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All,
I have a healthy spark on the 501, so now onto the carbs. I have a couple of sets of 28mm carbs, and I know the carbs that were fitted to the bike were this type in the pic below. Note the extra "jet hole" next to the choke jet (the carbs are date marked 1985) What is it for? and therefore what goes in there or should it be sealed off. The other set of 28mm carbs don't have this extra hole, and have a later date stamp.
The only Dellorto reference I have lists USA spec 501 camels with 30mm carbs, so I have set up the carb as given for an excalibur 501:

X18 needles, 76 main, 42 pilot, 50 choke, BC264 atomiser, 250 seat - but I don't have any 9.5g floats as specified, I only have 11g floats - are these ok?

the other set of carbs probably had 112 main jets

and what about float height? - I'm working without any workshop manual as a reference.

Hello,

I am not sure where it is located inside the carb but there is an overflow somewhere. The pipe on the Excalibur used to end towards the headstock, if I remember correctly. So, could it be the overflow in case the needle jet sticks. On my 350 the petrol pees out all over the engine...

Not sure what the extra hole is, sorry. I'd say regarding the carb jets that the main sounds pretty small. The 30mm carbs also had an acceleration pumper jet and were a bit notorious for setting up, most went to the US I think for emmissions rules there. I had a 501 Camel for a short while that was hopeless till I tried a set of 28mm carbs with jetting similar to the spec for a 500W (or road versions) So a main of around 125 was used.
The airbox and any noise restrictors present will have an effect too. I can't remember if the 501 Camel had a flowerpot restrictor like the Kanguros did, but that would make all the difference. Most people remove that and up the main jet to suit.

Note the extra "jet hole" next to the choke jet (the carbs are date marked 1985) What is it for

the 30mm carbs also had an acceleration pumper jet

PHBH carb? then its the accelerator pump feed drill way as Steve says, the carb has an extra screw to control the accelerator pump?
Cheers
Mark

yes phbh 28bs carbs, but no extra adjustment screws

Hi, I don't think accelerator pumps ever were fitted to the 501 engines as they use the smaller PHBH type carb

Without taking the carbs off my bike to look, I imagine that the hole is for air/petrol overflow if the float sticks?

The carbs may have twol push fit small metal elbows on the main body just above the float bowl these vent the float chamber via small plastic pipes that lead to a clip on the frame. Again I imagine one of them leads to the hole mentioned?

Squirt carb cleaner in all the holes and if not blocked you'll see where they lead

I removed all the elbows and pipes on my 28mm carbs as there are none on the 26mm versions found on Morini 500 engines

I think there are at least two different engine breathing and emission arrangements on the 501 Camels depending on the market/country

I wouldn't worry about it, just get the carbs clean, tune in and enjoy

Morning Ian, hope things are all ok with you?
Ref the pumper carbs-they were fitted to at least some of the American model 501s and I ended up buying one here about 10 years ago. The previous owner couldn't get it running right and nor could I. So I fitted a set of carbs from a 500W and it was spot on straightaway.
If I remember right, the bigger bore pumper type was fitted with a very small main jet and some other stuff to make it weaker for US emissions laws which were getting stricter then. I think even the engine and carb breather pipes were all recirculated to the engine intake as part of the plan.
I did look around a bit to see what riders in the USA had done to fix these carbs and most had binned them and used the older type 500 carbs or switched to Mikuni or even Amal. The bike I had went to George of this club who restored it as well as a 125 Morini. Nice job he did too.

I couldn't get these particular carbs in the photo to work properly, and I had a set of NOS 501 carbs which i tried on the bike way back in 2005 which fixed the poor running. Unfortunately i didn't take note of the jet sizes and the NOS carbs ended up on another 501 so it could be sold. Anybody's best guess on jets, needle and float will be attempted....

Hi these are the settings taken directly from Camel/Coguaro 28mm PHBH carbs

Pilot 42 (original Coguaru jet 55)
Starter 50
Main 76
Needle X18 (2nd groove)
Atomiser BC264
Slide 40
Float Valve 250

I'm using larger main jets in my 501, started with 128 and now 124; the engine wouldn't rev with the original 76 jets but I'm using non standard filters and silencer

Check these
viewtopic.php?f=4&t=5242&hilit=polini&start=15
viewtopic.php?f=7&t=5061&p=26624#p26624

thanks, i should spend time going thru the dutch site. I can put together a set of carbs out of parts from all the leftover carb bits I have.

The last problem is the floats - i cannot locate 9.5 g floats in all my NOS dellorto bits - can you give me the number on the float itself?
Phil

9010 Float Assembly

As Ian says that is the number for them. Trouble is, the new type white replacement floats end up leaking at the seam, ship fuel and the float sinks with the obvious result of a slowly richening mixture. I bought some too.
The weight doesn't seem to make a difference which defies logic but that is what they now supply and they worked great till they started to fill up with fuel. The weight change may be to do with modern fuels perhaps?

The weight of the float will determine how deep it sits in the fuel.

The position of the tab that operates the needle valve will determine the float height at which the fuel is shut off.

You will get the same fuel height in the float bowl for a relatively wide combination of float weight and tab position.

For a given style of float, the float weight will determine the fuel level. A heavier float will result in a higher fuel level and an overall richer mixture.

If the carb is going to be subject to a lot of vibration, then you may get fuel 'sloshing' over into the ventui, leading to inconsistent running. Lowering the fuel level and then adjusting all the jetting to suit may be a solution to the problem.