Cracked cases - PX150 2005
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Fri Nov 23, 2018 3:46 am quote
Hi all, a friend had recently split the cases on his PX150 from 2005 only to discover the horror that awaited him. Lots of cracks!

So now he is on two minds, to try and fix the original cases or go for a new Pinasco 125/150cc cases.


I know this community is very resourceful so I'm relying on the experts to help us decide what to do next with his build.


Brief history, the bike was imported from Greece, and had a DR 177 on it with a Cosa clutch, everything else was stock.

The auto-lube failed causing the DR to hard seize.

So he upgraded to a Polini 177 kit complemented by Mazzucheli crank and SI24-24 carb, and Simonnini exhaust.
Also all new bearing and seals, and had that fitted by a local motor shop.

You'll see in the pics that the mechanic clearly did something wrong when closing the cases together.

The funny thing is the PX ran great and had a lot of power. The only symptom was that he had a oil leak somewhere from the bottom of the case and was quite smokey through the rev range.

Currently the carb setup is 55-160 idle, 160-BE3-128main.

IMG_3405.jpeg
The first crack

IMG_3410.JPG

IMG_3412.JPG

IMG_3415.JPG

IMG_3416.JPG
Another crack

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Fri Nov 23, 2018 5:44 am quote
Just buy a set of used cases or a old motor and swap over the parts. That shouldn't be all that hard to find as the cases are pretty much the same through the years of the PX/P series from 125-150cc. Just depends on electric start or not.
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Fri Nov 23, 2018 6:00 am quote
Thanks for the reply, so your saying the old cases cant be fixed by welding?

Cause finding a second used motor or cases is next to impossible here. It can be imported but the cost comes close to new Pinasco cases.

My friend is inclined to purchase the Pinasco cases from scooter-center, since they now have a 10% discount till Monday.

The trouble is with the pinasco case, even the ones meant for the 150cc uses a 200cc crank. So the old crank can not be used.

So he is on two minds what to do. Any advice appreciated.

Anyone using a Pinasco cases with a Polini 177 by any chance?
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Fri Nov 23, 2018 7:30 am quote
jocco wrote:
Thanks for the reply, so your saying the old cases cant be fixed by welding?

Cause finding a second used motor or cases is next to impossible here. It can be imported but the cost comes close to new Pinasco cases.

My friend is inclined to purchase the Pinasco cases from scooter-center, since they now have a 10% discount till Monday.

The trouble is with the pinasco case, even the ones meant for the 150cc uses a 200cc crank. So the old crank can not be used.

So he is on two minds what to do. Any advice appreciated.

Anyone using a Pinasco cases with a Polini 177 by any chance?
You certainly can give TIG welding those cases a try. You will have to media blast them first, then TIG weld, then machine the sealing surface for the clutch. just a guess here, but your shoulder washer for the clutch came apart and went into the gear box, those parts jammed between the output shaft gears and case pushing all gears towards the crank.

no chance on using a small block kit on a big block case.

IMG_9993.JPG

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68sprint,65super,64Allstate
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Fri Nov 23, 2018 9:22 am quote
Cracked cases
Do not use your old cracked cases. Iíve been tig welding for 25 years, and where those are at....very difficult to get everything all aligned again. Buy new cases, or a set of used cases. It would be cheaper. Scott
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Fri Nov 23, 2018 9:36 am quote
Sjanuary wrote:
Do not use your old cracked cases. Iíve been tig welding for 25 years, and where those are at....very difficult to get everything all aligned again. Buy new cases, or a set of used cases. It would be cheaper. Scott
Thatís absolutely true. If the are not true, itís not going to work. If it were me in this situation, I would just buy new. But if this guy had time and the tools, it might be worth trying.
Molto Verboso
2005 PX150 In a Love-Hate Relationship with a 2-Stroke Vespa Since 2007
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Fri Nov 23, 2018 9:48 am quote
One more thing...

>99% of the time that autolube shoulder washer cracks from being installed backwards at some point in its life. The chamfered side must be facing the crank not the clutch, otherwise it gets torqued down onto a slightly conical surface which strains the metallurgy and some day, boom! down the pieces go into the gear case and if you're lucky, the rear wheel doesn't lock up hard.
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Fri Nov 23, 2018 10:04 am quote
Cracked cases
That is some good info there. That didnít cross my mind. Good observation from pdxjim. I will have to watch that one myself.
I will reiterate what I already said....do not try and weld. Scott
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Fri Nov 23, 2018 10:25 am quote
Sjanuary wrote:
That is some good info there. That didnít cross my mind. Good observation from pdxjim. I will have to watch that one myself.
I will reiterate what I already said....do not try and weld. Scott
Iíve seen Millerís welded up and machined in a lot worse condition. The p-case is not rare and can be sourced used or new, a Miller on the other hand is not.
Molto Verboso
2005 PX150 In a Love-Hate Relationship with a 2-Stroke Vespa Since 2007
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Fri Nov 23, 2018 10:32 am quote
Sjanuary: ^^^
If you ever find that shoulder gear backwards, do not turn it around and reuse, it's already compromised. They're not expensive, just replace it and have one less thing nagging at your peace of mind while tearing down the highway.

Last edited by pdxjim on Fri Nov 23, 2018 3:16 pm; edited 1 time in total
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Fri Nov 23, 2018 12:45 pm quote
150 cases
If Iím going to go through and try and weld a case as the one pictured...it better be a ďone of a kind.Ē
I donít think a p150 is.... have a great holiday weekend.scott
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Fri Nov 23, 2018 2:40 pm quote
Interesting info.

My friend decided to go for new Pinasco master crankcases for 125/150cc. With the original rotary valve.

Now the thing is will he be able to fit most of the stuff he already has?

The Polini 177, simonnini exhaust, the original stator amd flywheel.

I see that even the 125/150cc cases are meant exclusively for a 200cc crank, so can the 177 kit be used here or not?
Molto Verboso
2005 PX150 In a Love-Hate Relationship with a 2-Stroke Vespa Since 2007
Joined: 01 Sep 2007
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Fri Nov 23, 2018 3:23 pm quote
I'm curious how the cracks got there in the first place.
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Fri Nov 23, 2018 3:36 pm quote
Iím curius too Jim.

Right now all the blame goes to the mechanic that did the previous rebuild. Iím guessing he overtightened the cases and probably fitted the washer behind the clutch wrong.
Veni, Vidi, Posti
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Fri Nov 23, 2018 4:18 pm quote
jocco wrote:
II see that even the 125/150cc cases are meant exclusively for a 200cc crank, so can the 177 kit be used here or not?
Yes it can. The 150 case has the right stud spacing for any 150 - based cylinder kit.
The difference is that the 200 crank has a 5mm longer conrod, that's one reason the 150 crank won't fit. The other is that the 200 crank has a lip on the clutch side - which makes the rotary valve sealing surface wider. The 200 intake under the carber is also wider than a 150.

So if you were to fit the 150 crank (and it would definitely fit the space) you'd find there would be a small gap at the rotary valve. And of course the piston would stop at least 5mm short of the top of the cylinder.
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Sat Nov 24, 2018 1:55 am quote
Did you ever consider a set of LML cases? I realise that you need to be careful, but you can get good quality ones.
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Sat Nov 24, 2018 2:45 am quote
Ginch, thanks for the info. He will order a 200 crank then we'll see what spacer to use to compensate for the longer conrod.

swa, I tried to persuade him to go for a LML case, but he has already invested a lot in rebuilding this vespa so he wants it done properly.

SO we are planning on making the order tonight from scooter-center while they still have the 10% discount.


I attached pics of what he is getting so far, I think it will be enough for this build to be completed.

Pinasco_Case_Rotary.jpg
Pinasco cases

Mazzuchelli_200 Crank.jpg
200cc 60mm crank with a lip

Needle bearing_TKRJ.jpg
Needle bearing to fit the gudgeon pin on the Polini piston

Polini177_Spacer1.jpg
Polini spacer. I guess we will need 2 of these?

Veni, Vidi, Posti
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Sat Nov 24, 2018 3:10 am quote
If the case is made for a 200 crank, then you will not need a packer at all, just a normal gasket.

BUT - and I should have mentioned this before but forgot, sorry!
He will need a conversion bearing for the gudgeon pin. The 200 piston has a 16mm gudgeon pin and the 150 is a 15.

SCK have this one - https://www.scooter-center.com/en/7672564/small-end-needle-bearing-tkrj-15x20x17-8mm-vespa-px80-px125-px150-cc-for-using-px200-crankshaft?number=7672564

However since the original bearing for a 200 is 16x20x20 then there may be quite a bit of float sideways... I'd be more comfortable using this from LTH... only 1mm narrower instead of 2.2 at 15x20x19.

https://www.lambretta-teile.de/Small-end-bearing-15x20x197mm-conversion-PX200-crank-with-with-PX125-barrel-Vespa-PX
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Sat Nov 24, 2018 4:25 am quote
Ginch, surely the 110mm rod is still going to put the piston 5mm further up the cylinder, or does the Pinasco case take up the extra 5mm at the base?

Then there's the extra 1.5mm to consider with a longstroke crank.
Veni, Vidi, Posti
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Sat Nov 24, 2018 7:00 am quote
swa45 wrote:
Ginch, surely the 110mm rod is still going to put the piston 5mm further up the cylinder, or does the Pinasco case take up the extra 5mm at the base?
Yes I believe they do have that extra material. They don't explicitly say that but I'm sure that's correct.
swa45 wrote:
Then there's the extra 1.5mm to consider with a longstroke crank.
Ah yes of course you're right, I forgot that as well!

Given some of the reviews on these cases, I'd be paying particular attention to the way the bearings are fitted... be sure to use the correct Loctite (or similar product) to make sure the bearings stay in place.
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Sat Nov 24, 2018 7:34 am quote
Its not a problem to add spacer and get the timing right kn the cilinder, the thing is what will be the easiest setup to get a polini177 on a Pinasco case with a 200cc crank?

I just found a Mazzuchelli crank for 200cc with a 57mm conrod. Does the 200cc vespa come with 57 or 60mm?

958403A6-B8AE-43C5-B1CE-350A99C54483.png

Veni, Vidi, Posti
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Sat Nov 24, 2018 4:28 pm quote
The 200 is a development of the 150, the changes made were relatively minor.

The normal stroke for all largeframe motors (apart from the T5) is 57mm. You can fit a 60mm stroke crank to either motor and it'll add a bit under 10cc - so 187cc for the Polini 177.

That crank from LTH will work, but it's just a normal crank. The other one, the 60mm from SCK, is cut a bit differently so that the intake stays open a little longer each revolution. That, as well as the bigger area intake in the Pinasco case, will make more power from the same cylinder.

It shouldn't be any harder to set up than it was last time on the old (cracked) case. You can put it all together with the 1.5 packer in place of the normal thin gasket.
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Sat Nov 24, 2018 6:12 pm quote
Thanks again for the reply Ginch

Somehow I always though that all PX200 had 60mm cranks.

We are definitively going for a long stroke 200cc crank.

Now we are puzzled cause we saw on the Pinasco case instructions that pinasco recommends using a 5mm spacer for the cylinder base while using a stock 200cc crank.

So that would came to a 6.5mm spacer if we go long-stroke?
Veni, Vidi, Posti
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Sat Nov 24, 2018 6:43 pm quote
jocco wrote:
Thanks again for the reply Ginch

Somehow I always though that all PX200 had 60mm cranks.

We are definitively going for a long stroke 200cc crank.

Now we are puzzled cause we saw on the Pinasco case instructions that pinasco recommends using a 5mm spacer for the cylinder base while using a stock 200cc crank.

So that would came to a 6.5mm spacer if we go long-stroke?
I didn't see that! What an odd way to do things!
SCK and LTH don't have that in their descriptions... but I now see SIP does which is much better. In fact it says the packer and bearing is included in delivery. And now I look a bit harder the SCK and LTH have those parts shown in the pictures.
Sorry I seem to have given you a couple of incorrect bits of advice earlier!

None of them tell you which small end bearing is included. That bit of advice still stands however and I think the 15x20x19 is the right one.
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Sat Nov 24, 2018 8:51 pm quote
If you want more power the longer 60mm crank is a good thing. The longer inlet duration of the racing Mazz crank will help too.
With the 60mm crank the port timing will be stronger but with the longer conrod (110mm not 105mm) the port timing loses a bit of this advantage.
With the extra cc (187 not 177) the compression will go up. This is not always good for power on a 2 stroke.

When you get it all together, for the best compromise, I would set the height of TDC to be 0.5mm below the top of the cylinder. So when the cylinder is held down the piston doesn't quite get to the top. This can be measured with feeler gauges to be accurate.
Going to all this expense it might as well go faster
Veni, Vidi, Posti
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Mon Nov 26, 2018 5:43 pm quote
Jack221 wrote:
With the 60mm crank the port timing will be stronger but with the longer conrod (110mm not 105mm) the port timing loses a bit of this advantage.
Jack could you please expand on this a little? I had read that a longer rod will give you more port-time area, as well as more crankcase volume. Both of which ought to add up to a good thing - or do they?
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Mon Nov 26, 2018 8:15 pm quote
Longer conrods do give more crankcase volume, reed blocks also give more volume. Together these noticably reduce the transfer pressure, which can then handle higher durations with less losses. All good. Long conrods need the barrel set even higher to compensate for these factors. Only point of concern is the head and squish, which might need the head modifying, as there is now less scope in the transfers. In short longer conrods end up being a good thing.
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Mon Nov 26, 2018 8:42 pm quote
Doesn't the head/squish remain the same regardless of the length of rod? Assuming no change of stroke.
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Mon Nov 26, 2018 9:05 pm quote
To make the long rod work better than without it the barrel will need to be set higher. Reducing the pressure without increasing the duration would not go as well. Increasing duration by raising the packer will drop the squish. Very difficult to quantify the loss of crankcase pressure. Messy and not fantastically accurate to measure. If you have any data on this it would make interesting reading.
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Tue Nov 27, 2018 2:57 am quote
Just a small upgrade, we got the Pinasco master crankcase with a Mazzuchelli racing long stroke 200cc crank.

Scooter Center confirmed that with the Pinasco case you get both the 5mm spacer and a conrod needle bearing that will fit on a 150cc gudgeon pin along with everything else thats on the picture on their website.

We also bough a 1.5mm spacer to adjust the barrel higher for the 60mm stroke, so will see how it goes once we get the parts.

I also got a SI-24/24E and a Pinasco expansion exhaust for my 150 LML that runs the Malossi 166.


Thanks again for everyone's help and advice
Veni, Vidi, Posti
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Wed Nov 28, 2018 12:01 am quote
We expect pictures of the build Jocco! Hope it goes well.
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