Modern Vespa

Thanks, Jack!

I was trying to match the original shape, which had that exaggerated step to it.

So would you shape it to take off the corner like the red on the left, or square it out more, like the blue on the right?

I would do the red line. Do a rubbing of the exhaust port after and add the dimensions. From here the top centre doesn't look flat enough.

I figured you'd say Red Line, but always like to confirm with the master

I think the top is pretty level, but I'll double-check it to be on the safe side. I should have done that anyway.

I wonder why they designed those "corners" into the top of the exhaust port in the first place? This stock P200 barrel has nothing like that.

Per Jennings, "If port spacing is a problem, you will have no alternative other than to widen the exhaust port at the top. This type of port will give the engine good power from the upper mid-range to maximum hp."

This seems like an extreme version of that.

Also, as an aside, reading Norrie Kerr's "Tuning Vespas," he says that 2-2.5mm is enough sealing surface between the cylinder and the case, which seems thin to me. I usually try for 4-6mm of sealing surface myself.

CM - did a recent porting job and when I did the rubbing - it showed I was slanted. Kinda surprised me (different than what Jack is raising - ik.)

Went back with the glued in ring method and it allowed me to really assure I had a super level top. Stole the method from this guy below - been posted on various threads so maybe you've seen.

I bring it up 'cause - if you do decide to go back and flatten the top - but you love the level you are at in the middle and dont want to touch it - the glued in ring worked great for me to do exactly that. Used a sanding wheel and was able to alter out towards the edges without moving my timing.

https://youtu.be/8zIUhIrNk14?t=69

When I was reading about porting the red line pushes the ring back into its groove a bit better and helps the ring not to snag.

Last edited by Christopher_55934 on Mon Aug 10, 2020 6:15 pm; edited 4 times in total

So I had a chance to take a quick look at the alignment of the top of the exhaust port and it's just a touch low on the right (looking in from the top) corner, so that'll get fixed when I fix the overall shape.

I'm really looking forward to getting this thing back in the bike so I can see what a difference the changes made.

I spent some more time with the exhaust port and it looks a lot better. Cleaned up, generally re-shaped, and leveled off the top using a 2mm ring as my guide.

Took a rubbing and it looks pretty good, too. 48mm wide, 22mm tall.

I think it's time to put this sucker back together and see what it does.

Oooh. Perdy!
That thing is gonna have some grunt and some go.

We'll know soon enough. After I posted the exhaust port update, I headed back out to the garage, buttoned everything up and threw the motor in the bike.

Unfortunately, when I went to start it, I realized the flywheel for the P200 ignition is rubbing, and it was after 11 by that point, so it'll have to wait until tomorrow for the first run.

Probably just as well given the time, but it's soooooo close...

Looking like a fast shape now. Did you chamfer it top and bottom before it went on?

Flywheel rubbing on the cylinder fins?

What carb and jets?

Which exhaust?

Dangit...I didn't chamfer it. I thought about chamfering it. Does that count?

Not a big deal to do, just have to do it. More the principle of it than anything.

Yes, this is a 1,600g Pinasco flywheel and I think it's rubbed the cases and/or cylinder of every motor I've ever put it on. Typical Pinasco: High Price, Low Quality.

If I had access to decent lathe, I'd turn it down a bit, but instead, I just deal with it.

Right now, it has a SIP RoadXL on it, but I think it's going to have ground clearance issues, so it'll most likely get a Sip Road 2.0 I have on the shelf when all is said and done.

The carb is a 20/20. Previously, a 24/24 was too much carb and the mid-range would never dial in. I have a 24/24 on the shelf if it makes sense to upgrade down the road.

I'm not sure on the jetting, because I hadn't gotten to even looking at that before I blew it up the first time, was just using what was in the carb. I think it's a 55/160 idle, then somewhere in the neighborhood of a 160/BE3/118.

Just a note to myself and others who might follow this thread.

I followed the Shop Manual guide that Patrick posted for how to install the crank & bearings from The correct way to build VBB engine.

Need to do the chamfer. Port is wide, if the ring catches it will either wear out in a week or end up in the crankcase. Top and bottom only. Do the sides and the cylinder is trash.

XL exhaust is better than the 2.0 but ideal would be an expansion.

24/24 carb. Whatever happened before wasn't on this porting. AC120 is essential or it will seize.

Thanks, Jack!

I was planning on doing the chamfering tonight when I revisit the flywheel.

I'll put the 24/24 on it and re-flow the carb into the airbox, too, but probably stick with a box exhaust. The only expansion pipes I have on the shelf are a couple of JL knockoff's and they are both too loud and too tinny for my tastes.

I'm definitely curious to see how this turns out now as compared to before, though.

Is this still the two port motor?

Yep. Same motor, just went crazy on the intake & exhaust port.

OK...back out to the garage, sorted out the flywheel rubbing (it was the nylon on the back of the flywheel rubbing on the case. Easily enough fixed with a utility knife.

Then, I chamfered the top and bottom of the exhaust port, put it all back together, and fired it up.

https://youtu.be/zGKemvuaLTw

Truth, this is the second start. The first time, I hadn't started my camera, but it went pretty much just like this.

A little bit of tweaking on the clutch, hooking the throttle cable back up, and I had it tearing up and down the alley. Even in its current illegal and dangerous state, it's fun rolling on 8's

There's still a TON of work to do, though. I still need to:
- Swap to the 24/24 carb, port the airbox, and sort out jetting. Now that I've given it a test ride, I think it'll benefit.
- Install a CHT
- re-install the cylinder shroud and fan cover
- reconnect the electrical, but that's just crimping new ends on the wiring and plugging it back in.
- properly install the CDI Maybe have to fab a bracket
- fix a mis-located o-ring in my fuel filter, which is causing a leak
- The front brake is barely functional, so that'll need some investigation.
- The rear brake is not currently connected
- Shifter cables are too long and need adjustment. It shifts like buttah, though.
- The license plate is missing, so I'll need to get another. The plate came off around the time I started this project, and had been floating around the garage, but I never saw it during the Great Cleanup. Maybe it's in hiding with the Missing Snow Tire.
- Maybe replace the speedo cable
- either ditch the side stand, because it doesn't really work, or bend it to where it does. The bike is too upright and tends to want to fall over.


Craptastic design there, Pinasco.

Grats! Sounds smooth. And where’s all the smoke???

Bet this will motivate you to get the rest done ASAP.

Just remember cotter pins and oil and stuff ;P

Awesome on three levels!
- first start and sounds goood!
- the bit where you move the gas can...

- my absolute new signature:
“The front brake is barely functional, so that'll need some investigation.
The rear brake is not currently connected“

Sounds ok but lean already. And yeah, where is the smoke? Should be loads from the assembly oil.

Overfill the gearbox 1/4 inch. Those old engines have the filler plug too low.

Be very sure you don't ever ride it without an AC120. The more tuned the quicker real damage happens. If no vortex, just run the carb with no filter and bellows.

With the BGM piston did you ever check the boost port window alignment to the cylinder? Should be fully open at BDC.

I expect you're going to need brakes. Make them the best drums anyone ever had.

Sounds good!

Dunno how you do it... every time I try to pull the plug lead like that I get a belt off the ignition. It's horrible.

Like!

Thanks, everyone!

I'll up the gearbox oil a bit. That's good to know about the older bikes.

The jetting is the same as I had in it before this project ever began, with no porting and a smaller exhaust, so I'd fully expect it to be lean unless I'd done something really wrong along the way

And the lack of smoke is due in part to the fact that this was actually a recreation of the actual first start, when the camera wasn't rolling, but it still should have more going on that it did, I agree. I probably did a dumb thing by not dumping some 2t oil in the cylinder after I used a shot of brake parts cleaner to wash out the last of the dust from chamfering the top and bottom of the exhaust.

It's not going to go anywhere until I get the bulk of the punch list cleaned up and get to something approaching viable jetting. I'll put an AC120 in it before I even start it again and check the rest of the jetting next time I'm in the garage.

Yes, I checked the BGM piston window against the boost port into the cylinder. It has loads of excess clearance. Those BGM pistons are made to move some serious air.

The brakes...yeah...I was running out of daylight and had no lights, plus the impatience factor, so I hopped on without thinking about brakes. I did have a bit of an "oh shit" moment when I hit the front brake and it did nothing but agree in principle that I wanted to stop and the rear brake was not even in the room.

And Ginch, I know what you mean about pulling the plug cap, but the key is to make sure you're not grounded to the bike and it's fine. Plus, I'm very careful to only grab it by the plug cap, which is obviously an insulator.

I've had enough scooter-related fires in this workshop for one lifetime.

Well - I was aware that there had been an "incident" when I typed that - from your old signature line. Now I know the rest of the story - as well as the hedge trimmer through internet cable "event".

Wait! - Is that the genesis of this?!

But of course! Props to Ginch for the picture

My pleasure! Certainly seemed appropriate at the time!

Did you ever install a fire extinguisher in the garage? Maybe a small pump connected to the fish pond?

I could feel the harsh shock of reality pound through my body as he grabbed the HT lead and pulled it! I was yelling NO! at my screen - but it was too late.


Jumping through fiery hoop - much safer

I guess living dangerously is my jam

Livin on the edge....Who needs a fire extinguisher when you have a pond nearby! Ha! Thanks for the backstory

Exactly!

I do have a fire extinguisher, even if it's in the boat. I need to mount one on the wall in case it's winter and the pond is frozen over and I set myself on fire...again...

As to jetting, I snuck out to the garage during a Zoom call (installing that access point in the garage is paying off) and checked the jetting this morning.

It was:
idle 55/160
AC 160 / BE5 / 122

I swapped the AC for a 120 ant put the stack back in. Once I make some more progress on the punch list, I'll see what difference it makes.

Also, I still need to verify timing. I took a SWAG and it obviously seems to be in the ballpark, but haven't put a strobe on it yet to see where it's actually at.

Not enough room in my signature line for all of these.

I'm told that I'm fun at parties, too!

AC120 now safe. Next BE5, wtf. Needs a BE3 or it will feel rich, when it isn't.

Me too, which is why first time I started my I just pulled the choke but even that wouldn't kill the motor right away, realized I just had to ground headset switch.

Nothing like seeing a motor first time start up , I had to make the same list up, puts things in perspective and a organized way to stroke off the items. Getting there nicely.

I made some progress on the punch list today. I'm not in love with the bracket I made, but it's holding the CDI and regulator, so I'll roll with it.

I messed with jetting a tiny bit and rode it up to the gas station and back to throw some juice in the tank.

I still need to swap the carb to the 24/24, so that'll happen before I do anything on the jetting.

Nevertheless, it's progress.

Never heard of the term 'punch list', and now I've read it 8 times in the last page.