carb size vs. main jet... 32mil Amal jetting help

[stageman]

is there any relation between carb size and main jet size that could be used as a guide to jetting ?

e.g. if a 330 main jet on a 34mil Amal works OK then what could be a decent size on a 32mil Amal with an otherwise similar setup.

on a quick spin on the TS today I started out with a 310 main, engine bogged down when opening the throttle. changed to a 280 - better but still spluttery. in relation to a 34mil Amal where 330-350 main jets usually work fine this now seems dangerously small, although the feeling is I should go smaller still. idle and mid range seem OK.

setup is TS230, casings matched, JL 3 snail, yamaha reeds.

any thought ?

[J1MS]

Sounds a little small for a 32 Amal. How old is the needle And needle jet, miles of running, as they wear fast. Smaller main jets, once these are worn make the engine run smoother.

[stageman]

hmm.... never heard of that before ... not a bad thought though. the carb was thrown together from used parts, so yes possibly the needle or other parts may be worn. was surprised that with a 35 pilot jet it needed the mixture screw adjusting quite a lot .. guess it´s now approx one half turn out .. will def check the parts used and / or try other spares next weekend. thanks for the feedback.

btw anyone knows who stocks that "quick release" float bowl drain plug and jet holder ?

[byron]

btw anyone knows who stocks that "quick release" float bowl drain plug and jet holder ?

http://www.amalcarb.co.uk/AmalExplodedI ... pares=true used these a few times for Amal spares.
I do love an Amal, I've got a proper English 32mm I've had for 25 years, cleaned it up, bought a few new bits for it, stuck it on my scoot and it was pretty much good to go, needed a bit of tinkering to make rideable intraffic, but it let the bike rev more than the flatslide dell I had on there, which is now back on, but the slide is worn, so thinking baout chucking the Amal back on. love the snap back from the huge slide sping, compare that to the mikuni...

[vince]

Behind the bell mouth at the bottom of the carb there is what could be described as an air jet ,an aluminium tube with hole through. there are two sizes of these and this can influence the jets used. you should have the carb with the raised needle surround in the middle as well.
the jet size drop sounds large to me.
Amals are normally the easiest carb to play with thats why I stuck with my 36mm on the sprinter running methanol.

[sean brady scooters]

i too have always loved Amals......
still the best looking and neatest fitting ,big bore carbs in my oppinion.
performance wise i always prefered these also ,but this was just a seat in the pants evaluation prior to dynos...
sadly they went out of fashion for scoots for some reason and so like most folk i stopped using them,and concentrated on dellys......which were cheaper and more available.

I have never been keen on mikunis,for various reasons,although i realise that many shops /dealers now promote these........and so would love to see Amals re tested and used on scoots again...
just for the sake of nostalgia if nothing else...

[paulmgreen]

Especially chuffing big Amals like the one on here! >>

[byron]

.....and so would love to see Amals re tested and used on scoots again...
just for the sake of nostalgia if nothing else...

yeah, I'm in, might stick mine back on whilst I refurb the dell. pity my stator seems to have packed up tonite and I should really fix that first...

[sean brady scooters]

Especially chuffing big Amals like the one on here! >>

i was going to ask about that carb paul....and its spec...but then remembered how secretive you are...

[J1MS]

hmm.... never heard of that before ... not a bad thought though. the carb was thrown together from used parts, so yes possibly the needle or other parts may be worn. was surprised that with a 35 pilot jet it needed the mixture screw adjusting quite a lot .. guess it´s now approx one half turn out .. will def check the parts used and / or try other spares next weekend. thanks for the feedback.

btw anyone knows who stocks that "quick release" float bowl drain plug and jet holder ?

Last time I bought a quick release float bowl for an Amal I bought it off Midland Scooter Center, but that was probably 20 years ago. But some of the old British Bike dealers still stock Amal bits so try them if you have no joy.

Biggest problem that rears its ugly head with these carbs is if the bell mouth screws come loose they can get sucked into the inlet, so make sure they are nut locked in, or stud locked if you dont intend taking them back out.

Other niggle is the slide locator that sits in the alloy carb body, this has a little pressed over retainer, there very unreliable and they sometimes fall out in time, making the slide spin. The later ones are made of nylon or plastic but they still wear out and come loose...

But they are simple carbs to set only one needle and a couple of needle jets and a pilot jet somewhere between 25-35 not a lot of spares needed to set them up, and there seem to be a few knocking around for pennies...

I like these carbs even with a few niggles...