Modern Vespa

out of curiosity - can stock machines handle this ride? Let's say you showed up on your VBB - is it hopeless? or is there a pack of slow dudes that hang together?

Wonder how much is a re-plating something like a malossi 210?

https://kustom-kraft.com/nikasil-plating/

LA sleeve used to have metal sleeves for P2/malossi, but by the time everything is said and done unless you have some custom porting the cost of all the parts, machine work and labor it's just cheaper to get a new cylinder kit.

I need to get my cylinder back to send them pictures, but best I can tell, re-sleeving a nicasil cylinder is in the $3-400 range, which actually makes sense in my case, so I'll probably ultimately go that route.

https://kustom-kraft.com/nikasil-plating/

LA sleeve used to have metal sleeves for P2/malossi, but by the time everything is said and done unless you have some custom porting the cost of all the parts, machine work and labor it's just cheaper to get a new cylinder kit.

Are you going to get plating or a sleeve? How does porting work with a new sleeve?

Are you going to get plating or a sleeve? How does porting work with a new sleeve?

Guess I better let the War Department know that suitcase isn't ever coming home...

Last time I had to make that announcement I delivered it with this in hand

https://www.rimowa.com/us/en/luggage/colour/green/cabin-s/82352684.html

That bag has so much fuel soaked into it, I'll be shocked if there isn't a dumpster fire before it leaves my place!

Dumpster fire bad.

Can't wait to see the small state up and running again

Fingers crossed for you CM!

Hoping for stuck rings.

Either way, I expect I'll be back up and running by tomorrow afternoon.

But then, after a little sprits with water, they kicked off. When I realized how much they were expanding I closed it all up and put zip ties on. I'm pretty sure it was still expanding when I got to UPS.

I'm just glad the container didn't arrive exploded. That would have been ironic.

And...it's back!

New top end on, it passed the pressure test, then first start and it'll go back into the bike tomorrow.

The old jug had enough Nicasil damage that there was no point in having a go at fixing it.

Did you ever get a quote on replating?

And...it's back!

New top end on, it passed the pressure test, then first start and it'll go back into the bike tomorrow.

The old jug had enough Nicasil damage that there was no point in having a go at fixing it.

And...it's back!

The old jug had enough Nicasil damage that there was no point in hhaving a go at fixing it.

I'd gladly take that old cylinder off your hands

also, nice thing about analog gauges with a limit line is that there is zero mental computation, "is I is, or is I ain't over the limit"

I put a yellow line where I want to be running, and the red at here be dragons.

Sounds good. Why on the stand? In the frame would save time.

That old cylinder is really torn up for a quick seize. Is the cost $300 plus a new piston?

Do those aux ex ports break into the studs? Will be some fancy casting if they don't.

Been awhile I thought it was 5"-6" from piston? I thought I measured inside port to piston as part of distance. Let me see if I can find a reference, Patrick maybe?

One of the better carb tuning aids available is EGT monitoring. Exhaust Gas Temperature is typically measured in the expansion chamber, at a point about 6 inches from the face of the piston. The position of the probe is important in obtaining an accurate reading. If you look at the header burn pattern you will typically see a coloration difference in the first 3-6 inches of the pipe and you want to be just to the right of the darker area.

EGT is a relative number to your specific engine, and will vary from engine design to engine design. You will see lots of numbers used, but you have to find what number your engine produces. A higher compression ratio or timing that is advanced will tend to produce EGT's that are lower than the 1200° that a lot of people use…including myself. Depending upon the engine characteristics your max EGT may only be 1100° and to be on the safe side you would need to run an EGT of 1000°. Don't get caught up with the number so much as the method.

To understand how you can use EGT to tune by, you need to be brought up to speed on some important factors. One of which is that if you were to look at a graph of EGT, you would see a bell curve. This curve would show that the EGT rises to a peak and then starts to decline. On the left side of the peak, we are richer than stoichiometric, and on the right side of the peak, we are leaner. This temperature curve is controlled by the air/fuel ratio and will peak at a stoichiometric ratio of 14.7 parts of air to 1 part gasoline.

Stoichiometric who/what??? The combustion of gasoline is a chemical reaction that, like any other chemical reaction, has a specific a stoichiometric ratio. Remember Chemistry 101, probably not, but you were told that stoichiometric when referring to combustion is the ratio of air to fuel at point where the combustion reaction is the most efficient.

Now this would all be really cool if we were driving a lean burn Chrysler, where we were concerned about fuel economy and emissions, and had a sophisticated computer system to keep it spot on … but the last I heard… we were trying to tune our engine for the best power…not economy, and keep it from melting down. That requires a little richer mixture ratio of about 12.8 parts air to 1 part fuel, for best power and also leaves us a safety cushion.

During WOT acceleration EGT will rise to the peak and then start to decrease after the peak, if we are lean. We need to control where the engine runs by controlling the jetting so that we are on the left side of peak, near the richer ratio of 12.8 to 1 point for best power. If we jet at the peak, we will be at the mercy of a lot of load and weather variables, and without a knock sensor that is tied back to a computer to adjust the mixture and timing to fix things for us, we could very easily go lean, which is on the right side of the peak, and be in meltdown/detonation city… and that isn't a friendly town to be visiting.

So why don't we use an air/fuel ratio meter instead of an EGT meter. First of all you could, and it would work fine. It's purely a matter of cost and durability. An air/fuel ratio meter with the appropriate wide band O2 sensor is about 3X the cost of a simple EGT system and really doesn't tell us any more than the EGT does. Sensors tend to deteriorate due to the higher oil content of a two-stroke exhaust. Of course…if you run a multi-cylinder engine then you need a probe and gauge for each pipe.

So… How do we tune using EGT? It's really pretty easy to do, if we remember what we just learned about jetting in general, and how the EGT works.

EGT should rise rapidly with the RPM as you accelerate and should come to a point and stay there the time you are at full throttle and a constant load. If your EGT rises to a peak and then starts to fall as you maintain full throttle, you are now on the right (which is the wrong) side of the curve and lean.

Normal reading will vary slightly from machine to machine, due to slightly different probe positions and engine characteristics. So they are relative to a certain degree. When you're at the peak… you're at the stoichiometric ratio of 14.7 to 1 and EGT will typically be in the neighborhood of 1300°F or so. Remember that you are looking for a peak…not a specific number, and this number is relative to your engine only. We want to run on the upside of the curve at about 12.8 to 1 and that will normally be 100°F lower than the peak reading.

A typical Keihin main jet will change the EGT close to 50°F per jet size change. Using this example…let's say we had a peak of 1300°F running a 180 main jet. To drop the temp by 100°F, I would need a main jet that is 2 sizes larger, and would end up using a 185. At this setting your plug and piston reading should show you a great burn pattern and color. As you accelerate the EGT should rise quickly to 1200°F and stay there. Now that I have the machine jetted spot on… I make note of the weather conditions, particularly the Air Density and call my baseline a 185 main jet at whatever the AD was. Let's say the AD was 92% for my baseline… it's getting close to my first heat race so I look at the AD and see that it's now 89.5. What now coach? I can't make a few laps around the track to see what my EGT is, so I need some additional help to be jetted correctly for the upcoming heat race.