Carbs off bike - Total disassembly or not?

[Mikep328]

What is the general feeling about the level of disassembly that is typically needed for one of these carb sets? Should they be separated for cleaning?  TBH, I'm not really seeing a need to do so since most parts are accessible for removal/cleaning/adjusting but I have no experience with working on these 4-carb sets.   All four function properly - all airscrews affect the idle as they should and there are no leaks or any issues though I can already see that they need synchronization and the choke butterflies need to be better aligned.

Of course it is easier not to separate the carbs but I don't want to miss some obvious/well-known issue that separating the carbs takes care of. 

[Bryanj]

Only need to split them if fuel tees leak or im you need to ultrasonic the bodies

[Moorey]

   If you have them off it's worth splitting them just to change the seals to Viton.

[K2-K6]

 "All four function properly - all airscrews affect the idle as they should and there are no leaks or any issues though I can already see that they need synchronization"

It's this part that is so important on these to smooth stable idle and leading mixture up onto main jet needle taper. All the small holes have to scrupulously clean, and then some ! to get the fine atomiisation that gives even, cylinder by cylinder burn characteristic to keep parity in them and make them sound smooth.

Synchronisation of the main slides ultimately is for upper mixture air parity, with side effects of smooth running at lowered rpm. But real fine tuning AFTER that's done is the fine idle mixture adjustment with idle airscrews to micro trim that part of carb metering.  That is the icing on the smoothness cake, if all the other influences have been set according to correct routine.

[Mikep328]

Thanks!  I haven't started any work yet - waiting on carb cleaner to arrive - but one thing I see that I don't like is silicone sqeeze-out at the bowl/body joint.  So I expect the bowls will be a bit of a pain to remove since they will essentially be glued to the body.   Oh well, at least all screw heads are in very good shape so that's a decent sign that whoever worked on them wasn't too heavy-handed! 

In examining the carbs I'm seeing what appears to be a piece of very thin black tubing between each pair of carbs.  It doesn't seem to match the pics in the service manual which look like brass fittings with O-rings...   If it's tubing, what size?

[Laverda Dave]

That piece of tubing is correct. When you take the carbs apart you will find 1&2 and 3&4 are linked by a black plastic tube running between them. The tube has two o-rings on each end (so four in total on each tube). These push into to the carb bodies. Be very, very careful when pulling the carbs apart as these tubes are brittle and will snap if you try to twist the carbs apart. Try to pull them apart to prevent snapping the tube as they are hard to get hold of as they are not a spare part.
I think Nurse Julie sells the o-rings for these tubes in viton but check with her first. Do not be tempted to reuse the old o-rings as they will leak and it will be another strip down to replace them.
Another tip is to bench test the carb assembly for fuel leaks before you refit them to the cylinder head to ensure the float levels are correct.

[Mikep328]

THANKS!!!

Also...in this pic showing the bowls.  Is the orientation of the drain fittings correct?  It seems to me they should be reversed. In this view, carb one is on the right.  Shouldn't one/two drains be pointing to the right in this pic and 2 and 3 pointing to the left?

I pulled one float bowl - silicone, Oring, and some sort of red-orange sealant that is quite hard and difficult to scrape out of the groove. 

[Laverda Dave]

Yep, they appear to be fitted back to front. The large brass drain screw should be fitted to face outwards to enable a flat blade screwdriver to be used to open them. The bowls themselves only fit one way round so effectively no 4 bowl should actually be number 1 bowl.
For information, you will see the carb bodies are numbered on the flange. You will see the numbers 1, 2, 3, 4 cast on the flange with a feint circle cast around one on the numbers. This will tell you what carb number it is. They are hard to see when all the carbs are together but once apart are easy to see.

[Athame57]

I think Nurse Julie sells the o-rings for these tubes in viton but check with her first. Do not be tempted to reuse the old o-rings as they will leak and it will be another strip down to replace them.

Yes, she does, I just bought a set the other day. Thanks for the warning about the brittle tubes though. I'm soon to start renovating my own. I think I'll buy some Frost Ali Clean again for the bodies, it works wonders on unpolished ally. I'm not sure if that includes the wheel hubs, can anyone enlighten me?

[Athame57]

I pulled one float bowl - silicone, Oring, and some sort of red-orange sealant that is quite hard and difficult to scrape out of the groove. 

Someone has been too liberal with the Red Rubber Grease that one should put on rubber o-rings. https://www.redrubbergrease.com/

[Multiman]

I think Laverdaroo Dave us referring to the plastic fuel supply tubes when he talks about orings. There is also another thinner tube between each pair of carbs and it’s 2.5 mm id according to the parts book.

[Mikep328]

Yes, that's the tube!  Is it available as a part?  I haven't yet decided whether I'm going to separate the carbs but those little pieces of tubing would be a critical item!

[Nurse Julie]

Yes, that's the tube!  Is it available as a part?  I haven't yet decided whether I'm going to separate the carbs but those little pieces of tubing would be a critical item!

No, that part isn't available, I just used a thin piece of tube as a substitute.

[Deano400]

Mike, the small tubes you are asking about are vent tubes. If you look at the top of carbs 2 & 3 you'll see they each have a vent tube. The small tubes allow carbs 1 & 4 to vent through 2 & 3 and out of the two top vents.

[Deano400]

When I say top of the carbs it's just to distinguish between the vent and overflow tubes.