Difficulty Starting And Cold Running - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 47 (permalink) Old 06-02-2019, 04:57 PM Thread Starter
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Difficulty Starting And Cold Running

Evening all,

I picked up the bike yesterday, a 1979 T140E in generally great mechanical condition. It is a UK bike from new but was ordered with the Peanut Tank and High bars, like the US model. It has been uprated with nikasil-lined alloy barrels, Carillo con rods and pistons, balanced crank, updated push rods with Norman Hyde tappet adjusters, forged alloy push-rod tubes and Norman Hyde valve springs. There is an uprated oil pump and clutch, electronic ignition, 1.5 inch headers (no balance pipe) with straight-through Commando pea shooters (that sound fantastic). It has alloy rims with stainless spokes, Koni adjustable shocks, a 12 inch Norman Hyde front disk and fork brace. Other than that, it is a completely standard bike ;-) and a great base for my winter restoration plans.

However, whist the bike rides and stops very well, it is challenging to start and will not tickover when cold. Attempts at starting are most successful with the choke on between half and full, find compression stroke and kick it with a little throttle, but it may take a number of attempts before it finally goes and then I have to constantly blip the throttle or she dies. Once she is fully warmed up after a ride around the block (running really well / pulling very strongly and smoothly) she will settle on a lumpy idle. The LH exhaust firing cleanly on each ignition stroke but the RH exhaust firing sporadically (a bit like one of those old static engines you see being shown at steam fairs).

So, suspecting a carb / fuelling issue I have done the following:
Remove the airbox sides.
Cleaned and re-oiled the (rather dirty) air filters.
Removed and cleaned the throttle idle position screws and fitted new O rings.
Felt the slides to set the throttle idle position screws at the point where they just touch.
Removed the air bleed screws, cleaned the hole / passage with spray carb cleaner.
Fitted new O rings to the bleed screws, screwed them in all the way, them out 2.5 turns.
Removed the (very slightly sooty) plugs, cleaned, gapped and refitted.
I screwed both idle screws in a couple of turns, set choke and kicked her over. As before it took quite a few attempts to get her started (trying various combos of choke / throttle / cursing) but once she was running, I set the idle screws to get a 1000rpm idle with no choke (she does not like running with choke at any temperature).

After a little trial and error, I settled on 3 turns air bleed (this was how she came originally) as she seemed to run best that way but there was no improvement in the sporadic RH cylinder firing. I took her on a run around the block but once she was warmed up the idle was now 2500rpm so I tweaked the idle screws down so she was at 1000rpm again but still lumpy and occasionally stalling. Presumably when she is cold I will not have an idle as before. So, all that work has done nothing, other than to show that the problem lies elsewhere.

Are any of you Meridian Twin experts able to help me identify what this could be please?

Thanks,
Ian
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post #2 of 47 (permalink) Old 06-02-2019, 09:42 PM
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Hi Boggie,
After Amal had their joke with us on the mk1 carb, by giving us pilot jets that could not be removed to be cleaned, they wondered how they could top this on the mk2. The mk2 Amal had removable jets so the funniest thing they could think of was to hide a couple of them; the little tinkers.

Hilariously, they hid the cold start jets in the bottom of the float bowl. If you look along the outside of the float bowl there is a slot, one end is much deeper than the other and in the depths of this hole is the cold start jet. If you have not already found it in your previous incursion into the carb, this is a likely cause of your woes.
Amal also added a practical joke, if you don’t get a perfectly fitted screwdriver into the jet slot, the head breaks off-recovery from this point is near impossible-so be careful, just for the fun of it the deep hole the jet is in is only slightly bigger than the jet, so you might need to grind a screwdriver shaft down.
Once the jet is out, there is a passageway that leads to the enrichment hole just in front of the slide, this needs careful thorough cleaning.
Do not mix up the pilot and cold start jet, they are interchangeable and will give you some weird results if accidentally swapped.

Barry Johnston and Jeff Binks of Amal were genius, truly professional designers of fuel delivery systems and gifted amateur practical jokers.

If this was not your problem, I would next be suspect of the cold start plungers. These have a rubber seal at the end, the seal should look flat and not have a nipple in the middle. If they are like this then you need to replace them. Recently cold start devices with much lighter springs have become available, these have a much longer lifespan than the strong spring type.

You do not say in your text the method you use to synchronise the carbs on the cables and on the throttle stops, correctly and carefully this can have a large impact on how your bike runs on tickover and on pulling away.

It is unlikely that you will get a good cold tickover the way a modern bike does, even with careful setup.

Regards
Peg
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Last edited by Rancidpegwoman; 06-02-2019 at 09:45 PM.
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post #3 of 47 (permalink) Old 06-03-2019, 12:40 AM
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RPW thoroughly covered the carbies, fine wires, extra small drill bits or oxy acetylene welder tip cleaners, carb cleaner, and compressed air will help. But are you sure its fuel? And not spark? What EI do you have? Try swapping the coils, then try swapping the HT leads. If the issue is spark it will move to the other cylinder. Also check your connections and link wires between the coils.

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post #4 of 47 (permalink) Old 06-03-2019, 03:15 AM Thread Starter
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Great advice, thanks Chaps! I will strip the carbs, put them in my ultrasonic cleaner for a couple of hours and inspect everything before ordering the required bits from Amal. Are the needles and jets marked for easy identification?
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post #5 of 47 (permalink) Old 06-03-2019, 03:35 AM
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Quote:
Originally Posted by Boggie View Post
Great advice, thanks Chaps! I will strip the carbs, put them in my ultrasonic cleaner for a couple of hours and inspect everything before ordering the required bits from Amal. Are the needles and jets marked for easy identification?
Hi Boggie
A magnifying glass is an asset when identifying the markings—most people use their phone camera/screen these days-an unexpected the joy delivered by the modern world

I must say that I am impressed by the smorgasbord of sensible and expensive updates that you managed to acquire with this bike. The PO certainly knew what was required to allow these bikes to live in the 21st century.

Are the barrels Gilardoni?, I have quietly bought up loads of these when they appeared on e-bay, brilliant items, no oil burning, no piston slap, change the rings every 80,000 miles and that’s it, I only have a couple of sets left and not seen any for sale in 3 years.

The uprated oil pump, if it is the morgo rotary? Make sure the pump is primed after every oil change, failing to do that will destroy your engine very quickly (within seconds); once primed it will be fine.

What a fantastic find.

Regards
Peg

Don’t forget to carefully synchronise the carbs after rebuild-a most worthy exercise.

Last edited by Rancidpegwoman; 06-03-2019 at 11:21 AM.
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post #6 of 47 (permalink) Old 06-03-2019, 03:49 AM Thread Starter
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Thanks Peg, not sure who made the Alloy/Nikasil barrels but the bike came with a spare set so I will check.
Yes, it is a Morgo pump. Is priming a simple matter of kicking it over with the ignition off?
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post #7 of 47 (permalink) Old 06-03-2019, 05:00 AM
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Quote:
Originally Posted by Boggie View Post
Thanks Peg, not sure who made the Alloy/Nikasil barrels but the bike came with a spare set so I will check.
Yes, it is a Morgo pump. Is priming a simple matter of kicking it over with the ignition off?
Hi Boggie,
If you ever get the urge to sell the extra barrels, I will buy them from you without hesitation.

Priming the Morgo rotary pump is much simpler than just kicking it over with the ignition off

First mark the position of your ignition pickups, then remove them.
Remove the timing cover.
Refilling the oil tank.
There is a small bleed screw with a locking tab.
Remove the screw and wait until only oil dribbles from the hole (no more air bubbles).
Judge whether the lock tab is reusable, and refit screw with original or new tab.
Replace timing cover gasket and check or replace timing cover and crankshaft oil seal (there are some nasty cheap replacement seals that are to be avoided, seals made by Pioneer Western have a reputation for quality and reliability).
Refit timing cover.
Refit ignition pickup in the orientation that you had previously marked.
Kick the engine over (ignition off) and verify oil flow using;
a) Oil pressure gauge-40 psi within a couple of kicks is normal with this uprated pump.
b) Check oil pressure light goes out within a couple of kicks.
c) Remove oil pressure sender unit and check oil squirts out of the port- refit carefully without managing to crack the case.

If all is OK, start the engine and check the ignition timing with a strobe lamp.

I told you it was simple

I believe the rotary pump was designed originally for early bikes with an oil tank that retained the oil above the level of the pump, so there was always oil in the supply pipe to retain the pump prime.
The oil in frame tank falls below the level of the pump, so the supply pipe drains back and pump prime is lost.
Within the pump there is a check valve to prevent wet sumping, this is why the pump will not flow oil to automatically prime itself.

The good news is that you can avoid most of the above, by clamping the inlet hose before you change the oil. However the pressure checks are still essential after refilling.

Failing to ensure the pump is flowing oil before starting will result in a destroyed engine, the pump will not self prime no matter how long you run it and however many revs you give it.

Even with this protracted endeavour, I would personally favour the rotary pump over what I consider the barely adequate but easy to live with self priming original plunger pump, especially living in the city.

Others might disagree with me and prefer the plunger pump.

Regards
Peg.
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post #8 of 47 (permalink) Old 06-03-2019, 06:37 AM Thread Starter
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Wow. That is a pain! I hope in all the previous services they ensured the pump was primed.... She doesn't have any rattles or burn oil so I assume all is ok but there was a hand-written note in the manual about lack of oil pressure after fitting the Morgo.

I like the inlet clamp idea, I presume you mean the pipe that leads from the bottom of the frame tank? If I clamp that, drain the oil, refill, unclamp then with the ignition on but LT circuit disconnected, kick her over until the oil pressure light goes out, all will be ok?

I wonder if you can prime the Morgo by forcing oil up the intake pipe? I have a large syringe-type mechanic's pump I use for tricky fills, such as gearbox oil changes. This holds about 1L and I ciiod easily machine an adapter to hook it only the pipe....
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post #9 of 47 (permalink) Old 06-03-2019, 07:46 AM
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You said an 'uprated oil pump'.....we actually have no idea if it is a rotary pump or not??? Could be a Morgo plunger pump??

The rotary pumps are ideal if you are doing long hauls and frequent riding. They can be a PITA if you aren't.

And no you can't prime them from the hose line, they have a bleed screw you have to remove and then use the hole. They will not 'de-prime' if there is always a head of oil in the tank, they physically can't. It is as RPW said, you just need to clamp the hose when doing an oil change.

'The oil in frame tank falls below the level of the pump, so the supply pipe drains back and pump prime is lost.' This only happens when you are changing the oil.
An uprated Morgo pump doesn't need priming, once installed [and assuming an initial fill or kickover till it is] they will always self prime.

So its probably best if you find out which one you have before losing sleep, maybe documents supplied with the bike will tell you?

tridentt150v,
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post #10 of 47 (permalink) Old 06-03-2019, 04:51 PM Thread Starter
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Ok. So I pulled the RH carb from the bike and stripped it down. Here is a link to a picture of it:

https://www.amazon.co.uk/photos/shar...sC7zFkZU4G5K5G

Comparing this to the exploded view in my workshop manual has me a little confused so I have a few questions, if that's ok:

1. On the main body there is a blanking screw where my manual says there should be an idle jet.

2. On the main body, top centre above the intake, there is a hole where the manual shows there should be an air jet fitted of 1.5, 2.5 or 3.5mm. There is nothing fitted in this hole, so it is effectively 5mm diameter.

3. On the float bowl, I have removed the cold start jet (size 50). You can see this lying on the top, next to the deep passage it came from. At the back of the float bowl (centre, top) there is another jet (size 25) which is not shown in my manual at all. However, as it feeds up to a hole on the engine side of the slide in the main body, I am assuming this is the idle jet. Is this right?

Apart from the above; all of the jets and passageways appear to be clear. I have blasted through with carb cleaner and all seems well.

Any thoughts please?

Thanks,
Ian
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