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Amal threads and searches #762031
01/09/19 10:27 am
01/09/19 10:27 am
Joined: Jan 2017
Posts: 18
UK
R
richardvy Offline OP
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richardvy  Offline OP
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Posts: 18
UK
Hello all, just starting a new T150 850 t, all nice and new but not yet assembled.

So ....... thought I would search forums and notice boards to get the best consensus of advice on setup for a new set of Premiers I have. Oh dear, big mistake and after a few weeks all I have concluded is ...... I have just wasted a few weeks of my all to short life

Basic findings are

AMAL’s are rubbish go Japanese, Japanese are rubbish nothing wrong with AMAL, Premiers are brilliant Wassels rubbish, Wassels are good don’t pay for Premiers, don’t bother with new ones just buy slides and jets, never had chokes bike won’t start without chokes (seeing a patern yet) jets and slides well everything for 3 to 4 slides and same wide variation on jets, latest I have found is open up cross drill on needle jet to 1mm no that’s to big do 0.001 at a time and road test. And so it goes on, and on, and on ......

So my conclusions after all this scientific analysis
1. Take your bike to someone who knows what they are doing to tune carbs
2. Invest in range for jets and slides and go to dyno
3. Never ever open an AMAL post or search for AMAL on any forum and be prepared to spend time systematically working through carbs and road testing each change

Richard
ps, in the days before the internet I could go up the road to Kenilworth and ask messers Williams, Shermans or Jakeman what to do, all of whom were happy to help a T150 virgin. Ah simpler days eh

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Re: Amal threads and searches [Re: richardvy] #762032
01/09/19 10:44 am
01/09/19 10:44 am
Joined: Aug 2001
Posts: 7,726
scotland
triton thrasher Online content
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triton thrasher  Online Content
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Posts: 7,726
scotland
Follow the tuning procedure and address any problems you have, with the carburettors that you have bought.


Amateur Loctite enthusiast.
Re: Amal threads and searches [Re: richardvy] #762042
01/09/19 2:23 pm
01/09/19 2:23 pm
Joined: Oct 2018
Posts: 99
Vancouver, WA
K
Kara Chaffee Offline
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Kara Chaffee  Offline
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Posts: 99
Vancouver, WA
Hi Richard,
You must have been going over the responses to my learning curve regarding the tuning up of my T150V. I rode a T150V that ran well and it was fitted with new Premieres--so I know it can be done . I had a smattering of experience with Amals from my Norton , but the Trident is becoming a much deeper involvement. My bike runs about 90% ok , but the last 10% is where the learning curve really lurks. It starts well, idles well and accelerates well--but going along at a constant speed it is uneven and a little balky. I am starting to think this is what is called 8-stroking and is due to a rich condition. The next test is to buy a whole set of the leaner anodized slides for $150. Time to suck wind through one's teeth.

I will either end up an expert in tuning or totally frustrated. I will say I am totally proficient at pulling the carbs off the bike, swapping internal bits and putting it all back into place , even in the dark.
Sincerely,
Kara


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Re: Amal threads and searches [Re: richardvy] #762057
01/09/19 4:06 pm
01/09/19 4:06 pm
Joined: Dec 2013
Posts: 4,527
ohio, usa
kevin roberts Online content

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kevin roberts  Online Content

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ohio, usa
any decent carburetor will function decently if you take a bit of time with it and learn how it works, and there's scads of information around about how to figure them out, especially here. there's nothing magical about japanese carbs, and there's nothing magical about the british stuff. if they're worn out or mistakenly-modified nothing will ever work right.

i think the only carbs i wouldn't keep would be 1980's CV units, the really lean ones that manufacturers put on before they knew how to get decent emissions and drivability at the same time.

IMO the key to carb tuning on a newly-built machine is to first just make the bike run, no matter how badly. once you have it running, then just go through the steps to adjust each of the circuits until it runs as well as you can get to run. there's only three choices--lean, okay, and rich-- and once you get to where you can recognize those conditions you're home free.



every day you do not take a chance is a day of your life that you will never get back.
Re: Amal threads and searches [Re: richardvy] #762064
01/09/19 5:15 pm
01/09/19 5:15 pm
Joined: Aug 2001
Posts: 7,726
scotland
triton thrasher Online content
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triton thrasher  Online Content
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scotland
Kara
A lot of everyday steady running is done in the range of throttle opening where mixture is controlled by needle clip position.


Amateur Loctite enthusiast.
Re: Amal threads and searches [Re: richardvy] #762073
01/09/19 5:58 pm
01/09/19 5:58 pm
Joined: Apr 2005
Posts: 1,749
Mississauga, Ontario.
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Adam M. Online content
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Adam M.  Online Content
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Mississauga, Ontario.
Richard, you get all those confusing answers, because people answering your questions live in different parts of the world and what work on triple based in Arizona or California, doesn't work in your part of GB, or Kara's Vancouver.
Besides everybody has his own set of experiences with these bikes and different part makers.
If you are on TOL you should listen to what your own British experts say, mainly Phil Pick, Richard Darby ( darbs ), Stuart, Kilroy from N.Z. is also very knowledgeable triple guy.
Premiers are very good carbs, when everything went right the day they were in production in Burlen and you checked them for swarf inside and they are clean.
What size of Premiers did you buy ?

Re: Amal threads and searches [Re: richardvy] #762173
01/10/19 5:38 pm
01/10/19 5:38 pm
Joined: Mar 2005
Posts: 10,206
Boston, Massachusetts
J
John Healy Offline
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John Healy  Offline
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Posts: 10,206
Boston, Massachusetts
Tuning carburetors is not intuitive. Diagnosing fuel mixture problems without the aid of an exhaust gas analyzer is a learned art. Describing symptoms using common words is usually misleading. Understanding the fuel stages of a variable venturi carburetor is not well understood, and fuel stage charts are often misleading. Assuming the aftermarket, and even ones made by AMAL (the last time I checked they are human), parts you bought are on size are correct, when you are having a unique problem, can cause nothing but frustration.

IMHO there are no really bad carburetors, but there are a lot of "mechanics" and home mechanics who have not taken the time to learn the craft. It is a craft where you have to use ALL of your senses, from smell right down the list (or buy dyno and an exhaust gas analyzer). Learn what your senses are telling you. Then take the time to understand how the instrument works and what you have to do to make things right. With a variable venturi instrument, like Mikuni or AMAL, and haven't marked the throttle: 0, 1/4, 1/2, 3/4 and Full you are just winging it.

This all leads to people having opinions about a brand of carbs that are not based upon the carburetor in hand, but their ability to work with it. IMHO the most forgiving to tune is the AMAL Concentric.
The Mikuni is as easy, except people get buried in the Needle chart not understanding that it lists all of the needles for several Mikuni variations. It becomes much easier when you come to understand that out of the many listed only 4 or 5 apply to the model you are working with. This is similar to AMAL, but the use for each of the appropriate needles (there about 5) is described in their technical literature, and parts list. This way you won't spend a lot of time playing around with a 2 stroke needle, and get frustrated.

Someone commented on a post that my AMAL tech sheet in Vintage Bike Magazine.com was more than you will ever need to know. IMHO it is the least you will need to know to be successful. I learns something new almost every day.

http://vintagebikemagazine.com/technical-articles



Re: Amal threads and searches [Re: richardvy] #762209
01/11/19 12:21 am
01/11/19 12:21 am
Joined: Mar 2005
Posts: 10,206
Boston, Massachusetts
J
John Healy Offline
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John Healy  Offline
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Posts: 10,206
Boston, Massachusetts
Quote
but going along at a constant speed it is uneven and a little balky. I am starting to think this is what is called 8-stroking and is due to a rich condition


If what you are describing can be what is called "hunting."The carb is telling you it is lean.

It is a symptom where the bike will not hold a steady rpm with a fixed throttle position.

If you roll the throttle back (this makes the mixture richer) and the rpm steadies the carb is lean in the circuit that is responsible for supplying the fuel mixture at that throttle opening is lean.

What you mean when you say "balky" is when the engine will not take you opening the throttle. If you roll the throttle on fast it is apt to spit back through the carburetor. It is as if the plugs stopped firing for an instant.
------------------------
If what you mean when you say "balky" is when the engine runs and fires every power stroke, but is rough. It will also loose power. If it is very rich the engine will 8 stroke taking two power strokes to get in enough air to support combustion.

You need to experience 8 stroking to understand it as a symptom. Remove a main jet and take the bike for a ride. Above 1/2 - 2/3rds throttle the engine will continue to run, but be sluggish and loose power. At some point the bike will begin to fire every other power stroke. The exhaust will push out black smoke, the air will smell of unburnt hydro-carbons and the exhaust will turn from Brooom to Buh, Buh, Buh. If you roll the throttle back a bit it will get momentarily worse.


Re: Amal threads and searches [Re: richardvy] #762238
01/11/19 7:31 am
01/11/19 7:31 am
Joined: Oct 2008
Posts: 5,438
Crossville, TN
DavidP Online content

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In other words it will sound like a Harley, especially one with S&S carbs.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Amal threads and searches [Re: richardvy] #762257
01/11/19 2:33 pm
01/11/19 2:33 pm
Joined: Mar 2005
Posts: 10,206
Boston, Massachusetts
J
John Healy Offline
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John Healy  Offline
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Joined: Mar 2005
Posts: 10,206
Boston, Massachusetts
Actually, funny you mention Harley, David. The "roll back" technique of gaining more insight into fuel mixture is a common tool used in the Harley world. I hardly ever see the technique mentioned in tuning suggestions for British bikes. While Harley exhaust note is distinctive, they go Buh, Buh, Buh when they 8 stroke.


Re: Amal threads and searches [Re: richardvy] #762269
01/11/19 4:26 pm
01/11/19 4:26 pm
Joined: Jan 2004
Posts: 4,044
ca, us
D
DMadigan Online content
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DMadigan  Online Content
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ca, us
The Sudco Mikuni Carburetor, Parts and Tuning manual has charts showing the effect of the main jet, needle, needle jet, cutaway, pilot jet, altitude and temperature on tuning. The effects apply to AMAL carburetors also.

Re: Amal threads and searches [Re: John Healy] #762271
01/11/19 4:33 pm
01/11/19 4:33 pm
Joined: Dec 2013
Posts: 4,527
ohio, usa
kevin roberts Online content

DOPE
kevin roberts  Online Content

DOPE

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ohio, usa
Originally Posted by John Healy
Actually, funny you mention Harley, David. The "roll back" technique of gaining more insight into fuel mixture is a common tool used in the Harley world. I hardly ever see the technique mentioned in tuning suggestions for British bikes. While Harley exhaust note is distinctive, they go Buh, Buh, Buh when they 8 stroke.


mikuni talks about it in their manual for the HSR carb on harleys, but doesnt mention it in their other manuals. i use it all the time to see where i am.


every day you do not take a chance is a day of your life that you will never get back.
Re: Amal threads and searches [Re: richardvy] #762282
01/11/19 5:43 pm
01/11/19 5:43 pm
Joined: Mar 2005
Posts: 10,206
Boston, Massachusetts
J
John Healy Offline
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John Healy  Offline
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Posts: 10,206
Boston, Massachusetts
Quote
The effects apply to AMAL carburetors also.


While on the face of it this should make sense. They were both designed by the same people. But it doesn't.

While the Jet Needle (Their phraseology) in the Mikunit VM never leaves the needle jet orifice, with AMAL's the needle clears the needle jet orifice about 2/3rds throttle (depends upon the needle clip position). This means the needle is in play at wide open throttle with the Mikuni and the needle with the AMAL is out of play a around 2/3rds throttle. This can confuse people!!!

Also the chart on Bushman's site is the Mikuni showing the needle in play at wide open throttle.

You will find a more realistic chart for AMAL's at:

http://vintagebikemagazine.com/technical-articles


Re: Amal threads and searches [Re: richardvy] #762300
01/11/19 9:10 pm
01/11/19 9:10 pm
Joined: Apr 2005
Posts: 1,749
Mississauga, Ontario.
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Adam M. Online content
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From the picture there needle position has some influence of amount of fuel delivered to the carb just off idle.

Re: Amal threads and searches [Re: Adam M.] #762306
01/11/19 9:31 pm
01/11/19 9:31 pm
Joined: Oct 2018
Posts: 99
Vancouver, WA
K
Kara Chaffee Offline
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Kara Chaffee  Offline
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K

Joined: Oct 2018
Posts: 99
Vancouver, WA
Hi All,
I have been further testing the T150V and I notice that as I pull away in 1st gear-- the motor momentarily falters as I open the throttle (a momentary power drop) and then starts making power and goes fine. Note that I am calmly pulling away in 1st gear and not hammering the throttle. This cannot be an unknown symptom. Could this be the situation of the "too rich slide" as described by John Healy on the Princeton.edu web page ?? It seems like I have not been able to cure this via twisting the idle air screws. I am working with brand new 626 Premieres and #3-1/2 slides.
Sincerely,
Kara

Last edited by Kara Chaffee; 01/11/19 9:36 pm.

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Re: Amal threads and searches [Re: Adam M.] #762326
01/12/19 12:37 am
01/12/19 12:37 am
Joined: Mar 2005
Posts: 10,206
Boston, Massachusetts
J
John Healy Offline
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John Healy  Offline
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Posts: 10,206
Boston, Massachusetts
Quote
From the picture there needle position has some influence of amount of fuel delivered to the carb just off idle.


The straight part of the needle doesn't fully clear the needle jet's orifice until about 1/3rd throttle. Thus the needle's taper has little effect below 1/4 throttle. Of course when making this calculation one must consider which needle groove the clip is in. But even in the top groove the taper still doesn't have much effect below 1/4 throttle.

The effect that it does have below 1/3rd throttle is defined the delta area between the i.d. needle jet's orifice and the o.d. of the needle.

The straight part of the needle is .0985" (2.5mm) and the typical needle jet is .106" giving you the working delta, or doughnut, area. This delta area doesn't change until the taper starts to clear the needle jet orifice.

In the four stroke needle jet the flow is tempered while the straight part of the needle by a cross drilling just above the needle jet's orifice. The size of the cross drilling is .035" and it remains in play as long as the straight part of the needle remains in the jet orifice.

You must first understand that the carburetor will not work if the needle jet is smaller than .105". This is where the cross drilling comes in handy, especially if you are suffering reversion. Opening it a few thousandths will often get rid of that richness just below 1/4 throttle. The symptom is the carb comes off idle clean, then runs very rich. In extreme case fuel form a cloud outside the inlet of the carb. Often cleaning up as the needle's taper starts to take over. It will sound like broooom, bah, bah bah, and when it clears out it will broooom right up to full throttle (often referred to as megaphonitis).

Kara: To determine the correct slide you don't have to ride the motorcycle! Because it acts to aid in the transition from the idle carburetor to the main carburetor you only need to briskly open the throttle from idle while the bike is on the stand.

If the engine dies. No combustion. Instead of broooom. or bah, bah, bah it goes duh. The only noise is silence only to start up again as you let the throttle return to closed. Put in a lower number slide. The slide is too lean. If the transition is smooth and quick with an instant broom as the engine takes gas. The slide is good. If the transition has the engine STILL RUNNING, but lumpy (heavy sound) and not clearing out from the rough running until the throttle approaches 1/8 to 1/4 throttle. The slide is too rich. Put in a higher number slide. Often the richness can be seen in black smoke and noxious fumes coming from the exhaust, The bike smells rich. You can also sense the lumpy running by vibrations sensed through the bars and your butt.

A rick you can use easily on a single carb model is to remove the air cleaner and place the tip of your finger just in front of the slides cutaway. If the engine takes throttle better the slide is too lean. If it gets worse the slide is too rich. Two people can do this on a twin. A triple it is harder, especially where you have to remove the air cleaner. Turning the pilot air screw in and out will do the same thing, but the results for a turn in, or out from 1 1/2 turns is subtle. As a "rule of thumb" Bonneville - T120 - T140 models use a #3 slide. TR6 - TR7 and T150's use #3 1/2 slides. This with a bike set up without any changes from factory specifications.

Bikes with straight pipes like a leaner slide while bikes with megaphones like a richer slide to allow for the transition from idle to the main carburetor.


Re: Amal threads and searches [Re: John Healy] #762330
01/12/19 1:02 am
01/12/19 1:02 am
Joined: Oct 2018
Posts: 99
Vancouver, WA
K
Kara Chaffee Offline
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Kara Chaffee  Offline
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K

Joined: Oct 2018
Posts: 99
Vancouver, WA
Hi John,
Well I really notice the issue when starting off in 1st gear for example--the motor power dips momentarily as I open the throttle appropriately to the process of letting out the clutch. I am not giving it a lot of gas , just normally getting going in first. After the momentary lurch, the power gets going nicely. I don't notice it as much blipping the throttle whilst on the stand.
Overall it sounds like either I could use #4 slides , or open the cross drilling on the needle jets (3 on the T150V) by some small amount.
Does this make sense?
Sincerely,
Kara


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Re: Amal threads and searches [Re: richardvy] #762405
01/12/19 8:55 pm
01/12/19 8:55 pm
Joined: Dec 2013
Posts: 4,527
ohio, usa
kevin roberts Online content

DOPE
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DOPE

Joined: Dec 2013
Posts: 4,527
ohio, usa
AMAL

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mikuni

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every day you do not take a chance is a day of your life that you will never get back.

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