RGS Dell'Orto Carburettors

Stoutgoose

Stoutgoose

Junior member
Location
UK
When I bought the bike tick over was awful and uneven below 3000rpm. Upon dismantling the carbs I found that one of the pilot/secondary jets was completely blocked. I managed to clear this with fine wire and compressed air, and took the opportunity to remove the remainder of the jets and blow them and the drillings through. Upon reassembly the bike ran much better at tick over and could be ridden at below 3000rpm. I have dynamically balanced the carbs at 2000rpm using a manometer, but the carbs are still stumbly and intermittent between 2000 and 2800rpm especially when trickling along in slow traffic at small throttle openings.

Cams and engine are standard as are exhausts. Jetting is standard with idle circuit set at just over 1.5 turns which provides best running. Witt electronic ignition set at 32 degrees on number 2 curve.

I am going to pull them apart again and repeat the process, but before I do, how do your bikes ride at revs between 2000 and 3000rpm on light throttle openings? Is this just how they are or should it be completely smooth?
 
Stoutgoose said:
When I bought the bike tick over was awful and uneven below 3000rpm. Upon dismantling the carbs I found that one of the pilot/secondary jets was completely blocked. I managed to clear this with fine wire and compressed air, and took the opportunity to remove the remainder of the jets and blow them and the drillings through. Upon reassembly the bike ran much better at tick over and could be ridden at below 3000rpm. I have dynamically balanced the carbs at 2000rpm using a manometer, but the carbs are still stumbly and intermittent between 2000 and 2800rpm especially when trickling along in slow traffic at small throttle openings.

Cams and engine are standard as are exhausts. Jetting is standard with idle circuit set at just over 1.5 turns which provides best running. Witt electronic ignition set at 32 degrees on number 2 curve.

I am going to pull them apart again and repeat the process, but before I do, how do your bikes ride at revs between 2000 and 3000rpm on light throttle openings? Is this just how they are or should it be completely smooth?
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Which bike are you talking about?
If it's the GT in your avatar, it should be smooth from a fast tickover to blow up.
3000 revs is high revs already.

Have the carbs been through an ultrasonic bath or otherwise been cleaned totally? They should if the bike wasn't running regularly when you bought it.

Paul
 
It's a 1983 RGS Paul. The twin runs fine. Carbs haven't been through a bath.

Can you recommend any good/trusted Dell'Orto cleaners/rebuilders, preferably close to Woking/London?

I toyed with the idea of buying an ultrasonic bath; they are reasonably priced and I have five bikes with carburettors, but not sure I trust myself to do the job properly.
 
Stoutgoose said:
It's a 1983 RGS Paul. The twin runs fine. Carbs haven't been through a bath.

Can you recommend any good/trusted Dell'Orto cleaners/rebuilders, preferably close to Woking/London?

I toyed with the idea of buying an ultrasonic bath; they are reasonably priced and I have five bikes with carburettors, but not sure I trust myself to do the job properly.
Click to expand...
Ah, a complicated bike!
For your carb work, try https://www.ducatipaddy.com/

Paul
 
Have you -
Checked float heights?
Checked choke plunger cable adjustment for slack and their rubber seals for condition?
Replaced the needles and their atomiser jets?

I'd also suggest checking ignition timing (set DMC to curve 1 and strobe at 3000+ rpm to confirm 32 degrees advance using an accurate TDC mark.)
I'd also try curve 10 in preference to 2.

And yes, Paddy is good!
 
Stoutgoose said:
It's a 1983 RGS Paul. The twin runs fine. Carbs haven't been through a bath.

Can you recommend any good/trusted Dell'Orto cleaners/rebuilders, preferably close to Woking/London?

I toyed with the idea of buying an ultrasonic bath; they are reasonably priced and I have five bikes with carburettors, but not sure I trust myself to do the job properly.
Click to expand...
if you have already taken them apart once, you can tackle the full rebuild yourself. Not complicated. Buy an inexpensive ultrasonic. Make sure you get the float heights correct. Idle low range issues can come from a couple of issues, but look first at the rubber tips on the float plungers. Likely petrified and not sealing, and likely not properly adjusted on their individual cables to all fully hit bottom when the choke is off. One old timey trick to save the cost of the plungers is to pry the rubber tips out and flip them over to get a fresh sealing surface, if someone has not already done it before you. I always just replace all the brass with new, including the needle jets, and replace the needles as well. You can probably reuse the slides unless they are really worn.

whle you have the carbs off, remove the intake stubs and check the O rings between intake and head, often perished and leaking air.

there has to be hundreds of carb rebuild/setup/jetting discussions here on this forum and the prior forum version which is also here. The search function is your friend. If you get stuck on anything, just ask, lots of knowledge here.

Paul LeClair
 
If it is an RGS it will have the rubber inlet manifolds which like to crack and leak. They do not have a O ring as it is part of the manifold. Take off the carbs and squeeze the manifold where the carbs attach, you will probably see they are cracked.

Unfortunately they are expensive to replace and a few years from now will crack and leak again!

And I agree, get a cheap Chinese made ultrasonic cleaner. It save many hours of cleaning the carbs.
 
1200ts said:
And I agree, get a cheap Chinese made ultrasonic cleaner. It save many hours of cleaning the carbs.
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Not sure why you have to buy a cheap made in china ultrasonic cleaner :unsure:
That is unless you like buying crap gear and supporting the CCP :unsure: :unsure:

Plenty of others on the market, did a 20 second search and came up with these.

unisonics.com.au

Ultrasonic Cleaners & Accessories | Unisonics Australia

Ultrasonic Cleaners & Accessories ➤ 100% Australian Designed & Manufactured ✓ 30-Day Trial Period Available ✓ 24-Hour Warranty Response Time ☎️ (02) 9939 4800
unisonics.com.au unisonics.com.au
 
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Why buy a Chinese cheap one, because if you only going to use it once every few years, you are going to spend more on the ultrasonic cleaner than paying someone else to do it for you.

I have three of them in different sizes. Two are Chinese and one is a USA made industrial unit which is over $1000 new. The USA made one works better but not enough to justify the price.

And regardless of what country they claimed to be made in, they all have the same Chinese electronics and transducers. My USA made one says it was made here but if you take it apart you will see most of the parts inside are either Mexico or China.
 
1200ts said:
Why buy a Chinese cheap one, because if you only going to use it once every few years, you are going to spend more on the ultrasonic cleaner than paying someone else to do it for you.

I
Click to expand...
Maybe if you are only going to use it once every few years then dont buy one at all, there's a thought.


I dont have one, and have managed quite well without one, I find their results marginal at best when compared to a total strip down and clean using a good aluminium cleaner and a bit of elbow grease.

But hey , go ahead and buy your cheap Chinese tools, and encourage others to do the same,use them once and then after storing them for years consign them to landfill.
Im sure it makes no difference to anything......
 
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Stoutgoose said:
..... how do your bikes ride at revs between 2000 and 3000rpm on light throttle openings? Is this just how they are or should it be completely smooth?
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.... it took me quite a while to get mine to rev smoothly from idle to ~ 3000 (stumble from idle and then kinda dead up until it kicked in) and although it has Mikunis, I'd guess at similar set-up problems. Now, blocked galleries are not good, but aside from that ... minor timing changes of around 2 degrees (advance) made a significant change in running as did progressively getting leaner on the idle circuit. Any other motor wouldn't even notice the changes .. but the LAVERDA (mine anyway) is pretty fussy. Now it runs like a charm, but it took a while to find a combination that it likes.
 
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