Smoooooking

[numbnut]

Hi all. Just finished restoring a vespa 125 px. Can you help with a question please. I might get ridiculed for asking but my knowledge of these machines is still limited.

When I finished building it I put 2 litres of 50:1 fuel in the tank until the self oiling system got primed. Starts up instantly and runs ok (to my untrained ear) but lots of smoke. Initially thought that's just oil from assembly but kept doing it. So drained the fuel tank and refilled with just fuel. On the basis maybe it's getting double dose oil if the autolub now working ( I don't know how they take to prime). Still smoking bad. It's hard to say if it's white blue or grey smoke. Looking on tinternet it would seem the obvious cause is I've damaged or wrongly fitted the clutch side seal. My question is can I drain the gearbox oil and run the engine to prove this one way or the other (static and in neutral). Also I don't know if the carb is set right can a really rich mix cause a lot of smoke (too much to make it usable).
If the engine has to come out again and be stripped then so be it but don't want to do that and find that in my ignorance it might be something simple. So can I run the engine with no gearbox oil without damaging it ?

Thanks guys. Ps I live in Dartford Kent anyone recommend a good scoot garage for having it checked over and mot'd ?

[phattanglo]

If you don't know the answer then it's a valid question.
I don't know if you could test it without gearbox damage as there would still be some residual oil around the seal to be sucked through but I don't know how long oil would stay on the cogs as they will still be rotating even in neutral while the oil around the seal dried up.
A very rich set up probably would be smoky but if the pilot screw is 1.5 to 2.5 turns out from fully in it shouldn't be miles off.
The default setting is around 1.5 turns for a Dellorto 2.5 turns for a Spaco as the thread pitch is different.
I've heard you can spray wd40 or similar behind the clutch while the engine is running and if there's a leak it may change the revs but I think if you've newly rebuilt the engine you're better off stripping and checking for the sake of a couple of hours work and a couple of quid for a new seal.

I suppose you could take the clutch off completely and start your scoot with a drill and socket on the flywheel nut but honestly for the time it would take you I'd strip and check.

[numbnut]

Thank you for your quick reply, much appreciate your advice. I will strip the engine down and have a look, after all doesn't look like I will be going anywhere soon. I was pretty sure it would need a strip and inspect but didn't want to do that and find out that two strokes can have these symptoms because of something simpler like tuning or autolubs can over supply if faulty.

Thanks again, will update post once I've sorted it.

[alan34]

Hello did you run the engine till it was hot my px smokes when stood for3to4 days but clears when hot. when scoots have been stood 2 stroke oil drips into crankcase and the longer u leave it the more it will smoke this happened to me and thinking gear oil was getting into crankcase I stripped it rebuilt and after it smoked again then I found it was dripping 2stroke through carb as it is gravety fed.this is a common thing on px hope this helps cheers alan.

[numbnut]

Thanks for that Alan. Maybe another dumb question but how long does it take for engine to get hot ? I have ran it several times but probably for not much longer then 7 or 8 minutes at the most.  Then it's stationery and mixture of revving and tick over.  

[phattanglo]

I would say 15/20 minutes of riding rather than sat ticking over. To be fair my scoot smokes a little bit in the morning but I pre mix my oil so gravity isn't going to have an effect and by the time I've got to work there's practically no smoke at all.

[swm]

I'm no expert but !!!  Might be worth trying before engine strip .  3 ways to see if your seal has gone are -

1 -  Gear oil smells of petrol

2 -  Loads of billowing white smoke ( you'd know !) 

3 -  Remove breather on clutch cover and plug  with your finger . If revs drop it's gone . ( see here modernvespa.com/forum/topic78579 )

As both alan34 and phattanglo say , mine smokes when cold but clears after a short while of riding . (mines tuned so 3% pre mix) Can you give it a run and see if it clears ?

Also, without starting the old "which 2 stroke" debate , some oils are smokier than others !

I think I've read somewhere on other forums (prob Scooterotica) that you can run it not ride it for a SHORT while , with  a drained gearbox . Have a search !

Good luck !

Cheers

[numbnut]

Thanks guys for the advice. Riding it for 15-20 mins will be a problem as I've never ridden a scooter. No insurance tax or mot. But I will follow SWM advice and check the oil and the breather. Will update this post when I know more. Thanks again guys.

[phattanglo]

Shame about the lockdown, I'm sure a member local to you would have been happy to take a look.
We'll always lend a hand when we can.

[numbnut]

Thank you guys for your advice. You were spot on. When I stripped the engine down again I found the clutch side seal had split between the blue seal and the metal casing. Not sure how that happened as it was a new seal and bike hasn't been used but the engine is now smoke free.

On the downside now the clutch doesn't disconnect when I operate it. Adjusted up the cable and it's all moving externally correctly. Stripped the clutch out and all looks fine. Doesn't rattle so don't think any springs are broken and it looks correct so not sure what's happening there. When it's in gear , pulling the clutch lever doesn't disconnect the drive. Could it be a gearbox problem ? Appears to get all the gears when stationary.

Anyway thanks again for your advice on the smoking engine problem.

[scooterg]

Pull clutch lever then tie it ,(pulled in) cable tie , string
Leave scooter running for a good ten mins ,
Cut ties Then try clutch again
Hopefully all’s ok

[numbnut]

Many thanks Scooterg. I will try that today. Just for my education what is the theory of doing this ? Thanks. Dave

[L4NFF]

May 21, 2020 11:21:09 GMT numbnut said:

Many thanks Scooterg. I will try that today. Just for my education what is the theory of doing this ? Thanks. Dave

  I believe Scooterg may be thinking your clutch plates are sticking and in doing what he advises will give the chance for the plates to release and for oil to get between the corks and plates. It is unusual for a clutch to stick, on your recent engine strip down you didnt bang the clutch basket at all or drop the clutch unit etc. ? As this could have prevented the clutch releasing by fouling on the basket.

[numbnut]

Thanks L4NFF. I have done did as prescribed. Maybe I'm mistaken in my understanding of how bike clutches work as a complete novice. I'm ok with cars just know very little about bikes. On a car holding the clutch in like that would just wear out the the thrust bearing. Now maybe one of you guys can help me with a bit more of your knowledge please. Because maybe I'm mistaken and the clutch is fine. With the back jacked up so rear wheel is off the floor if I start the engine and out it in first gear and release the clutch the rear wheel rotates as you expect. If I pull the clutch in the wheel still spins. If I apply the footbrake with the clutch held in the wheel stops but the engine still ticks over without faultering and wheel is stationery. Release footbrake and rear wheel starts to spin again slowly and then picking up speed. Stop the engine with bike in first gear pull clutch in I can't spin the wheel. My question is is this normal for a bike clutch. ? Wheel on the floor, start engine put in first with clutch in and bike doesn't stall so clutch must be working. It just doesn't seem to fully disengage when I pull clutch in. Adjust clutch right up and it makes no difference. To me from cars when you press the clutch the engine and transmission are completely disconnected. Should it be the same on bikes ?

[L4NFF]

So what you have desribed sounds perfectly normal to me. If the wheel is off the ground and you select neutral the rear wheel will more than likely spin but you would be able to stop it very easily with a gloved hand unless the clutch was grabbing which would mean it isnt adjusted up correctly. The reason it may spin in neutral is because of friction. The crank is spinning the clutch, the clutch is bathed in oil and has an element of friction and stickyness. The clutch in turn will then rotate the nice and free gearbox and the back wheel will rotate. When you are setting the clutch, make sure you move the clutch arm beyond where it stops a little, before tightening the cable, that way you will get a bit more disengagement and you can work back in from there.

[scooterg]

Engine off put in first gear .. Pull clutch in and walk the scooter,
Let go of clutch ,,should bite
Car not got a WET clutch..
on a bike I got told to ride the clutch to go very very slow,utun crawl at lights,
Amazing how much control you have riding a clutch.and how slow you can go (without putting a foot down)

[numbnut]

Thank you guys. So I have spent a couple of days trying to sort a problem that doesn't exist. Ha. Oh well love and learn. I have adjusted the clutch to just take out the free play in the actuating arm. This is all the complete opposite of what I was taught in driving a car i.e riding the clutch and the fact that when you do ride the clutch you won't damage it. Many thanks again for your help and advice. We live and learn.

[scooterg]

Glad it’s sorted 👍