Smoke issues

[G3L1946]

Good morning all,

Just replaced my carburettor with a replacement from Amal ( original fitted was beyond economic repair ). Now being able to start and have the engine running I’m now conscious of other problems. The exhaust smokes ( blue/white) more than acceptable. The bike does suffer from wet sumping quite badly. Knowing this I drained the sump prior to starting in the hope this could be causing the problem. Initially my hopes were raised as the smoke was very less apparent. Hopes then dashed when smoke reappeared. I did also notice that when kicking over with valve lifter open the engine ‘popped’ through the exhaust? Residual fuel igniting? Probably something completely different!
My thought now moves towards piston and or piston rings. When I reassembled the engine, having performed a restoration of the machine, the piston appeared fine as did the rings ( wound ). If I need to replace the piston and rings would I be better replacing with a JP piston set ( as in club stores) or is there something that can be done with the wound piston? I’ll obviously need to deal with the wet sumping issue at some point. I considered borrowing a compression tester but not sure if this would be any real help. The piston is probably quite old and is stamped +020”, or just replace rings if this can be be done? If replacement is recommended would I replace with a +020 ? The bore seems pretty much in good shape. Anything I may have missed causing the excessive smoke? Replacement of the oil plunger ( 012967 )?
G3LS 1955.
Any help, as always, much appreciated.

Steve

[jackstringer]

More importantly, does it ride?

I have had bikes that have sat for years and need a little bit of a ride to clear all the old oil etc away. If you are getting good compression, I would just carry on and fix the piston when it dies.

[G3L1946]

I’m still ironing out a clutch problem , but basically, it would ride. I’m concerned about the amount of smoke on two levels. 1, is it damaging anything whilst wasting precious oil and 2, environmental. ( coupled with will I get a tug from the boys in blue).
It starts first kick so maybe a short spin might clear it out?

Thanks,
Steve

[SPRIDDLER]

Were you using the bike and did the engine smoke like that before you rebuilt it?

I did also notice that when kicking over with valve lifter open the engine ‘popped’ through the exhaust?

That's quite normal in my experience when kicking it over as there'll still be some compression with the valve lifted.
Just as a trick whilst trickling along I have occasionally operated the valve lifter with the throttle open to 'entertain' bystanders.

1, is it damaging anything whilst wasting precious oil

No it won't damage anything but the sparkling plug may become oiled, particularly/possibly making starting a bit tricky.

and 2, environmental. ( coupled with will I get a tug from the boys in blue).

I doubt that the boys will pull you in, unless it's affecting other road users' visibility. Mind you, if it's smoking badly all the time you'll need to sort it out anyway.

It starts first kick so maybe a short spin might clear it out?

It won't hurt to give it a go.

-------------------

The wire-wound pistons were designed to run with around 1 to 1.5 thou clearance so bear in mind that a JP or other non wire-wound piston will need about 3.5 to 4.0 thou clearance.
There are many things to check when diagnosing smoking issues, including obstructed oil return (the pick-up) drilling in the c/case, obstructed/kinked oil return pipe, air leak at the oil pump end plates etc.
If you have fitted a new filter (not sure about a '55 which I think has the slab oil tank) some new filters have too much felt rolled over the ends which can impede oil return.

Filter oil faulty.jpg

Filter from Club Spares..........

Filter oil Correct.jpg

[G3L1946]

Hi Spriddler,
Nice to hear from you again. O.K. I’m unable to comment as to smoking prior to rebuild as it didn’t run. This was due to a multitude of issues ( many subject of past posts ) including incorrect carburettor and faulty magneto. The oil filter was replaced (and is shown your second photo) and sourced from the club. When rebuilding the bike I did liberally coat the inside of the tank with oil which I later emptied. Might be a bit of that lingering about? I think I’ll give it little test up the road ( avoiding the A64!) and see how we go. Still figuring out the clutch issue. Can’t seem to obtain sufficient clearance for non clunking, difficult gear shift. Reset centre thrust nut of clutch, re set springs but movement seems minimal. Ensured ball was inserted prior to new replacement actuator rod. Set cable to the books 1/8” lift.
Such fun,

Cheers,

Steve

[SPRIDDLER]

Just replaced my carburettor with a replacement from Amal ( original fitted was beyond economic repair ).

As an afterthought...........

Having learned from Jack Stringer's earlier post and been on a wild goose chase trying to solve an ignition issue which turned out to be a fuel starvation problem have you ensured that the new carb is correctly jetted and that the smoke isn't due to over-richness? I appreciate that the smoke from an over-rich setting is usually described as 'black' but one man's black may be another's blue. Is the sparking plug becoming sooty or is it oily? (You'll not know I suppose until you've ridden it a while).

[SPRIDDLER]

Hi Spriddler,
Nice to hear from you again.

You're too kind. Most of my chums turn out their shed light and hide when they hear me coughing my way up their garden.
However, Resto Ray hasn't quite got the hang of hiding yet.

CIMG1654.JPG

Still figuring out the clutch issue. Can’t seem to obtain sufficient clearance for non clunking, Set cable to the books 1/8” lift.

Trying to visualise my B52 clutch lift (plates separation) but I'm pretty sure it's more than 1/8". Do you have the correct thrust rod? It should be 9 7/8" long for the 4 plate clutch which is what you should have, and 10 3/16" for the 5 plate clutch (which you just might have if the bike is new to you).

Re the carb (again)....You've fitted a new one. On later carbs no fibre washer should be fitted between the fuel feed banjo and the float chamber. If you've fitted one it will raise the fuel level in the float chamber resulting in over-richness.

Re the piston........On reflection I'm surprised that a '55 would have wire-wound piston as I think they were discontinued by the factory well before 1955.

[G3L1946]

Hi Spriddler,

I have checked the jets and they are correct as is the bore and slide. Needle is set on centre slot as per ‘55 manual. It is as a 376/5 should be. There is a fibre washer under the banjo to body but this was fitted on delivery.Would it not be susceptible to leakage without? It has the updated ‘stay up float’.
The thrust rod is the correct length, again, sourced from the club. Incidentally, when I stripped the clutch down originally it had a second ball at the other end ( a ball each end thus lengthening it ). I did not replace this on advice. The clutch friction plates were also replaced with new ones.
The piston is definitely wire wound. I’d never seen one before so I asked! As it’s +020 maybe a previous owner had NOS at hand? The 1/8” lift is cable lifting from out of its mounting ferrule ( screw adjuster ) on the kick starter case. I’ve had another go at adjusting it but still not sure I’ve solved it.Always tomorrow, hopefully!
On a separate note, is that a 46/47 G3L lurking in the shed? Been after one of those for ages!

Regards,

Steve

[Duncan]

It may be worth checking that you do not have undue wear in the thrust dowel 35-3-4
https://www.amoc-parts.com//store/comer ... duct=21995

[G3L1946]

Thank you Duncan, I will check that out.
Regards,
Steve

Post. Checked the part, I actually replaced it but somehow forgot I had! Only confirmed this when doubled checked invoice from club and found it there!

Steve