will not run properly

johnny Lagdon · Mar 29, 2020

I bought a 73 - 74 850, with an alleged new engine new carbs etc, tri spark ignition, etc
I have completed everything wrong with the bike and am trying to get running properly.
It will start, but coughs and splutters, kicks back and generally very undisciplined! I have checked ignition, static timed and double checked, done self testing procedure, all good. Carbs have been ultrasonically cleaned and set and synced as well as I can. Battery fully charged. Tappets set. Compression checked. new fuel. I have added a MK3 type ground cable direct from engine to battery.
Running out of ideas...
Any wisdom from the assembled?
Thanks very much, hair being torn out in isolation

Tornado · Mar 29, 2020

Carb age? Ultrasonic is generally not considered sufficient for clearing the pilot jets on Amals. You need to poke in there with a piano wire or better yet, a #72(?) Drill bit so as to physically remove crud.

With float bowl off, push a WD40 straw up the fuel pick up opening on body underside and work it past the sharp bend in the passage so it gets all the way to the actual jet. Now block air side using the air mixture screw fully turned in and squirt carb cleaner in straw. You should see two strong streams coming up the tiny holes in the carb throat floor.

Check out Bushmans Amal tuning guide here for more details:
http://www.jba.bc.ca/Bushmans Carb Tuning.html

1up3down · Mar 29, 2020

you may have static checked timing but you do need to put a strobe light on it
and put in new plugs if you have not already
I stil feel that what is perceived as carburation more often results in an electrical fix

kicking back is a too far advanced ignition timing

HRD · Mar 29, 2020

1 When you first purchased this bike did it run correctly or is this a project bike that you have not seen running ?
2 As 1up3down said kick back is a timing issue .

Scout63 · Mar 29, 2020

#78 drill bit or in a pinch a .016” guitar string. I ultrasonically cleaned my Amal 932s and it wouldn’t start. I physically cleaned the pilot jets per the Bushmans article and this solved the problem. I’m not sure about the kickback. Best of luck.

jbruney · Mar 29, 2020

Sounds like timing to me also. Perhaps a combo.

Scout63 · Mar 29, 2020

Maybe check TDC with a piston stop and degree wheel and recheck the static timing?

acadian · Mar 29, 2020

Scout63 said:
Maybe check TDC with a piston stop and degree wheel and recheck the static timing?

This. Verify the marks on the timing gauge at 28 BTDC (for thr Trispark) with a degree wheel, then time it with a strobe light.

Tornado · Mar 29, 2020

acadian said:
This. Verify the marks on the timing gauge at 28 BTDC (for thr Trispark) with a degree wheel, then time it with a strobe light.

++1

Just to be clear, the timing scale on the primary cover has been known to be off by quite a few degrees on some bikes. Need to verify with the timing wheel/piston stop method to know for sure on a bike of unknown providence.

Fullauto · Mar 29, 2020

Who built the motor?

Fast Eddie · Mar 30, 2020

Dunno if this applies to you Johnnie, but the fact the Norton cam goes backwards has caught me out when static timing the Tri-Spark before!

And now I have to repeat my old ‘stuck record’ trick: plugs, plugs, plugs... at times like this, one should always do the simple stuff first. Fouled plugs, old plugs, duff new plugs, fake plugs are ALL capable of giving the symptoms you describe. Always try new plugs first. You don’t have to through the old ones away until you’ve proved they’re duff.

johnny Lagdon · Mar 31, 2020

Fullauto said:
Who built the motor?

don,t know, apparently it came from QLD, has brand new cases. has good compression both sides. However there must be a shortage of Thackeray washers in Q.L.D...

johnny Lagdon · Mar 31, 2020

Fast Eddie said:
Dunno if this applies to you Johnnie, but the fact the Norton cam goes backwards has caught me out when static timing the Tri-Spark before!

And now I have to repeat my old ‘stuck record’ trick: plugs, plugs, plugs... at times like this, one should always do the simple stuff first. Fouled plugs, old plugs, duff new plugs, fake plugs are ALL capable of giving the symptoms you describe. Always try new plugs first. You don’t have to through the old ones away until you’ve proved they’re duff.

I put brand new NGK BP6ES in it... no change

johnny Lagdon · Mar 31, 2020

Tornado said:
Carb age? Ultrasonic is generally not considered sufficient for clearing the pilot jets on Amals. You need to poke in there with a piano wire or better yet, a #72(?) Drill bit so as to physically remove crud.

With float bowl off, push a WD40 straw up the fuel pick up opening on body underside and work it past the sharp bend in the passage so it gets all the way to the actual jet. Now block air side using the air mixture screw fully turned in and squirt carb cleaner in straw. You should see two strong streams coming up the tiny holes in the carb throat floor.

Check out Bushmans Amal tuning guide here for more details:
http://www.jba.bc.ca/Bushmans Carb Tuning.html

brand new

johnny Lagdon · Mar 31, 2020

Update:
I am swapping carbs over from another bike that, whilst not brand new, are sleeved and I know run well. If that doesnt change anything will do same with ignition

johnny Lagdon · Apr 2, 2020

Carb swap fixed problem. Bran new problematic carbs going in the ultrasonic clearer again

concours · Apr 2, 2020

Please. Stop.
The ultrasonic is not the end all. The passages must ALL BE MECHANICALLY CLEANED. As in poked with wires, the flow then VERIFIED with an aerosol stream of solvent. Half a century of carb cleaning. You haven’t yet cleaned them as best you can. An improved process..

Tornado · Apr 2, 2020

Also, there have been reports of new carbs, even the much vaunted Amal Premiers, having swarf blockages in the drilled passages right out of the box.
Got to get in there with something solid to have a poke through.

will not run properly

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