750's air filters

71Laverda750SF

71Laverda750SF

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The Sunshine State
When I acquired my SF it had V stacks, and later I added the air filter assembly. Since I am restoring to original, were the V stacks the only thing they came with, or was the filter available too? Also, if the filter was available are the elements still available?

Clay
 
Hi Clay,

If your machine is a 71 or 72 SF it should have the flat horizontal type filter.
I'm not sure of a source, they were unobtainable for quite a while. Clem who lurks around here had some made a few years back.
Otherwise, the bike works just fine without any filter and the original trumpets.
I presume your bike has the original 30 mm square slide carbs?

Ciao
Paul
 
if your bike has (as Paul says) the oval flat filter under the battery tray,(30mm square slide carbs) then my stocks of the remade filters are gone, I do have a few of the later type ,where the filter is vertical and in front of the batterry (36mm round slide carbs)

I gave the UK franchise to Richard Slater at Slater bros, for those filters, mainly because I was sick and tired of dealing with Unifilter in Australia, but also because of as guilt complex as there were reports of riders sufferring poor running when using them, mainly on triples, although I have never had such problems, and neither have 300 others who bought them worldwide, but for sure some did get  grief, so it was enough for me to pass the whole thing to Richard,I seem to remember him saying that demand for the 30mm carbed tyoe filter was so small that he would not buy any, and expected to sell one fillter every three years, myabe that has changed, so if you need a later one I can help.
CLEM
 
Bought my 71/72 750 SF NEW with VHB 30A(S) and 2" Velocity Cones. In the mid 70's I went to Slater's 2 into 1 pipes - which may play a big part in my issue. To prevent the engine from leaning out in the upper end I changed out the 125 main jets to 130's. To this day, with all sorts of Filter, Cone, Needle and Jet combinations, I have NOT succeeded to use either a Velocity Cone or Independent Air Filtration and I have had to run the VHB 30A(S) OPEN with absolutely no form of restriction near the carb's intake. It seems any object near the intake disrupts the air flow characteristics of these Hi-Velocity small bore carbs. Believe me they work great open but at the concern of eating dirt and changing oil frequently. I've been toying with the idea of fabricating an Air Box using a large flat, square or oval filter but I think it will be futile. I believe if you want to use any sort of Air Filtration on the early SF's you have to, just as the Breganze Factory did, change out the VHB 30A(S) for bigger 34 or 36mm carbs.

I do have a set of Mikuni 34CV's and 36VMS that I might play around with this summer, if I have the time.

If anyone has found a solution with this issue, I would like to hear from you as well :o
 
1971/1972 SF had no air filter but velocity stacks! The airfilter appeared at the 1973 SF.
Click to expand...

That is correct and used an Air Box with runners and larger 36mm Carbs, which suggest a 71/72 SF model would have to be fitted with 73 parts including the 36mm carb if you want Air Filtration.
 
The Laverda factory fitted air filters to "bikes" with both 30mm carbs and 36mm carbs, the filters differ between the two carb types,my understanding is that this was an option where normally fitted with stacks, as (probably) were stacks if normally fitted with a filer (as in GT) the confusing thing here is that the GTL most of which had 30mm  carbs uses the filter that acompnies the 36mm carbs and a few GTL's leaked out with 36mm  carbs
confused,
its complicated isnt it
CLEM
 
I have pics of 71 and 72 SF with air filter.
Click to expand...
I can take PIC's of my bike with Velocity Stacks or individual Air Filters mounted and can guarantee it will not work. As mentioned above I tried true K&N's, Morrosso and a host of other Filters to no avail - It would crap out before 5000rpm. It wouldn't even accept the original 2" Velocity Stacks after installing the 2 into 1 pipes but runs great OPEN and with larger jets.

An air box, without runners and attached directly & FLUSH to the carb mouth, may work but forget individual breathers.

I'm considering using something like a Tin Bread Pan cutting holes in the bottom with rubber gaskets to fit flush on the mouth of the carbs then fitting a Flat (VOLVO) Air Filter over the opening of the Bread Pan. Another answer maybe to use 2 flat plates and sandwiching a big square or oval shaped 2" Filter between them. Any concept of a runner does not work.  

I love the sound of open carbs but the fuel stand off is messy and your always thinking about an oil change.

Velocity Stacks don't always improve a carbs performance and can hinder Air Flow.

CLEM: 40 years with this bike - Wish I new the answer - LOL
 
Well all these posts cleared up this dilemma  :o. And yep, square slides. Thanks for the info, all of it has me wondering a bit. Since I want it to be "Original" then the V Stacks looks like the winner (although much riding in the dust and dirt will definitely kill the engine, rode it through Idaho and Washington after Mt St Helen's erupted in 1980-ash everywhere), but keeping the engine airworthy makes more $$$ sense.

"One answer leads to another question"

I think the chicks will dig the V Stacks! 8) 8) 8)
 
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