Modern Vespa

Maybe I need new engine mounts is what I'm thinking. But that's kind of a pain in the ass.

The back one is easy but I don't think I ever tried to do the front ones yet.

Hang on there, hombré.

I'm not so sure bombing a steep hill earns the coveted Plaid Sticker.

We need a definitive ruling by the judges.

Who's in charge of this thing?

Probably whoever controls the stickers.

I doubt even a steep hill gets this one to 60. Will need a better cylinder.

But I don't see any published rules…

Johnny mule over here twisting up the rule book!

careful or the committee might send you out a very strongly written letter that includes the phrases:

>not in the spirit of competition.
>always adhere to the intent of a rule when the exact wording of the rule may be interpreted in various ways.
>attempts to gain unfair advantage of any kind will be met with swift discipline

.... or so I've been told...

I always assumed it was on level ground. I wouldn't rule against a mild downslope, because it's really about the suspension, gearing, and cojones more than the power to drive the bike that fast with all the top end options out there these days.

I "officially" went Plaid (logged max speed on GPS) on the VBB going uphill, but was out bombing around at 60-65 that whole weekend, too.

Ha you guys are funny. Even if I earned it going downhill it would gnaw at my soul and force me to keep going until I could claim it without reservation. I am a bit of a perfectionist.

I agree, bombing downhill isn't the same. Totally doable on the straights with a 177 kit.

On another point, I reached 52 mph pedaling downhill on my roadbike. I wanted to break the 50 mph speed limit. Definitely not interested in doing that now in my old age. 🤣

I hit 54. It's frightening having no padding and just a helmet on. I too was much younger and dumber when I did that. I.e. less than 10yrs ago lol

"I used to be young and dumb, now I'm just dumb."

Well, for science, we will see how much the hill is worth on my not so plaid engine. I hope to report back later today on that.

sooooo here is the scoop:

3rd gear revs out near 38ish MPH (6000 RPM). I seized it about 42 (downhill assist), so that's probably over the top RPM (6500). The noise gets a bit weird and it's probably choked, so there's that. I am usually good about stopping before weird noises get the best of me, but I guess I was a bit on the wild side today. I have another 2 port top end if push comes to shove. It recovered OK, and seems to be none the worse for wear afterward. I was taken aback though - I've never had one lock up on me, even temporarily. The plug has looked good so far, so I think it's really just bad news to force it into the overrev.

In 4th, you hit the wall at 52MPH, which is what I noticed before. Now that I bring back up my gearing calculator, it makes total sense, it's the same RPM as in 3rd, just a bit harder to get there without a hill. So the hill didn't buy me ANY extra MPH/RPM and is NOT a useful cheating device.

I think it's geared appropriately. What it needs is expanded RPM range. 6000 and done is not gonna work. The exhaust and 20/20 carb will help. I might raise that exhaust port when I do the exhaust, because it's likely I should have a look at that piston and cylinder anyway. Plaid needs 7000 RPM. Or - 6600 and a 24 tooth clutch, with power to pull it.

Go for the plaid!

Well at least I know where I'm at and what it looks like to get there.

In other news, there are annoying squeaks when the front suspension dips and from the springy seat. I'm not so sure what either one needs yet.

extending your intake timings will also go a long way toward getting to plaid.

I'd like not to open the bottom end if possible, but I hear ya.

After the soft seize, it's gonna be a hone it and raise the exhaust port at least when the exhaust arrives. Or maybe I will just go ahead and prep that on my other 2 port top end that's sitting on the shelf.

Since I'm too lazy to dig them out, what're your port timings, other than "low?"

And 57 or 60mm crank?

57mm crank, it's a stock sprint 2 port Bajaj motor. The only weirdness was I had to raise the barrel or the piston hit the head, but I don't know why.

I didn't measure any port timings, it's so stock.

Gotcha. Time to start measuring. Let us know what you've got and we can figure out your best bet.

Did you use a head or base spacer to fix the piston clearance issue? How thick was it?

To get the 7,000 Plaid RPM's, you're going to need timings along the lines of 122 TD / 170 ED / 24 BD (or a little better).

Did you pull the trigger on the SIP Road 2? If not, you're going to want that.

And we can leave intake timings be for the moment, but be prepared that if you can't get there with these port timings, it's going to be time to pull the motor, crack the cases and bust out the dremel.

If you pull the carb, throw your degree wheel on and get us a rough measure of intake duration even though we know it's going to be too short. If nothing else, having some before-and-after comparisons won't be the worst thing in the world.

Likewise, if you can get a sound recording of winding out the motor in 3rd, we can use that to generate a dyno and make sure you have enough power to push through the air at 60 mph, too.

Base spacer, 1.5 if I remember right.

The exhaust is ordered.

Gotcha. Get those measurements and we can work out a plan.

I don't want to turn this into my P200, even if I have to miss plaid. A solid performer at 50-55 is really all I need. Performance on par with my old smallframe. I need 500 more RPM to pull that off.

I'm definitely down for 20/20, sip road 2, and eventually the 2 port pinasco 177.

Since I have to clean up any residuals from the soft seize, I'm also into raising / widening the exhaust port on the stock top end. I'm assuming it was just going wide open throttle against the rev limit down hill that caused it, there are no signs of air leak, the idle has been so solid and continues to be. It pressure tested good when I built it.

I'm going to guess that you just couldn't pull enough mixture to keep up when gravity was helping you out in over-rev.

Get the 20/20 on there with the Road 2.0 and that should get you your missing RPM's, at which time you can go back to riding it like you were already planning to.

I'll get some measurements when it's apart. Not sure when that exhaust will arrive since I SIP ordered it from Mercato to get the one made for the old style exhaust setup.

ooh the exhaust is shipping out, I got the e-mail! love it.

i'm just over here contemplating credit card statement end dates and how that might affect when the pinasco gets ordered....

mjrally has a carb for me, gonna pick that up this weekend.

OK, carb secured, thanks MJRally!

for jetting - assuming 2 port 150 with a bit of juice applied to the exhaust port, and a SIP road 2.

I'm currently running the stock setup on a 20/17 for a 2 port sprint, because that's what the motor has been and has had stock exhaust.

I'm thinking 160/BE3/106 to start, maybe 108?

Idle jet 55/160? Have some more, like a 45/140 and a 48/160. It's nice to have a stockpile of SI carb stuff. I'm gonna have to throw away the jets that I can't read the sizes on at some point though.

Exhaust and top end off. Measurements grabbed, using the feeler gauge method for exhaust and transfer, and my eyeball for intake.

Weird oil pooling but the base plate looks like it was sealed. Head was sealed well. No splatter by the exhaust stub.

Exhaust 150 degrees
Transfer 118 degrees
Intake 165 degrees
Pbt = 0.030"

Let me know if you have an idea how much to raise that exhaust port and whether to widen it at all.

That exhaust port is so cute. Tiny!