Modern Vespa

I'm going to sand cast it, but first I have to grind some stones into sand and refine some bauxite.

Here we go mate… good luck!

My experience with the PWK… what had the biggest effect on dialing in on the idle (Except choosing the right jet of course..) was the ignition timing, then the needle thickness, THEN the main jet.

If you have the same setup, THEN have a bigger/smaller main jet or pull the main jet out all together… you'll be playing around the air mix screw to get a decent idle… which messes up your 1/8-1/4-1/2…

Just something to keep in mind… jack's process of dialling in what and when was key… if not you end up going in circles like I did at the beginning

Some good news from yesterday...the idle is finally starting to richen up.

I'm still on the 60(!) pilot jet, but after aggressively cleaning the pilot circuit, then adding carb cleaning fuel additive to the tank and running it a little, the idle came down to, coincidentally I'm sure, 14.7 on the AFR meter, but with the screw only half a turn out.

So while I'll have to keep an eye on that to see if it continues to drop (I suspect, or at least hope, that it will), I'm back in business.

So current setup is 60 pilot, KLG, 2nd clip needle, 162 main.

If you're mentioning about the air screw. The screw should be around 1.5 - 2.5 turns out… there's not enough air balancing the pilot at 0.5 turn out…

You won't get very consistent running with 0.5turns out… you'll be good one second with the idle… then running lean the next… especially when it gets hot…

I thought the target was 1-1.5 out on a PWK air screw, but, yeah, it's not ideal. At least it's heading in the right direction.

I'm going to re-clean it again this morning before I start it up, see where that gets me.

Yeah seen a lot of documentation that mentions 1-1.5 turns, I'm guessing it depends on the engine…

I was dabbling around the "1-1.25 turns out area" for the longest time and could never get it running properly…

It was either sweet for 2-3 days, then be terrible for a longer 10km run…

gave up and came back to it this year with the latest setup… i called some folks up in Germany on the phone about the setup (who have tuned a fair amount of pwks… lol) and they mentioned 2.5 turn out…

So gave it a try… and seems to have worked…

Seems like there is an issue. 60 pilot is big for PWK. Normal for PHBH but that don't matter. Something isn't right. The diameter is nearer the richer end so no issue now. Careful 'till you find it.
Never less than 1.5 turns on a scooter.

Yesterday, the carb quit delivering fuel at all and I got to push the bike a mile home. Something is now properly broken in it. I'm going to tear it down and give it a proper cleaning and rebuild before I do anything more with it.

Maybe the float is stuck, but that wouldn't explain the pilot jet issues.

I'm thinking that a good long soak in carb cleaner in the ultrasonic cleaner followed by a lot of compressed air should be a good start.

That blows…

You're using a fuel pump..? (Sorry lost track of the setup…)

Not to be a killjoy, but doubt the cleaning will have much effect… the pwk seems pretty robust…

Yup. I'm running a self-regulating pump (which actually works really well), and I pulled the fuel line yesterday and confirmed fuel was flowing, even without the motor running, it's just not getting into the venturi

It starts and rev's momentarily if I hit it with starting fluid, but the plug was bone dry when I pulled it.

Best case for this would be a stuck float, but that wouldn't explain the lean idle.

Good to have the pump…

Still running on the 0.5 turns out though?

no, I cranked it out to 1 turn, but I'm probably going to swap to a spare carb (I have a 28 and a 30 on the shelf) if I can't get this one to behave after a good cleaning.

This afternoon, I needed a thought break from building a risk & controls matrices, so I snuck out to the garage for a few minutes and took a look at my motor. I discovered two loose cylinder studs (that's my lesson learned the hard way about pulling the jug by removing the studs) and evidence of detonation on both the crown & piston. No scoring on the cylinder, but I'm going to guess that I've got a stuck ring which isn't enough to trash compression, but is enough to keep it from firing on anything but starter fluid.

I'll pull the cylinder off sooner than later and see what's up, but I'm kicking myself pretty hard right now for assuming that I didn't have an air leak and trying to jet around it rather than re-running the pressure test to see.

Hopefully this isn't going to result in me busting out that new BGM 177 after all...

Welp...found my air leak...

I went back and looked at my build photo's and, sure enough, I'd broken through right there and filled it with Lab Metal, so that plug must have finally popped loose on Sunday. It's fixed (I hope) now with JBWeld. Cleaned the hell out of it, scuffed it up good with 120 grit paper, and I'll see how it's holding in the morning.

On the bright side, other than a few detonation marks on the head and piston crown that need to get sanded off, the barrel and rings are just fine, so I'll get it buttoned up and re-tested, then back on the road with, I'm guessing, a much more normal jet setup.

The cylinder studs may or may not have been part of the problem, but they're going back in with a little bit of blue loctite, and maybe things will break my way for a change so I can get on to my next projects.

At this point, I'm just happy that I didn't have to replace any parts to get back up and running.

Ummm that hole is gonna leak a wee bit

Happy it turned out to be no big deal. Pilot jet in the 40s next time out. Keep the rich needle for now until the main jet is adjusted leaner.

I buttoned things back up tonight, went to pressure test and...still have a massive leak.

I can hear it hissing out as fast as I pump air in. Start looking with the ol' bottle o' soapy water. Nothing.

Pull off the oil breather and cover it with my thumb...goes up when I pump it, air rushes out when I take my thumb off.

Looks like my clutch side seal is trashed.

On the bright side (because I always try to find a bright side), at least the motor is already dropped down with the wheel and exhaust off, so I'm like a third of the way there.

How the hell I didn't seize this thing in the state it was in, I will never know. I guess Guard Tiki was watching over me after all, even if it didn't seem like it until just now.

So good to have spotted it now… the biggest positive!

Atleast it wasn't when you buttoned everything up and got up and running

So after entirely too much pain and trouble, things are finally buttoned up and back together. After I patched up the failed patch with one that held, I buttoned everything back up, ran another pressure test...and failed again. Nothing terrible this time. Just a very minor leak where I installed the nipple for the fuel pump, which I would not have found without my smoke jar.

So I fixed that, and right as I was about to declare victory, I saw something. Something I didn't want to see. Something decidedly...kickstart gear-shaped...

That meant that I got to re-re-re-split the cases (this is like the 4th time in this adventure, after all) so I could button them up, with the kickstart gear inside this time. After all that, though, I did get it fully assembled, timing set and adjusted, and even took it for a little run around the town.

The motor is running WONDERFULLY, even with what's effectively now random rich jetting. It'll lift the front wheel easily and I lifted it in second gear at one point, so this motor is not messing around. And it even started first kick after I finally got it re-assembled.

It's amazing what a difference having your motor airtight makes.

And now for some video...

Skip the verbiage and jump to the parts with the motor running:
First re-start
Second re-start
with timing adjusted

Or enjoy it all:

So crazy frustrating to get a good leak test with the kickstart gear out -DOH

I've tweaked the carb setup and things are getting pretty darn close, I think.

Right on - I like the last pass - the camera swayed from the mighty breeze kicked up when you flew by!

I think it might finally be time to install that final floor rail endcap and declare this puppy finished.

Sounds great!! I'm sure your neighbors must love you as much as they love me…

Half the vehicles in my neighborhood are some form of loud-ass truck, hoopty, or tuner, so I fit right in!

I still have a little room for improvement, but the dyno is looking pretty solid, even if I didn't get an optimal run. This was third gear, which really needs a quiet highway to get a solid result.

I think that it's reading a little high, but the inputs were accurate for the day, so maybe not. Fun ride either way.

I'm going to go up a jet on the main (I think I'm at 162 now, so 165) and need to get some shims for the needle so I can adjust it in sub-clip intervals.

Even so, 24 HP is far from shabby and getting very close to dialed in.

I think the GL is just about finished.

I installed a locking helmet hook and finally got rid of the last of the rear tire rubbing today, then spent a little time dialing in the carb.

Other than possibly shimming the needle to get it less than one clip richer, it's now good on the carb. I settled at a 165 main and had it up past 80 today, which was faster than I really wanted to go, to be honest. It had more top end in it, I just didn't go there.

I also found the missing floor rail cap, so I guess it's time to rivet that sucker on and call this one fertig .

Next up... The SECOND bodywork adventure, my 62 VBB!

This was one hell of an adventure. I enjoyed it thoroughly! Thanks for taking us along!

yes congrats and thanks for all the sharing

Thanks, gents!

It was a heck of a ride getting to this point, and there are always more little things to do, like hooking up the choke now that the weather is turning colder.

And on a couple levels, the project is far from complete. I still have the P200 motor that's living in my Sprint with a mild tune on it that I want to take to the Next Level, plus another project involving this bike that's going to get its own thread as soon as I get around to posting about it. Maybe now...

Great well documented topic.

Welp...time to resurrect this thread since I'm going to be doing a fairly significant motor rebuild.

To get up to speed, go get the [today i ..... bollox 2.1 (Post 2695082)]backstory from Today, I...[/url], but basically, the crank's big end bearing died and took out the top end with it, so now I'm thinking about options to do something new and different than the P200 bell and BGM 177.

I thought the barrel had survived, but closer inspection tonight proved me wrong on that point.

The thing I couldn't find were any cracks in the cases, so I think I'm going to stick with them, but since I have to replace the crank and top end, maybe look at doing something new and different.

I'm thinking the Uncle Tom 62mm bell crank from SIP, since I can't get a non-Mazzi P200 bell crank and the KingWelle is both $200 more and, most importantly, sold out.

But what top end (and from that, crank & and eventually maybe exhaust)

I'm leaning toward the Quattrini M1XL with a Malossi 60mm 110 rod crank.

Direct intake and full circle are a winning combination on my Smallie and Lammy.

The other combination I'm still contemplating would be a Parmakit with the 62mm Uncle Tom bell crank.

Either way, it's a chunk of cash and I may not pull the trigger straight away as a result, but it's one of those things where I kind've know what I want to do, just have to execute on it.

Sad. But gives you room to buy new parts. Happy!

I guess the M1XL was not one of the kits that got the update that upped the power to Quattrini kits in the last couple of years? I've always thought it would be an impressive kit, think Jack runs one (and it's fast, surprise!)

I wouldn't say that cylinder was dead. Wounded for sure. That dent don't matter, scores just surface. Don't over do the clean up and new piston (size stamped on the cylinder somewhere, in code). New Conrod on the crank. It would run again.

If not, I do have a M1XL and definitely worth a go. Bolt on 57mm is strong, 70mph max. Later upped to 60mm mazz bell crank (on 2nd big end!) and cylinder tuned, 80mph and possibly still more in it with a decent run. I'd guess similar power to your boobadge.

Hot Rod Al can rebuild that crank

I agree with Jack. Have seen worse. I have a friend's Rally with an old Malossi 210 with delaminated plating on a section of the bore (rings pass through it). It's been 4 or 5 years now that I fixed the air leak he had that resulted in seizing it and it still runs great…

Maybe a better crank or conrod from Primatist?? They do the SIP cranks and rods for Fabbri, Kingwelle, etc.

https://www.primatistsrl.com/en/

Pretty much! Yeah, I was a little surprised and disappointed to see that it didn't get the full flow modeling treatment, because I'd have thought it would be a much bigger seller than the smallframe or Lambretta kits.

I'm suitably impressed by both of those that it makes me want to go there. Especially since I'm going to be committing to a $500 crank in any case, so might as well max it out. I have an old Malossi 166 cast iron on the shelf with a much worse dent in the wall than those combined that was running perfectly, so I don't doubt you. Boobadge levels of power would actually be fine, so long as I could keep the noise level down a little.

As to the Mazzi bell, I simply don't trust Mazzi cranks at this point. I'd rather pay more and not worry, plus deny them the sale.

I'm curious on your decision process for bell vs. full circle since the M1XL is direct intake. Is it that the bell gives higher crankcase volume, which benefits the lower RPM ranges?

I'm less interested in peak power than I am in broad power band, which would align with the bell crank, right?

And given the lack of 60mm/110 rod options, would I be bonkers going with a 62mm crank, even knowing I have to grind out the crankcase wall?

(That wall is probably twice as thick on the LML cases as on smallframe cases, so I'm not worried about doing it. I might even break my own 100% DIY rule and see about having it done.)

Sorry to hear about your engine, but I know you will have it going even better this time around.

Doesn't bode well for the Mazzi bell crank I am planning on using in my VR-1 setup. At the same time, I will be setting it up to be pretty tame. More of a stock + build with better parts and power to spare.

Thanks, dude!

I agree that you'll be okay with the Mazzi, given that you're not doing a crazy build. The big end bearings on these things seem to be the weak spot, though. Naturally, it's also the most difficult part to monitor/inspect.

I'm curious about what the failure mode is with them. Are they just not using adequately hard bearings? Was it self-inflicted and related to running lean and causing accelerated wear as a result? Or some other factor.