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...so do you say that refit the #20 again and see what happens with the screws all the way in?
Very possible that I needed to run with the screws less than 1 turn and that is too much in my opinion; all in the border of the lean condition. The engine performance was lack of power and die with the screws at 1 turn AND with 0.5mm more richer float level AND the 6DH2 that are richer than the 6F5.

-I just returned from those 70kms on the road. I checked the plugs at low RPMs in second gear and looked the same than the checking two days ago.
I am not sure enough if I need to change the P2 for the P4. At 120km/h in fifth gear felt similar to the last tests and before the test with the others jets.

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Originally Posted by reverb
...so do you say that refit the #20 again and see what happens with the screws all the way in?


In the name of testing, I'd try it but I can understand if you're reluctant. It sounds like the #20 pilots are too lean. Before I switched anything the first thing I'd try would be to leave the #25 pilots in there and make some air screw adjustments. Start at 1 turn out and keep unscrewing them while watching engine rpm. If it keeps rising and you go past 3 turns I'd say they are too rich and a 22.5 pilot might be better. If engine speed peaks and then starts to fall back off somewhere between 1 and 3 turns out on the air screw you've got a pilot jet that is sized right.

Originally Posted by reverb
-I just returned from those 70kms on the road. I checked the plugs at low RPMs in second gear and looked the same than the checking two days ago.
I am not sure enough if I need to change the P2 for the P4. At 120km/h in fifth gear felt similar to the last tests and before the test with the others jets.


Once the idle mixture is set we can figure out what needle jet might work best for the small throttle openings and figure out a needle for the larger openings. I worry more about the transient throttle response than I do about steady state mixture in those areas but a compromise may need to be made since those two items control the mixture in the throttle openings most commonly used during cruise.

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Your initial settings are exactly what I have on my A65. It runs well, bu the gas mileage is lower than when it had Amals on it.
With the 25 pilot jets my screws end up at 1.7 turns out for the best idle.
Sometimes in hot weather I fit #3 slides. It takes more time to warm up, but seems to pull better once it's up to temperature.
Never tried 6DH2 needle, but the 6DH7 worked well. I ended up with the 6F5 just trying to get the mileage to improve.
I don't know how dual-plug heads affect things, but a B6ES is a hot plug (same as Champion N5.) The standard for a normal T140 is two steps colder.


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...ok, I will try again.

Hi DavidP, the N5 are the ones that go in the T140E with MKII; This is a T140E with these MKII inspired carburetors.

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Hello, the engine RPM s barely rising unscrewing them but no good in acceleration. Screwing in is worst and wants to shut off. I screw in the slide screws but no good in this position.
Starts first kick always. Idling speed too high on all the stages of the air screws.
There is no way I can obtain lower idling speed; wants to shut off.
With the #25 the best set is the way I had them yesterday: at 1 1/2 turn. Good acceleration; of course idle too high and the sound is not totally right but ok; then when you put the gears; the sound is no good; like too rich.
I will order from USA (more and more money in these carbs) the 22.5 s

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It almost sounds like the pilot jets aren't doing anything if the response to air screw adjustment is minimal and you can't control the idle speed. Do we know that the throttle cables are adjusted correctly and that the slides close all the way? Is there an air leak? Perhaps the rubber balance tube that is installed between the intake ports is leaking or missing?

I wouldn't order anything quite yet.

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Have you inspected the rubber seals on the ends of the cold-start plungers? If those leak any adjustments are futile. I know that both the A65, with VM32's and my T120, with Mk2 Amals will die very soon after starting if the enrichment valves are left open. I would think that the same would happen if the seals leak.
Also, if you must keep the revs up to keep it running you're not really tuning the idle circuit. That's the reason the air screw has no effect.


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The cables look and feel ok. Yes, the throttles can close all if you do not use the side screws.
The rubber of the balance tube looks ok.
With the #25 I have too much fuel; is just that. May be I need to move the float arm the other way, to have a leaner condition; but I prefer to order the 22.5 to see. Those 2 jets plus shipping and taxes (if the customs do not stop the package in the main office at 250km from here; so more money to ride there and pick it up) and time waiting are something that is a pain in the arse but I do not see other solution yet.
I am thinking to spend big bucks and order 2 new AMAL MKII and just forget about these trash.

May be the valve seats are just worn? I cannot remove them (the spindles do not cooperate); Are the only jets that are not new but the operation seems correct.

-Tomorrow I will dismantle all again to put the #20 to disregard definitely the doubts.

Hi David, I am not keeping the revs up but that is where the idle decided to set; I mean, the throttles are at the minimum of air entry. Cables are free. The bike just idle too high between 1600-1900RPM or so. When you are riding (with the #25 because with the #20 did not go through gears; shuts off) you can go ok with the throttle grip just sound not so good and rich.

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Originally Posted by reverb
The cables look and feel ok. Yes, the throttles can close all if you do not use the side screws.


Are you using the screws to hold the slides open? Try backing them out until they no longer are touching the slide and have no effect. Start the bike again and see where (or if) it idles at then.

With a 1600-1900 rpm idle I doubt the pilot jet and air screw circuit are doing much. If the idle can be made lower by backing the screws out all the way, try the idle mixture adjustment procedure again.


Originally Posted by reverb
May be the valve seats are just worn? I cannot remove them (the spindles do not cooperate)


The needle valve and seat may be worn, but that usually just leads to the carburetor bowl overflowing and likely running rich. This was another reason I suggested using a sight tube to see where the fuel level actually was in the bowl.

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...well, you always use the screws (idle adjusters screws) to adjust the slides...
I will try in the morning (now is 1:30 AM)
Until the other day, before the changes, the bike could idle at lower RPM, but sounded wrong and very rich.

-Can the needle valve and seat be suspicious of the continuous rich condition?

Do not know exactly what s going on; you know, I had the #25 pilots and the P4 and almost the same float level; the air screws at about 1 3/4 or 1 7/8; the 6DH2 needles; the bike was idling better but too rich and the plugs sooty; now I have the #25 pilots the P2 and the 6F5; better plug color at idling, idling too high; slightly better low rpm sound; better "snap" and acceleration in the take off.

Thanks

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Originally Posted by reverb

I am thinking to spend big bucks and order 2 new AMAL MKII and just forget about these trash.

I was actually searching for a pair of them when I bought the VMs for my A65. The pair of Mikunis came at a cheap price, but I spent at least as much on jets to get them close to correct. I really cannot recommend them for anything but a single-carb head. I'm in the process of reverting to Amals on that bike.
That said, I found some Mk2s soon after I bought the T120. At 32mm, they're really a bit much for a 650. But, with euro jetting they're almost perfect. Never done any plug chops, but the pipes still look new after a year.


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Originally Posted by reverb
...well, you always use the screws (idle adjusters screws) to adjust the slides...


Why?

If the bike idles where it should, assuming no air leaks, with the screws backed all the way out, what’s the harm?

Every time I’d make a pilot jet or air screw adjustment to mine I’d back the screws out, make the adjustments, see where it idled, then set the idle screws as needed, then proceed with the next tuning adjustment or check. With the TMs my bike idles smoothly at 1000rpm with the screws barely cracking open the slides. If I left them all the way out it would idle rough at 750rpm or so.

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Originally Posted by DavidP
Originally Posted by reverb

I am thinking to spend big bucks and order 2 new AMAL MKII and just forget about these trash.

I was actually searching for a pair of them when I bought the VMs for my A65. The pair of Mikunis came at a cheap price, but I spent at least as much on jets to get them close to correct. I really cannot recommend them for anything but a single-carb head. I'm in the process of reverting to Amals on that bike.
That said, I found some Mk2s soon after I bought the T120. At 32mm, they're really a bit much for a 650. But, with euro jetting they're almost perfect. Never done any plug chops, but the pipes still look new after a year.


If you rode my T140D with flat slide Mikunis would have a different opinion....I spent $250 for two carbs, $75 on jetting, about 10 actual hours of tuning and some frustration. Tuning may not be for the feign of heart..But it is so worth it.The engine reponse is something only dreamed about with AMAL's....Just ask Mondster on this thread.....


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...TM Mikuni s seem better carburetors.
In jets, slides etc I am more than 200 Dollars and yet nothing (low salaries here are between 500-800 Dollars per month)
I am not lazy is that the dismantling in this bike is complicated and the rubbers do not like so much dismantle; also the carburetors are BOTH RH side so the fuel lines are complicated too plus no space for them so are in an awkward position plus the side covers that do not cooperate so plenty of removing and back again in place every time with a very care movements to not damage anything...cause there s no anything similar here to retrofit...
Regarding combinations or possibilities; well, there are a bunch but most of the users are not racers so needle jet, needle and slide are what is important; however, to run around town you need the pilot jet and air screw dialed (and the float level) but I think that this engine with the spitfire ex camshaft etc does not like the #20 jets and the #25 seem rich (due to the sound and riding at low speed) so possibly the P2 is not the way to go too; but as mentioned before, I do not know a relation or how to choose between different combos, like 6F5 in second notch, P2 and 2.5 slide or 6DH2 in third notch, P2 and 2.0 slide or 6DH2 in second notch, P4 and 2.5 slide. I understand that I should have the pilot jets dialed before but there s not too much to do; only change the jets and move the air screw in and out.
May be too that this engine cannot idle right; I remember P Russell commentary that with his tuning a 750 engine would idle higher and a bit rougher...
This engine does not has his tuning but as an example.

-if you ride with those screws all the way out how do it not fall down?

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Fernando, you need to walk away from the bike and problems for a week so you can refresh your mind....I've run into carburetor jetting problems on my T140D and Ducati 900, the more i worked on it, the worse it got...I walked away and did something else.. When I returned to the carburetor tuning it seemed better as if by magic...And with a few slight adjustments it was great...
And if you have not done it yet, convert the ignition to single plugs while you are tuning the problems.You have to be 100% that the ignition is not part of the problem....You should be able to do it with no extra money spent...


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In addition to taking a break, another thing to consider (if you aren’t already doing it) is doing some more riding. Sometimes the problems that you initially think you have are different than the problems you actually have and as you ride and analyze how the bike is running under various conditions things become more clear.

It might also be helpful to leave the side panels and air filters off temporarily while tuning. Configuration changes can be accomplished much quicker that way.

The TM May be a better carburetor than the VM but both of them and the MK2 tune the same way. Jumping ship on the VM might not net any progress, just another set of problems that need to be resolved.

With the parts you have for the VM I think you should at least be able to get things close. My suspicion is that there is one or more outside factors contributing to the frustration you’re experiencing.

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...hello,
the rain stopped, so I dismantled the stuff, fitted the #20 jets again, and DH2 needles. As the first time, do not work; too lean.
Removed again and put the #25 because I do not have the 22.5; let the DH2s so still rich in low RPMs and fat sound; better speed with the DH2.

Tony, I do not find here the ballast to do that test but the EI seems ok, however I want to buy the smartfire for dual plug head to have more spark at higher RPMs.
Do you know a place there to buy more jets but with a fair shipping cost? Also a place to buy the smartfire kit for these heads?

Thanks

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Do you really think dual fire plugs will really help at all ? I thought I had a carb problem for a week. Changed jet, adjusted and adjusted stuff , put different carb on it. Nothing. After all that crap it turned out to be timing. So sometimes you have start checking everything one thing st a time. I just don’t get the dual plug head. Unless your maybe running some crazy high HP racing bike i don’t see how it helps.

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...Mori, these mods came with the bike; are not mine and I am dealing with all these; but I tell ya that now has better everything regarding the no service that the bike had. However, I am riding on it; about 7000kms in a few months; not bad. If I only rode it around the block or so I never have been experiencing any problem at all, but now the bike that is not perfect, I mean, these mods; are feeling the kilometers.

I do not think that this could be the ignition timing due to always starts on first kick and have power and snap in the take off; just one pilot is too lean and this other is not right too.

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Have you checked the cold start plungers as David P suggested above? Maybe block them off to rule out any leaking there.

Last edited by Nick H; 07/25/19 11:46 pm.

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Hello, I have been only supervising its. I do not know exactly how to differentiate if its leaking (internally). Outside look good.
No doubt that this is a point to consider and I was consider it.
They work good for the starting and when you release its the sound of the engine changes automatically; that is a symptom that they are working and that is not a severe internal leaking; but can be possible to have a constant small internal leak; I do not know if dismantle its due the rubber washer etc; may be I do more hurt than what I have now.

Its raining all day here, mud everywhere to test the bike. The weather here is worst than in UK no doubt. And no doubt that the weather changed here due to no more rain forest.

Thanks

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Hi

I may have missed it on another thread, but did we get a resolution to this

















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Even at idle the slide and needle are lifted slightly, so the slide and needle and needle position actually do affect the idle mixture. I've found with my VM32s that changing the pilot jet had less of an effect on the idle mixture than the needle and needle position.

At the beginning of this thread, you (reverb) said that the plugs were sooty so you "raised the needles". I don't know if this was caught further down, but raising the needles RICHENS the mixture, so this is the wrong way to go if you're already too rich.

I haven't offered up exact jetting specs because I have an A65 rather than a T140.

Now I'll quote jimmy so as not to bury his reply:
Originally Posted by jimmymckenna
Hi

I may have missed it on another thread, but did we get a resolution to this


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Quote
Even at idle the slide and needle are lifted slightly, so the slide and needle and needle position actually do affect the idle mixture. I've found with my VM32s that changing the pilot jet had less of an effect on the idle mixture than the needle and needle position.


I read it on the internet it must be true.

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Originally Posted by John Healy
Quote
Even at idle the slide and needle are lifted slightly, so the slide and needle and needle position actually do affect the idle mixture. I've found with my VM32s that changing the pilot jet had less of an effect on the idle mixture than the needle and needle position.


I read it on the internet it must be true.


Do I detect a note of sarcasm John?


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