932 conc carb on a 350nc update

[wrinkleygit]

hello , is any body out there running a 350 with an amal concetric fitted that I could compare carb set up with, my biggest headache is restarting when hot,bike spits back & frequently stalls when coming off idle,possibly running too lean ?cold start & low speed running not too much of a problem when using cable operated choke lever,currently has a 3 1/2 throttle slide fitted which I may change to a 2 or 2 1/2 to richen lower speed running ( I belive cut away on slide has little effect at higher speeds)bike performs well at speed only a problem at low revs & when trying to restart when hot,sometimes will only restart after flooding carb with tickler, Ht spark is excellent before anyone asks, happy new year to you all, mike b.

see last post, mike

[Pete]

My Mototrans 350 has an Amal 930 fitted as stock. My owners booklet lists the jets as follows:

Atomizer 106 I think this is the needle jet
Diffuser 27
Main jet 250
Idling jet 25 I think this is the pilot jet

I was planning on taking apart the carb in the spring. I will make note of everything then. This morning it was -6°F so there is no work going on in the garage!

You can go here to find out everything you wanted to know about Amal carbs.http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=42112#Post42112

Pete

[Bevel bob]

if nothing else works try raising the float level a tad. Or closing the points gap a thou or so to retard the ign a bit.

[DewCatTea-Bob]

By: wrinkleygit...
" is any body out there running a 350 with an amal concetric fitted that I could compare carb set up with, my biggest headache is restarting when hot,bike spits back & frequently stalls when coming off idle,possibly running too lean ?
cold start & low speed running not too much of a problem when using cable operated choke lever,currently has a 3 1/2 throttle slide fitted
bike performs well at speed only a problem at low revs & when trying to restart when hot,sometimes will only restart after flooding carb with tickler, "

____ The idle-mix screw has a surprising amount of influence at above idle engine-speeds ! _ If it's indeed set too lean, then ya should get some popping (or even louder backfiring-like sounds) out-from your exhaust whenever you shut-down the throttle while at higher revs !
__ Do you know what Brit-bike your Amal-carb originally came from ? _ If it was off-from a 750Norton-Combat, then that carb should've been good-to-go (jetting-wise) on a 350-Duke !
____ Another thing, (probably non-directly related to your issue),, your chosen thread-title indicates you have this rather large 32mm carb on a "350nc"... While a 32mm sized carb is a fair fit on most other 350-models, the narrow-case 350s (named: 'Sebring') only have an intake-port size of just 26.5mm !
So has your cyl.head been properly ported-out to match your non-stock carb ?


Hopeful-Cheers,
-Bob

[wrinkleygit]

Hello everyone, just a quick update having done a little more research, as the carb sits at an angle & mk1 concentrics origionaly had a nylon non adjustable float, low fuel level in the float chamber is a distinct possibilty, Amal have now produced an adjustable float together with an alloy needle to counter similar problems to mine (much useful info found on their website http://www.amalcarb.co.uk ). With the local Bristol Classic Bike Show only a few weeks away I hope to pick up some spares & discuss the matter further on the Amal trade stand. I won't have the bike running again until the end of Feb but I will post up the results (good or bad ) at a later date.

With regards Bob's last post,sadly I have no history on the bike, I bought it as shown in the photo section & while it obviously started life as a sebring it now bears little ressemblance, previous owner bought it in this condition at an auction & kept it virtualy unused as a show piece in a conservatory during his 7 year ownership.On first viewing the bike before I bought it nearly 2 years ago, several things struck me, boranni flanged rims, twin leading shoe front brake ( looks japanese )with massive venting holes, rev counter drive, non std silencer (I think it is a mick walker item) rear sets, tomasseli adjustable ace bars & of course a 32mm amal & and yes the hole in the head behind the carb does measure 32mm not a paltry 26.5. It rides like it looks,only downfall is stalling & hot restarting which I have promised myself to sort out before spring arrives I will also post up some more pics when the weather improves, thanks for the replies, mike b.

[wrinkleygit]

hello , is any body out there running a 350 with an amal concetric fitted that I could compare carb set up with, my biggest headache is restarting when hot,bike spits back & frequently stalls when coming off idle,possibly running too lean ?cold start & low speed running not too much of a problem when using cable operated choke lever,currently has a 3 1/2 throttle slide fitted which I may change to a 2 or 2 1/2 to richen lower speed running ( I belive cut away on slide has little effect at higher speeds)bike performs well at speed only a problem at low revs & when trying to restart when hot,sometimes will only restart after flooding carb with tickler, Ht spark is excellent before anyone asks, happy new year to you all, mike b

Hello quick update- replaced throttle slide with slightly richer No3,also fitted new "stay up float kit" from Amal UK which replaces old non adj nylon float with new type that has metal "tangs" to allow adj of float height, this has made a big difference,raisng height of float means carb floods quicker when using tickler & extra fuel in bowl together with richer throttle slide has improved idle & starting tremendously,also throttle response coming off idle has improved, nearly forgot also replaced 3" long intake trumpet with a shorter 1". Carried out a couple of test rides now & the grin gets wider every time, all the best everyone, mike b.