Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

Guessing off road at least 20 years. Bore and piston look good/oil at correct level. One conrod circlip was incomplete/damaged(the curly bit to fit it missing).

Turning the engine over....mucho noisio/rumblio down below !

I've had these bikes before and they are normally quite bullet-broof....I was hoping a good plan might be to fill the engine with something suitable and let it sit and work it's magic......or am I being unrealistic. John (in the UK).

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Re: Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

How much play in the rod in and out , without moving the crank ?

Re: Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

daan SJAARLOOS /

I have the orange version of this. Love this colour too. And you have the three speed instead of two. Nice!

Id check for play in the crankshaft too. Does it move freely? Id try and flush out the engine to see if the missing circlip bits come out, you dont want those moving around in your cases.

If its been sitting for 20 years its probably best to rebuilt it with fresh seals and bearings anyway so you could opt to take it apart (edited)

Re: Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

John Beever /

Thanks.....doesn't seem to be any play. I too had the orange 2-speed which was almost like new.....sold it 6 months ago and now regret it.....pretty original ones hard to find. This green 3-speed....I reckon a teenager has given it a bit of a hard life and it was then taken off the road. I'll drain the oil....see what comes out !

Re: Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

John Beever /

Small movement sideways.....none up-and-down.....which I'm hoping is a good sign !?

Re: Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

> John Beever wrote:

> -------------------------------------------------------

> Small movement sideways.....none up-and-down.....which I'm hoping is a

> good sign !?

That sounds OK to me .

Have you tried the same test in different locations as you rotate the crank ?

That would be telling .

You might also hold outward pressure on the rod while turning the crank , feeling for any resistance and listening for 'growls' .

Smooth and quiet , but for maybe a bit of bearing sound . Hopefully you know what a good bearing sounds like . ;)

Re: Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

John Beever /

Thanks....I will investigate further. I've rested my finger under rod and rotated crank with pedal....rough constant friction noise all the way.

The right pedal has at some stage been bent inwards which would take some force. I wonder if 20/30/40 years ago...maybe bike was abused by young lads then taken off the road. I guess the force to bend a pedal might damage the crank.

The bike (like many mopeds) has not been loved but I'd like to save it if possible.

Not sure how complicated to split one of these engines ?

Re: Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

Pushrod Fifty /

Could be the dry crank bearings that you hear, or it is partially in gear. I have a red one, I like the green.

Re: Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

Pushrod Fifty /

Re: Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

Pull the flywheel cover and turn the crank by hand . Feel and listen . ;)

Re: Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

> Pushrod Fifty wrote:

> -------------------------------------------------------

> https://www.motorwestmotorcycles.com/shop/index.php?main_page=product_info&cPath=1&products_id=395&zenid=28gdvlrrnt9s6dj0i3k3pc1e20

>

> There is a download somewhere for a service manual.

OR :

https://puchmaxi.co.uk/manuals/

Re: Puch MV50 Sports Moped (1975)....Engine rumble.Unused 20+years.

John Beever /

So I've had piston/head off.....all good. No noticeable play on rod in different positions (slight sideways movement). Moderate bearing-type noise when rotating with pedal......with piston/head re-installed there is much more noise and quite hard to turn over.

So I guess all the main bearings are shot ? A complete new set is 42 euros but I'm not sure/confident about taking engine apart really with my limited skills/tools. Or is this relatively straight-forward ? Any suggestions appreciated.

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