VBB Lockdown Project -- Maybe I'll finish before lockdown...
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Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Fri Jul 17, 2020 3:54 am quote
Christopher_55934 wrote:
That's not the 5th time I've seen that, how do they keep coming out? Almost makes me want to put some loctite retaining compound on when I put them together.

Maybe just a few bits between the web and connecting rod? Or do you think small bits ended up in the bearings?
It's hard to say for sure. Optimistically, if I can find the bulk of the pieces, the rest of it is aluminum, and while any pieces left in there will degrade the life of the motor long-term, steel beats aluminum every time and will eventually just grind it to paste and wash it out.

I'm hoping that I'll find the other 3/4 of the circlip jamming the crank against the case. Assuming that happens, I think I'll be OK. I don't think it's shattered, because there doesn't seem to be enough piston damage for that. Ultimately, only time and further inspection will tell.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Fri Jul 17, 2020 1:47 pm quote
It lives again!

Sometimes, what you need to solve a problem is to get into a state of having No Fucks To Give.

I went out to take a further look and wound up cleaning out the bits of aluminum and finding the bulk of the Suicidal Circlip. I blew things out with lots of compressed air and brake parts cleaning until it all looked and felt good, then decided to assemble it and see what happened under the theory that the worst outcome would be that I'd have to tear it down that much more to replace parts.

The original piston skirt had broken off under the lefthand window, which was the bulk of the mashed up aluminum.

I found a BGM 177 piston on the shelf that had like .001 more clearance than the original piston, so I dropped that in, the port timings and squish stayed more or less identical, so I buttoned it up and...it Just Worked!

I need to put some gas in it, and the shift cables still need some adjustment, but it's back up and running, so I'm happy about that.

Video to follow at some point, but it's been a hell of a week scooter-wise.

IMG_20200717_151426.jpg
Piston skirts are totally overrated.

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2036
Location: california
Fri Jul 17, 2020 3:32 pm quote
Awesome!!!
And by that - I mean my your new signature line:

"Sometimes, what you need to solve a problem is to get into a state of having No Fucks To Give. "

Fix isn't too bad either...
🙂
Nice save.

Bodge O Meter1.jpg
Charlieman gives that a solid pearl clutching on the fainting bed score.

Molto Verboso
2007 Stella 225
Joined: 02 Nov 2019
Posts: 1447
Location: Rochester, Minnesota
Fri Jul 17, 2020 4:58 pm quote
chandlerman wrote:
It lives again!

Sometimes, what you need to solve a problem is to get into a state of having No Fucks To Give.

I went out to take a further look and wound up cleaning out the bits of aluminum and finding the bulk of the Suicidal Circlip. I blew things out with lots of compressed air and brake parts cleaning until it all looked and felt good, then decided to assemble it and see what happened under the theory that the worst outcome would be that I'd have to tear it down that much more to replace parts.

The original piston skirt had broken off under the lefthand window, which was the bulk of the mashed up aluminum.

I found a BGM 177 piston on the shelf that had like .001 more clearance than the original piston, so I dropped that in, the port timings and squish stayed more or less identical, so I buttoned it up and...it Just Worked!

I need to put some gas in it, and the shift cables still need some adjustment, but it's back up and running, so I'm happy about that.

Video to follow at some point, but it's been a hell of a week scooter-wise.
With there being nothing you wont Dremel, I'm surprised you didn't cut the other side to match, round off the corners and put it back together. Glad it worked out for you, something has to go your way every once in awhile.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Fri Jul 17, 2020 5:14 pm quote
Christopher_55934 wrote:
With there being nothing you wont Dremel, I'm surprised you didn't cut the other side to match, round off the corners and put it back together. Glad it worked out for you, something has to go your way every once in awhile.
that was actually Plan A. I was going to do exactly that, but the upper ring broke, so then I decided to see if the meteor piston would fit, but ran across the BGM piston, which was a little beat up, but still functional and with two good rings, so I went for it.
charlieman22 wrote:
Awesome!!!
And by that - I mean my your new signature line:

"Sometimes, what you need to solve a problem is to get into a state of having No Fucks To Give. "

Fix isn't too bad either...
🙂
Nice save.
I love the Bodge-o-meter! And, yeah, that may make it into my signature.

I normally don't rage-fix stuff, but this one just set me off. It worked out that I was able to clean all the bits n' pieces out with a combination of compressed air and brake parts cleaner. I caught the first blast solid in my chest, so I probably smell like a combination gas station & dry cleaners, but whatev's. Luckily, I had a piston, circlips, and a quiet afternoon (after a pretty hectic morning) so I could sneak away from my desk to make it happen.

Next, I need to get the lights sorted out since I'm going from 12v back to 6v.
Then, it'll be time to get out the air-fuel meter and dial in the carb.

And on the bright side, it feels like it has a little more low-end torque than before, even if it's MUCH milder than my other bikes.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2602
Location: London UK
Sat Jul 18, 2020 12:56 am quote
Running again must be nice to have gotten away with it.

That old piston can easy be cut as said. Whole bottom off leaving it at least 62 mm ( cover ex port at TDC) long will work.

Top tip for circlips. Always rotate them in the groove after fitting to leave the gap at the top. Best chance of staying put.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sat Jul 18, 2020 5:29 am quote
Jack221 wrote:
Running again must be nice to have gotten away with it.

That old piston can easy be cut as said. Whole bottom off leaving it at least 62 mm ( cover ex port at TDC) long will work.

Top tip for circlips. Always rotate them in the groove after fitting to leave the gap at the top. Best chance of staying put.
I'm not sure I'd say I've gotten away with it quite yet, but once I can put a few more miles on it without incident I'll declare the coast clear.

I switched over to standard CW-15 wire circlips this time around, same as I run in my high performance motors. The old circlip was the retaining ring style, which are great for ease of installation and removal, but clearly not so good for staying in place. In hindsight, I think the reason you don't see those any more is pretty obvious...
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2602
Location: London UK
Sat Jul 18, 2020 7:52 am quote
chandlerman wrote:
Then, it'll be time to get out the air-fuel meter and dial in the carb
I'm not a fan of the AFR meter for 2 strokes. Especially premix ones. Sure use it to get close but fine tune by plug colour, piston crown and feel. Set it up to maybe 11 from zero to WOT then go old school for the final adjustments. Won't end up lean if done manually.
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2295

Tue Jul 21, 2020 4:34 am quote
Ahh man , thats a bit of bad luck.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Fri Jul 24, 2020 7:35 pm quote
Well, I didn't get all the pieces out, so I split the cases tonight and pulled the crank, which I knew I should have done all along.

The clutch side bearing is toast and there are two nice big scores in the rotary pad. The pad looked worse when I first got it, so I'll have another go at it with the JB Weld and see if that gets me another ten years out of it.

If I can't repair the pad, it'll be reed time. First attempt will be fitting an LML reed block to it. I may have to add a spacer underneath. I have a spare LML reed block and some 1/4" aluminum sheet that I could fabricate a spacer out of, and that would allow me to keep the si carb. Otherwise, I'm not sure the whole project is really worth it when I have the LML motor I converted to 8" that I could tear down, fix an air leak, and put it back in.

I'm also contemplating a new crank. The runout on the old one is suspect, I think, and I'd rather bite the bullet now than deal with it all over again when the crank kills a seal prematurely or blows up entirely.

IMG_20200724_215132.jpg

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2036
Location: california
Fri Jul 24, 2020 7:59 pm quote
CM - So frustrating!
Jack gave me a tip that worked well.
Passing it on with my own twist here.
When you use the JB - put the crank in.
Add a sheet(s) of something between crank and JB welded pad - thick enough to give desired tolerance but on the low on the low end.
Grease it - with the thinest oil you have - to keep it from bonding in.
Use the highest compression long cure stuff.
Leave it in garage - under a spot light so it looks good - head inside - and mix a cocktail.
Will be super smooth when you go to see it in the morning over coffee.
-CM
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2602
Location: London UK
Fri Jul 24, 2020 10:20 pm quote
Unfortunate but fully fixable. Those old inlets are really tiny. If you open out that pad to 190 degrees and a bit wider, before the JB goes on there will be much less to fix. Speed and economy.
Crank can be fixed with a dial gauge and a mallet.
This time it will work. Would rather run these cases than LML, no offence.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sat Jul 25, 2020 6:08 am quote
I'm not actually all that worried about the rotary pad damage. It looked worse than that when I got the bike and I cleaned it up just fine.

I've pretty much decided that I'm going to go ahead and order a 60mm crank from SIP with a P style flywheel taper. I have a P200 electrical system not in use right now, so that will solve the next problem on the list, de-converting the electrical from 12v to 6v and all the misery that entails. I am the guy with "It will live again. Chuck more money at it.," in my signature, after all

I'm changing up my parameters a little bit since the BGM piston was working well and is unscathed from the latest disaster. I'm going to up the port timings a couple degrees, like from 122 to 124 on the main, but it's still just a 2-port motor with no room on the cases to open things up, so I'm can't get THAT excited.

Which brings me back to inlet timings...

This is one of those topics that I've largely avoided since pretty much all of my tuning has been done on reed valves.

The concept makes sense, but I'm really struggling to find any good information on how to calculate desired timings, as well as the nomenclature to discuss it on here.

There's some great explanation of this in discussion between Jack & Sime in SDJohn's Malossi 210 Build thread, so I'm going to summarize here both for posterity as well as my own learning process.

- There are three key measures of inlet timing:
-- Total duration. This is the 190 that Jack mentions above
-- Duration before TDC
-- Duration after TDC
-- The sum of the before + after durations = the total, i.e. in my case, 190 degrees
- The measurements refer to degrees of the crank vs. the rotary pad

- Timings can be changed by both expanding the intake and cutting the crank. It doesn't matter how to get to your target intake timings, you just need to get there. Expanding the intake is less work and somewhat less risk, but also more permanent, than cutting the crank.

- Minimum overlap of the crank to the rotary pad is 2mm for a good seal, assuming the pad is in good condition.

I still don't feel like I understand where the target durations (before, after, and total) come from, other than that it ties to port timings and target peak RPM's.
- Higher intake timings prefer high-RPM power, with the tradeoff being that lower-end power and, at some point, idle stability will suffer, similar to port timings. In my case, I'm going to want something more stable, so I completely trust Jack's recommendation of 190.

Quoting Rob Hodge, " If you are at 163 ish degrees open, that's very conservative, and virtually stock. Road tunes on stock top ends call for around 170-185 degfrees. Kits can go as high as 220-230"

I threw a copy of "Tuning Vespa's by Norrie Kerr into my SIP cart, since it apparently covers intake timing in great detail.

Once I have my SIP order in hand, I'll begin exploring all of this in more detail.

For now, I'm out of time, but still have research & learning to do. Please feel free to add updates (especially about how to determine desired intake timings) or corrections and I'll update this post accordingly.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2602
Location: London UK
Sat Jul 25, 2020 8:07 am quote
Your kit does have a 3rd port, with internal transfer.

60 P crank is a good idea. Aim for 124/184/30

To save you looking. 190 degrees is 125 before and 65 after. This is mild to moderate.You'll need to cut a bit off casing and crank. Fit the crank and draw through the inlet to check the overlap at the sides. They all fit different. Very individual. At least 1mm overlap at the sides and 2mm front and back. Quality of rotary pad is overrated. They leak even when perfect. Leaking might even be faster.
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2295

Sat Jul 25, 2020 8:10 am quote
Nothing to add but sure will be following along to give moral support, you can do it
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sat Jul 25, 2020 3:19 pm quote
Thanks, Jack!

I'm still going to do the research, because I want to know how to determine what those timings should be for myself, but I appreciate the guidance since the immediate goal is to get this thing back on the road.

The long stroke P cone crank is ordered from SIP, so it should show up by next weekend. Once I have that, the measuring, dremel-ing, and JBWelding can begin. It'll be a project that exemplifies everything I do to scooter motors!
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1261
Location: California
Sun Jul 26, 2020 6:38 am quote
Seems like a good idea for plenty of reasons. I have a P200 electronic stator and BGM small taper flywheel on my GL. Initially had trouble with BGM stator so ended up buying a LML stator and it's been working flawless for 3,800 miles.

On the Bajaj went with the Mazzucchelli 60mm crank with large taper. The 60mm crank along with the tuning is impressive compared to it's older brother Gran Lusso. Also with this taper the myriad of flywheel options. I am using a self lightened P flywheel on the Bajaj my driving style appreciates the inertia as I putt around.
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2036
Location: california
Sun Jul 26, 2020 9:16 am quote
CM - I am interested to see what you find on timing.
185-195 of crank timing is certainly not uncommon.
I have the lower end of that on mine - and have now tested multiple cylinders on it with various port timings, and various carbs and jetting.
What I have found with all has been that the motor requires very lean 1/8 throttle jetting to knock out any 4 stroking (and fairly rich WOT jetting), and is happiest idling in the 1300rpm range rather than at 1000.
I suspect these traits are related to the inlet timing - but no way to know for certain.

The question is: for 185-195 of inlet duration - how does putting more up front or in back bias performance?

Anyone wanna take a stab at that?
CM - if you find something in your readings - it would be of interest.

BTW - having done these cases - I would share the following.
That stud at the front will come in to play for the 65 closing.
The one at the back will be right at the edge and may also.

I ground the front of my inlet to within a hair of that stud - and it developed a buzzard leak. If you look - that stud hole runs all the way through the cases and in to the clutch chamber. That was done for machining purposes I think when they threaded the cases.
Do yourself a favor and seal the hole inside the clutch side chamber when you build.[/b]

img_0484_46758_10519.jpg
Can just barely see I am at the edge of the threads where the aluminum is darker.

img_4998_69014.jpg
Bubbles coming out on clutch side. You will find a threaded hole there at about 11 o'clock looking at the front of the clutch. Bit of Honda bond plugged it nicely.

Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sun Jul 26, 2020 9:20 am quote
Charlieman, you're thinking about the exact same sorts of questions I am about how inlet timings affect things. I have the Norrie Kerr book coming in my SIP order, which is apparently a fairly definitive reference on the topic, so I'll see what he has to say on the topic.

And thanks for the heads up on that clutch-side leak risk. I'll plug that hole when I skim the rotary pad, for sure.
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2036
Location: california
Mon Jul 27, 2020 9:08 am quote
Great.
Super interested to hear what he has to say on biasing as well as various limits.
Example - how much overlap of inlet and transfers being open is ok - and what effect does it have...

Found one other image of interest.
Reminded me I also ended up grinding in to the bottom of the carb stud hole at the back.
For that one - I took the stud out - it was shorter than the hole in the case - greased the tip of the stud and put a small piece of cotton on it- re-inserted - and filled the hole from the inlet side with JB weld. This closed it off securely - and avoided the JB either bonding to the stud or sitting right up against it (cracking concern).

img_2015_10187-2.jpg
Ended up just grinding the back side of the inlet to the shape I wanted - rather than grinding around the stud as this suggest.

Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sat Aug 08, 2020 1:10 pm quote
Today was Dremel the Intake Day at Casa Chandlerman.

After lots and lots of measuring, I marked the rotary pad and busted out the dremel. Other than hitting the studs exactly as you predicted, CM, it was all pretty uninteresting.

Final port timings with the 60mm crank and BGM piston came to 124/155/16 with no base gasket vs. a target of 124/184/30. I need to spend a little time on that exhaust port, but right now, that'd be raising the top of the exhaust a whopping 7mm, which I don't think is happening.

And since I was working, I checked the flow from the airbox to the case and found a little room for improvement there, so I dealt with that as well.

Finally, I skimmed the remains of the rotary pad with JB Weld, coated the crank with Silicone mold release, and slid it in to cure.

Next update tomorrow when we see how the JB Weld took.

IMG_20200808_124723.jpg
Custom degree wheel measuring point

IMG_20200808_140059.jpg
Measuring. Lots of measuring.

IMG_20200808_144427.jpg
Stud. Right where CM predicted.

Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2602
Location: London UK
Sat Aug 08, 2020 1:27 pm quote
How many degrees is the rotary inlet with your 60 crank?

Might get 7mm out of the exhaust. Usually pretty thick there. Be sure to get it as close to that's you dare.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sat Aug 08, 2020 1:59 pm quote
Getting to 25 degress BTDC was pretty easy. I'm about 7 degrees short of 125* 65 ATDC, though, and I decided I didn't want to cut the crank at this point.

I built up the pad some with JBWeld out past the forward end. I could potentially extend it a little bit once it's cured if it's all looking good up there, but that feels a bit aggressive, even for me.

I'm going to take a look at the cylinder tomorrow and see what I think I can take out of the exhaust port.

* corrected for posterity

Last edited by chandlerman on Sun Aug 09, 2020 5:18 am; edited 1 time in total
Molto Verboso
2007 Stella 225
Joined: 02 Nov 2019
Posts: 1447
Location: Rochester, Minnesota
Sat Aug 08, 2020 2:09 pm quote
chandlerman wrote:
Getting to 25 degress BTDC was pretty easy. I'm about 7 degrees short of 125 ATDC, though, and I decided I didn't want to cut the crank at this point.

I built up the pad some with JBWeld out past the forward end. I could potentially extend it a little bit once it's cured if it's all looking good up there, but that feels a bit aggressive, even for me.

I'm going to take a look at the cylinder tomorrow and see what I think I can take out of the exhaust port.
What? I thought youd Dremel anything? 😀
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sat Aug 08, 2020 3:08 pm quote
Christopher_55934 wrote:
What? I thought youd Dremel anything? 😀
"Pretty much anything."
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2036
Location: california
Sat Aug 08, 2020 3:41 pm quote
I've posted but looks like nothing showing?
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2036
Location: california
Sat Aug 08, 2020 3:50 pm quote
ahhh - user error - here is what I typed.
CM - Your inlet looks great - though it looks to me to be about ~120 something/60 something - based on my experiences. Maybe even right at 120/60.
Quote:
Getting to 25 degress BTDC was pretty easy. I'm about 7 degrees short of 125 ATDC,
did you mean 25 or 65?

Measuring and calculating the inlet confused the hell out of me when I did mine.
I confused where the numbers came from - tho if I had to explain why it would take me 3 re-reads in a row to relearn what I had figured out. Had to do with other similar measures you can take that I was using - incorrectly. You probably know all this - but just raising it if helpful.

Sime did a great job walking me through it here about half way down the page if any use: Vintage vespa with sidecar (Page 20) which included a means to double check the math.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2602
Location: London UK
Sat Aug 08, 2020 10:26 pm quote
chandlerman wrote:
Getting to 25 degress BTDC was pretty easy. I'm about 7 degrees short of 125 ATDC, though, and I decided I didn't want to cut the crank at this point.

I built up the pad some with JBWeld out past the forward end. I could potentially extend it a little bit once it's cured if it's all looking good up there, but that feels a bit aggressive, even for me.
I wrote this below a few posts back. I hope it's not cut round the wrong way. There shouldn't be any need to put JB weld out the front. Put the crank in and measure where you are.
Jack221 wrote:
60 P crank is a good idea. Aim for 124/184/30

To save you looking. 190 degrees is 125 before and 65 after.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sun Aug 09, 2020 5:24 am quote
It's all good . The error was in my writeup, not my work.

I went out and re-checked this morning and it's dead on at 125 before, but only 58 after. Looks like the JBWeld sealed things properly, and it'll be on to the cylinder today.

I took a look at how much extra meat is on the Pinasco and you were spot on, Jack. It's a LOT. The barrel itself is 77mm outside diameter, so 7mm walls, and there's another 5-6mm of meat on the top of the exhaust port, too. In fact, the port has a bit of a lip to it, so what I'll mostly be doing is just taking that off.

Assuming that I get back out to the garage, I should get the exhaust port knocked out and be able to start buttoning things back up again.

I'll be interested to see how these changes feel on the Butt Dyno compared to the original build.

And, while I still don't understand it yet, I feel comfortable working on rotary intakes rather than just jumping to a reed, since that's what I started with on my Stella.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1261
Location: California
Sun Aug 09, 2020 5:32 am quote
Inlet porting looks great think you might like the changes. Im a big fan of the Vespa rotary valve and SI carb.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2602
Location: London UK
Sun Aug 09, 2020 6:28 am quote
Good it's just a typo. Would have been quite an achievement to get 125 ATDC.

Exhaust port can be 48mm wide on the arc. Measure by rubbing and measure that.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sun Aug 09, 2020 8:19 am quote
I took a rubbing of the exhaust port. It's 42mm wide right now, looking at the wider part up at the top, so that means adding 3mm on the arc to each side, then extending the whole thing up 7mm to get the timings right.

Gonna be a lotta swarf in the ol' garage today.

And, yes, I was stressing pretty hard that I'd gotten the measurements backwards after folks' comments and was already thinking about where my spare LML reed block was to see if I could fit that to the motor if it came to that.

IMG_20200809_110620-markup.jpg
Blue is the existing, red is the planned.

The bottom of the drawing is the toward the top of the cylinder, like you're looking down into it.

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2036
Location: california
Sun Aug 09, 2020 10:46 am quote
Hey CM.
Enjoying watching this.
Something I would consider:
While 48mm width is clearly viable with the wire 1mm rings - the 48mm wide openings have pretty gradual hand offs for the rings to transition from that very wide opening to no opening.

On the stock Pinasco - they have that two stage exhaust port with a wider section and narrower section that happens very quickly.
However that is done at a max width of only 45mm.
Id be concerned about going 48 and keeping the two stage unless the transition was lessened - personally.

Perhaps others have done this conversion and do it like you are showing - Im not familiar - just strikes me as a harsh transition for the rings to pass over on their way down - when they are fully extended in to a 48mm hole and then have to compress down to that really narrow area so fast.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sun Aug 09, 2020 11:38 am quote
Well, CM, I just got back from the garage so we'll just have to wait and see if the exhaust port is too aggressive or not

The exhaust port had the two-stage design, and I kept that. I cleaned up the right-hand corner in the picture after I noticed it so it's not that sharp, but also scratched the cylinder wall at that same place (though not at the same time), which I'm pretty unhappy about.

Best part is that when I re-measured timing, I'm now at exactly 185 exhaust duration, so final timings are 185/124/31 Right now, the crank is in the freezer for bearing install, then the whole thing gets buttoned up and it'll be game on again in the next couple days.

Also, because this was new to me, I found an outstanding port timing calculator, https://www.vespmoto.de/tools/port-time-calculator/. It an embedded spreadsheet, so you can grab it and save a copy locally, which means I can now keep a copy with each of my builds for reference.

IMG_20200809_133637.jpg
For some reason, the post content isn't displaying, so I'll stuff it in here and go on. Back-end database issue, maybe...

Well, CM, I just got back from the garage so we'll just have to wait and see if the exhaust port is too aggressive or not :)

The e

final port timings.PNG
Cool new tool



Last edited by chandlerman on Sun Aug 09, 2020 6:39 pm; edited 1 time in total
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sun Aug 09, 2020 6:40 pm quote
figured it out...I didn't get the bracket closed on the /url tag. For some reason, it posted without an error, but then wouldn't display.

Technology for the win. Meh.
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2036
Location: california
Sun Aug 09, 2020 6:41 pm quote
CM - if you are having trouble posting - and you have a URL or other code like IMG in the post - try removing. I had that same issue yesterday.
If this is the third unhelpful suggestion I have made this week - then my wife - stuff happens in threes.
Best,
-CM

Edit - Hahahaha - as I was typing you sorted it...
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2036
Location: california
Sun Aug 09, 2020 6:47 pm quote
yeah - as I posted I was like - oh - there is probably aluminum flying right now - he is going to love reading this when he returns...
Rings will clean up the slip and you will never know it exists.
It'l get scarred worse in use!
Enjoying the ride from my couch.
Cheers.
The other CM.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3058
Location: Nashville
Sun Aug 09, 2020 7:08 pm quote
charlieman22 wrote:
yeah - as I posted I was like - oh - there is probably aluminum flying right now - he is going to love reading this when he returns...
It was cast iron, but absolutelyl! The work went more quickly than I was expecting and other than the burr, which I'm more annoyed about on principle than any fear of it hurting anything, very pleased with the results.

I think I've started buying better cutting bits than when I was first starting out working on DR's, plus little sanding drums by the hundred pack, a flex shaft and right angle adapter for the dremel, etc. etc. etc.
charlieman22 wrote:
Rings will clean up the slip and you will never know it exists.
It'l get scarred worse in use!
Enjoying the ride from my couch.
Cheers.
The other CM.
I every time I type CM, I think, "Anybody who's reading this thread and not paying attention to who's posting has *got* to be getting confused by this!"

-The other other CM
Ossessionato
2015 GTS300, 1974 Primavera, 04 Ninja 250
Joined: 04 Apr 2013
Posts: 4589
Location: San Diego, CA
Sun Aug 09, 2020 7:46 pm quote
I've not been watching the forum too much lately but your thread is interesting - added to my favorites.

I'm pondering new projects and enjoy the inspiration!
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2602
Location: London UK
Sun Aug 09, 2020 10:58 pm quote
All good, except those corners on the exhaust port. The transition is too sudden. Angle it from full width to the bottom.
Land of 10,000 Scoots Rally   DoubleGood Vespa T-Shirts   Cool Ass scooter seat cover
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