Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board Mikuni back to Amal for my A65?

There's a video ( probably a lot of them) on you tube of a lawnmower type engine's carb.........with a see through bowl. Yes sir it's crazy in there with it running.

Not that a BSA unit single vibrates but I'm betting it's pretty much the same thing going on in there.

Does a 3D printer have the ability to do something clear?

Andover Norton makes this fuel level test bit ,
13.1688
last time I checked it was 9 £ in the UK ... shipping ? who knows .
... and someone on this side of the pond was selling them for about $24

There is clear 3D printer filament but it is PLA which is based on cornstarch. Might not be something that will last long in fuel. Unless the exact shape of the bowl is needed it could be made by gluing a plate for the top and bottom, a block for the needle and a section of a cylinder for the bowl. It would not require polishing to make it clear enough to see through.
I guess if I add a nylon seal washer instead of reusing the one off the drain (McMaster $0.20), added a piece of plastic hose ($0.55/ft), a clamp ($0.16), expensive packaging ($5?) and have the shop churn them out I could get the price up to $10. Of course it would have to have the CA Prop. 65 reproductive harm warning on it. That might add a few more dollars.

We used to go to a plumbing & gas fitting shop & just buy a nipple that was small enough to fit inside the old plastic drain plugs And do the same thing .
Usually with one that had been buggered from overtightening with a pair of multigrips

So the conversion is complete, at least for now. I'll explain: After raising the jet needles to the center notch, I can get it to idle. Every so often, after it idles for a while, like 20 seconds, it just all of a sudden quits - or tries to, but I can save it by blipping the throttle. Spark plug porcelains and electrodes are medium-gray after normal riding. There may still be a fuel level problem, and I may have to make one of those "dynamic" fuel level gauges, BUT...

I've experienced more vibration and engine noise since last winter's hone-and-ring job, and this is with no other changes. Piston clearance was .006-.0065" after honing, and I think I should have bit the bullet and gone for a bore job. It kicks over easily, and a cold compression check shows 110 psi on the right and 90 on the left.

So I think I should address the engine problems before messing around with the carbs any more.

If you have just done rings the forget about the carbs till the rings have bedded in properly .
So go do some long rides then cpome back & sort out the carb.

Oh yes, after the ring job, I ran it all summer with the Mikunis on, including a couple of 100-mile rides. I was running the Mik VM32s before and after the ring job (actually for twenty years!). The vibration and engine noise (not full-blown piston slap, but a kind of "shukka shukka", worse when cold) worsened after the ring job, idle was not crisp, and it kicked over a bit too easily IMO, so I did a compression check, and it is not up to par, as I wrote above.

So you're right on about forgetting about the carbs for now, but for the purpose of overhauling the engine. I may even have to address the lower engine this time. On the last rebuild, my engine man, who put the lower together, said the main bush was "ok", which could mean it was on the high side of acceptable clearance.

(BTW, the mechanic/machinist who did my last three A65 lower end rebuilds passed away in 2019, so I will be on the hunt for someone within reasonable driving distance who can rebuild an A65 lower.)

Those compression figures show the rings have not bedded in.
Take it out and give it a thrashing not a 3000rpm ride.
5 or 6 thou piston clearance will not make for those numbers, it's
the rings that aren't sealing.

+1 with Nick--- the bike needs an Italian decoke.
Dont be afraid of using your right hand!

Use your left hand.
It'll feel like someone else is driving it.

Don't lower the tone.....,Huge.

What about all this talk, dissertations by John H., etc., that the major part of break-in with these engines occurs within the first few minutes of riding under load? True, I don't ride at 5000 rpm, but I've ridden the bike all summer, logging at least 500 miles.

But if you say ride it more and harder, I will; I really don't want to tear it down unnecessarily. But winter is coming on here, so it will have to wait until next spring.

That only works if you do what he says in the dissertations.

You mean, coarse hone, dry assembly, high-ZDDP break in oil, put a load on it right away, change oil and re-torque head after first few heat cycles?

Yeah I did all of that.

Did you take it to 6 thousand revs on second and third during first 100 km of riding ( only for a moment ) ? If not you can still do it, specially during a colder day after warming up the engine properly.. Perhaps this will save you another tear down.

just a suggestion ..........
I have used the Yamaha (Yamalube) Combustion Chamber Cleaner many times on glazed up, stuck ring, carboned, motors, especially outboards. It seems to work wonders. Could it be an idea to use it in your motor to "go back to square one" then try to re bed in the rings?

Of course, you might just have oval bores, especially low down, it can be missed even after honing (please don't ask me how I know!)

I don't have a tachometer, but I'll do the best I can.
I guess you spray that into the carbs?
Per my measurements and the machinist's, they were not oval BEFORE honing, but I didn't re-measure afterward.

Yep, spray into carbs with motor running, then stall the motor with it and let it soak.

I don't usually go for these "miracles in a bottle" but this stuff is from a major manufacturer and it seems to do good!!

Tip, do it outdoors, it makes copious amounts of noxious fumes (again, don't ask me how I know!)