B44 Old girl starts, needs lots of tickling to warm up then go's well!

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csx355
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B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by csx355 »

Hi all - I know it sounds like one of those dodgy ads in the personal columns, not that any of us read them!
My rebuilt B44 is running an Electrex World STK-100D ignition and lighting kit timed to 28' BTDC and is fitted with a brand new Amal Mk1 930/1 concentric bought from Amal and set to their standard specs for a Victor Special. The bike generally starts 2nd, 3rd or 4th kick providing I follow the procedure.

Free the clutch -
Tickle till flooded -
Turn over to compression -
Nudge past TDC on the de-compressor till the resistance is felt -
Kick it with throttle closed and catch it with 1/4 throttle as it fires.

Occasionally she will kick back at me for which I am contemplating retarding the ignition another half a degree, but generally off she go's. However keeping the bike running to warm up just on the throttle is almost impossible. When the bike is warm she pulls like a train right through the rev range (as far as I feel comfortable taking her) and ticks over at low revs with no issue. However the only way to keep the bike running from start is to continually tickle the carb. So she starts, runs on the fuel in the bowl, begins to die, tickle and the revs pick up, not excessively, runs revs begin to drop tickle and repeat. Once warm everything is fine.

I have thought that maybe the pilot jet is too small - and also the the fuel tap might not be delivering enough fuel. It's not a major issue but seems unusual and I would welcome any thoughts on it.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by kommando »

Fit a choke, also extended throttle stop screw which you can turn on 1 turn on cold starts and then unscrew with gloved hand.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by madsundaysurvivor »

Hello csx,
Try these things:
-make a strobe timing, in my ignition hpi, the marks don't mach with the spark moment.
-with the engine running and hot, and the idle screw a little high, open the mixture screew until two or three turns, then begin to screw up it, until the bike begins to speed up. Then open it 1/4 turn
All this assuming that the valve seats and piston rings are ok. :roll:
Another time I don't know if I explainedmyself well
Good luck,
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by BSA_WM20 »

Have you checked the fuel level in the float bowl ?
London to a brick & on you will find it a touch low.
And yes I know you said the carb was new but that is no reason to assume that the float is set right.

Decades ago I fitted a nipple to a drain plug and use that to check the float heights.
They ware almost never correct in the old days.
Don't know about the new ones as I have only fitted one & it was spot on.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by madsundaysurvivor »

I'm sorry csx,
My instructions are for a dellorto, I amal carbrettors it's the opposite, when you unscrew it the mixture is poor and when you screw it enriches. But the system to tune is the same.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by csx355 »

Hi guys - many thanks for the pointers - I rang and spoke with Amal today and they felt that a choke slide was a good move so that's ordered and en-route, and will be my first port of call. Thanks Kommando

Mad Sunday - my intention is to ultimately have a play with the ignition to reduce the incidence of the bike kicking back. My current thoughts are though that as the bike is running clean and well once warmed up that I would address the cold start issue first.

M20 - Many thanks I had considered adjusting the float level and changing the fuel tap for one with more flow, however as the bike runs so well at full gas I thought that the level and fuel flow must be correct, or at least pretty close. There has to be so much more fuel going through the system at WOT than at tickover. I did wander though if the pilot jet was drawing from higher in the float bowl but have not checked that out yet.

I am going to do the choke first as that is least intrusive on that rest of the system and then go to the fuel level should that not work. I should have said at the start that the bike is fairly stripped back and basic and running a K&N conical air filter so could be a tad lean over a stock system with a paper filter in an air box.
b44.jpg
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by ampshire-og »

Just because you have a "new" carb I would not rule out a fuel problem! I would check float height first. Also don't rely on timing marks on an electrex world ignition. I would retard the ignition as you mention to help with kick back.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by eebtr7 »

Back when Christ was a PFC and ol' Hector was a pup, the given advice at Pierce Bros BSA Shop in San Antonio was to open the mixture screw on the Amal Concentric 1 1/2 turns from the seated position. I religiously adhered to this sacred mantra for many years with the engine stalling at traffic lights unless the idle speed screw was opened at least 3 1/2 turns from the seated position.

A few years ago I became a heretic to find when the mixture screw is opened from the seated position 3/4 of a turn, and backed off further on the idle speed screw, the engine !!!WILL!!! sit there chugging away contentedly at a far slower idle. Indeed, with the idle speed screw backed off, the slide is now closed and the carburetor is operating properly on its idle circuit.

A mixture screw opened 1 1/2 turns provides a too lean mixture for the engine to idle unless the slide is lifted so it operates from the needle jet, which is too fast an idle. We all see this on most every YouTube video. The engine speed, once started, is way too fast. So, please try this setting on your next start up.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by csx355 »

Thanks eeb - that's another nice and easy option to test out and it makes sense as it relates specifically to enriching the pilot system. The symptoms are of it being too lean at idle and not responding well to the throttle. How did you come by this? As you say it is contrary to most of the tuning tips out there.

I will try it tonight. Because the carb is essentially 'just so many separate systems' I am reluctant to change too much as the bike is going so well once warm / off the pilot circuit. From experience it's easy for me to add 2+2 and make 5 and end up changing / swapping stuff that wasn't the issue.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by kommando »

Back when Christ was a PFC and ol' Hector was a pup, the given advice at Pierce Bros BSA Shop in San Antonio was to open the mixture screw on the Amal Concentric 1 1/2 turns from the seated position.
The 1.5 turns is just a starting point, you then tune using the mixture screw when the engine is fully warmed up but if the best running is less than 1 or more than 2 turns out then either the pilot circuit is in need of a clean or the pilot jet size is wrong.

When you start the bike from cold the carb is not tuned for cold starts so needs enriching by tickling or/and using the choke plus a slightly opened throttle, all carbs work this way and cold running is never ideal. ECU controlled fuel injection has hidden this truth and made people think their carbed engines should run well cold or hot. They do not, and they must be tuned for the warm engine and leave the cold to be a pain mitigated by an enrichened mixture and a higher idle speed using the extended throttle stop screw.

If you want a 100% reliable cold idle fit fuel injection.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by BSA_WM20 »

At idle all of the fuel passes through the primary circuit, not the main jet
Thus you can be lean at idle & rich at WFO
This is exactly the problem that occurs when the pilot circuit is blocked
Float height affect the pilot far more than the main because there is a very tiny amount of suction ( ok signal fr the carb wonks ) to lift the fuel so a mm or less can make a drastic difference
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by eebtr7 »

Here I go again, relying on the printed words in foreign publications from decades ago. In this case, the owners manual from BSA, publication 00-4139, for Models B44 and Models B25. Also, from the BSA Workshop Manual for the Models 1966, 1967 and 1968, revised edition. I can already hear the boulders of damnation being rolled off the peaks toward my lil' ol' pumpkin head.

Believe it or not, the Amal Concentric carburetor does, in fact, have an idle circuit. It functions when the slide is up to 1/8's open and is fed by the pilot jet. Note; the pilot jet can be either the actual brass screw-in jet or the tiny orifice in the mixture screw hole. Screwing in the mixture screw results in a richer mixture, while screwing out the screw results in the leaner mixture. The idle mixture screw only regulates the incoming air, not fuel.

I now quote from the BSA Owners manual, page 34-35.

"PILOT JET ADJUSTMENT
Screwing in the pilot air screw restricts the air supply, thus giving a richer mixture, and unscrewing it weakens the mixture. The best way to adjust is to screw in the pilot air screw until the mixture is obviously too rich and the engine starts to run irregularly, then unscrew the adjuster until the engine runs evenly. When the proper adjustment has been determined, the engine may be running too fast and in this case the throttle stop should be unscrewed until a steady and even tick-over is achieved.If considerable alteration to the throttle stop has been made, the pilot air screw should be re-adjusted. Both throttle stop and pilot air screw are fitted with "O" rings to retain the adjustment by friction. Do not attempt to obtain an excessively slow tick-over as it will probably become unreliable under different atmospheric conditions."

There it is, the holy words. As I have previously complained, every unit single engine I have ever seen was idling too fast because the idle mixture was set too lean as the owner/operator/dealer mechanic set it at 1-1/2 turns out, then screwed in the idle speed screw to lift the slide above 1/8 open into the area where the needle jet was now feeding gas into the mixture. Just to keep the engine running. This results in a hard to start engine; being too lean at cranking or flooded by the overly intense tickler manipulation, or a combination of the two.

Here is my hot OR cold starting drill. First kick is to free the clutch plates. Second kick is with the compression release pulled to draw combustible vapors into the cylinder. Third kick ignites the mixture to set the engine in motion. After the engine has fired about 6 or 7 times, the throttle is gently opened to accelerate the engine into full idle. The tickler is NOT used. Granted this successful start-up drill has only been used during the Godawful South Texas summer with high dew points and high temperatures. It has yet to cool down to a bearable outside climate. When morning temperatures finally start off in the lower forties, I will readvise on the need for the tickler.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by catseyes »

Just wondering if the choke kit sorted out the starting problem?
Any updates available?
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by csx355 »

Hi Cat - so a quick update - I started with the timing and carb settings as the choke kit took a couple of days to arrive. When I initially timed the bike I set my TDC and used the Electrex markings to set the advance at 28' BTDC. And that's where it's been ever since. She has always started, I have always used the decompressor but I have suffered the odd kick back which can be . . . interesting!!

Anyway foot peg, brake lever and casing off and a recheck showed that the actual timing was closer to 29' BTDC which I am going to put down to a combination of Milky old eyes, a too dark garage, working on my knees and a touch of paralax error.

So working on the principle of more is more and such like I retarded the timing a degree or two :roll: With the casing off and following my usual start procedure she started first kick and ran well with me again having to tickle the carb but no throttle.

Next bit was easy - as was suggested I screwed the mixture in and then too it out one turn to start. The throttle stop was screwed all the way in until the cable had slack.

Result - easy start and a tick over that was strong and tickle free but had to be controlled on the throttle to be maintained in order to prevent it front stalling.

Next the choke kit turns up and I fitted that. I have to admit that I am still honing my cable soldering skills and I didn't have the correct nipples for the job but wading on I fitted the kit and I'm not sure that I can honestly tell any difference in the running with the lever open or closed!! Which suggests to me that I have probably messed up the soldering and my motor has gobbled up and spat out my soldered nipple. Which I'm sure is of little consequence to a beast that sounds like it could suck old folk off the pavement in town. (that sounds wrong on so many levels).

Anyway out on the road and the bike starts easy and when warm ticks over strongly. There is a little fluffiness at WOT so I might need to advance the ignition a tad but as I tend to short shift the bike and ride the mid range it is not an immediate issue. There is no doubt that the tuning and running characteristics are totally different on starting from cold and when run and I need to keep that in mind as it's easy to chase smoke.

So all is good - I thank that everyone who responded to my post as it sent me in the right direction and I now have the correct nipples to correct the choke and I reckon everything is hunky dory until the next event.

Little video of her on a run out after the adjustments.

[youtube]https://youtu.be/BX_kcbOGDrA[/youtube]

These bikes so own me!!
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by kommando »

The Amal choke works oddly in comparison to the one you see on most carbs as its hidden inside the slide, so it only comes into play when starting if it reaches full travel and hits the carb body and can go no further. When you are doing 100mph with the throttle wide open then you can drop it so it just appears in the venturi and it will start having an effect, good for seeing if the main jet is sized correctly.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by csx355 »

kommando wrote: Thu Oct 17, 2019 5:57 pm When you are doing 100mph with the throttle wide open
I love where you are coming from with this but have you seen the size of my rear sprocket??

Ref the Amal choke working oddly - you're not wrong on that, I know that this sounds a bit naive but, is the carb 'choked' with the lever pulling the slide up or is the choke operating in the 'natural' state with the slide down. Because I can't tell the difference in running either way. As I said it is possible that I might have b*ggered up the soldering on the slide end cable nipple which I meant to check yesterday but it feels like it's all happening at the lever.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by minetymenace »

csx355 wrote:I love where you are coming from with this but have you seen the size of my rear sprocket??
LMFAO :laugh :laugh
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by kommando »

I know that this sounds a bit naive but, is the carb 'choked' with the lever pulling the slide up or is the choke operating in the 'natural' state with the slide down.
When the cable goes slack the choke slide is down fully and the choke is on.

If the cable never goes slack the inner cable is not long enough.
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Re: B44 Old girl starts, needs lots of tickling to warm up then go's well!

Post by FGF »

Hello CSX355 ,

i 'm looking for an electronic ignition with lighting to replace my wassel vape on a B50SS.
This one seem to be tired, problems to start.

i'd like to fit one on the crankshaft and not the camshaft.

are you satisfied with the STK 100 D ?
''Kommando'' send me a post where a commando cafe racer rider was very angry about Electrex stk 100D...

may be the B50 or B44 fitting is better ?
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