750 dual throttle cable conversion

I agree with Piet. The closer to the carbs you can get the split into 2 cables, the better the carb synchronisation will be and the less cable friction you'll have. If your cable splitter is causing problems, replace the splitter.

My Guzzi LM1 has dual throttle cables from twistgrip to carbs and it's a bit of a pain in the bum because it goes out of synch all the time. Even a change in air temperature will affect carb synch. I presume one cable or its outer sleeve has a different thermal expansion to the other.

My Ducati has a cable splitter and carb synch is much more reliable.

There was a rather complicated aftermarket conversion that you could buy for the Guzzi (from Guzbits I think) that used a transverse shaft to operate both carbs, like an in-line multi-cylinder bike. It's purpose was to eliminate the troublesome 2 cable system. I think they called it a "synch rod" or something similar. I haven't seen one for sale for ages, but a mate bought one back in the day. It mounts in bearings fixed to the frame above the carbs and has a bell crank in the middle that's connected to the throttle cable from the twistgrip. There's a lever arm at each end of the synch rod that lifts the carb slides via a very short cable. My mate never fitted it to his bike because it was too complicated. The complications arise because the carbs are individually rubber mounted rather than being rigidly connected together (I forget what the fix for that was). Also, the carbs are angled outwards (not parallel to the bike's centreline) and one carb is slightly forward of the other. Fitting a cross-shaft to a Laverda twin would probably be a simpler proposition.
 
I bought a Tomaselli dual throttle w appropriate cables and installed it, and the single cables now route directly to each carb without the cables hanging up w the splitter and jumping out of the splitter or carb body tops. BUT the throttle body housing doesn't have the same adjuster mechanism as the single cable, so there's not enough slack in the cables, and there's not enough free play in the cables as needed. It's got a spring loaded adjuster screw that doesn't do anything, so if anybody has experience w this, please chime in, or I'll go back to the horrible single cable and splitter.
 
You might have cables for a 30mm carbie, which would have shorter travel, so less free length. You could attempt to cut a little off the outer casing but that's definitely not easy without damaging the inner wire. The consensus is that you should really have persevered with your one-into-two - a NOS splitter surely would have worked fine. Properly set up they have none of the problems you've experienced with yours.
 
I got rid of that 2/1 splitter on my US spec SFC installing an original Magura throttle and twin cables. Never looked back.
Your nearly there Teddy. I buy Venhill make your own cable kits that will have every thing you need. Made a small solder pot to solder on the nipples. Ignore the distractors. Nothing wrong with twin cables.
 
Incidently, that faired Commando in front of the church will be doing an Australian trip next year.
That bike covers a lot of miles. Did 10 000 km through North America some years ago.
Paul
 
It looks very clean and tidy and original. Being picky, Concentric carbs instead of Monoblocks, but it's pretty bloody nice. Are you enjoying it?
 
Vince said:
It looks very clean and tidy and original. Being picky, Concentric carbs instead of Monoblocks, but it's pretty bloody nice. Are you enjoying it?
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Love it. That engine is fabulous.
Far from original.
Apart from the Concentrics, there's a Gosset electronic ignition, a Gosset electric starter and a Kubota alternator.
The bike hadn't run for a few years, so a few teething problems.
The starter freewheel functions when I'm about to have a stroke. I'm getting better at kicking it but haven't quite understood the amount of fuel it needs for starting, cold or hot.
The clutch took a while to shake the cobwebs out. It's a one finger clutch and the little finger at that.
Changing gear needs taking your time. But you don't need to change gear much once on the way.
It's low and reasonably light. Makes even a 750 Laverda feel like a lorry.

I spent a month getting it ready to run.
It's back on the bench getting that starter freewheel sorted and checking gear selection. I'm putting an aftermarket centre stand on it. That rear stand necessitates hazardous manoeuvres. Carburation needs tweaking.

Compared to Laverda, getting spares is easier than with last years Honda. The Laverda clubs really missed the boat by not getting a spares scheme together and they're all dying oblivious to their fate.

The VOC Spares Co Ltd

vincentspares.co.uk vincentspares.co.uk

Paul
 
Vince said:
It looks very clean and tidy and original. Being picky, Concentric carbs instead of Monoblocks, but it's pretty bloody nice. Are you enjoying it?
Click to expand...
I think Vincent had already folded by the time Monoblocs hit the market. Always seperate float bowls imho, Amal TT, GP, 276 and the like.

Seems the PO dreaded grubby bikes, I see a chainguard extension and breathers routed to the rear. Guess the jambe electrique is a great help. ;)
Were is it located Paul?

piet
 
sfcpiet said:
I think Vincent had already folded by the time Monoblocs hit the market. Always seperate float bowls imho, Amal TT, GP, 276 and the like.

Seems the PO dreaded grubby bikes, I see a chainguard extension and breathers routed to the rear. Guess the jambe electrique is a great help. ;)
Were is it located Paul?

piet
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Yep, Vincents never used Concentrics but 2786s. They folded in 1955.
On the right hand side of the bike, you'll see a bulge underneath, vertical from the rider footrest. That's the end of the starter motor which is located under the gearbox. The freewheel is behind the gear box cover which is coming off tomorrow. It's a strange system which drives the engine via the mainshaft, the clutch and the primary drive.
The Alton system on the other hand works directly on the crank or the primary drive, I forget, but needs extensive, and expensive mods on the primary side.
Paul
 
I see it now, thanks. Guess you'll need to be carefull rolling over a curb.

Wondering for how long I can kick the Matchless to life, electric legs for them are quite complicated and expensive.

I'd fit a single throttle cable with splitter to the Vinnie, if only to tidy things up a bit. I've neen told these were actually a Vincent factory option at some stage... single pull;
DSCN1844.JPG


piet
 
sfcpiet said:
I see it now, thanks. Guess you'll need to be carefull rolling over a curb.

Wondering for how long I can kick the Matchless to life, electric legs for them are quite complicated and expensive.

I'd fit a single throttle cable with splitter to the Vinnie, if only to tidy things up a bit. I've neen told these were actually a Vincent factory option at some stage... single pull;
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piet
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Twin throttle cables with adjusters make synchro easy. :)
Throw those cross head screws out.
Paul
 
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