BSA A65 Lighting

[terryk]

My mate has just bought a BSA A65 650cc Lighting

Does anyone have any tips on the carby adjustments 2 x AMAL carby with tickliers.

Can't get the idle right & the mixture screw does not appear to make any difference....bitch to start & won't idle.

Cheers in advance Terry

[davidc]

My experience with those Amals is this:

Warm up motor, then shut down.
Thread in a/f adjusters all the way, then back out a few turns.
Disconnect spark plug wire from one side - the side not being adjusted. [Check to see the condition of the little rubber O rings on the screw, if hammered, all else is a waste of time]
Start machine and adjust the a/f screw until you get the smoothest running possible [good idea to note number of turns for the whole operation].
Then, do the same for the other side.
The Amals on my 1972 were pretty hammered, to the point I could not get a good, smooth operation. I wound up buying new Amals and my problems, along with $200, were gone.
Looked into re-sleeving, but that was nearly the cost of new carburettors.

[BluesRider]

If you disconnect the coil like Dave said,figure out some way to ground the plug lead on the head.Although it doesn't mention this in any of the manuals I've seen,it can burn out your coils to let them try to spark with no outlet.

How about the battery? Make sure the battery is fully charged,and in good condition.If you're not running a battery,just capacitor,then hook a battery into the circuit.it makes the bike a lot easier to start.If nothing else,replace the capacitor with a new one,because those things do go bad just from sitting

On to the carbs........

You don't say what year the Beezer is.The earlier models,I think thru 1967(Don't quote me!) used Amal Monoblocks,the later ones used Amal Mark 1 carbs,what have become known as Concentrics.I don't have a lot of experience with repairing the Monoblock.I've had two bikes with Monoblocks,and never had trouble with them.I've also found that most older bikes have been retro-fitted with Concentrics,because they cost about half as much as Monoblocks,and offer better all out performance,although they wear out faster,and don't meter fuel as well at lower RPM.

So,I'm limiting this to Concentrics,since I don't know squat about Monoblocks. Tuning would be the same,but repair,no doubt,much different.

There are basically three issues with the Concentric,all can be remedied,or circumvented. The biggie is that the slide,and the carb body are made out of similar metal.That causes galling of the slide in it's bore,eventually wearing the bore to the point that the slide allows air to flow around it,in effect causing a vacuum leak,and making the bike run too lean.

At the same time the slide is rattling around in it's bore,it's making the needle rattle around in it's jet,wearing it oblong,and richening the mixture.

Unfortunately,this rich/lean thing never seem to coincide,balancing each other out.That would be too simple.It's usually too lean at low throttle openings,then too rich in the middle,but not always.

There are a few ways to fix this.If the carbs are new,get chrome slides.They wont gall in the bores the way the pot metal ones do.

If the galling has already started,you can get the bores sleeved.There are several companies that do this.Or,the bodies can be bored out,and an oversize chrome plated brass slide,from a Mikuni,can be installed. AMR,in Tucson,AZ does this.

Another problem is in the idle circuit.Two things.One,the carb body is very soft,and the threads on the air bleed screw are very fine.It's really easy to cross thread,or strip them out. If you have the screws out,make sure the threads are clean,and be very careful to start them straight.A little dab of anti-sieze is a good idea too.And obviously,don't tighten them too hard against their seat.Just til you feel them bottom. If they do get stripped,they can be heli-coiled.

(This next bit sounds like it pertains to your carbs,since the air screws do nothing)

The other thing is the tiny hole that feeds fuel from the float bowl to
the pilot well.Corrosion,or fuel additive residue can plug it up.It's on the opposite side of the carb from the air screw.You can usually take the air screw out,and stick a stiff,thin wire(Like the high E string on a guitar)through there,and clean it out.If not,then the little bung plug has to come out,and be epoxied back in.

Like I said,the bodies on these carbs is soft,and care must be taken whenever tightening screws. This includes the flange nuts.If yours uses o-rings,make sure you have the right size o-rings,and that they are seated in their grooves properly.It's very easy to warp the carbs if you try to tighten them down on an out of groove or oversize o-ring.

Good luck.Keep us posted.

[davidc]

Yeah, I was going to tell all that Blues did....but I had a casserole in the oven and had to watch the time. ;D

[Midnight]

Bruces advice is spot on especially cleaning the pilot holes unless there clean you have big problems .
your float levels are important as well in concentrics.
also check both slides are opening at exactly the same level.
mixture usually about 1/12 turns out is a good start.
vitron tipped needles are a good idea especially the alloy bodied ones,

[terryk]

Thanks guys