Dellorto floats

Garry

Garry

Junior member
Location
Eelde, Netherlands
The RGS drives me crazy sometimes...😱
I have/had the problem that after driving for about five minutes, it would run on two cylinders and sometimes on just one. Because I’ve completely restored it and replaced or modified all sorts of things, I didn’t know where to start looking...
Eventually I got round to the Dellortos, where I replaced all the brass parts (jets etc.) and the throttle needels, as well as the floats.
The black 10g ones were no longer available and were replaced with the equivalent type 7450-01 in white.
When fitting them, I didn’t compare them with the old ones, only to discover that these are actually the right ones.
I swapped the floats back to the old black ones, and only then did I notice the differences.
Looking at the photos, does she get too much fuel with those white ones?
Which might explain why she then runs on just 2 or 1 cylinder?
After a short test drive, she does indeed run better and the exhaust headers are turning more brownish-blue.
A longer, more thorough test drive will show whether this was indeed the problem.

Does anyone have any experience with these white floats?
 

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piranha-bro2 said:
What i was thinking - it has always been an alternative method for measuring fuel height. Are you serious that the new float bowls have no adjustability???

And yes, a very small discrepancy in float height can indeed spell 'bad things' DAMHIK.

As for WOT, why in hell wouldn't you be able to operate a Laverda at WOT??? I must be one seriously anomalous gent. In fact, I think I must know quite a few anomalous Laverda owners. The bikes didn't just suddenly become allergic to WOT throttle because a few decades had passed FFS.
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Quentin,

The "new" white floats have a very different tang that acts on the valve. They sort of fit the old PHB/PHF and are not really meant to be adjusted, the adjustment range is extremely limited. Apparently made for a new variation of float valve.

The thickness of the sealing washer under the float valve seat alone has an enormous influence on float height, having a means of adjustment is paramount. The original Dellorto PHB/PHF service sets contain 2 almost identical fibre washers that fit under the float valves, they differ only in thickness and colour (to keep them apart). I've found many "overhauled" triple carbs with different washers fitted across the 3 carbs resulting in heights differing by as much as 3mm. Would have lasted about 20-25 seconds at WOT.

Lavs were made for WOT, it's in their DNA. Not using a Lav at WOT? Go buy a H-D... or Vincent?:unsure:;)

piet
 
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sfcpiet said:
Quentin,

The "new" white floats have a very different tang that acts on the valve. They sort of fit the old PHB/PHF and are not really meant to be adjusted, the adjustment range is extremely limited. Apparently made for a new variation of float valve.

The thickness of the sealing washer under the float valve seat alone has an enormous influence on float height, having a means of adjustment is paramount. The original Dellorto PHB/PHF service sets contain 2 almost identical fibre washers that fit under the float valves, they differ only in thickness and colour (to keep them apart). I've found many "overhauled" triple carbs with different washers fitted across the 3 carbs resulting in heights differing by as much as 3mm. Would have lasted about 20-25 seconds at WOT.

Lavs were made for WOT, it's in their DNA. Not using a Lav at WOT? Go buy a H-D... or Vincent?:unsure:;)

piet
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Put Amals on them. No need to worry about float level, just throw petrol in the bores.
Paul
 
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Vince said:
Wasn't there an issue a while back about some fuel taps not flowing enough at WOT, some talk about adding a third fuel tap? It didnt get much traction as a story, pun intended
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The same story goes around for a lot of motorcycles I think.
Same for Vincents, some recommend opening both taps for fast riding.

Be it on the Vincent, or the Falcone, which have two taps without reserve, practice is to use one tap and keep the other as reserve.

What would be the point of three taps on a single or a twin?

Paul
 
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Garry said:
One more question about height. I know now that height is very important, but does a lower height mean I’ll use more or less fuel?
The margin is small, but I’d rather have a bit too much fuel than too little.
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Low fuel height (which is the opposite of a low measurement of the float against the carb body!!) is lean. Basically, the higher the float position when the needle valve shuts off the incoming fuel, the richer the mixture will be.

You'll use a lot less fuel once the slugs (pistons) have nice holes in them :ROFLMAO:
 
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@Piet, yes again..If it ain't broke, fix it till it is.😟

I’d taken the white one out and hadn’t looked at it since... but after 5 days I still saw this... which is why the solid-foam black ones are probably better.🫣 This white one is brand new!
One side is still half-full of petrol. So definitely not 8.5g.....
 

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MB in UK makes spare parts for the Dellorto company and he makes his own floats as there is a known problem. He also makes high flow shut off valves. I think these floats are probably too small for a Laverda. Whether Dellorto sub stuff out for obsolete carbs now I don’t know but apparently genuine main jets have hugely differing flow rates- massive problem on a two stroke but still not good an a marginally lean four stroke either.
 

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I’m going to take the carburettors off again just to be on the safe side, and I’m going to take my time adjusting the black floats. I’ve finally figured out where and how to adjust the height...🫣
I’m not the only one with leaky floats. I’ve seen this problem mentioned on the Ducati forum as well.
 
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chrisk said:
Pigments colouring plastics have no bearing on the makeup or sealability of plastics.

I’m not suggesting the white and black jobbies are exactly the same, save for colour, rather, just saying….. because it is black doesn’t mean it is less likely to leak.
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Ducati Paddy would rather sell 2nd hand black floats instead of the new white ones which were known to leak. He never had that issue with the black ones.
He didn't build his "go to Dellorto guy " reputation selling sinkers !! Just saying !
 
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My white floats are OK, for now at least, after a small trim with a file at the ends of the hinge, and a cleanup of the hinge pin holes. Maybe the latter is all they needed, but I was in a rush to fix it, and it worked. The dark originals sat in gasoline for 20+ years, and one was melted/deformed, so I didn't think it was long for this world. I didn't have this much info on such problems at the time of purchase, so I made what seemed a logical decision at the time to buy Dell'Orto reproductions, and the white ones all I found. So far, so good after the fix, but who knows how they'll do. This is with California gas. Not sure what the mix was in 2001 or so, but it was deforming them. One was was really bad.
 
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