2007 Stella P200 Motor Install
Post Reply    Forum -> Not-So-Modern 12Next
Author Message
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Sat Aug 22, 2020 7:59 am quote
Starting a new thread, Iíve had a P200 motor on my garage floor for about 3 weeks now. Bought it with no clutch, ordered parts went on vacation and all the parts are finally back in stock. Should get the clutch parts early next week. These were basic off the shelf parts at that. Damn COVID!!!!

Anyway itís a P200 with a 60 mm Pinasco crankshaft and Pinasco 215 big bore kit. Mikuni TMX 30mm carburetor. Also a SIP Big Box Xl.
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Sat Aug 22, 2020 8:10 am quote
Stator Wiring Using P200 Stator
Stator wiring which I know, I posted about before. Iíll find it at some point and copy and paste it here. The factory P200 stator should work. Just have to ground one of the yellow wires. Also going to see what the lighting AC looks like now that I have an oscilloscope at home to see if I can add it.


P200 with Blue Ducati CDI and Kytronix in Stella

Last edited by Christopher_55934 on Sat Aug 22, 2020 8:53 am; edited 1 time in total
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Sat Aug 22, 2020 8:46 am quote
TMX30 Carburetor Details
Choke conversion

http://modernvespa.com/forum/post2424583#2424583


Current jetting

Power jet - 80

Pilot jet - 25

Main jet - 092

Needle jet - 622 N-9

Jet needle - 5EL68

Combining the main and power jet that about a 172.

Last edited by Christopher_55934 on Sun Aug 23, 2020 8:02 am; edited 1 time in total
Enthusiast
P200e
Joined: 29 Jul 2018
Posts: 52
Location: Orange , Ca
Sat Aug 22, 2020 8:56 am quote
Looking Forward to your progress !!
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Sun Aug 23, 2020 7:41 am quote
VSX1T wrote:
Looking Forward to your progress !!
Me too

Can you post what you remember as far as the fourth gear change. I'm going to copy and paste the add in Here also as a start.

150 miles on complete rebuild
All new bearings and seals
Pinasco 60 mm crank
Pinasco 215 cylinder
kytronic ignition
Lightened electric start flywheel
New TMX 30 mikuni carb with power valve
MRP rotary intake
Cases have no repairs and have no porting to them at all ,stock.I
Rear brakes are new as well .
Clutch cover is CNC clearanced for a BGM super strong.
23 tooth cosa gear on its way.


Squish 2.12mm with no base gasket.


Piston edge to top -1.68mm or 1.68 mm below top edge where head rests. With the 1.50 mm base gasket.

Stroke 60 mm, measured it twice second guessing myself with the squish measurements.

Exhaust port top 37.83mm factory. With a general clean up of port 36.28 mm at center.


Intake well thats a mixed bag. The two side ports have a top at an angle from 50.15mm to 48.59mm.

The boost ports are about 48.58

The funny l shaped port is about 48.58 also.

Base gasket 1.50mm


Crankshaft
https://www.sip-scootershop.com/en/products/long+stroke+crankshaft+pinasco+_45028000

78fb5d04_7b42_4d8b_ab26_e9f64aeb3a9a_98183.jpeg

60ab0dc3_c45a_43c3_aa99_f7a884fb216c_67408.jpeg

2020-08-23_12-49-46_949.jpg

2020-08-23_12-49-43_490.jpg

2020-08-23_12-13-17_969.jpg

2020-08-23_12-12-31_352.jpg

2020-08-23_12-08-10_079.jpg

2020-08-23_12-07-56_409.jpg

2020-08-23_11-55-30_689.jpg

2020-08-23_11-53-10_419.jpg



Last edited by Christopher_55934 on Tue Aug 25, 2020 9:31 am; edited 6 times in total
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2399
Location: London UK
Sun Aug 23, 2020 7:47 am quote
Looks well built (expensive). With a 60mm crank and a 215 cylinder there are packers and squish variables. You know where these are are just hoping its ok?
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Sun Aug 23, 2020 7:51 am quote
Jack221 wrote:
Looks well built (expensive). With a 60mm crank and a 215 cylinder there are packers and squish variables. You know where these are are just hoping its ok?
I don't know yet, going to go measure squish shortly to verify what it is set at. Hoping VSX1T will chime in and fill in some of the blanks.
Ossessionato
Joined: 26 Oct 2015
Posts: 2633

Sun Aug 23, 2020 8:00 am quote
The lighter weight E start PX flywheel is a great upgrade. That was usually one of my first (of many little) performance mods to all of my stock P200's. I found that a PX flywheel weighed less than a standard P flywheel that has been turned down on a lathe.

So what gear ratios did you use for both the clutch and 4th gear?
"and no porting"...what about matching the cylinder ports to the cases?
Like Jack, i'm also curious about the packers and squish...especially with a Pinasco kit.
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Sun Aug 23, 2020 8:17 am quote
whodatschrome wrote:
The lighter weight E start PX flywheel is a great upgrade. That was usually one of my first (of many little) performance mods to all of my stock P200's. I found that a PX flywheel weighed less than a standard P flywheel that has been turned down on a lathe.

So what gear ratios did you use for both the clutch and 4th gear?
"and no porting"...what about matching the cylinder ports to the cases?
Like Jack, i'm also curious about the packers and squish...especially with a Pinasco kit.
I know Chris said he went to a closer ratio 4th, less teeth I think in this case. He sent me the original gear also. I went with a 23 tooth clutch gear for now. Didn't think I needed a shorter clutch gear with a shorter 4th. I only ride solo and for short rides into town 15 miles or so. I figure I can adjust from there but needed a starting point.

I don't plan on touching anything until I get this setup running and see how it fits my riding and driving style. Might do what I want as is. Also want to work on a few runs with GSF dyno and get my AFR meter installed.
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1517
Location: UK (South East)
Sun Aug 23, 2020 8:59 am quote
A P2 4th has 35T, so a 'shorter' 4th would be 36T ie. a PX125 or T5 gear. You describe the setup as the 215 cylinder with a 60mm crank, rather than the 225 cylinder, but do you know how old the kit is? Does it have the step for the head to slot in to?
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Sun Aug 23, 2020 10:33 am quote
swa45 wrote:
A P2 4th has 35T, so a 'shorter' 4th would be 36T ie. a PX125 or T5 gear. You describe the setup as the 215 cylinder with a 60mm crank, rather than the 225 cylinder, but do you know how old the kit is? Does it have the step for the head to slot in to?
Updated the engine post with pictures.
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Sun Aug 23, 2020 10:45 am quote
http://ddog.at/stz/rechnen.php


I need to figure out where numbers plug into the calculator for a rotary motor. I think I need measurements I don't have yet.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 2798
Location: Chicago. Well, Evanston, but that's almost Chicago
Sun Aug 23, 2020 11:16 am quote
I MUCH prefer this excel sheet for calculating port timings. It's embedded by default, but it will let you download it.

Now, I can capture and save that data as a series of workbooks rather than screenshots.

For the intake timings, Jack can tell you what they should be, but I don't know if there's any good way to measure them without splitting the cases to see it. Of course, if you decide you don't like them, you'll be opening things up to get the ol' Dremel going either way, so maybe that's irrelevant other than committing to doing it.

This should be a fun thread. I'm looking forward to following along
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Sun Aug 23, 2020 11:41 am quote
Currently I just want to put it in and get it running. The squish of 3.0mm isn't going to be the greatest. Will have to see about finding a different cylinder head. I see a SIP has a few options.
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1517
Location: UK (South East)
Sun Aug 23, 2020 1:44 pm quote
So you have the 225 by the looks of things, the one they call 'Super Sport'. I have the same on my tourer. The huge squish is due to the 1.5mm base packer and that really needs to come out. Use a stock P2 base gasket instead to reduce the squish. The piston will cover the exhaust port ever so slightly at BDC, but that's just the nature of the kit. It's not ideal, but probably better than a 3.0mm squish. I ran mine last year with no base gasket at all to reduce the squish a bit more.

The other option, as you've mentioned, is to source a 3rd party head with zero squish, and then drop to a 1.0mm base packer to give you ~1.2mm squish. For this type of kit, even a 1.0mm lift is too much IMHO. These are not revvy kits, but they make wonderful 65-70 mph long distance workhorses, and are great for two up riding and a bit of luggage.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2399
Location: London UK
Sun Aug 23, 2020 1:55 pm quote
Your squish is measuring 3.0mm as it is now? From the photos it has a 1.5mm base packer. With 3.0mm squish this means it's a 60mm cylinder. Take this packer out and you have 1.5mm squish. However, now you have lower ports. Someone has been dremelling in that exhaust port and it was no professional job. Needs some re-shaping and adjusting no doubt. You'll need the cylinder off to have a good look and accurate measure in any case.

While your at it, shine a light up the crank and check the inlet timing with a degree wheel.

Lucky it's one of the newer pinasco cylinders. These are made for lower rpm. Gearing should be stock 200 or higher. Can work around the lower 4th if you want to tune it slightly higher. Or just get a 24 cog.
Plenty of options and all good.
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Sun Aug 23, 2020 2:29 pm quote
Jack221 wrote:
Your squish is measuring 3.0mm as it is now? From the photos it has a 1.5mm base packer. With 3.0mm squish this means it's a 60mm cylinder. Take this packer out and you have 1.5mm squish. However, now you have lower ports. Someone has been dremelling in that exhaust port and it was no professional job. Needs some re-shaping and adjusting no doubt. You'll need the cylinder off to have a good look and accurate measure in any case.

While your at it, shine a light up the crank and check the inlet timing with a degree wheel.

Lucky it's one of the newer Pinasco cylinders. These are made for lower rpm. Gearing should be stock 200 or higher. Can work around the lower 4th if you want to tune it slightly higher. Or just get a 24 cog.
Plenty of options and all good.
That's factory Pinasco casting, I was feeling around when I was measuring the port height. You could feel the casting bumps.

Chris said the set up hadn't been touched including porting. No reason to doubt that by anything I've seen so far. Even the cylinder cases look untouched.

I thought about pulling the base packer, my conundrum is that the top edge of the piston is barely below the exhaust port currently. On the other hand the piston covers up part of the port most of the time while running anyway. Any suggestions on what to use as a sealer on the base?

I was looking on SIPs website and found a MMW head made for a 57mm stroke with 0.0 squish band built in. Just not sure if it will work with my cylinder.


https://www.sip-scootershop.com/en/products/cylinder+head+mmw+px200+for_13013965
Ossessionato
Joined: 26 Oct 2015
Posts: 2633

Sun Aug 23, 2020 3:24 pm quote
The first thing Iíd do is take a few compression tests in order to get a baseline. If you remove the base packing, then take another comp test again. Same thing if you get an aftermarket head too.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 2798
Location: Chicago. Well, Evanston, but that's almost Chicago
Sun Aug 23, 2020 3:30 pm quote
Whatever was done to that exhaust port is going to need some Bad Touch Dolls for or it to explain what the Bad Dremel did to it.

As to the squish, get rid of the base packer and get some measurements for the port timings. Those will provide the road map for what you'll need to do in terms of Dremel work to actually make this motor what you want it to be.
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Sun Aug 23, 2020 4:10 pm quote
chandlerman wrote:
Whatever was done to that exhaust port is going to need some Bad Touch Dolls for or it to explain what the Bad Dremel did to it.

As to the squish, get rid of the base packer and get some measurements for the port timings. Those will provide the road map for what you'll need to do in terms of Dremel work to actually make this motor what you want it to be.
That's the factory exhaust port, you can feel the casting bumps in the metal. It would be much smoother if any rotary tool had been used.

I have cylinder timing measurements, the issue is crankshaft inlet measurement. I've never done them and have to figure that out.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2399
Location: London UK
Sun Aug 23, 2020 11:49 pm quote
Pinasco can occasionally make some low quality stuff...... and stuff that has questionable fit but it always makes stuff that looks pretty. That exhaust port is far from pretty. That can't have left the factory that bad. Someone's been in there and they didn't know what they were doing. Same goes for fitting a 1.5mm packer on a 60mm cylinder.
It will run but not well or for many years.
Needs to be taken apart, measured and fixed.
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Mon Aug 24, 2020 3:21 am quote
I have metal shim material from McMaster, any reason not to cut a gasket out of it? Is the P200 base gasket metal like the LML 150 base gasket? If it is any guesses on how thin I can reliably go? I had a look at SIP and they have base gaskets down to 0.5 mm. Not sure how thin the stuff I have goes.
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Mon Aug 24, 2020 5:41 am quote
Going to be stuck at home for a few days again. Guess Iíll pull the cylinder make a thinner base gasket and clean up the exhaust port. Not trying to adjust anything just clean it up a bit. Iíll get a few before and after pictures and a few traces of the shape. Will save any adjusting for after I get a baseline established. Really just want the tractor like pulling and a steady 60mph.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2399
Location: London UK
Mon Aug 24, 2020 7:02 am quote
Base gasket should be 0.1 or 0.2mm either is ok. Can use a stock 200 one and cut the holes out.

Rub the shape of the exhaust port and we'll see what it will take to make it better. Once measured we can tell roughly how it will go from the durations.
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1517
Location: UK (South East)
Mon Aug 24, 2020 7:09 am quote
The Pinasco A3611 head has the benefit of central plug and the extra bolts, but I suspect the squish is similar to the VRH head that came with the kit. The MMW head looks like it won't work with the recess, but I could be wrong
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Mon Aug 24, 2020 8:56 am quote
swa45 wrote:
The Pinasco A3611 head has the benefit of central plug and the extra bolts, but I suspect the squish is similar to the VRH head that came with the kit. The MMW head looks like it won't work with the recess, but I could be wrong
I dont think this is a VRH head, from the pictures I've seen, the VRH has extra machining that mine doesn't.


Trying to figure out the difference between the A3610 and A3611. The a3610 is for a 57mm stroke and the 3611 is for a 60 mm stroke. I wish they'd post exact squish measurements for the squish ring in the head.

Found a 2019 Pinasco catalog which explains a few things and makes some things make since. This cylinder was designed as a 215 at 57mm, 225 at 60mm or 235 at 62mm. It's setup as a 235 at the moment with the 1.5mm packer with a squish of about 3.0mm. I say about because it is huge and I didn't spend time trying to get an exact measument. If I were to add another 1 mm to the stroke the squish would be about 2mm.


https://www.google.com/url?q=http://www.pinasco.com/racing/pinasco_catalogo_066.pdf&sa=U&ved=2ahUKEwj2-dmLtrTrAhU5AZ0JHQSzB8QQFjAJegQIBBAB&usg=AOvVaw0G9T0GNsaF2kD4O7_c9HgT

Last edited by Christopher_55934 on Mon Aug 24, 2020 10:25 am; edited 2 times in total
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Mon Aug 24, 2020 9:05 am quote
Jack221 wrote:
Base gasket should be 0.1 or 0.2mm either is ok. Can use a stock 200 one and cut the holes out.

Rub the shape of the exhaust port and we'll see what it will take to make it better. Once measured we can tell roughly how it will go from the durations.
I don't have a stock gasket, that's why I was going to use my own material. No close shops to pick one up.
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1517
Location: UK (South East)
Mon Aug 24, 2020 9:06 am quote
I think A3610 may be for a 57mm crank and A3611 is for 60mm. It also has the slanting plug and just the fours stud holes. The A3611 is definitely the best Pinasco head for the 225 kits. I was thinking about getting one last year, but decided that I was happy with the performance of my scoot, and would put the money towards the Malossi 210 Sport that will eventually replace the Pinasco. I've been waiting and waiting for the piston to fail, but alas it soldiers on in brilliant fashion
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Mon Aug 24, 2020 1:40 pm quote
Exhaust Port Should be Cleaned Up
I took a few more pictures of the exhaust port, you'd have a hard time convincing me it's not factory. No rotary tool marks and it has a lip around the edge I can catch my finger on. I do want to lightly clean it up with a drum sander. Need to cut out a paper template shape to make it concentric.


Removed the base gasket and the squish is now a measurable 2.12 mm, checked above the piston pin twice and got the same readings. A head with less squish would be nice. Need to get a base gasket in, and a clutch installed so I can use the kick starter and get compression measurements. Then I can see if I can take any off the head squish band. Also have an email into Pinasco asking about the squish band of their two heads.

2020-08-24_16-12-16_418_kindlephoto-373743053.jpg

2020-08-24_15-46-03_507.jpg

2020-08-24_15-45-46_392.jpg

2020-08-24_15-45-44_433.jpg

2020-08-24_15-44-24_903.jpg

2020-08-24_15-43-05_816.jpg

2020-08-24_15-42-28_749.jpg

2020-08-24_15-16-57_825.jpg

2020-08-24_15-16-56_324.jpg

2020-08-24_15-16-41_502.jpg

2020-08-24_15-16-23_411.jpg

2020-08-24_15-16-19_007.jpg

2020-08-24_15-15-58_112.jpg

2020-08-24_15-14-27_768.jpg

2020-08-24_15-14-11_636.jpg

Molto Verboso
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 1727
Location: california
Mon Aug 24, 2020 2:26 pm quote
Christopher - a fine job documenting the untouched exhaust port.
🙂.
Now that that's to bed...
2 notes:
1. looks to me like there is some light pinging. That's what I would be concerned with with the larger squish.
Anyone: It is normal for Pinasco kits to come with a honkin big unadjustable squish like that?. Would be nice for Christopher to know if that is the norm.
2. Assume you are familiar with Honda Bond - or Yama Bond - or any of its derivatives. It is excellent on base gasket if you have any issue with sealing.

Motor looks great - will be a terrific upgrade to the Stella.
60MPH cruising no problem - here you come.

Screen Shot 2020-08-24 at 3.13.51 PM.png
Keep an eye on that acne (I didnt circle all of it - just examples). If you rub a fingernail over it - I think you will find it is 3D. that will be the area most likely to show pinging if it is occurring.

Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Mon Aug 24, 2020 4:44 pm quote
Cleaned up exhaust port with a sanding drum
I cleaned up the exhaust port, with a 160 grit sanding drum to get rid of the worst part of that casting lip you could catch your finger nail on. Then used a 80 grit buffing wheel, to get rid of the worst of the flash from casting and other garbage in there. Here's a new rubbing of the port that looks a bit better. Shape isn't symmetrical but it does have a curved top still.

What's a good way to get the shape symmetrical? Measured the port width and it's 41.89 mm now. Don't think I want to go much wider as that is 61% of the bore. Maybe use some graph paper to get a better view?

2020-08-24_18-50-57_597_kindlephoto-385802705.jpg

2020-08-24_18-51-06_970_kindlephoto-385834698.jpg

Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1517
Location: UK (South East)
Mon Aug 24, 2020 10:35 pm quote
CM, it is normal for these kits to have so much squish, but they do work well in my experience. When I last looked at mine, I considered sanding the head to get it closer to top of bore. It looks like I could take maybe 0.5mm off while still maintaining a good seal, but any more could compromise the head seal where it slots into the cylinder recess. Beyond that, a machined head would be required with much less squish. I get ~0.5mm between piston and top of bore, so a head with 0.5mm built-in squish would be nice.

Whilst a 62mm crank is supposed to be good for these kits (=235cc), it doesn't solve the squish issue for me, as I cannot have the piston poking out the top of bore at TDC (mine is the older piston with top dykes ring). A new crank, new piston, and/or a fancy machined head is not economically viable, given my kit is six years old and a Malossi Sport would cost less and perform better with the existing 60mm crank.

My advise to Christopher is to run it on a stock/wafer thin base gasket and just accept the ~2.00m squish. Think of it as a stock P2 motor with quite a bit more oomph and loads of pulling power
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2399
Location: London UK
Mon Aug 24, 2020 10:36 pm quote
Not sure if it's better that it was that rough from the factory. Not symmetrical, jagged edges, no chamfers and poorly sized. Is like they are making porting blanks for home tuning. No better than a kit from India. Hey, maybe they are now being made in India, there's a thought.

The port could go to 52mm wide with those piston rings. I don't suggest you go that far for your first go but if you have a try at squaring up the sides, there is no risk of going too wide.

Drawing some lines with a Sharpie will help. A vertical line each side and one across the top and try to make it square with rounded corners.

Measure how far the port is to the top of the bore. And how far the piston sits from the same top at TDC.

Piston. That piston is the one made from hard cheese. Remove all the casting marks from inside and out of the window edges. All corners rounded. Nice and smooth. There will be a chance it stays in one piece.
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Tue Aug 25, 2020 2:27 am quote
Jack221 wrote:
Not sure if it's better that it was that rough from the factory. Not symmetrical, jagged edges, no chamfers and poorly sized. Is like they are making porting blanks for home tuning. No better than a kit from India. Hey, maybe they are now being made in India, there's a thought.

The port could go to 52mm wide with those piston rings. I don't suggest you go that far for your first go but if you have a try at squaring up the sides, there is no risk of going too wide.

Drawing some lines with a Sharpie will help. A vertical line each side and one across the top and try to make it square with rounded corners.

Measure how far the port is to the top of the bore. And how far the piston sits from the same top at TDC.

Piston. That piston is the one made from hard cheese. Remove all the casting marks from inside and out of the window edges. All corners rounded. Nice and smooth. There will be a chance it stays in one piece.
Thank you, good idea, I'll try a ruler, a sharpie and a small sanding drum to get it symmetrical. I would like to try an oval shape per Jennings two stroke book, to make it a bit easier on the rings.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2399
Location: London UK
Tue Aug 25, 2020 5:33 am quote
When Jennings wrote that book the piston rings you have were not invented. We know a lot more now.

Your port should be the shape it was supposed to be when it left the factory, Square...ish. With rounded corners (6mm) and a slightly bowed top (and bottom).
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Tue Aug 25, 2020 5:50 am quote
Jack221 wrote:
When Jennings wrote that book the piston rings you have were not invented. We know a lot more now.

Your port should be the shape it was supposed to be when it left the factory, Square...ish. With rounded corners (6mm) and a slightly bowed top (and bottom).
Ok I'll give it shot I dug out a fine tip marker and a ruler, going to head out before it's 36 C here today.

Last edited by Christopher_55934 on Thu Sep 17, 2020 2:52 am; edited 1 time in total
Molto Verboso
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 1727
Location: california
Tue Aug 25, 2020 6:48 am quote
Christopher - if you take one of your rings, and put it in the bore - you can then use the piston to slide it along until it is in position at the top or bottom of your ex. port. it will be perfectly level as the piston will have pushed it there.

I keep a spare set of rings to do this with - that I super glue in place while I do my sanding. But you can also us it to then mark a perfectly straight horizontal line - and remove it.

Swa - thanks for the explanation. I was miffed by the large squish - but your experience seems promising for the type of powerful output touring motor he is looking for.

Christopher - Jack's comments are right on in my regarding rings - these thin 1mm wire ones (if that's what you have) are very different than the casted thick ones that were the norm. Still - corner should have a nice radius of course - rather than something sharp. There are some tracings of the BGM (modern cylinder) on my thread if you want to see what they do - that would be a pretty good target I would think.
Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Tue Aug 25, 2020 9:41 am quote
Cleaned up port and shape some
Cleaned the exhaust port up a bit, could use more work on the right side. The bottom right should come down a bit, to even things up. It's covered up by the piston top partially, but is should still be fixed. I should try using a smaller drum sander, I've been using a medium size to this point but it's harder to get in the corners. Trying not to chip the nikasil coating taking it nice and slow. Trying to blend in behind the port edge deeper into the port also as I go so along.

Moved the left side over a bit getting rid of the mouse bite that was on the edge of the port from a casting flaw.

The port width is about 61.6% of the bore diameter measured using chord width 42.54 mm.

Timing number for just the exhaust port is about a 173, using the middle 36.28 mm measurement.

Pictures or it didn't happen.

2020-08-25_12-31-56_321.jpg

2020-08-25_11-39-49_480.jpg

2020-08-25_11-39-37_567.jpg

2020-08-25_11-39-20_222.jpg

2020-08-25_11-39-17_819.jpg

2020-08-25_11-39-07_376.jpg
Should get in here with a flap disc and clean the casting up a bit more. Easier to see now that it's cleaned up a bit.

2020-08-25_11-38-40_556.jpg
No base gasket piston is above the bottom lip a bit. You can see the ring groove through the exhaust port.

2020-08-25_11-38-37_619.jpg

Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1022
Location: Rochester, Minnesota
Tue Aug 25, 2020 10:13 am quote
charlieman22 wrote:
Christopher - if you take one of your rings, and put it in the bore - you can then use the piston to slide it along until it is in position at the top or bottom of your ex. port. it will be perfectly level as the piston will have pushed it there.

I keep a spare set of rings to do this with - that I super glue in place while I do my sanding. But you can also us it to then mark a perfectly straight horizontal line - and remove it.

Swa - thanks for the explanation. I was miffed by the large squish - but your experience seems promising for the type of powerful output touring motor he is looking for.

Christopher - Jack's comments are right on in my regarding rings - these thin 1mm wire ones (if that's what you have) are very different than the casted thick ones that were the norm. Still - corner should have a nice radius of course - rather than something sharp. There are some tracings of the BGM (modern cylinder) on my thread if you want to see what they do - that would be a pretty good target I would think.
I feel inadequate, yours is 6 mm wider than mine, back out to the garage I go. 😁

That's a port width of 77%.

Out of curiosity, the area of my exhaust port is 42.54mm x 27.96mm = 1189 mm

35mm is the inner diameter of the exhaust stub, so the area is 962mm, that means the port in the cylinder can flow more and is a funnel at this point. Which is what I was starting to notice while cleaning it up.

When do you stop making the port larger?

img_7114_19855.jpg

Team Scooter Trash for Petfinder Foundation   vespa scooterwest scooter west Motorsport Scooters   Yelcome Leather Top Cases and Roll Bags for Piaggio Vespa PX LX LXV GTS GTV
Post Reply    Forum -> Not-So-Modern 12Next
[ Time: 0.1845s ][ Queries: 25 (0.0326s) ][ Debug on ]