36mm Dell Orto carbs on a 3C

L

LaverdaWicklow

New member
Location
Wicklow, Ireland
Hi guys, I'm dealing with a Laverda 3C triple that came with 36mm Dell Orto carbs. Has anyone else had experience with these larger carbs?

The motor gags on acceleration with even just a small amount of throttle. I am wondering if it's worth persevering with 36mm carbs. Has anyone here had experience with these larger carbs and if so, what needle adjustments and jetting did they find that worked? The motor has been rebuilt very recently. It starts and idles well, although it's a bit rough at low speeds and low throttle openings.

If I decide to persevere, I will check the float levels and lower the needles a notch to see if this has any positive effect. If not, perhaps richer needles and needle jets, and after that, main jet changes.

I welcome any comments from those who have used larger carbs on their 180 triples.

Cheers,

Dave
 
LaverdaWicklow said:
Hi guys, I'm dealing with a Laverda 3C triple that came with 36mm Dell Orto carbs. Has anyone else had experience with these larger carbs?

The motor gags on acceleration with even just a small amount of throttle. I am wondering if it's worth persevering with 36mm carbs. Has anyone here had experience with these larger carbs and if so, what needle adjustments and jetting did they find that worked? The motor has been rebuilt very recently. It starts and idles well, although it's a bit rough at low speeds and low throttle openings.

If I decide to persevere, I will check the float levels and lower the needles a notch to see if this has any positive effect. If not, perhaps richer needles and needle jets, and after that, main jet changes.

I welcome any comments from those who have used larger carbs on their 180 triples.

Cheers,

Dave
Click to expand...
Hi Dave,
First up, has the inlet been ported up to match the 36mm carbs?

Mine (32s) were smoothbored out to 36mm, back in the mid '80s along with a myriad of other "Prepared by Motodd" enhancements.
As many would be able to confirm, mine runs very well on them.
Check that the starter enrichment cables aren't compromised and that the seals on the bottom of the plungers are in good condition.
Check what size jets you have and that the accelerator pumps are working correctly?
What colour are the plugs?
 
I ran (proper) 36mm carbs on my 3C for many years without issues. But then, the engine was appropriately tweaked and actually needed them. The engine got on well with those carbs, even to the extent that I was able to completely delete the accelerator pumps. The Dellortos were eventually replaced with a set of Mikuni RS.

If the 32mm carbs are still present, not at all pointless to swap back. The 1000SFC managed nicely with the stock 32mm Dells, despite the mild porting the factory performed.

piet
 
> wot Piet says above. If not -
36mm carbs means slow gas flow at low throttle openings so correct setup becomes more critical.
First thing to do is check valve clearances (and valve timing if you're in anorak mode) and ignition timing.
Then set correct float heights
Then balance carbs and set idle mixtures
Unless you know the needle and its jet has been replaced recently, replace them. They wear, making for rich mixture. AB265 and K1 should still work OK.
 
Check there balanced and counter the turns on the mix screws. Does turning on a bit of choke make it better?
 
Thank you all for your experience and insights. I'm encouraged that 36mm carbs can be made to work on these motors. I've only taken it out for one short test spin so far. I will be testing it again on Wednesday and I will see how I get on with some adjustments and I will report back!

Thanks again and talk soon,

Dave
 
If it idles fine and goes ok from quarter throttle up, if it is related to the carburettors, it will be the slide cutaway, which is what governs pickup from idle. It is best to have it correct instead of compensating with other settings.
 
From my perspective, it all depends on the whole setup of your bike to make a real good guess of what makes sense. As long as we do not know what the engine is about, it is hard to say what works and what not.

I would defenitely check though if the head is ported or not and what cams are installed (A11, 4/C or 7/C are factory cams, A11 was the street cam, 4/C a mild tuning cam with improved midrange and slightly better peak power and 7/C is a cam with massive opening times and overlaps that only makes sense on a highly tuned engine).

Check what ever you can check on the bike without taking the engine appart (port sizes and manifold diameters, compression etc.) and make sure the valve gaps and ignition timing is set right. If the basics are cleared, you can check the carb settings. everything else is potentially just trying to fix the consequence of other issues...
 
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