Amal fuel levels

I hope you guys can see my photo's? Let me know?

In an attempt to get the engine running sweet, I followed the instruction on optimising the fuel levels, rather than just setting the floats to an arbitary height. The new stay up floats help. First thing I noticed, just trying to set the fuel levels, with the bowls off and hooked up to a fuel supply, then trying to read the levels is...

messy
tricky
inaccurate

So I set about making a manometer by machining up a new float bowl plug with a hose spigot. Then fitting plastic tube and holding it against the float to carb joint area. This is a bar better method, and I can get some meaning full results. I made up a little gauge out of 20 gauge plate, with the maximum and minimum settings, so I just hold it up against the levels and check.

My right side carb is a fraction low, and it is quite tedious to set it, a small adjustment and the results are either to much or not enough, but I am still playing with it. It is interesting to run the engine and turn the fuel of and monitor at what height the engine changes. The heights are very critical mixture strength at idle, with the setting pretty close, left side 170 thou and right side a tad over 240 thou the idle air screws are @ 1 1/4 to 1 1/2 for a clean idle. I have found that a slightly over rich idle gives better low speed response, so the trade off is either clean running or smoother low speed running. Maybe this is illustrating a slight missmatch with my standard cut aways, or slight wear in the slides?

Anyway, I have to say that this fiddling does show me that setting the floats by height with a measurement is not really close enough to get perfect results.

Cheers Rchard

Very Cunning . Nice & simple .

I bolted my float bowls to a flat piece of metal and fed them. Wasn't too messy for me. Like this. leaky-float-bowl-seat-t8025.html

Dave
69S

Good on ya Stockie,
I too have had a pretty fair go at it, never got around to the "sight tube" setup though.
It took me a while to get a handle on the whole set up, because some guys refered to....
Float height, where as others refered to.... Fuel height. Very different.
I've had my Amals sleeved, stayup floats and seats, new needles and jets and bodies were Acid dipped.
My Combat is easiest to start when it's a tad rich on the mixture screws, and it also eliminates that
irritateing spit back we get occasionally, just off Idle, but it doesn't want to idle properly when it gets hot, so invariably
I end up back at a leaner screw setting.
I was a bit too slow off the mark, when the slides were sleeved, I wanted to have them fitted with a little
less cuttaway, but by the time I had remembered to ring him the job was done.
Such is life.
I'm in no way an Amal basher, but these will go into a box out in the shed soon, while they still work ok and
another set of carbs will go on.
AC.

Reading the new aquisition ' road tests ' book , the general whine is that , New , the Concentrics are good .
At 5.000 there NOT , you wont get a consistant idle or lift of idle .

When I was . . . etc , out rideing , you sayed 6 ft back from anything with concentrics , as they didnt have good transition .
People used to talk about ' twitter silencers ' , Er maybe but stutter was the Carbs .

People engrossed with concentrics recond to turf them at about 10.000 miles , unless they rode a BSA .


Not trying to be a rissole or the like .

Both bikes I built had NEW carbs, Monoblocks on the Bonne , Mk II Amals on the Commando .
At 10.000 miles the Amals had light scoreing DUE TO NO AIRCLEANERS . ( ) Same on Bonne .
25.000 on the Bonnie , a lot of it on back roads with the notorious Gravle and noxious DUST had the Monoblocks a bit worn
but still functioning satisfactorilly at 25.000 . Didnt do the bores a world of good unfiltered .

SO any Filtration that seals fully is paramout , for starters . Airboxes and the like intresting ( back roads , M-X thinking )

But , the Accuracy and Progression & economy ( Range ) on the Mk IIs make them tops in my books if O.E.M.
has any relevance . So , they never got round to it , but preumeably would have if still produced in the 80s .

Just my ten cents worth .

THE Gravie and THE Dustie ugh Matt I think a gap in my carb air boots done did in my rings this summer.

The perfect float setting gives pilot air screw 1.5 turns out. Its way too complex a fluid supercomputing non linear condition to simply set by any measure or calculation so nothing will optimalize the float level per fuel used in a particular carb and bike as just diddling float up or dn to get 1.5 turns out as best idle and thereby best base line for jet and needle and slide. Same as spark timing diddle by effect subjectively then go measure and mark objectively.

Talk about SPARK and Lighting it Up . Allways went for spot on 31 Deg. a bit chuntery and inflexable , but goes like a cut cat.
can get more fuel in too , then .
Aways found the ' Ciggarette paper ' between the points to give exact setting if the whole advance mechanism & c.b. assembly were top line undamadged condition .

Though with a Mag. and Manual Advance . . . you put it WHERE you want it . Infinately Variable :lol: . Progress . . .
Still cant figure where youre supposed to put the Crank Handle in Cars these days though .

The Dreaded Concentrics / Float Levels . The BOOK is the ' Near Recomendation ' . A miser will run em low ,
a throttle merchant bias them high . ( the fuels going out as fast as its going in ) The old ' Plug Checks ' etc
for establishing the setting , along with the Seat of the Pants impression , with FIRST haveing the ignition System
SPOT ON , are prerequisettes .
The under duress pinking , dead right . with our antiquated specification :lol: A gear up from Desired and coarse throttle WILL cause pinking / detonation . JUST . Searching for it will estabish there IS sufficent advance in the Ignition .

Though . . .

Weak springs in the avance mechanism from old age , heat of misstreatment should be considered . . .
High Speed Detonation unheard equates to MELTDOWN . . .

Checking the centre electrode is not melting / rounding off , is the check there .

So , the Old Mk II Amals with the ignition set at 31 allowed speeds in excess of that possible in third , the entire insides of the exhaust system WHITE , as were plugs with trace off yellowing on centre insulator . Frightening but satisfactory .
And Economical .

Most of the Mk 1 concentric blokes biased float / fuel level a notch ( maybe 1/16th max. 1 / 32 min ) High to obtain usefull operation .