Commando Running rich no matter what

Hi Guy's,

Trying to tune my 850 MK3 now and it seems no matter what I do it runs rich. Don't seem
to get much response out of adjusting the Pilot Screw.

Specs:
-Amal 932's "220/106 Jets", Floats set 80 Thou under bowl lip, Slides matched
I'm no expert on amals but the slides don't look excessively worn to me.
-Chokes Removed
-Pilot screw start point 1.5 Turns Out
-Peashooters
-K&N Single filter
-Champion N7YC New plugs gapped to 0.023

over the last couple of days I have been trying to get it running right and it instantly fowls plugs
I had NGK B8ES plugs in that came with the bike but today hecked them and
put in Champion N7YC's but after a couple of minutes running they are black, I have been starting
at 1.5 Turns out and getting even to 3 turns out without any real significant difference in running
and black fuel smoke coming out both sides?

I assume this is where my problem is, the pilot circuit is 100% not blocked, where to next?

Can anyone offer info on where there pilot screw is set on a bike with similar specs so I can try
get an idea where I should be at?

Cheers

When I hear failure to respond to pilot adjustments, like stalling out at either extreme, I think of too high floats in your case &/or blocked pilot jet or ugh jets, which implies more likely fuel level as not likely both carbs that clogged. Put some grease on slides to eliminate that question for a good while. Ideal float level with ideal clear pilot allows Amal ideal 1.5 air screw turns out of best idle, after timing spot of of course. Once float level closer to right pilot adjustment will be effective and can have great idle even if pilot turns way off ideal side to side - like my Combat last couple years .9 & .7 turns after by golly seat bumping to get runing ok its as good as I desire so quit while ahead. Float can hang up on hinge or gasket so nothing for it but back in again, ugh. At least you got yours running.

Should I try lowering the floats below the recommended 2mm/80thou?

PS: Needles are set on the very top Clip which I read as "Weakest" setting and
i believe is stock for the MK3

What purpose does the rubber o-ring on the Pilot screw serve, is it purely just to keep the
screw from vibrating loose?

I have noticed since adjusting the floats tickling the carbs gets a rapid fuel flow now

What purpose does the rubber o-ring on the Pilot screw serve, is it purely just to keep the
screw from vibrating loose?

Click to expand...

Yes and seal the hole, if your bike does not respond to the pilot screw then get a #78 drill and glue it into the end of a WD40 red tube or similar, remove the pilot mixture screw and use the #78 drill twisted with you fingers to clean the pilot jet.

I assume these carbs have pressed-in pilot jets. Someone could have gouged the orifices to a bigger size,trying to clean the pilots. The orifice size should be 0.016".If it's bigger, fit screw-in pilot jets size 20.Leave the pressed in jets as they are.
That should bring your air screw closer to 1.5 turns at best idle.

How worn are the needle jets? 0.0005" wear is a lot, and will cause richness.

Do you know these carbs ?? have you used them before and were they working OK. Or are they unknown??
Hard to suggest a "quick fix" without all the info...

Gotta start at the beginning...........

I have read and youtubed alot, haven't had heaps of hands on experience though

Guess you could say they are unknown.... I bought the bike a few months back, it had been sitting for a while
last started probably a year before I got it but hadn't been properly ridden in maybe 10 or more prior to this,
has 28000ks on the clock, real kilometres honestly unknown, rear speedo drive missing.

Where I am at now is I just re checked the float levels, adjusted them down even a tad more
to where they are probably between 2-3mm below the lip.

Triple checked the pilot circuit, I can push silicone tube against the pilot screw hole with screw removed
and clearly blow through the passage, have ran fine guitar string through the pilot hole, it has never appeared
blocked even sicne my first tear down of the carbs, they always looked mint inside actually, no varnish

Have tried the single cylinder tune suggested in the manual however I get the same results, my pilot screw
tweaks seem to make no change to it running rich as hell

Guess I lean towards worn needles or slides now, I did notice one slide was a little wet with fuel, could this
suggest excessive wear?

I just ran it again then after the Bowl re adjustment and only after 2mins the plugs are 100% black

Think I mite just buy new carbs and be done with it, any suggestions on the cheapest place to buy?

The only thing I know that can cause this richness at idle is pilot jets that have been reamed oversize.

Needles don't ever get much wear, but needle-jets do. The needle jet size won't have any effect at idle ,but a big effect from 1/8 throttle to 3/8 throttle.

IMO if its "maybe" done 28000k's on the original carbs its time to move on (Amal x 2 = 10k mls in dusty OZ) . Plenty of combinations out there, but expect to spend $500- Au for a new carb setup that will last.

Any suggestions where to buy and anything to look out for

looking at these at the mo http://www.ebay.com.au/itm/Norton-T..._Parts_Accessories&hash=item3f37f5b664&_uhb=1

I assume all Amal 932's are not alike, and I assume these would not come with jets?

CHARGER said:

Hi Guy's,

Trying to tune my 850 MK3 now and it seems no matter what I do it runs rich. Don't seem
to get much response out of adjusting the Pilot Screw.

Specs:
-Amal 932's "220/106 Jets", Floats set 80 Thou under bowl lip, Slides matched
I'm no expert on amals but the slides don't look excessively worn to me.
-Chokes Removed
-Pilot screw start point 1.5 Turns Out
-Peashooters
-K&N Single filter
-Champion N7YC New plugs gapped to 0.023

over the last couple of days I have been trying to get it running right and it instantly fowls plugs
I had NGK B8ES plugs in that came with the bike but today hecked them and
put in Champion N7YC's but after a couple of minutes running they are black, I have been starting
at 1.5 Turns out and getting even to 3 turns out without any real significant difference in running
and black fuel smoke coming out both sides?

I assume this is where my problem is, the pilot circuit is 100% not blocked, where to next?

Can anyone offer info on where there pilot screw is set on a bike with similar specs so I can try
get an idea where I should be at?

Click to expand...

Gooday Charger,

What ignition do you have. ? How does the bike run ? My plugs are black around town and grey if I do a plug chop on the freeway.

There is no setting on the pilot screws, just a starting point. If you can go from 1.5 to 3 turns without a difference, I would mechanically clean the idle jets. That should not happen. I have very worn slides and a good idle. Have you read the Bushmans setup ?

Have you checked that the float bowls are not flooding but the float needles are worn an not sealing even though the floats are raised trying to cut off fuel supply.
Try leaving fuel taps on with engine not running an see if carbs flood from ticklers or look to see if fuel comes out of main jet an runs down inlet into engine.

If you do decide to change for new carbs I can vouch for a new pair of Amal Premiers. They should be straight swap for yours. Then you will not be wondering condition or what may have happened to them in past. Also order Mk3 carbs as they come with flats machined so you don't have to file bits and cut away spray tubes. (now here comes a flood of opinions on spray tubes)

CHARGER said:

I assume all Amal 932's are not alike,

Click to expand...

You assume correctly, as there are at least six variants of Commando '932' carb, and that's not including the fact there are left and right handed versions of each.

CHARGER said:

Should I try lowering the floats below the recommended 2mm/80thou?

Click to expand...

The current method recommended by Amal is to set the fuel level rather than by float height.

http://amalcarb.co.uk/optimising-mark-1 ... uel-levels

Are chokes fitted and are the cables tight? Just a thought and I don't see it mentioned in the thread.

I just had a similar problem and it turned out that the needles had popped out of the clips, probably on reinstalling.
If you undo the jet holders you should see both the needles and usually spot if somethings amiss.

I'm having the same problem in one cylinder on my '73 850. The first determination that needs to be made is whether the plugs are gas-fouled ( too rich ) or oil-fouled ( head gasket, rings, valve guides ). I am 99% sure at this point my issue is that the plug is oil-fouled as absolutely no adjustment on the carbie makes any difference to the symptoms. I have further investigation to do, but you may want to consider the same possibility.

Charger

What exactly do you want to achieve . I am asruffasabadgersarse as a mechanic and if it's no revvin it's head off, or conking out and the plugs are tanish after a blast I'm happy .as for sooty plugs as long as they are not making it hard to start
Stuff it. I have also been told that the newer plugs don't give a good heavy spark if contaminated.

So buy plenty plus or clean the old ones with oven cleaner.
My bike is 69. 50k plus miles original carbs, no black reek but got to flood when warm.

I hate spark plugs and carbs. J

Nortiboy said:

There is no setting on the pilot screws, just a starting point. If you can go from 1.5 to 3 turns without a difference, I would mechanically clean the idle jets. That should not happen.

Click to expand...

The mixture screws can be a little bit either side of 1.5 turns for best running, but if they're not somewhere close to that there's something wrong. If the engine runs better (or runs at all) with the screws almost fully in, the pilot jet is probably blocked (or too small). That's not what's happening.

If the engine still runs happily with the mixture screw at 3 turns out,and black smoke is coming out the exhaust,the pilot jet is oversize.Even if the carb has pressed-in pilot jets, the body is often tapped 5BA above the float, to allow a screw-in pilot jet to be fitted. That's the easiest way to fix oversize pressed-in pilot jets.

Keith1069 mayhave asked the most pertinent question. You do know that the bike is meant to run with the choke cable fully tensioned and when the choke lever looks like it is in the rest position it is actually on. This looks counter intuitive and many first time British owners make this mistake. I would also recommend that you do all of your diagnosis with the air filters removed.

Hm maybe the pilot got over probed opened up clearing in past. As plugs said to foul right away there is no danger to disconnect head oil lines [into catcher and even ride off dozens of miles] to see if plugs last longer to know if too much oil fouling might be stopping the show but every case I've had of oil fouling left no doubt d/t mufflers smoke/smell. If pilot jet too big might still try to lower float to see if brings pilot screw into effective range for clue on next move. Only need to drop bowls to try that.