Struggling with MK11 carbs

Triton Thrasher said:

I reckon that’s what I said.

Click to expand...

I reckon you’re right ! I got it wrapped around my neck.

I’ve edited the post to avoid confusing folk who may read this down the line...

Chaps,
Are the pilot jet and the cold start jet the same product family?
I only see pilot jets on Amals web site, so I assume I’d buy two #35 pilot jets in order to have #35 cold start jets. Correct?

I think they are the same part.

But it’s been a few years!

Triton Thrasher said:

I think they are the same part.

But it’s been a few years!

Click to expand...

You’re correct TT, I got an answer from Amal on this question, they are the same.

Ok chaps, update time:

Mk11 bits came from Burlen before the mk1.5 airbox adapters, so I worked on the mk11s.

I bought new pilot and cold start jets, new 3.5 slides (went for chromed brass ones) and new 2A1 needles.

First finding; the ‘new’ 2A1 needles I fitted previously from my ‘stock’ (no idea where they came from or when) were different to the new ones from Burlens, so I may well have introduced an issue there.

I removed the air jet bush as suggested by John Healey.

I had to spend an hour or so making the brand new ‘genuine’ chrome brass slide fit properly in the brand new ‘genuine’ f*cking carb! My missus, who is Japanese, took great delight in dismissively saying “wouldn’t have happened with Mikuni’s or Keihin’s” which, of course, is quite true!

Once fitted though, the brass slides really do give a nicer feel, highly recommended.

So I now had the carbs set up exactly according to John Healey non EPA spec.

And...

It was shite! Really running rough. I went through everything again. I went through the ign system again (I recently fitted a Tri Spark), and nuthin. I was just about to start ripping the ign off the T120 to try when I thought I’d just try some other plugs... the new iridium jobs I fitted MUST be fine I thought, but I tried swapping them anyway...

And bingo... duff bloody plug!!

So, with new plugs (am trying Denso iridium jobs this time) and the John Healey carb settings it runs superbly, really superbly in fact!

Several morals to this story:

1. You can’t trust workshop manuals! The carb settings in the genuine Triumph manual are what Burlen used, and they were definitely no good (they are a mix n match between what John Healey calls non EPA and EPA).

2. Always remember the basics (duff plug story).

3. Sorry to say it, but Burlen quality control just ain’t good enough.

4. If you’ve got a Triumph, get reading stuff posted by John Healey. I dunno who he is, but he knows his stuff!

5. T140s are Ace when you get ‘em sorted !!

Now I just gotta get some blasting in before the weather turns...

I was quite fortunate with my T140 that I bought restored. It had 200 very careful break in miles on it. The really cool part is, the person that restored it, a Triumph dealer from Pennsylvania, kept a journal of all the changes and rebuilds he's done to the bike including experimenting with different carb jets and the like. All since the 90s. To me, having that journal was worth half the price of the bike. Poor fella passed away and a collector purchased from the estate sale. It just didn't fit into his collection which were older Bonnies, Ducs, bikes from the 50s and 60s/. Lucky me.

Update on the mk11 carb saga...

I had the bike running very well, but still wasn’t quite happy and narrowed the ‘area of unhappiness’ down to the throttle valve / slide cut away.

I had them set up to John Healey’s none EPA spec, which according to John Healey was:

European (non-EPA)
124/026 #15 pilot jet
124/012 #35 choke jet
2928/122 .106 needle jet
2928/030 #3 1/2 slide (leaner than US equivelent)
2622/124 2A1 needle
No air jet fitted”

The bike is basically stock apart from having Commando style peashooters fitted.

Today I tried #3 slides and it made exactly the difference I was hoping for.

I was considering selling this bike, I’m now having serious second thoughts cos it’s SO nice to ride!

For those treading the same path in future. The carbs are now beautiful! It pootles along at walking pace like a low comp single carb bike. But pulls like a train when opened up. It feels really nice. Starts first or second kick and ticks over perfectly.

Final settings are:

Pilot # 20 (up from #15)
Choke jet # 35
Needle jet # 106
Slide # 3 (changed from # 3.5)
Needles # 2A1
Needle clip position changed one notch weaker
Air jets removed (those funny ‘bushes’ fitted to the inlets).

That’s with Norton Commando style peashooters.

Jobs a good un.

Great thread Eddie. Thanks for making the effort to inform us

xbacksideslider said:

Great thread Eddie. Thanks for making the effort to inform us

Click to expand...

Thanks, glad you liked it!

Not much help to you though as yours is a pre EPA bike with mk1 concentrics.

That should actually make life a lot easier for you.

106 needle jets, number 3 slides, 200 mains. These are the ‘standard’ settings for this bike according to Amal and mine ran well with mk1.5 concentrics set up like this, even though I was running straight through Commando style peashooters.

And by the way, you need to junk the stock cigar silencers, if yours has them, and fit peashooters. It’s compulsory.

I’m away from home at the moment, but re-reading this is making me want to hurry home and get out on the T140 again !

Yep, cigars are on it. Look to be long heavy road scrapers. I’ve got some old pea shooters that I might try after I get it going

Thanks for the specs, I’ll check against what I have

Norton peashooters will require custom brackets making. You can buy Norton type peashooters specifically for the T140 which bolt straight on using your stock brackets.

It's good to hear you got it all running nicely....The Mk2's on my 79 T140D have had the same jetting as yours...But they still have a brief richness burble off idle...But otherwise fine.Diffrent slides and jetting didn't change it...The carbs aren't worn. they just don't like the engine..

Hillbilly Bike said:

It's good to hear you got it all running nicely....The Mk2's on my 79 T140D have had the same jetting as yours...But they still have a brief richness burble off idle...But otherwise fine.Diffrent slides and jetting didn't change it...The carbs aren't worn. they just don't like the engine..

Click to expand...

Thanks. I’m very pleased with them now, can’t fault ‘em in fact!

I’m on Denso iridium plugs now BTW.

I have the stock "reconditioned" Lucas Rita ignition using two Dyna type coils...They will fire a .035" plug gap that the engine does like...I use #7 NGK competition plugs that feature a shortened ground electrode..

Totally enjoying this thread. I love my 2. T2
140D AND the MkII.
One, I'm original owner needs some sprucing up. Lucas Rita ignition still works like a champ.

I fought a pair of M2 amals on a T140 for months. Tried all the suggested jetting. Changed out the plungers. Tried every possible variation. did you spot the dual pilot jets?
It would idle at 2500 and NO response to the air screw or the throttle screws. Foul plugs in no time. Finally I stuffed kleenex into any and all ports leading to the enriching circuit and instantly got control over the idle and mixture. It was sucking in an uncontrollable amount of air and fuel through the enriching circuit. At this point I ran into a pair of decent MK1 concentrics and used them instead. But I was on the right track.

Fast Eddie said:

Thanks, glad you liked it!

Not much help to you though as yours is a pre EPA bike with mk1 concentrics.

That should actually make life a lot easier for you.

106 needle jets, number 3 slides, 200 mains. These are the ‘standard’ settings for this bike according to Amal and mine ran well with mk1.5 concentrics set up like this, even though I was running straight through Commando style peashooters.

And by the way, you need to junk the stock cigar silencers, if yours has them, and fit peashooters. It’s compulsory.

I’m away from home at the moment, but re-reading this is with needles full leanmaking me want to hurry home and get out on the T140 again !

Click to expand...

These short 19” by 1.75 ID Emgos improved power and sound. 130 mains the rest stock with needles full lean

seattle##gs said:

I fought a pair of M2 amals on a T140 for months. Tried all the suggested jetting. Changed out the plungers. Tried every possible variation. did you spot the dual pilot jets?
It would idle at 2500 and NO response to the air screw or the throttle screws. Foul plugs in no time. Finally I stuffed kleenex into any and all ports leading to the enriching circuit and instantly got control over the idle and mixture. It was sucking in an uncontrollable amount of air and fuel through the enriching circuit. At this point I ran into a pair of decent MK1 concentrics and used them instead. But I was on the right track.

Click to expand...

I had a pair of Mk 1.5 Amals, which have Mk 2 type chokes.

There was no cold start jet size which was good for very cold mornings and less cold mornings.

I blocked the whole cold start circuit up too, with cork and drilled down into the float chambers to fit ticklers made from welding rod and ballpoint pen springs.

I finally got my Mk2 problem fixed......