Modern Vespa

Seized and locked the back wheel up, was free off the kickstart, fired up after a few attempts and limped home well down on power.

This is a piston ported largeframe engine with a dellorto UA 19 carb.

The barrel was already worn needing a rebore and has already been taken out to 58.5, and it's also missing a fin alone with part of the sealing surface. It wasn't responding well to jetting, no rich or lean feel, passed a leak test, low temps around 140F and just not wanting to rev over around 5200 and I guess I went too far with a 76 main as temp suddenly spiked but only to 290F and it locked up skidding a fair way before I grabbed the clutch.

What I'm now looking for is another motor - something less oddball with good parts support standard 200 preferred but I'm open to options

I may still rebuild this motor as a spare if I can find a top end, I don't fancy having this one bored out further and trying to find a piston for it. Recambios in Spain have barrels and pistons but wont ship to the UK, other options are piston ported quattrini which would take some effort to do right or opening up the normal inlet in the casing and running a reed valve with a normal 2 port kit.

I think finding a p150 motor or similar and slapping on 177/187 kit would probably be a quick and less expensive path than a 200.

(But…. keep the og motor and find a top end at your leisure when one comes up for a fair price. )

Yes I'd be happy kiting a p150 if I can find one.

I've found some post forwarding services that will do Spain to UK for 20 to 30 euro so I can get the parts for 250 if nothing else comes up.

You will then have the import tax and the admin fee too. If its £135 or more, 20% plus admin charge and wont be delivered until paid.

I forgot about that, it's the admin charge that always annoys me.

Recambios said to try Buzzsolomoto so I've just emailed them.

I'd still prefer to fit another motor and fix this one when the parts come up, but since I haven't found anything that doesn't need a lot of work then fixing this one might get it back on the road sooner.

Complete decent engines aren't cheap anymore ; LML replacement engines have dried up , I've seen NOS px engines going for £1300 upwards . You might want to find a wreck with a decent engine ? I was quoted 500 euros for a pkxl engine in bits from Barcelona , which would be another 100 in VAT, plus admin and postage , pushing 675 euros for possible junk .

I've been looking for a while since even when fixed this motor is only 6.5hp with no easy upgrade option. So far I've only seen motors which look like they've got 200 years worth of baked on grime before being left in a field for a while at 300 to 500 and they're normally 2 port, or "new" motors shipped from India that all have the same photo for around 650, or occasionally something high end with aftermarket cases etc for 4k+.

I'd probable take a NOS PX for £1300

https://www.ebay.co.uk/itm/305670218989

This could be an option, but opposite end of the country so I couldn't check it over before buying, and I doubt I'd get the cover over that centre plug head.

I striped the top end today, pics below

I've seen many motovespa TX 200's sell in uk for 1400 to 1600 quid . They look like a T5 , but with a p200 engine. I'm surprised they go so cheap considering you could whip the engine out and use on something else. Then the frame etc can sell on as many T5s are rotten through . The TX having lived its life on Spanish heat have very solid bodies . An idea maybe for you ?

I'd be reluctant to break a scooter, I'd more than likely buy it and decide it was too good to break, and if I did break it then selling parts is always a major hassle.

I've found a px150 collecting it tonight. I need to decide between running it as is for the summer vs splitting it to check it over and probably kitting it.

I'm tempted to see how the MotoVespa motor runs after just removing the seize marks, if it's usable I'll split the PX if it's not I'll fit the PX as it's.
I haven't had a vespa motor apart before so I don't want to rush it.

Also need to decide what ignition to run on the PX, probably the vape road ac from the current motor but I think the crank taper will be different so I'll need a different flywheel.

It was said that the Px 150 was the best capacity for all round reliability and economical; didn't drink fuel like the P2 and had a bit more torque than the 125. If I could find one I wouldn't kit it, I'd just enjoy the trouble free scootering for what it is .

I doubt this one is going to be trouble free without a rebuild, it looks neglected and came out of a rough scooter with loads of rot, it's filthy and missing covers.


The scooter is just for fun local rides, no touring, no commuting, and I chose to spend more time working on bikes than riding them so I don't need to be sensible with it. Although I also don't want a narrow power band high up the rev range.
Being able to maintain 55 to 60 on slight hills for a couple of junctions (A1 and A19) isn't essential but would really open up where I can ride it.

For some reason I didn't think to scrape off enough grime to check the model number on the engine when buying it. I've now looked and it's VNX1M which isn't listed on scooter help but from a few searches it seems to be a 1982 PX125E.
I'm not ready to start on it though, got to fit a new swingarm and sprocket carrier on a CCM to get it out of the way.

With a lot of drilling, dremeling, and a couple of angle grinder cuts I eventually got the swingarm out of the CCM, the remains of the pivot bolt out of the engine cradle, the new swingarm in, the front engine mount welded up and it passed an MOT so I've finally got some space in the workshop again.

Buzzsolomoto are picking up a reconditioned barrel and piston for me from Recambios in Spain so I'll be able to rebuild the MotoVespa 150. That'll hopefully get it back on the road quickly so I can take my time on the PX 125 motor.

So for on the PX; I've scrubbed the crud off it with a range of wire brushes, removed the exhaust which I'm told was off a T5 but that doesn't matter since it's scrap anyway having rusted through at the rear seam, found my flywheel puller doesn't fit, and found an odd nut on the rear hub.
So it's time to order some tools, what other tools will I need to strip it down along with the puller and hub socket? I've seen a tool for pushing the crank out to split the cases, is this needed on a PX?

I've also come across the first problem, the remains of an exhaust mount are seized in the swingarm. Somone has had a go at it in the past and basically just flared over both ends turning it into a big rivet, I've lightly skimmed it with a flap wheel to remove the flared bits. What's the best approach for this, welding a nut on to try to heat and rotate it to crack it loose, or putting it in a press? I've got a MIG and a 10 ton press. Since one side is broke on an angle you can only really go at it from one side, pics below.

this is the type that passes through the case? if so, heat and your press will do the job. you may need to set it up in a mill the drill through the flared end. I was set a case once with this situation, used heat, punch, and a 5 pound hammer and nocked it free.

If this is the type that screws into the case, then You will need to find a machinist to do this right. Here is how i do it

It the type that passes through, I'm assuming it's just a hole but I don't know for certain if they are threaded in. I think I've got rid of the flared end with the flap wheel, I don't have a mill or even a pillar drill but I could probably trim it a bit with a Dremel to make sure the flare is all gone.

it shouldn't be threaded for pass-through type. i would heat it up and use your press.

Thanks GickSpeed

I've also now realised that it's some kind of lock washer setup on the rear hub not a many sided nut, I had been searching for a socket for it.

Flywheel puller wont thread in. Flywheel threads look to be a left hand thread but it's hard to make out, my puller and all of those online that I've just zoomed in on are normal right hand threads. Tried a 3 legged puller and just broke chunks out of the fan, good job I don't plan to reuse it. I'll have to get the magnifier out to see what I'm dealing with.

Weld a large nut onto the flywheel and use the bolt to extract the flywheel. That is one way to do it.

Should not be left handed threads; never heard of it for a Vespa flywheel.

I got the flywheel puller to fit, just needed to clean up the threads a bit more on the flywheel.

It turned out to have a DR kit on it, it's a bit worn though there are groves that you can feel below the exhaust port. Also has a 24.24G carb.

Crank feels good with no play, but has pitting on the taper and scoring in the rotary valve area, I'm concerned that the pad might be chewed up but I haven't spilt the cases yet.

Will a T5 24.24G autolube airbox mounted on a PX clear the frame on a 62 GL?

I've done a few searches and I've seen the odd comment about clearance issues but none of the specified which frames and airboxes were a problem.

Just finished stripping the PX motor, I could do with some advice on the condition of a couple bits.......

The front section of the rotary pad has some deep gouges, the rear doesn't look too bad to me. JB Weld it?

Is the end of the Christmas tree ok? The kick start gear that engages it is quite chewed up, the Christmas tree looks ok too me as it's very consistent across all teeth, but I haven't seen another one close up so I've got nothing to compare it to.

I was told elsewhere that the gears pictured above are ok, and the new starter gear has arrived and meshes with them ok. Also a few searches turned up pics of rotary pads much worse than mine being fixed with JB Weld so it should be ok. I'll order the parts and start the rebuild soon, but I've been working on the MotoVespa engine that's currently on the scooter.......


The recon cylinder and new piston turned up for the MotoVespa engine. Looked spot on, good honing, ring gaps slightly tight so needed filling, all went back together ok. Started first kick which was a shock, first 8 miles of test ride went great, taking it easy kept it under 40 and avoided full throttle, then it nipped up again FFS. Temp was 165F I was keeping an eye on it, I'd just rolled off the throttle slightly to go down a hill when it locked up. I waited about a minute before trying to restart it, only took a couple of kicks and when the dash came back on (no battery) temp was 240F so it had spiked rapidly when it seized. It seemed to run ok the rest of the way home.

I've just moved the needle two notches richer, hopefully that'll help. I'm never sure what order they're numbered in but I've moved it from 2 to 4 or vise versa.

The MotoVespa 150 has ran flawless since that nip up back in September, I guess it just needed that needle position adjustment.

I'm still going to replace it with a PX based BGM 177 over winter, just stared putting it together.

I see you replaced the crank, good move.
What about the rotary pad ? Did you fix it ?

I skimmed the pad with JB Weld, basically just filled in the groves.

Finished assembling the PX 125 BGM 177 but the leak test loses 1psi every 3 min so I'm going to have to track down the leak.

Started out with a bigger leak from a test kit hose, it now seems to be air tight.

What are the other usual suspects?
Transfers are just matched to the gasket so there's plenty of sealing area, and there's a little hylomar on both sides of the gasket.
Case gasket also has a smear of hylomar on it.
Crank seals are new. Clutch side has metal outer so it has a little loctite bearing loc around it.
Head uses a copper gasket on this kit, as it's the only thing I fitted dry and the easiest to access I'm guessing/hoping that it may be the leak.
Exhaust stub is cast as part of the barrel, has a silicone cap on it that I've used successfully to leak test before.
Inlet has a piece of inner tube between it and the airbox.
Pressuring through the spark plug hole using a hose from a compression tester.

I've found a suggestion that under 1psi per min is ok, any views on that?

https://archive.scooterlab.uk/engine-pressure-testing-leak-cheap-tech/

dish soap in water in a spray bottle

pressurize the system

start squirting and look for bubbles - all gasket areas and seals, etc.

Absolutely not. If it holds 6psi for 15mins you're good. Anything less and you're not good.

Found two leaks, big one at the head, small one at the base gasket. Haven't checked the clutch side crank seal, didn't want to spray soapy water in there unnecessarily, I'll fix these leaks and retest first.

To test the clutch side, take off the clutch cover breather nipple. Then make a bubble on top of the hole with your finger dipped in soapy water. There should be no other way out if pressure is seeping to the transmission side.

I haven't assembled the clutch cover yet but that'll take 5 min, if it leaks after the head and base are sorted I'll test it that way.

Test passed

you've made it! and without doing it you'd have had a ton of unpredictable behavior out of that engine.

good work!

Well sorted