New carb option

I've always been interested in these. Anyone ever tried anything like this?
I wouldn't know where to start with regard needle and needle jet. Idle and main jets should be easy enought for an 850 commando
I have across to a jetting chart for guzzi 850 and Ducati ss etcetera but how do you think these would go on a commando.
They look fantastic IMHO and are reputed to be a very high quality performance carb but that is just word of mouth.

https://store.bevelheaven.com/carb-fuel ... -set-pair/

Any thought or advice would be well recieved
DKT

Too much money for what you get in the end; I'd go with FCRs at few bucks less.

I think they look great! I have no experience with them, but am interested in hearing what others have to say.

Dellorto has a reputation for building good carbs. Hope so, I just bought a pair of phm 41s from Bevel Heaven. I get the sense that Bevel Heaven is a one man show, the owner is hands on and knowledgeable. Good guy, would certainly deal with him again.
Can't comment on how the carbs work as the bike isn't running just yet.
One of the sweetest running Vincents I have ever ridden had a big pair of Dellortos fitted. BMW used Dellortos as did Ducati. That is the extent of my Dellorto knowledge!

Glen

I think the Dellortos are less than half the price of the FCRs. The price is 535.00 per pair which is a very good price for two carburettors of such good quality. They are very nice carburettors. I have them on my Ducati and have had them on Guzzis as well. They might be narrow enough to fit onto the Norton without them needing to be splayed out as the Mikunis have to be.

I don't think you would be able to get as light a throttle action as with the FCRs. Also you would still have two cables to sychronize. I never thought sychronizing two carburettors was any problem though. You would be pretty much completely on your own when it comes to figuring out the right jetting. A good selection of parts is available though.

I don't know why no one else has mentioned how ugly the FCRs are. I think it must be because people pay so much for them that they don't want to mention that!

Nigel

I have a pair of 34mm DellOrtos on my 750 at the moment.
They are a very tight squeeze and they just touch so the are rubbing the overflow pipes away. I think the Mikuni manifolds are splayed for wider carbs, so they might be better on that kind of manifold.

I from memory I have k18 needles, 40 slide, and the main jets are I think 135.
They are a good carb, used on many quality Italian bikes. I haven't got mine properly set up yet and I've had to take the head off again, so I've only run them for a few dozen miles.
I can give you a better idea of how they are in a couple of months.

Like John, I ran a pair of 34 mm Dellortos on my 750 racer for a couple decades, and really like them. Ron Wood used both 34 mm and 36 mm Dellortos on his flat track bikes, depending on the length of the track. I used some fabricated manifolds for clearance, that splay them out a bit like the Mikuni manifolds, but not as wide an angle. I also removed the accelerator pumps to meet AHRMA rules, with no ill effects. This is the best picture I have showing the carbs mounted.



Ken

Back when, my 750 Ducati Sport came with them; worked great.

That experience convinced me to spend the money for them for my Ducati singles, with manifolds and jetting supplied by Mike and Gay at Axtell's. Immediate gratification. Substantial improvement over the Dellorto square slides and Amal concentrics that they replaced. The accelerator pump erased off idle hesitation and eliminated the need to run fat on the bottom to cover the lean spot that inevitably occurs when the fuel can't accelerate fast enough, can't keep up with, the speed at which the throttle is whacked open. Bikes jumped where before, by comparison, they bogged. It was "wow, didn't know what I was missing!"

Better carbs for the Norton are a problem. Amals fit and are Ok until you try a better carb and then its hard to go back. The problem is that none of the Mikunis fit in pairs without splaying, The Mikuni RS won't even fit as a pair because the bellcrank interferes with the frame (I tried). Neither will the Del Ortos I don't think - too wide. That leaves the super expensive FCRs and they are a bit much at 35mm. The 32 or 34mm PWK flatslides fit well and they are smooth and stable but like the Del Ortos and Mikunis - they tune to a finer degree than amals and you need an ear for that. What we need is something like the FCRs with no synchronizing needed but more affordable and not so bulky.

Dkt26 said:

Any thought or advice would be well recieved
DKT

Click to expand...

I have been around Delloto's since 1983 on Ducati's and asked about them here last year as I have plenty of spare parts from various performance upgrades, 32's to 40's to 41 FCR's.
When I asked about them last year space seemed to be the concern but the Dellorto is a much better carburetor than the Amal, even Ducati dropped the Amal on early bikes to fit the Dellorto across the range.
I think those 36's are to big for a street bike personally, a better bet might be the 30 mm off a Sport or late 750 GT on a Norton 750 but they are expensive even if you can find them.
On a 850 Norton the 32 mm Dellorto off a 860 GT / GTS - 900 GTS or 900 SD might be better, those bikes make around 50/52 rwhp so the jetting might be in the ballpark.
I have spare 32's in my overseas storage locker so grabbing a set is on the list to do when I get back to it.
The Dellorto manifold is female with a nylon sleeve to suit the spigot on the carburetor so there would be some fabrication/machining to fit them to a Norton.
It may well be a case as a lot of mods are, if you have a lathe and mill handy anything is possible.

FCR's for Norton's run around $1500 so there is no comparison but as said before IMO) , putting them on a stock Norton is fine if you have money to burn, the frame getting in the way means they can never be mounted at the optimum angle let alone the right angle for the fuel bowl even on the side draft.
If you do not have the ability to fine tune them they are even more debatable and if you can not do that you will never know.

That is a very reasonable price for two Dellortos so wonder where they come from, you still have to go beyond band-aid tuning though.

excellent carb (i had them on all my laverda and ducati) but for the $ if your going to replace the amals i'd go with mikuni's (or the flatslides that Jim sells) if i could fit them-

i've replace the Dell's on both my laverda triples (with mikuni's) and am much more happy with the mikunis - while i still run them on my laverda twin i think the mikunis would be better their too (i spent some $ recondition the dell's so trying to make them last)

Its debatable if the pumps in the dell's really do anything - i have removed them in my laverda twin and the only difference i found was i got better mileage without the pumpers

I've had amals in 32's, JS 32's and JS 34's and am now running a vm36 as the tm36-68 Flatslide pumper did not fit.
I have always wondered about these delorto a and splayed longer intake manifolds could only improve there performance I believe.
So jetting for the 750 is k18 needle and 40 slides + 135 mains?
I am (nearly there) running stock 850 with fullauto head.
Any suggestions? I think $535 is a very affordable option so am dead keen.
I have an old jetting chart that I have misplaced that covered the entire guzzi and duc range. I sent it to Pete v (I think) so he may have some extra info to add.

Hmmmmm....

I bought a pre-jetted pair of FCRs from Kenny Dreer for $400; i thought they were cheaper...

Dkt26 said:

I've had amals in 32's, JS 32's and JS 34's and am now running a vm36 as the tm36-68 Flatslide pumper did not fit.
I have always wondered about these delorto a and splayed longer intake manifolds could only improve there performance I believe.
So jetting for the 750 is k18 needle and 40 slides + 135 mains?
I am (nearly there) running stock 850 with fullauto head.
Any suggestions? I think $535 is a very affordable option so am dead keen.
I have an old jetting chart that I have misplaced that covered the entire guzzi and duc range. I sent it to Pete v (I think) so he may have some extra info to add.

Click to expand...

On my 750 with open megaphone exhausts and no air cleaners, I typically used 135 main jets, and sometimes 140. I only used 128 for higher elevation tracks like Steamboat. I use a 65 pilot, and a 60 slide with 0.6 mm removed from the bottom. The needle clip was usually in the second groove from the top. The carbs also had the accelerator pumps removed. For street use with a conventional exhaust, you would probably end up with a somewhat different setup.

Ken

Whatever you do, make sure the carbs fit side by side and are not too wide. So far the only carbs that I find to fit are Amals, FCRs and the PWK flatslides. The FCRs may require special short manifolds to keep the carbs from rubbing the frame. You might be able to get some other brands to fit but it will take some machining or custom work to get the carbs to fit closer together and if anyone gets another dual carb setup to actually fit in a commando without problems I'd like to know about it.

Does anyone know if the FCRs will fit using the standard Amal manifolds with rubber boots?

If you don't want to use splayed manifolds, or a single carb, I think you are right about Amals, FCRs, and PWK being your only choices. I haven't seen anything else that will allow the carbs to be parallel on the Commando. I'm currently running a pair of Amal MK2 34 mm carbs bored out to 36 mm on the Bonneville bike. You can also get the MK2 36 mm carbs to fit the manifolds parallel, but they do rub together a bit. All the Mikunis and Dellortos (both round and flat slide versions) that I've fitted have required splayed manifolds. I have a pair of 37 mm Keihin roundslide CR racing carbs that look like they might be able to fit. I'll check them out and see.

Ken

The other option I had seen on a norton was to have the carbs ever so slightly tilted this was with the tm's I think??? Custom manifolds but carbs slightly off vertical top inward bowl outward. Barely noticibly to the eye.
A custom tapered manifold with slight splay should also give a similar effect and potentially give rise for induction/intake lengthening.
The xs650 extended manifolds I helped my mate with were a simple affair to look at. 2 diamond shaped bits of polished alloy really. No curve but I'm sure that a decent machinist could carve something up to spec so fitment may not be the larger of the two issues.
Jetting for an 850 guzzi may be a good start but am worried most about slide size and needle/needle jet combo.
We all know what happens when you plonk the wrong size slide in an Amal!!