Heavy ball bearing when turning engine off

[paulwaite]

This is the same Rally200 engine that stars in the "Lightened Flywheel not firing spark," in this Technical section, but that problem is now solved, as it was not a problem in the end.

But first some background on this engine. I bought around 2010 from someone who knows someone else type of buy. The purchaser told me that the only thing wrong was the kickstart slipped, so it would need sorting. Never stripped a Vespa engine, so bought Sausages great Video and split the engine and noted that there was no conventional coiled spring. Posted the thread below and learn't that the rally had the  flat spring. Anyway, in the end, the coiled spring went in and engine into my GS

scooterotica.org/forum/viewtopic.php?f=8&t=29052

Kick start still slipped, but found that the clutch had sheared the wood ruff key and the clutch was in a bad state, so replaced. Anyway, it was a lesson learn't on how vespa engines work, as they are not a direct comparison with Lambretta engines.

Move on to the last 2 weeks and yesterday, fired up the engine with no problems, except for this heavy rattle when i turn off the engine. See video below.

The sound, as the engine shuts down, is like a heavy ball bearing spinning around a metal can as the ball bearing  slowly comes to a halt. Its hard to say where its coming from, but it could be the top end, or could it be that additional kick start spring, but i doubt it is the spring. This noise does not seem to be there when the engine is running.

Clearly i will need to strip down, but any clues before I rip every living part out of the engine. 

[vespasco]

Check all the bearings if you can hear a bearing type noise......
Flywheel, Clutch, primary drive, big end, small end.
It wont be the driveshaft but theyd also be worth checking while youre there.

Or knackered clutch plates/drive cog spinning round?

[sime66]

I don't know much, but I have watched your film and heard the sound, and have to ask; is your kick-start returning to fully up? (looks a bit like it's not - just for a split-second of the film). Is it possible that it isn't, and that the starter cog isn't disengaging properly and catching as the engine come to a stop? Just a thought; probably nonsense - no harm done if it is nonsense.

[vespasco]

I just had a quick look at the film. It doesn't sound like bearings, more like sime says

[henri]

ooh video scooter porn ,best start to my sunday , as above , theres been a issue with kicker before so my main suspects going to be that again . an as sime n vespaco says it dont sound bearing but kicker cog.either way i'm afraid its a full strip down n look-see . H

[paulwaite]

Think that I've found the source of the heavy metallic sound as the engine shuts down, but still a Vespa novice, so could just do with others thoughts, plus a couple of other questions before I put it together again.

As I released the exhaust clam, the tubular exhaust flange came off as well, in otherwords, it was not screwed into the barrel. And the clanging noise it made when struck sounds just the same as when the engine stops. Anyway, glad I found this as it is an air leak to seal. But just to make sure, has anyone else had a loose one making the rattle sound.




Anyway, whilst I'm at it I split the casing to see if there was anything else and this is the kickstart mechanism. Note the kickstatr spring that I put in at the time, but I understand that the Rally engine didn't need a coil spring as it had that sprung plate. However, the couil spring doesn't seem to be harming anything, so would you recommend keeping the coil spring in as an extra help to the sprung plate.




Then looking at the small end, there is a big gap between the piuston and conrod. Now on a Lambretta, this is not an issue as the piston is fixed in the barrel and in general, no need to shim up. So I presume this will be the same for a Vespa




Finally, the shaft that moves in and out to change the gears. I can pull and push this shaft and it has around 3mm of horizontal play; is this normal?




Thanks

Paul

[henri]

1 , never heard of a barrel stub unscrewing before , are the threads in barrel damaged ,main suspects bodgery/poor assembly in my mind .
2 theres always wide clearances on vespa piston small ends ,no shimming needed ,that looks normal to me .
3 with out the support of selecter end roller bearing an fly-side cases a output shaft that wobbles/droops is normal ,3mm sounds about the max you'd accept tho . maybe a new drive side output shaft bearings called for if you want less play .tho it sounds "usable" as is ,its a judgement call an without hands on hard to say. if me i'd decide on it by how long engines going to be used for before re-bearing/re-build . couple of months/til nxt mot i'd use , not wanting to split again for fore-seeable future i'd replace .
4 , tut-tut, has somebody been hard on his spanners/toys , thats you in the naughty corner with me then . H

[vespasco]

Coil spring... Have the cases been machined for the spring to sit flat on your cases? (i cant remember without looking)

While you're there, check the cruxiform for signs of wear. (remember its a left hand thread )!
You can also check the play in the gear stack

The cylinder stud...as H says. Likely a sloppy rebuild and it could cause the noise mentioned.

[henri]

i hesitated to say earlier ,but if it was me an i found a engine were guy couldnt even get a barrel stub in right i'd doubt all his work . for piece of mind i'd have to tear it down n re-build rather than ride a possible grenade . H

[paulwaite]

Out all day yesterday, so no chance to get back, but thanks for replies.
The last photo Henri shows the selector rod. What I meant by the movement is that it pushes in horizontally and pulls out by up to 3mm, is this normal. In any event, I'll strip down and check cruciform, not that I know what is worn or not, but I can always google that. As for being heavy handed, I'm usually stripping or shearing things, even when using correct torque. But that's a special spanner for getting to the bretta exhaust nuts, or so that add told me, but it was bit of a lie.
As for the barrel stub, all looks OK thread wise, so will fix back using Copper RTV Silicone or loctite.
And Vespasco, the case does have a flat part machined in, so I will probably keep the coil spring there. As for the Rally, I haven't forgotten your suggestions about fuel etc from another thread, but at the moments I'm consumed with maintenance and what with the weather, haven't had chance to take it out since I stripped down carb.

Garage as at today, all need tinkering to some extent. Gold series 2 is the one that I sheared the layshaft. Now replaced with a new shaft, but in rush, think that I have shimmed the gears too tight.

[henri]

aah , in an out by 3mm sounds about right to me , the cruccys moving inside the loose gear from 1st to neutral an then being stopped by the driving dogs on 2nd gear , if you spin the shaft as you move selecter it will line up an move into 2nd. then 3rd n 4th ,thats normal ,dont forget the selecter rods a lefty thread ,an wear on a cruccy is obvious .but there so cheap its a norm to change at every time .
did wonder if the spanner was a "special" but in piccy looked like there was no jaw on 1 side at all , an no what ya mean about lammie exhaust nuts , them n bridge piece fixings are the biggest pain on them .lovely looking shed by the way ,have to say its the mustard yellow GP for me , H

[paulwaite]

Well, got engine casings back on last week, whilst engine was still in the frame. Just put exhaust on this morning and fired the motor up. Unfortunately, the noise is still there, but does sound to be coming from the cylinder. So to eliminate things and avoid a full engine out strip, I'm thinking piston slab. So I'll take off the top end and piston and check it for bore clearance. However, how do you get the gudgeon pin out, because it looks like you need to drive it from the side of the piston that is close to the frame?

But just thinking aloud, I suppose I can leave the piston on the con rod, take off the rings and slide the barrel back on and check for bore clearance that way, but am I right?

Thanks

[henri]

yes , an whilst rings are off if ya had another piston ya can push em down bore an measure gap . but i'd want to have that piston off n check little end . remove outer circlip an either fiddle around with a mirror an circlip pliers an push piston pin thru ,or warm piston an use a stubby screwdriver to push it outwards .there a light fit an will move fairly easily . H

[shipscat]

Dec 11, 2015 15:11:30 GMT paulwaite said:

Well, got engine casings back on last week, whilst engine was still in the frame. Just put exhaust on this morning and fired the motor up. Unfortunately, the noise is still there, but does sound to be coming from the cylinder. So to eliminate things and avoid a full engine out strip, I'm thinking piston slab. So I'll take off the top end and piston and check it for bore clearance. However, how do you get the gudgeon pin out, because it looks like you need to drive it from the side of the piston that is close to the frame?

But just thinking aloud, I suppose I can leave the piston on the con rod, take off the rings and slide the barrel back on and check for bore clearance that way, but am I right?

Thanks

this may sound like i'm taking the p*sh but
get a long thin screwdriver and press on the engine in various places with engine running and put your ear to the handle of screwdriver = stethoscope

[henri]

ive a fancy solid probe stethascope thingy , but mostly do as shipscat says ,tho, do push screwydriver with palm of hand an listen to back of hand,will allow ya to narrow down the areas to inspect , H

[paulwaite]

Solved it.

Tried the stethoscope thing, but no rattle on top end. Then I thought it may be a loose exhaust baffle, but not so.

Therefore, took the engine out and found a badly built clutch in photo. The top plate is in the middle of the stack and one of the middle plates was on the top of the stack, but running loose. So when the engine turned off, this plate kept on spinning. As for top end, all rings and piston within tolerance. I could have checked the clutch without taking the engine out, but I'll split casings and replace the clutch side oil seal as I don't want to be taking the engine out again.

Just need to stop myself putting back a Malossi top end, see other thread.

[henri]

what,thats insane bodgery , i'd def have that lump apart ,god knows what else is lurking inside ,bubble gum clutch seals ,back to front gears shimmed with coke cans , lord lucan ,the answer to world peace .anything .H