Getting an old Vespa (P200) back on the road
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2008 GTS 250, 1979 P200E
Joined: 11 Jan 2006
Posts: 892
Location: Florence, OR
Sat Feb 09, 2019 9:27 pm quote
Jack221 wrote:
you're picking up this engine splitting thing fast.
Thanks Jack - I'm having fun with it, and taking my time. If I can keep doing that, all is golden.
Jack221 wrote:
If you took the back of the inlet out 10mm it would have a bit more torque and uphill pull.
Do you mean open the hole by 10mm or just fan out the inside 10mm? I'm assuming the hole. I'll probably chicken out and only do a few mm..
Jack221 wrote:
While in there fit the carb box and blend it all in together. Some have some nasty edges between the two.
I'll check it out, thanks!
Jack221 wrote:
I would be concerned about using that old crank. It may be fine, it may not. Assuming its tight now and no visible rust in there, the proof will be in a few hundred miles time.
I'm going to give it a go. It seems OK, but what do I know. Like you said, we'll find out soon enough!
Jack221 wrote:
While in the cylinder with a Dremel it would be rude not to dress the exhaust port. The original intention is 38.8mm from deck to the inside of the port. If its less don't worry but if its more you could do a bit of 'blueprinting' (for a bit extra 38mm holding the same shape has good results).
I wish I knew what this looked like. Like a Before and After. Or maybe a paper "Original" and the Paper "After". I'll search for a thread, but I haven't had any success in this earlier. Thank you for this though. It tells me this is the way to go.
Jack221 wrote:
Edit: btw that rotary inlet is fine. There are way worse running very well. The marks are just from an overheat, probably the same time the piston was damaged. I would assume from a lack of 2 stroke oil.
OK, cool - I just didn't know so I figured better to be safe than sorry. I've seen some pictures of some messed up rotary pads - like a bearing exploded or something went down the carb throat like a screw. Yeah, the overhead had to have been from someone putting the wrong kind of oil in the oil tank. It was almost blocked solid. Even after I drained the oil I couldn't blow air through the filler. Rinsing it with gas did the trick!

Thanks again for your insight - I sure appreciate it!
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PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 993
Location: London UK
Sat Feb 09, 2019 10:25 pm quote
qascooter wrote:
Jack221 wrote:
If you took the back of the inlet out 10mm it would have a bit more torque and uphill pull.
Do you mean open the hole by 10mm or just fan out the inside 10mm? I'm assuming the hole. I'll probably chicken out and only do a few mm..
Yeah.....If you are going to do this you need to be careful, obviously. Its a sensitive area. The original is too short so no need to ever go back but not messing it up is the priority.
I meant fan out the back on the inside at the rotary pad. Similar to how the front is. 10mm from where the inlet hole is now and blended back into the inlet
For some idea (remember you're stock, so, only 10mm at the back), here's a video from our favorite Austrian.
qascooter wrote:
Jack221 wrote:
While in the cylinder with a Dremel it would be rude not to dress the exhaust port. The original intention is 38.8mm from deck to the inside of the port. If its less don't worry but if its more you could do a bit of 'blueprinting' (for a bit extra 38mm holding the same shape has good results).
I wish I knew what this looked like. Like a Before and After. Or maybe a paper "Original" and the Paper "After". I'll search for a thread, but I haven't had any success in this earlier. Thank you for this though. It tells me this is the way to go.
Measure where yours is from the factory and go from there. To be original it should be 38.8mm. I have moved these 1/4 inch in the past so plenty of metal there. the after should look just the same as before but 38.8mm or less from deck.
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2008 GTS 250, 1979 P200E
Joined: 11 Jan 2006
Posts: 892
Location: Florence, OR
Sun Feb 10, 2019 6:17 pm quote
Thanks for the vid Jack. I've seen it before but understand it a little more now. So I went for it. I measured a line 9 mm out and ground away. I also shaped the airbox to fit the engine opening. It was way off. It's not perfect, but should do the trick.

I didn't even look at the cylinder yet.

Oh, and I was going to rebuild the cush drive, but I shook the crap out of it and the springs are solid, so I'm just replacing the bearings on both ends and calling it good.

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Let the grinding begin!

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OK, got on the edge of the line. The far edge is 9mm.

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Put the carb box on and it's way off!

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Drew a line on where to grind.

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The fit is getting better.

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The final carb box hole size. I forgot to take a pic of it on the case.

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These are the bits I used. I went through a couple of sanding discs.

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PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 993
Location: London UK
Sun Feb 10, 2019 7:18 pm quote
I didn't think you would go for it. That's some nice work for a first try. Takes your inlet from somewhere near 165 degrees to more like 175 degrees. A scooter heavily tuned might be 220 degrees and a decent tourer is about 180. This will need a slight upjet, if you don't have already put a 120 to 130 set of main jets on your shopping list.

The carb box was about as bad as they get. Now nice and smooth. Some guys open out the bottom lip of the carb too (you'll see that doesn't line up either). If you do it, only go a few mm in and watch out for the mixture screw hole.

How did the cylinder measure up?
Addicted
2008 GTS 250, 1979 P200E
Joined: 11 Jan 2006
Posts: 892
Location: Florence, OR
Sun Feb 10, 2019 10:12 pm quote
Jack221 wrote:
I didn't think you would go for it. That's some nice work for a first try. Takes your inlet from somewhere near 165 degrees to more like 175 degrees. A scooter heavily tuned might be 220 degrees and a decent tourer is about 180. This will need a slight upjet, if you don't have already put a 120 to 130 set of main jets on your shopping list.

The carb box was about as bad as they get. Now nice and smooth. Some guys open out the bottom lip of the carb too (you'll see that doesn't line up either). If you do it, only go a few mm in and watch out for the mixture screw hole.

How did the cylinder measure up?
Thanks Jack - It's nice this is the project scooter and not the one I ride daily. If it was, I might not have been as ballsy with the dremel. And I'm learning on this one, so when it's time for my daily ride, I'll have an idea of what I'm doing.

OK, now I understand the degrees a bit more. Thank you for that.

The carb that came with this P200 is a 20/20 and I'm going to use it and upjet from what I set up Luckybears - like a SS180 but with a bigger main and go from there. I forget the exact jetting but I've got it written down in a notebook in the garage. And I just looked at the carb and how it lines up with the carb box and it's off on the carb side, so I'll whittle a little down on the carb to match. Thanks for the heads up on a couple of mm's only.

And I just measured the cylinder and exhaust from the deck - 38.5. This is what I want, correct?

Thanks again for your help!

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Should I do anything with this?

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PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 993
Location: London UK
Mon Feb 11, 2019 4:09 am quote
That bore came out nice too. Cleaned up well.

38.5mm is a good factory one. Seen some over 39mm which are noticeably slower.

No need to cut anything.......however, if it were mine I wouldn't be able to put it back together like that. If you're feeling bold, take it down to 38.00mm. Will be hardly any different, as the transfers are too low but will be making a little more power. Could be worth 1mph
If your 57mm crank does turn out to be no good and knocking be sure to buy a 60mm stroke to replace it. Then with the higher main transfer duration from that and +1mm out of the exhaust port it will still be about right. With the 60 the exhaust has to go up but on the 57 its an option.

No issue with the 20/20 carb. Whatever jets you are planning to put in the main air corrector should be a 140 and atomiser BE5. Timing can stay at 23 degrees (A).

Even after all this its going to be hardly any different but even with the smaller carb it will feel better and crawl past the red one every time.
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2008 GTS 250, 1979 P200E
Joined: 11 Jan 2006
Posts: 892
Location: Florence, OR
Tue Feb 12, 2019 7:39 pm quote
Jack221 wrote:
That bore came out nice too. Cleaned up well.

No need to cut anything.......however, if it were mine I wouldn't be able to put it back together like that. If you're feeling bold, take it down to 38.00mm.
Thanks Jack! This is the info I was looking for. 38.03 is what it is now!
Jack221 wrote:
No issue with the 20/20 carb. Whatever jets you are planning to put in the main air corrector should be a 140 and atomiser BE5. Timing can stay at 23 degrees (A).

Even after all this its going to be hardly any different but even with the smaller carb it will feel better and crawl past the red one every time.
That's awesome news and good to know info on the 20/20 carb. Thank you, thank you, thank you!

I put in a new shifting cross (with locktite) and inspected the gears. Installed the bearings, Cush drive, kickstarter. Gotta take the wheel off the hub to draw the gear stack into place. Once I put the crankshaft in it'll be almost time to put the cases together! Woohooo!

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Gear stack disassembled.

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38.03. That is the distance from the top of the cylinder too the top of the exhaust port.

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It's getting there...

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P125X, P200E
Joined: 02 Apr 2011
Posts: 552
Location: Fresno, CA
Wed Feb 13, 2019 11:28 am quote
Looking good my friend!
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2008 GTS 250, 1979 P200E
Joined: 11 Jan 2006
Posts: 892
Location: Florence, OR
Wed Feb 13, 2019 6:05 pm quote
Thanks Luckybear! Today I got a chance to do a little more.

I got all the internals in and put together the case halves! Of course I needed to clean up the hub before I could suck in the rear axle and gear cluster. Then I put in the seal.

Also relieved the piston port edges, installed piston, filed one set of rings to get .3mm clearance, installed cylinder, head, and torqued it down.

I'm starting to see a glimmer of light at the end of the parts tunnel.

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Two halves ready to go together, spring? - check. kick start gear? - check. - OK, triple checked everything to hopefully not forget anything.

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Case nuts and bolts almost ready - gotta clean them up with a wire wheel on the drill.

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Case halves together - a little jiggling and it clicked together nicely. I learned many years ago that a little shaking or vibration helps things fall together - or apart....

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Cylinder, piston, and head installed. The rings were time consuming to get them into the cylinder.

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PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 993
Location: London UK
Thu Feb 14, 2019 12:28 am quote
qascooter wrote:
Thanks Jack! This is the info I was looking for. 38.03 is what it is now!
When measuring like this, using the depth gauge, it's most accurate when something flat (like a feeler gauge) is put inside the port and measure down to it. With ports the chamfer doesn't count.

You're not hanging about. Be sure to do a crankcase pressure test. Especially as this is your first go. Was going to suggest you check the piston distance from deck and adjust the base gaskets to set it correctly. This is another point where power can be lost.

When I say the 20/20 is ok, is that it's ok. A 24/24 would go better if you can get one (for free is best). I have 2 lube ones on my shelf doing nothing but the postage would be more than they're worth. The 20/20 jetting is especially important as it is running at its limit and will lean out easily.
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2008 GTS 250, 1979 P200E
Joined: 11 Jan 2006
Posts: 892
Location: Florence, OR
Thu Feb 14, 2019 11:05 am quote
Jack221 wrote:
When measuring like this, using the depth gauge, it's most accurate when something flat (like a feeler gauge) is put inside the port and measure down to it. With ports the chamfer doesn't count.
I stuck a big flat bladed screwdriver and measured to it!
Jack221 wrote:
You're not hanging about.
I've been doing this 15 minutes here, 20 minutes there. I can only imagine if I had several hours in a row how much I could get done.
Jack221 wrote:
Be sure to do a crankcase pressure test. Especially as this is your first go. Was going to suggest you check the piston distance from deck and adjust the base gaskets to set it correctly. This is another point where power can be lost.
Yes - Pressure Test! I don't have a carb manifold to put an inner tube on - gonna have to rig something up. And I knew I was getting ahead of myself with the piston. Should've done the brakeplate and brakes first. I was just excited to actually fit the new piston. What distance should I be looking for because it's only 4 nuts, and it's on the bench!
Jack221 wrote:
When I say the 20/20 is ok, is that it's ok. A 24/24 would go better if you can get one (for free is best). I have 2 lube ones on my shelf doing nothing but the postage would be more than they're worth. The 20/20 jetting is especially important as it is running at its limit and will lean out easily.
Wow - Thank you for the offer! I'll PM you about it. And thanks again for your help!
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P125X, P200E
Joined: 02 Apr 2011
Posts: 552
Location: Fresno, CA
Thu Feb 14, 2019 3:50 pm quote
Your Dremel work inspired me to finally chamfer the ports on my new cylinder. Unfortunately, my vice was too small so I had to ad lib.

ad lib vice 2.jpg

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2008 GTS 250, 1979 P200E
Joined: 11 Jan 2006
Posts: 892
Location: Florence, OR
Sat Feb 16, 2019 9:58 pm quote
You crack me up Luckybear!

Today I made some more progress. Put on the brakes and hub. New seals, lubed the brake arm, sanded the drum, cleaned the threads of the cable adjustment.

And finally got the clutch built and installed, and replaced o-rings in clutch arm.

Also reassembled the autolube in the carb box and installed it, with some locktite. Currently getting ready to pressure test. Gonna do what Chandlerman suggested and just block off the carb and get air in the exhaust.

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It's getting there!

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Gotta love this old school torque wrench. Ive got a click one but don't trust it for some reason. Maybe someday I'll get a digital beep one...

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Autolube has been cleaned out and is good to go.

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2008 GTS 250, 1979 P200E
Joined: 11 Jan 2006
Posts: 892
Location: Florence, OR
Tue Feb 19, 2019 8:28 am quote
Leakdown Beatdown
So this whole leakdown test has been a bit of an issue. I'm getting 2 min and 15 secs from 200 to 150 mm/Hg (1 psi).

This after tightening the carb. The rubber gasket was leaking. And tightening the tube to exhaust flange connection. Bubbling there also. I used glass cleaner and could hear the leaks - very faint bubbling.

The final leak is coming from the exhaust manifold where it screws into the exhaust - bubbling out of the threads.

Should I call it good and move on? If not, what should I do with the threads of this pipe - plumbers putty? Grease?

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The gauge I'm using.

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The test apparatus...

Member
P200e, ss90
Joined: 05 Feb 2018
Posts: 34
Location: NZ
Tue Feb 19, 2019 8:55 am quote
Hi Qa, first thanks for posting this rebuild. I have a P2 engine on my bench i did awhile ago as a spare, and i think i may go again to give a few tweaks following what youve done. Great pictures and info.

With the exhaust stub, maybe unscrew it and put it back with hylomar or similar in the thread?
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