1.5 turns out and once the bike was running I seemed to get the smoothest idle running them both at just over 2 turns out.

I did not replace the plungers. As everything looked clean when I reassembled them and the cold start levers still had a firm 'up/down', I assumed those were fine but perhaps not. Is there a way to test and see if the cold start levers are working properly inside the carbs?

I'll be disassembling the carbs again today and plan to inspect more closely the cold start and pilot jets and clean out further if needed.

Any other thoughts are appreciated!

TJ

TJ
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post #4 of 16 (permalink) Old 04-29-2019, 03:21 PM
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Just a couple of things that may help. I have a '78 T140E and have recently spent some time sorting the carbs.

The Mk 2 Amals have the Pilot Jet air screw 2.5 turns out as a starting point, not 1.5 like the Mk 1's.

It could be well worth poking the pilot jets through with a thin wire (google it for other suggestions) especially as you are playing with the screws, and this can be done without removing the carbs.

Finding out about and doing these two things stopped my bike being hard to start and running on one cylinder at tick over.

Good luck.
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post #5 of 16 (permalink) Old 04-29-2019, 04:32 PM
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Hi Tjsei,
Congratulations on the resurrection of the T140 this Easter.

If you remove your float bowls, towards the outside there are two slots in the gasket face, one end of the slot goes a long way down in the float bowl. At the bottom of this hole is the screw in starter jet, if these are blocked then the enrichment circuit will not work giving the symptoms that you describe.

Removal of these jets can be a tricky process. You will need a good screwdriver with no wear or damage, that just fits (or you grind to just fit) down the hole. Apply plenty of pressure on the screwdriver when unscrewing the jet, any slip will damage the screwdriver slot in the jet, making removal impossible.
Do not break the head off of the jet.
Once the jets are out clean them and the passageways to the little hole behind the slide.
Best of luck with this tricky task.
Peg.

Last edited by Rancidpegwoman; 04-29-2019 at 04:35 PM.
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post #6 of 16 (permalink) Old 04-29-2019, 09:16 PM
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My t140e runs fine on 1 1/2 turn out. I always thought the 2 1/2 was a misprint.

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post #7 of 16 (permalink) Old 04-29-2019, 10:06 PM
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US jetting left a bit to be desired. Suggest you rejet to UK specs


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post #8 of 16 (permalink) Old 04-29-2019, 10:13 PM Thread Starter
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Wow - great info Peg! This was indeed an area I totally missed during my mini-rebuild.

So far I've disassembled one carb and got the cold start jet out without issue (had the perfect screwdriver!). The jet itself wasn't too bad, but I see a whole bunch of debris in the passageway behind it. I've poked a small wire through it to loosen things up and now have the bowl and jet soaking in carb cleaner to get it fully cleaned out.

I'll repeat the same process for carb #2 as well.

Once I get it all back together, I'll report back to the group on how it comes out. Thanks again!
Happyfeet likes this.

TJ
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post #9 of 16 (permalink) Old 05-02-2019, 10:02 PM Thread Starter
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An update for anyone interested.

After removing, wire probing, and thoroughly cleaning out the cold start and pilot jets, I've been able to start the bike several times without needing any starter fluid. Many thanks to all for sharing your experience.

As a follow up, I do find that it takes about a dozen attempts to kick start the bike in order to get it started from cold. (about 3-4 with chokes on until I smell gas, then another 9-10 with chokes closed before it finally fires up). I can't help but assume I should be able to do better than that, though I'm not sure where I adjust from here. Any thoughts? Perhaps it will get better after getting some runtime after 36 years in hibernation?

In addition, I've noted that kicking over the bike with the chokes on eventually starts dumping gas out of the air vent pipes on either side of the carb body. Is this normal if you keep the chokes open too long or do I need to go back through the carbs again and adjust further?

TJ

Last edited by tjsei; 05-02-2019 at 10:05 PM.
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post #10 of 16 (permalink) Old 05-03-2019, 12:30 AM
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I would try using the cold start with the ignition OFF and give the bike 1 or 2 prime kicks. Then turn the ignition ON and kick again. Each bike has a technique it likes, I find mine likes 1 prime kick, some don't need one at all, others need 2. But essentially if the bike doesn't start in 2-4 kicks total [prime and ignition on] then there is another issue.

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