Jetting and timing a DR177 with Vespatronic
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Hooked
Bodgerific 150 Super, 50s in progress
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Location: Melbourne, Way Downunder
Tue Feb 13, 2018 7:11 am quote
Awesome, thanks a bunch.

So I canít slide the Sprint gears on the p200 shaft and use its cruciform, shifter etc with the sprint primary stack. Good to know- Iíd have screwed up again...

Will make up a 2mm ally spacer, and shave down the head by 2mm, my buddyís machine shop is bloody convenient!

If I decide to chase squish, what should I aim for?

Craig
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2134
Location: London UK
Tue Feb 13, 2018 7:53 am quote
Not saying the gears won't fit but just there are combinations that fit together properly. If you loose fit the casings be sure you can get all the gears and neutral with the selector, before bolting it up.

Squish can be as tight as 0.6mm with no issues but 0.9mm is a reasonable maximum clearance for a 177.

I don't think you will get 2mm out of the head unless you slip it inside the barrel. 1mm off each is preobably best.
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 7660
Location: Victoria, Australia
Tue Feb 13, 2018 6:07 pm quote
Gt6MK3 wrote:
Jack I'll have access tonight to a nicely equipped machine room with a cnc and a manual bridgeport and a nice centre lathe...
You are my new best friend.

You can get aluminum flashing that is easy enough to cut with scissors.
Hooked
Bodgerific 150 Super, 50s in progress
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Wed Feb 14, 2018 7:15 am quote
Measured the squish prior to any machining. It wasn't quite the 0.6 to 0.9 recommended. The piston is short of the cylinder edge, and the head has a pronounced lip above the squish ramp.

Out of the box, cylinder and head on the block torqued to spec, it didn't even touch 1.6 mm solder.

So I got some 3mm solder. It just, barely, kissed it.

Squish - 2.96mm. That's with no gaskets, and the head/cylinder cleaned first with acetone.

Time to hit the machine room

Machining takes almost no time at all.

Setting up to machine stuff takes forever. Figuring out how to clamp cast, breakable pieces even more so.

Cylinder clamped down and getting some love.



Getting a machinable setup on the head had two of us thinking hard, and took a few goes..



If you look at the photo above, the 2.9andabitmm squish becomes clear. The piston was just over 1mm short of the cylinder lip, and here you can see the 1.85mm lip the contact ring was proud of the squish coming off.

Ginch, I'm not great with scissors, but I'm a dab hand with a digital vernier and a conversational programming interface. Here's 45 minutes programming work ready for 5 minutes of cutter spinning.



Finished all this at about 10pm, and cut a 2mm prototype to test, but my mate whose mill I was running had to get out of the workshop and into the house (apparently it's Valentine's day), so I haven't had a chance top see if it all fits together. Mark 1 CNC prototypes usually need some adjustment (especially when I program them!), so I've booked more mill time for Friday night. I'll test fit it all tomorrow and figure out what needs changing.

C.
Molto Verboso
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Wed Feb 14, 2018 8:43 am quote
thats awesome
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
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Wed Feb 14, 2018 1:20 pm quote
Fantastic Craig, nice work!
Hooked
Bodgerific 150 Super, 50s in progress
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Location: Melbourne, Way Downunder
Wed Feb 14, 2018 9:12 pm quote
Shim design worked out nicely.



Mark one is not usually a keeper, but will be this time.



To get the squish down, I ended up recessing the barrel,



And lowering the base of the head, giving it a lip to locate it in the recess in the jug. Head seen here ready to re-measure squish.



Which is now at 0.6mm to 0.7mm all around.



Was aiming for 0.75, but the fixturing was a bitch, (hope I didn't go too far!).

Last edited by Gt6MK3 on Thu Feb 15, 2018 3:28 am; edited 1 time in total
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2134
Location: London UK
Wed Feb 14, 2018 11:25 pm quote
You don't hang about Some really nice work.

Just in case it's running by the next post, as its a new kit it will be tight. Now with more power too it will get even hotter. Be sure its rich through the running in. Run 3% mix for the first tank but back to 2% for ever after that. No holding steady low throttle speed for a few hunderd km.

Be sure the carb float bowl is drilled to at least 1.8mm. Starting jetting in a 24/24 is 55/160 AC160 BE3 MJ135

Need to clean up the head inside. All those dimples will glow red hot and could cause knocking.

If you give me some measurements of the barrel I'll check the durations and whether it needs shims. Exhaust and main transfer mm to the new barrel top. And how far the piston sits above or below the barrel top ('deck' as it is usually called).
Hooked
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Thu Feb 15, 2018 3:27 am quote
Thanks Guys. I'm lucky enough to have friends who have great toys, and are willing to teach me how to use them. That CNC Bridgeport is one of my favourite toys.
Jack221 wrote:
If you give me some measurements of the barrel I'll check the durations and whether it needs shims. Exhaust and main transfer mm to the new barrel top. And how far the piston sits above or below the barrel top ('deck' as it is usually called).
Sorry, I'm a 2 stroke neophyte, so please excuse the dumb questions...

By barrel top, I assume you mean the inside lip thats been created by cutting into the top of the cylinder.

For the main and exhaust ports, where do I datum them from - top (head and), bottom (head end), or somewhere else? Is there a thread somewhere I can use to educate myself? I assume I measure how far they are from the new lip of the head, then measure how far the piston is short of that at TDC. Do I measure anything on the piston?

On the drilling the carb issue, all the threads I can find on it reference photobucket photos, and I can't figure out which hole need relieving - anyone got a reference with actual photos?

I'd love to say that it's back together and roaring to life, but the only noise coming from the garage has been me swearing. I ground, drilled and punched out the rivets from the Malosi primary, flipped out the springs, swapped in the 67 tooth original primary gear, and pulled out my spare rebuild kit to grab the covers and rivets.

Unfortunately, it's a VNA rebuild kit, with the short rivets and undersize straight covers, not the larger kit with the pressed top skin.

The used covers aren't salvageable, and the local supplier (GPS) have nil stock. So unless I can find a Cush rebuild kit somewhere in Australia, I'm stuck for at least a week. How annoying!

Craig

[/quote]
Hooked
1984 PX(BGM187)EFL
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Location: Cornwall UK
Thu Feb 15, 2018 4:30 am quote
Quote:
On the drilling the carb issue, anyone got a reference with actual photos?
The one marked ĎDí here needs to be 1.8mm.


I did some other mods too, but not sure if consensus is theyíre necessary:



While Iím digging through photos, hereís my DR barrel and head, skimmed 3mm (barrel raised 2.2mm); note especially the cleaning of the bowl to free it of hot spots Jack mentioned:



Itís top of transfer and exhaust ports (just inside Ė remember that youíll be chamfering them) relative to piston at TDC you need, so easiest is to measure top of port to new barrel, and measure piston to barrel (deck height) when bolted down. From these you can calculate you transfer and exhaust timings; your transfer duration determines where your peak power will be. Raising the barrel with your packer (or the raising the ports themselves) makes your peak revs higher. The online calculators need the two measurements and deck height; you might like to play with this (I've made my own because I wanted to follow the maths of it, but still check it against this):

http://lambretta-images.com/archive/porttiming.php

Now you have such a small squish, thereís the option of adjusting that as well with spacers between barrel and head, and at the same time measure your head volume and calculate and tweak your compression ratio

What you havenít done (yet?) is altered your intake timing (needs casings split though), or opened your transfers. I opened my transfers in the barrel and at the same time tweaked them for piston alignment, then made a base packer, and used that as the template to open and match my casings as well. Then a few tweaks, a bit more opening, and the 0.2mm copper base gasket tweak:







Love your work and your toys by the way; Iíve been itching to chip in, but not had much to offer whilst youíre getting advice from the same chap I did a couple of years ago. I had such a palaver getting my head skimmed; no one wanted to touch it because it was so heavy and fragile (that was on a lathe though), but eventually found someone who had similar setting-up problems as you had, but did a fine job in the end.

Hope the photos are helpful, rather than clutter; good luck with it Ė watching with interestÖÖ
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 7660
Location: Victoria, Australia
Thu Feb 15, 2018 5:40 pm quote
I'm pretty sure I have a rebuild kit here which I could send to you but not until next week. Or you could come to Ballarat and pick them up. Just need to double check what's in my box of stuff.
Or Derek at Scooterlabs in Collingwood probably has one.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
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Location: London UK
Fri Feb 16, 2018 12:55 am quote
The datum is as Sime66 said. All from the new recessed barrel top.

Exhaust port and main transfer port measured up to the deck in 0.01mm accuracy. Where the piston sits at deck too.

I will assume 57.00mm stroke and 105.00mm con rod. They won't be spot on but close enough as a guide.

You can check this yourself on one of the online calculators.

You can see from Sime66's re-build a few years ago that there is more that can be done. And still even more to the barrel than he has done but for yours I think the 2mm packer will be plenty enough for an older type frame.
Hooked
Bodgerific 150 Super, 50s in progress
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Sun Feb 18, 2018 10:30 pm quote
Exhaust is 34.2
Intake is 43.9
Piston edge to barrel edge is 0.25mm below at tdc

Crank is this one https://www.sip-scootershop.com/main/base/Details.aspx?ProductNumber=45003000, pretty sure its a 105 conrod?
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
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Mon Feb 19, 2018 6:54 am quote
These seem too short. Attach a picture of what is being measured.

If your exhaust is really 34.2 your transfer should be 44.9 and not 43.9

Need to get a few mm into the port to measure the height, to be sure you are not measuring the chamfer.
Addicted
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Joined: 12 Sep 2014
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Mon Feb 19, 2018 7:37 am quote
This has really progressed. I love all the work and thought you are putting into this. Youíre gonna be blasting by folks in a blaze of DR glory!
Hooked
Bodgerific 150 Super, 50s in progress
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Mon Feb 19, 2018 9:29 pm quote
Jack221 wrote:
These seem too short. Attach a picture of what is being measured.

If your exhaust is really 34.2 your transfer should be 44.9 and not 43.9

Need to get a few mm into the port to measure the height, to be sure you are not measuring the chamfer.
My preferred measuement method is my buddy's multi axis CMM



but I cant get to it till next week.

So what I tried yesterday was sticking a feeler gauge into the port, and measuring up from there.



Although this seemed repeatable, it was obviously wrong.

Today I bolted the cylinder back up, and took a 0.1mm feeler, (stiff but not too stiff), held it flat across the cylinder and into the port by a fem mm. Then I wound the flywheel till the feeler contacted the port wall enough to _just_ want to deflect. Then I held the flywheel and extracted the feeler without moving the piston, measured from the piston to the barrel edge, and subtracted the 0.1 for the feeler. Kinda like this



Except I needed both hands, a toe, and my chin. The exhaust was much easier than the intakes (the chamfer on these is tricky), but I'm more confident in these numbers

Repeatable results average out to:

Exhaust 35.0
Intake 45.65

Piston to barrel edge still 0.25.

Hopefully they make more sense.
PureDrivenSnow wrote:
This has really progressed. I love all the work and thought you are putting into this. Youíre gonna be blasting by folks in a blaze of DR glory!
Patience isnt my strong suit. I'm dying to go for a ride!!!!!!
Jet Eye Master
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Tue Feb 20, 2018 12:42 am quote
Much better. Right on the money. Doesn't need any trimming just bolt it up like that and get ready to be impressed
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
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Tue Feb 20, 2018 12:48 am quote
This still applies and is essential to have a chance at getting through the run in phase.

Be sure the carb float bowl is drilled to at least 1.8mm. Starting jetting in a 24/24 is 55/160 AC160 BE3 MJ135

As you have a squish on the tighter end and still in the running in phase, it would be best to have the ignition timing at 16 degrees for now. Will probably end up a few degrees higher in the final set up once run in. Must be set with a strobed test as the marks are a guide at best and better accuracy is needed.
Hooked
Bodgerific 150 Super, 50s in progress
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Wed Feb 21, 2018 4:37 am quote
Jack221 wrote:
Much better. Right on the money. Doesn't need any trimming just bolt it up like that and get ready to be impressed
Cheers, Bolting away!

Thanks muchly for the help - the value of forums like these is the generosity of its knowledgeable members.

Hit a snag today when the bolted up version failed to hold pressure in the leak test (I'd chucked in a blue oils seal with plenty of 603). Seals were both OK this time, so I moved onto the spacer and cylinder. I'd given these a smear of Permatex Formagasket 2 (the non hardening version), but I figured they were the most likely culprits. Nope - no bubbles. So I tried the head to cylinder join - thats a challenge now given the machining, but it seemed OK.

But the pressure kept dropping.

So I grabbed a length of 3/16 fuel hose, stuck one end in my ear, and the other end into the case behind the primary.. Either there's a snake in there, or I've found my error.


The confused face of a bloke who's not sure if he should be happy he's found the problem, or pissed because he caused it...

So I pumped up from 6 to 10psi, and it became a steady nasty hiss.

My fault - I re-used the gasket from the bearing replacement. I hadn't been run with it in, and it's better quality than all the other I've been able to buy here in Aus, so I tried it again (using the put it on the flyside first method). This one's obviously blown where the last one did. Time for a new one. I'll try the paper ones I have with some hylomar.

Otherwise I'll be shipping in these

http://www.scooter-center.com/product/BGM1212/Engine+gasket+set+BGM+Pro+silicone+Vespa+Largeframe+PX80+125+150+200+all+Rally200+Cosa+Sprint+Veloce+incl+O+Rings+with+without+autolube

I keep looking at that incredibly thin lip at that point on the case, , and I want to go back and ask the designer what he was thinking!

Anyway,

1. These were low stock when I looked, so I went for one of these https://www.sip-scootershop.com/en/products/clutch+sip+cosa+2+sport+_93404000. I figure I'll need to cut back the clutch cover or make a spacer. Anyone got a handy link to instructions needed?

2.
Quote:
As you have a squish on the tighter end and still in the running in phase, it would be best to have the ignition timing at 16 degrees for now. Will probably end up a few degrees higher in the final set up once run in. Must be set with a strobed test as the marks are a guide at best and better accuracy is needed.
Again, thanks all for the continuing help.
Vespatronic starts at 20 degrees at 600rpm, jumps to 23 degrees from 1500 to 4000rpm, then steadily sinks to 21 degrees at 5000rpm, 18 degrees at 6000rpm, 16 degrees at 7000rpm, and 15 at 8 and beyond.



I can adjust where the curve lands by winding it back, but the curve doesn't change. Any thoughts what to aim for at 2000rpm to have that curve work?

Ta,

Craig[/i]
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 7660
Location: Victoria, Australia
Wed Feb 21, 2018 1:22 pm quote
You will find that Scooter-Center (SCK) has flat-rate shipping and that's 27 euro on top of the purchase price. Great if you're buying legshields. GPS Imports will get genuine Piaggio gaskets to you in 2 days if care to brave their website.
It's just a matter of careful installation really. Here's a video looking at the issue. https://youtu.be/1p9Nbgac5Go
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
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Wed Feb 21, 2018 2:23 pm quote
Forgot you had a Vespatronic. Set it up with the 16 degrees at 7000 rpm.

You're not having a lot of luck with the gaskets. For what its worth, you are showing everybody how important a pressure test is. Even when you know what you are doing and what to watch out for, no matter how many engines you did before, it still doesn't seal everytime. Might take months to notice the affects of a minor leak too (and by notice I mean seize up).

Get a brown seal and a few gaskets on the shelf ready for the next time.
Hooked
Bodgerific 150 Super, 50s in progress
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Thu Feb 22, 2018 4:00 am quote
Cases cracked, and the culprit is clear. I put the gasket on the fly side first, but the evidence is damming



Thatís one mm of slippage, and itís toast.

So I cleaned it all down again. (Razor blades, picks, rags, green scouring pads, compressed air, elbow grease and carb cleaner, I like a clean and tidy engine)



I cleaned it a lot - especially the recalcitrant flange.



(Heineken helped make the work more beerable!)

This time, I followed the instructions from the video linked above. First, I put the sealant on the outer casing, not the gasket, and built up a bridge under the weak spot, but being careful to keep the corner and wall of the flange clean of sealant.



Then I put the gasket onto the tacky sealant, centered all the bolt holes, snugged it in tight to the walls, and ran a broad blunt screwdriver blade over it to smooth it all down and squeeze out the excess.



(Note the sealant bridge support)

I cleaned off the excess, and tidied up the edges and the excess that I'd gotten on the flange wall.

After an equally thorough clean I put a smeared layer of sealant on the main case.



Then married them up oh so carefully, symmetrically and gently, gave them all new hardware, and bolted them up in order, sneaking the torques up slowly and in order till they were all at 11ft/lbs.

The head and cylinder both got a smear of Permatex,



I mated them up on the bench, pushed down hard, then separated them and cleaned off all the excess, leaving the lightest of light coating in the contact ring.

I gave the casing mating surface a light smear since thereís no gasket with the spacer, being careful to keep the ports clear,



Then buttoned up the head, making sure I got no permatex in the cylinder or on the rings or piston.



New hardware all around, and head sneaked slowly up to 14ft/lbs.

Then, rather than pressure test it right away, I gave it an hour to settle, and re-torqued it all round.

Then I razor bladed and cleaned off any excess permatex Iíd squeezed out, and generally cleaned it all up. (Did I mention I like a clean and tidy engine).

Itís time to pressure test it, but also time to eat. So I had some dinner, and posted this. Iím about to go out and see if itís airtight. It's lurking in the garage, and I'm apprehensive of the result... Not sure what more I could do if it leaks. I may chicken out till morning.

Craig

P.S. Sorry if the posts are a little photo or detail heavy, I realize I'm preaching to the converted, it just gives me a record of what's been done and whether it works, and I'm sure if (when) I do something stoopid it will get pointed out - C.
Hooked
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Fri Feb 23, 2018 4:14 am quote
So, at midnight, I hardened up, and went back to the garage.

It still had a slow leak somewhere. Rude words were used. Very rude.

Only promosing thing is that even in the dead of night, it didnít have an audible hiss with the hose-o-scope in the crankcase.

So maybe itís the cylinder/casing or cylinder/head seal this time.

I went to bed pissed off.

Autopsy on the head and cylinder this morning

Head contact looks ok, the smear of permatex pushed wide on compression, leaving the contact ring pretty much clean.



Ditto the cylinder to spacer join,



Permatex has squashed out to leave a clean mating surface, spacer is clean too



But, on the space to casing join, thereís a small web of permatex left on both surfaces on the bottom of the flywheel side.





So I decided to try another approach, and get some RTV in there.

After another cleaning session, I went Ultra Copper all round, using the put on a bead and push to squeeze method.





The Cylinder head I was pretty generous with on the outside of the ring, but I cleaned up the inside to ensure nothing got in the bore.





Everything was then put together, hand tightened, and left to cure for an hour.

Then I torqued it all down and went to work.

Came home tonight hoping that Iíd find it holding air at last.

Yeah, naaaah.

300mmHg becomes 200 in 50 seconds, than 100 seventy seconds after that, then nil after about 3 more minutes.

I can still hear nothing in the case..

Thereís no sign of a leak on the fly side, including around the studs and around the cylinder join.



Thereís nothing showing around the top of the cylinder join, the case join or the test kit join.



Ditto the base of the cylinder and the exhaust plug.



Clutch side shows no results



Testing in the cylinder/ head gap was hard, but flooding it with bubbles showed nothing



Grrrrr.

Time for a logical approach. If a leak isn't showing at the places I can test, then it (or they!) is probably somewhere I can't. The likely spots are the head to cylinder, or the seal.

To test these I'll need some more test parts.

For the gasket, I figure if make up a blocking plate for the gear shift, put on the clutch cover, and block the breather,I'll be able to check if that then hold pressure. If it does, it's the gasket.

For the cylinder, I can make up a blank with a higher offset so I can leak test it properly. If that hold air, I'll look at the cylinder.

So I need to see if I can get access to a mill tomorrow. If I do, an option might also be to clock up the casing and clean up the face, but that would change my already tight squish (and it would be a major pita to get it fixtured.)


Patience Grasshopper...
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
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Location: London UK
Fri Feb 23, 2018 7:36 am quote
Must be still leaking in the casing at the thin bit. Was it a new gasket?
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 7660
Location: Victoria, Australia
Fri Feb 23, 2018 4:17 pm quote
That's frustrating.

I was wondering how you might eliminate sections to help zero in on the issue. I'm thinking you could use some inner tube from a car to block off the case from the cylinder... you would need to turn the cylinder upside down to clamp it down, and with the crank at bdc it would make it easier. But maybe you don't need to do this at all, because -

The other thing you might try is a smoke tester, since you can't seem to get in with your bubble mix. This one looks perfect to me...

Molto Verboso
1979 P150X, 1983 P200E, 1987 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
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Fri Feb 23, 2018 4:53 pm quote
Hope you find your leak. Just an FYI. The Permatex Ultra series (blue, black, copper, etc.) aren't compatible with gasoline. It's in the fine print. I hadn't noticed it either and Mike (SoCalGuy) pointed it out...
Hooked
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Sat Feb 24, 2018 2:57 am quote
For the cases I've had good results using loctite number 3 non-hardening aviation gasket sealant. It's resistant to gasoline.

I also have an lml engine running with only permatex anaerobic gasket maker as the gasket. No paper gasket at all. It's been fine for a couple of years now. It's great stuff. Only hardens and seals in the absence of air between the two surfaces.
Hooked
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Sat Feb 24, 2018 6:14 am quote
Jack221 wrote:
Must be still leaking in the casing at the thin bit. Was it a new gasket?
I've no doubt your right. The nerd in me just want's to find a way to confirm it so I can (as Ginch said) zero on the problem. Yep brand new one of these http://www.gpsimports.com.au/products-details.php?productId=4796 - I have 3 left of the 5 I got, and they have no original piaggio in stock.

Weather was too crappy for aviation today, so I got a few hours on my mate's CNC bridgeport instead, and build some test jig bits that hopefully will let me do that.
Ginch wrote:
This one looks perfect to me..
That smoke getup looks awesome. If I'm still struggling this week I'll be at Aldi looking for a jar of pickles!
SaFiS wrote:
The Permatex Ultra series (blue, black, copper, etc.) aren't compatible with gasoline.
No argument. But experience has shown that they're really talking about constant, 100 percent contact. My logic with this was that at the Cylinder/Casing join, it's really just a vapor join - the cylinder barrel down the casing throat takes all the fluid wetting. really it's just locking off vapors from 2 faces. All thats left in the post torquing photos is a hint of what I'm putting on. But point taken, and yes, I'd prefer to use Holomar/Permatex Flange/Aviation , but I need to try something else just incase.
Warhorse wrote:
" loctite number 3 non-hardening aviation "... "Permatex anaerobic gasket maker"...
Pretty sure I've got both in the drawer. Could be a second to and last resort.

Once I'd build the test jigs, I decided not to depress myself with whats not working. Instead, I took my spare clutch cover, and clocked it up in the mill to bore it out for the SIP Cosa 2 sport clutch.



Banded cosa clutch should be ready to go once I find the engine gremlins.

Weather looks good tomorrow so I'd be jumping outa planes for fun and profit, hopefully will be able to test all the parts Monday night.

Thanks as always for the help and support.

Craig
Jet Eye Master
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Sun Feb 25, 2018 2:51 am quote
Shows up my work with the clutch covers I run round mine with a Dremel holding is on my knee. Result it quite functional though.

At least some pressure held after 10 minutes is the pass level for the cases.

There is a fair leak somewhere.
Do you have a valve on your test gear to be sure that is not leaking back?
Molto Verboso
Joined: 31 May 2009
Posts: 1221
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Sun Feb 25, 2018 6:18 am quote
Warhorse wrote:
For the cases I've had good results using loctite number 3 non-hardening aviation gasket sealant. It's resistant to gasoline.

I also have an lml engine running with only permatex anaerobic gasket maker as the gasket. No paper gasket at all. It's been fine for a couple of years now. It's great stuff. Only hardens and seals in the absence of air between the two surfaces.
Aviation gasket sealer proponent here as well. Apply to one side and allow to set up to avoid later gasket slippage.

Another old trick for the thin crankcase sealing area is to use thin cotton string coated with the sealer, then place one or more strands beside each other between the bolts and flange on top of the adhered on one side gasket.

Great, informative write-up and pictures.
Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
Posts: 292
Location: Melbourne, Way Downunder
Mon Mar 05, 2018 6:20 am quote
So I'm still in fail mode.

I'm looking hard at the usual spot.

I'm thinking that I'm not getting enough sealing pressure to properly clamp the weak region.

With the permatex blue applied as per above, It still leaked, and when I pulled it apart, I still had a hint of blue on the fly side



On the main side, the gasket had pulled away on splitting, and it looked "wet" like it had never been squeezed properly.



Retrying it all with aviation sealant had the same result.

A gasket that pulls away on one side



and leaves the other side heavy with residue



To really confuse myself I build a fake test head,



Which when bolted up lets me test for leaks at the cylinder head join - (None)



And a gear change sealing plate



Even with these on, and a sealed up clutch cover in place, still no pressure holding.

I tried building one (possibly two) of Ginch's smoke pressure pots,



They're a nice thought, but under anything over 2 psi, the lid of the pot pops off, because it flexes with the heat. Tape and/or silicone don't fix it, modern pickle jars are flimsy...
Ossessionato
2015 GTS300, 1974 Primavera, 04 Ninja 250
Joined: 04 Apr 2013
Posts: 4426
Location: San Diego, CA
Mon Mar 05, 2018 8:19 am quote
Maybe build up the flange in that area with some JB to get it wider and fix any low spots? Seems like you need more surface area and you might have a low spot to boot.
Molto Verboso
1979 P150X, 1983 P200E, 1987 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 1924
Location: Veria, Greece
Mon Mar 05, 2018 8:26 am quote
And get the newer, green gasket from Piaggio. It's of better quality and a bit thicker...
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2134
Location: London UK
Mon Mar 05, 2018 8:28 am quote
Next time you have it all sealed up for test (including the gearbox!), maybe put the whole engine in a big vat of water? If the engine isn't waterproof it shouldn't be driven in the rain
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 7660
Location: Victoria, Australia
Mon Mar 05, 2018 1:24 pm quote
I'll have to import a better quality pickle jar then, thanks for the heads up!

Sorry to hear, that is very tricky. Dumb question, I assume you're leaving it time to go off before testing? Perhaps try Blackbart's cotton trick? Or (unless you already did this) try it with no gasket and use just one of the silicone-based sealers? Seems like it can't NOT work because it will fill the low spots.
Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
Posts: 292
Location: Melbourne, Way Downunder
Tue Mar 06, 2018 12:15 am quote
No one in Oz had stock of piaggio green.

Shipping to here is expensive and often slow, but it can be done.

1A448629-4502-4C9E-8389-FC30A2ED3D7E.jpeg

Molto Verboso
1979 P150X, 1983 P200E, 1987 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 1924
Location: Veria, Greece
Tue Mar 06, 2018 1:30 am quote
Heads up on the BGM ones. I had 2 fall apart at the studs, on two different engines. Less than 2k Kms on them. I had leaks and the gasket had slipped outwards. I contacted them just to let them know (maybe a dried out batch) and they started making excuses, that I didn't use a torque wrench and shit like that...
Hooked
Bodgerific 150 Super, 50s in progress
Joined: 18 Aug 2016
Posts: 292
Location: Melbourne, Way Downunder
Tue Mar 06, 2018 6:41 pm quote
Molto Verboso
1979 P150X, 1983 P200E, 1987 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 1924
Location: Veria, Greece
Tue Mar 06, 2018 7:00 pm quote
Found the photos...

898.JPG

900.JPG

901.JPG

902.JPG

Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 7660
Location: Victoria, Australia
Tue Mar 06, 2018 11:38 pm quote
Yikes.
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