Modern Vespa

Can't get hold of the Malossi ones unless I pay over 50 quid. Not paying that.

Did you get the right one?

Shouldn't need to grind down.

3.5mm and 4.3mm variations

https://www.scooter-center.com/en/oil-seal-31x62-1x5-8/3-5mm-bgm-pro-fkm/viton-e10/etahnol-resistant-metal-brown-extra-flat-oil-seal-for-crankshaft-drive-side-vespa-px-from-1984-t5-125cc-cosa-bgm1034m

Postage to UK is double what the seal costs. Rip off.

Can't be helped. Price of logistics these days…

Just grateful people are still making seals for a 40year old engine design so folks like us still get to ride them.

If you've got the corteco seal, just grind it down with a dremel. Takes 5mins.

Loctite it too, there's not much area for the seal to hold onto in the bearing journal… so just to be on the safe side

I watched a video YouTube where some guy flattens the seal rather than grinding it. He made a special tool to do this. I have no loctite and if ordered will take days to get here. That's my build delayed another few days. Lol.

Flatten the lip of the seal…

I think you can do it without any tool or holder (beside the tool used to take material away).

But I'm sure there's plenty of ways to do it.

Loctite isn't a "must", but if you have it, I'd use it. Added safety to avoid having to go back in because the seal popped out.

Seen plenty of engines not have any problems with seals without loctite. Not my bikes though…

I will order some as I don't want to be going in there again for a long time if possible.

All put back together. Waiting for the sealant to dry before leak testing. Guaranteed it leaks from the usual spot. Piece of shit.

Leakdown test done. Masive fail. Pissing out at the same point on the flywheen side Its like the cylinder is not even touching the casing. It was ok up until the point the sealant blew out and pressue drop was almost instant. What the fuck is going on? I fucking give up. Base of cylinder seems flat. Cases seem flat. Used a rule and no gaps.

As said some posts ago, some cylinders are tight on the studs but only on some unlucky engines. The cylinder stops just before the bottom. This is exactly what you are describing.
Clean it all up. Take the studs out one by one and see which one(s) are stopping the cylinder from bottoming out.

All the studs are new and seem fine. The cylinder clunks down on the base when fitted. I don't think the studs are causing the issue. The tollerance between the port on the piston and and the case is tiny. I think this is where the issues lies.

Does the transfer port on the cylinder exceed the mating surface on the case? Do you have a gasket that matches the cylinder ports to drop onto the case to photo? I need to run a gasket on my Pinasco to seal the cylinder transfer to the case.

I think this is the issue. The gasket that came with the cyliner didnt even fit so I bought another pinasco one. The gasket is upside down in the photo. I fitted it the other way.

Can you post top three pictures cleaned up without sealant etc? Maybe use a pointing device such as an ink pen to point at exactly what your seeing? Engine case doesn't look like it has had ports matched to a cylinder so there should be plenty of metal there to seal. Unless as was mentioned earlier that cylinder has part of an exposed port.

That cylinder base gasket looks like a gasket from a stock rebuild kit not one for the Pinasco cylinder.

That is what I thought but that is what was included in the actual kit from Pinasco. I am out at the moment so can't clean them up. They are clean enough to see how much metal is there. I think the port is exposed near the flywheel. It has to be as there is no other explanation.

You need to fill the gap. Most people use JB Weld, welding and machining the surface is the best way. Sealants, etc. won't work…

So exactly what base gasket do I need as I have already tried 2 pinasco ones which seemed to match the cylinder?

Fuck sake. Why on earth would that be expected? I wish I had never bought this bike now. Nothing but trouble.

So if I use the pinasco 1.5mm spacer that was fitted to the kit before and use selant, I can maintain pressure. No leak. But, this makes the squish 3mm and lifts all the ports by 1.5mm so fucks up the timing. The spacer is made in such a way that it slightly covers the intake ports on the cylinder and adds a bit more to the cases if you get what I mean. It will run like shit though will it not? I am having a few rum and cokes. It's my birthday today. Lol.

What should I do? What is the best course of action? Maybe I can shave 1.5mm from the head to bring down the squish. I am not after absloutle power. This is the kit that came with the bike. I did not choose it. I would have bought a different, less sporty one.

Thanks.

Its the joy of tuned scooters. Have you considered looking for a standard engine to put in for now while you sort this one out.

I dont know about the PX world but with smallframes you have simple kits that bolt straight on with no work and give a bit of a power gain, or more exotic stuff where you need to make changes to the cases etc to get stuff to work.

If the pinasco kit you have isn't just bolt on and ride, is there a different kit you could get for now that would be more plug and play and then use this one later on when you've got a bit more experience.

I dont' want to spend much more on this thing at the minute. Will it run with 2.8mm squish? If so I will use it like that unless I can get 1.5mm machined from the rim on the head.

The 125/150 cases seem to need the most attention when tuned/port matching. There's a bunch of places where it gets really thin and the gasket faces don't have much to ride on.

The 200s are a bit boring in that regard.

Once you get it right, you'll be singing

I'd look into skimming off the cylinder head. The gasket overhang won't affect performance. It might irritate you to know it's not matched though (joking…)

https://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=324629017133&category=25645&pm=1&ds=0&t=1639448294000&ver=0

That is the kit that was fitted when it seized but utilising a 1.5mm spacer. The place where I bought the bike from ordered the 190cc Vespone kit for me by mistake. Maybe I should buy that kit and fit that.

Happy birthday!

That PNP gasket you binned matches your current case ports, so not blocking anything. Too late to dig it out?

Can't tell the difference between a magny cours and a vespone…

But make a difference for you?

Bollocks. Binned it ages ago. It matches the case ports but covers the cylinder ports quitea bit.

I am not after a neck snapper but rather sometihing that is a bit quicker than stock with the added bonus of reliability; oh, and not a twat to fit.

Ah I see the difference, the vespone transfers are way bigger… no wonder the leak issue

See I didn't notice that. But now you mention it I see it. Might try and sell it and recoup some cash for a new kit. In which case I could keep my 20/20 carb as it will suffice for that kit. Save me money on a new carb etc. Looks like that is the way ahead unless I get 1.5mm taken from the head.

You might want to think about why it seized in the first place.

Maybe swapping to a different kit might be worth thinking about…

The kit that seized was the Magny Cours. The bloke who had the bike before had it dynoed and then after fitted a Polini Road Exhaust and a drilled heart carb. However he did not upjet. I was uinaware of this. I think this was the reason.

If it matches your case ports it isn't blocking anything.

Had the same issue, same spot. Honestly, not sure why. Had plenty of meat like yours.

VERY little Dirko (like a 2mm or so bead -- went around the bolts as well) on the case side, and a thin metal gasket. They crush where they can if torqued evenly.

Not totally sure how or why, but it worked.

When I placed the gasket on the cylinder the top port was OK but the side ports where party covered by the gasket. Just didn't seem right.

Quite some developments here. That explains everything. Old kit was a 57 new kit is a 60. Newer engine cases with gaps. Packers gaskets squish. All clear.

Easiest way out, get some JB weld and fill the gaps. Make your own paper gasket.

Expensive way out, get a 62mm crank and use a packer.

Best way out, strip the engine again. Get the ports matched, welded and the casing refaced flat. Packer and gasket to suit after.

None easy but you have options.

Yes. I think the old kit used a 1.5mm spacer but still used the 60mm crank. The transfer ports must not have been as wide so fully sealed.

I am going to try the jb weld first. If that fails then fuck knows. Don't want to spend loads of money. I don't know anyone who could match and weld the ports.

That pic is nuts.
Chasing those gaps with epoxy will stay in your mind as you ride. Not fun.

"If I were you" I'd buy myself a birthday present, and shelve that current kit for a future project. Just bolt this on and have fun:

https://www.scooter-center.com/en/cylinder-bgm-pro-177/187-cc-vespa-px125-px150-cosa125-cosa150-gtr125-ts125-sprint-veloce-vlb1t-0150001-lml-star-125/150-stella-125/150-bgm1770n?number=BGM1770N

The transfer ports look a lot more realistic for my cases on that kit. This should just bolt on and jet to suit?

Thanks for you help.

Would this kit run with a normal PX air filter or not?