Carb insulator removal

piranha-bro2 said:
If you go Red's route (simplest and least expensive) make sure the alu inlet manifold seals completely against the mating surface of the head. The insulator you remove has an o-ring on each side that does this.

mikunioz.com in Australia have a stack of suitable manifolds that I'm guessing the Guzzi style male spigot carbswould fit straight into - and they seal against the head.

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That’s a good site thanks, might prove useful once I’ve established best way to sort this out.
Sean
 
No Laverda production twins were fitted with the rubber-mount type carbs. Triples only. They can be found on the 125/175cc 2-strokes though.

These PHF36 carbs are found mainly on M-G V-twins, oftenn ditched in favour of PHM40s The smaller de Tomaso-era M-G inline 4s had tiny VHBs on rubber connectors, same as the Benellis. IIrc, Ducati bevels all had the clamp type, rubber-band models had the rubber connector.

The rubber tube isolates the carb from vibes as well as heat.

piet
 
Thanks Piet,
That leads me to think the rubber mount is actually beneficial, if I can get them in there. And I guess Laverda must have thought that in order to switch to rubber on the triples.
Sean
 
smlav said:
Thanks Piet,
That leads me to think the rubber mount is actually beneficial, if I can get them in there. And I guess Laverda must have thought that in order to switch to rubber on the triples.
Sean
Click to expand...
The old type were discontinued by Dellorto, the factory had no choice. The rubber mount was almost in universal use by then.

Yes, the rubber connector is mostly beneficiary, but it also opened up problems that needed to be dealt with in the production of the triples. For instance, the bridge between the carbs needed to be considerably stiffer than previously, otherwise carb synchronisation would be compromised with the carbs throbbing back and forth, each fighting against the others. This can be best observed on the 120° triples with their OE type stubs, which are softer still than the connectors on the 180° engines.

No such thing as free lunch...

piet
 
smlav said:
Especially if lunch is a first course of too much air followed by second course of piston a La hole.

So if I go the Mikuni route, which ones are recommended?

Cheers
Sean
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Have made a number of these Mikuni RS 36mm Flatslides, to fit 750 engines and have them in stock
But choke position is an issue and they are not cheap
you would be better off looking for a set of Mikuni Vac carbs if not staying with the Dells
Personally I would stay with the Dells

8th March rear brake set up
 
Laverda 500 Harris with inlet manifolds from a triple, rubber mounts and 40 mm dellorto’s.
 

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so its not a GTL its a GTL with an SF1,2,or3 engine, we needed to know that in the begining, but you wer'nt listening to me where you Sean?, I told you the carbs were incorrect (as stock) and that the 750's never had rubber inlets, and that the mounting of PHF's has two options, the correct ones are pictured in post #8 and then you listened to all the others!!!!!!! the PHF's that you are seeking (solid clamp type) are VERY VERY thin on the ground, I told you that and why as well (again not listening) since you dont seem to want power, get a set of VHB30's as fitted to earlier 750's and Roberts your father brother.Much easier to obtain, but all used parts are dear these days.
CLEM
 
CLEMTOG said:
so its not a GTL its a GTL with an SF1,2,or3 engine, we needed to know that in the begining, but you wer'nt listening to me where you Sean?, I told you the carbs were incorrect (as stock) and that the 750's never had rubber inlets, and that the mounting of PHF's has two options, the correct ones are pictured in post #8 and then you listened to all the others!!!!!!! the PHF's that you are seeking (solid clamp type) are VERY VERY thin on the ground, I told you that and why as well (again not listening) since you dont seem to want power, get a set of VHB30's as fitted to earlier 750's and Roberts your father brother.Much easier to obtain, but all used parts are dear these days.
CLEM
Click to expand...
Sorry Clem, I thought I’d been clear it’s a GTL fitted with SF1 motor. I had thought my issues were wholly due to getting 36’s into GTL brackets and frame. I hadn’t appreciated the different methods of mounting standard 36’s and the 36’s I have which came from a Guzzi. I thank you for starting my learning curve on that by pointing out that standard is clamp, where the 36’s I have are rubber connected. After the many knowledgeable contributions to this thread, including yours, I feel much better informed. I do have the original GTL VHB’s, and when the GTL motor has been rebuilt by Keith Nairn they may end up back on the bike, I’ll take his advice on that.

My ideal is a sorted GTL power delivery, low and mid range torque. I’d prefer a V motor, but given that I bought this lump almost 50 years ago there’s an element of emotional attachment to it.

Sean
 
no worries Sean, you do at least have the VHB's available, but on the ILOC website their is a "for sale" item that may be of interest to you

750SF2 - Carburettors (pair) 36mm Dellorto PHF36A and Inlet Manifolds​

this is exactly what you want all complete and he is asking for offers, dont go below £39.50 though por he might spit out his coffee.
CLEM
ps there are at least 7 differring Laverda 750 frames, a few of them just bracketry but the early ones changed a lot in the top tubes and rear of gearbox area's, the differring frame top tubes can affect carb fitment as well as the two types of air filter box
 
You would want to thoroughly check the condition of used Dellórto 36. High mileage ones will most likely have very worn slide bores that will eat slides and wear out needle jets. You could be lucky. I would work out a way to keep the rubber spigot ones you have.
 
Thanks Clem, yes I spotted the carbs on ILOC but unfortunately they had gone when I mailed him. I’ve been in touch with ducatipaddy who has some clamp carb bodies, he’s going to look at my carbs and advise if the internals are in good order and will transfer to the clamp type bodies. Gives me the option of clamp or rubber.

I found out the hard way about the various frame differences. I bought a seat and a tank from GT and SF models thinking they would fit my GTL frame, but that was no go. So I’ve sent my GTL tank and seat off to be restored, and will put the others I bought up for sale later this year to help fund the restore.

This is the first restore I’ve done, and I’m learning the hard (expensive) way that pretty much everything you touch needs attention. Ignition and regulator are next up. My bike is on points, and I have several sets of all the bits, so I’ll get the bike running okay and then go Sachs electronic and also electronic regulator. I’m a fan of changing one thing at a time, but I’ll leave those for another thread.
Sean
 
My 36mm dells had badly worn bores at about 250,000km - a few years without air filters in northern Australia didn't help (what an idiot!). I rebored them and made bronze slides that I had hard chromed (no accel pumps - had ditched them years ago anyway). Tricky job but they worked a treat. Might sell 'em, as i'll be fitting the other half of the 4 x FCR 39mm bank to my original SF ... if i ever manage to rebuild it!
 
I think my Del’s are okay wrt wear, but they’ve sat for many years and from reading on the forum there are internal passages which prove impossible to clean. The benefit of going to clamps for me is that they will open up space and not rub against the brackets for regulator. I hope.
 
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