Modern Vespa

When the math says you can

figure that if you increase the ID of the exhaust port to 39mm (so increase it 2 mm all around), that puts you at 1194 mm^2, which is pretty much a match for area. I didn't measure it exactly, but I definitely took a a couple mm off the walls of the exhaust port on the VBB's Pinasco when I opened the port up, although I didn't specifically calculate and set a target.

I got a return email from Pinasco, about the two different heads A3610 and A3611. I could be in for a long email conversation to get an answer. The language barrier could be an issue. I specifically wrote I had a Pinasco 60 mm crankshaft. The return email asked what stroke motor I had. 😳

Port width is 70% chord width, not arc width, on your type of piston ring. So max is 54mm but as said aim for 52mm, as going over max requires adult supervision and careful attention to shape.

Port area and stub area are more dynamic than they appear. Most of the exhaust flow has occured by one third open (approx). The full area is for the low pressure functions, like the baffle wave assisting transfer etc.

Porting looking great Chris glad you decided to work on it think it will be worth it.

Do you have a degree wheel to check the inlet duration?

What do you mean by chord width vs arc width? I have been using chord width straight across the front of the port. Not the width measured flat on a piece of paper using a trace for example.

Will have to work on the port width a bit more. I spent a few hours cleaning, polishing and blending everything back to the stub. Adding another 4 mm to one side would get both to 14 mm. Giving me a port width of 46.5 mm. Then remove ~ 3mm more each side getting me to a width of ~ 52.5 mm. That would put me about 11 mm from both ports.

How far back do you blend when removing the much material? What does the port look like from the top? Do you go for a funnel shape? Working from inside the exhaust port I would think it would almost have to look like a funnel. That is what I started noticing when I was cleaning up.What I had.

The other issue could be getting to close to the intake ports. The left is 14 mm from one and the right was 18 mm from the other. How close is to close? I thought I read something about short circuiting, and the intake going right back down the exhaust.

I'm going to try it as is with a cleaned up exhaust port for today. I've spent to much time cleaning up ports today, running out of patients. I'll get a few dyno runs and jetting dialed then. Then open up the port and see what the change does, will be interesting to see the data point.

Cleaned up the piston getting rid of any flashing remains from the casting process. Used a small and medium sanding drum to clean up radii etc.

My clutch parts came in today and I had to know what the compression was without that 1.5 mm base packer. Another reason I said enough port work for today. Made a 0.12 mm aluminum base gasket from shim stock. That is easier to cut than a soda can. I bought a set of hole punches so the 5 holes were easy enough also. The compression is 185 -190 PSI, that on the higher than I normal aim for side and that's on a cold motor. It feels like 185, harder to kick them the 177. I usually aim for 150 psi for street use. Definitely not taking anything off the head squish band ring to reduce squish. Surprised it was that high with that large of a squish.
My DR had a large squish and a lower psi about 120. Removed a few mm off the head squish band, got down to 1 mm squish and bumped the compression up to 150 psi.

It has a Kytronik so will take advantage of that with the higher compression retard it a bit more at higher rpm.

I don't have intake numbers, ran out of time and didn't want to pull the flywheel today. I have a piston stop and all that good stuff, I'll find TDC if it's not already marked to verify timing with a timing light. With an assembled motor how do I find intake timing? I've only done it on !y Stella with reeds so I only had to measure the cylinder.

I think that's it for today I need a shower finally cooling off and have just about stopped sweating.

Christopher - looks good from my chair.
Just FYI - my measure are all taken on flat paper.
Trace - lay flat- measure.
You can compare your current width by doing the same on your trace.

Couple of quick points. Exhaust port should not funnel at the top. From bore to stub should have no lumps. Fully straight. Sides will always funnel as the studs are in the way.

PSI compression is a little meaningless on a 2 stroke. For 4 stroke great. 2 stroke pointless. Need to calculate by measurement. Full capacity and only above the exhaust port. So there are two calculations for a 2 stroke. Both relevant in different ways.

Thank you, that is what I meant for the shape. Flat on top and the sides funnel down. A dustpan maybe? 😁

huh?

Finally last part is here, SIP reinforced basket.

Clutch is in, with a 23 tooth gear.

Out to the Garage I go will report back in a few hours.

Motor mounted, transmission oil full, wiring adapted, two stroke oil added to tank, ran fuel through hose until it ran blue. Mixed at 50:1 or 2%. Now to figure out the fuel line which is a bit short and the throttle cable.


Anybody know the factory Stella throttle cable and sheathing length? I bought this but I'm not convinced it's long enough.


https://www.sip-scootershop.com/en/products/cable+kit+phb+for+vespa+125_94110000

I have a spare throttle cable that is 79" and should reach. Could extend the sheathing with a piece of spare sheathing if I can find some. Maybe I can find a piece of tubing to slide the two ends into for alignment and heat shrink the hole joint thing together.




Cables are a few inches short, so is the fuel line. When I figure out the throttle cable and pull, the tank for new sheathing, I'll replace the hose or add a 90 metal bend there instead of a long fuel hose loop.

Connected green to green with white stripe from headset. Soldered and heat shrinking applied. Next time I pull the tank I'll just pull these into the frame.

I'd recommend to just get the throttle cable and sheathing from a bicycle shop. You can buy it in bulk length. The cables also have a very smooth action for a very nice throttle return.

I was thinking the same thing, I just measured my Malossi throttle cable sheathing and it is 65.75" or 1670mm. Found an old reference that says a P cable sheathing is 62" or 1574mm. That extra length would be great if the lengths are correct.

Looks like I might be pulling my gas tank sooner than later.

This says 62" also, another reason to pull the tank and give it a try.

https://www.scooterwest.com/vintage-vespa-throttle-cable-w-solder-nipple-62-inches.html

The length dimensions are correct for a Stella also, the Malossi cable is 3.75" or about 96 mm longer and fits. I did have to shorten up the 90° fitting, I needed more cable length to fit the TMX 30. I didn't want to cut a new cable unless necessary. The throttle side was a perfect fit didn't have to touch anything. The throttle does have enough movement to open the slide wide open.

The choke conversion thread I started is correct and I was able to hook up to the TMX 30 and use the adapters and cabling. The SIP choke handle replaced the Stella perfectly.




I sanded off about 4mm or 1/4" off the long side, the cable adjuster screws into. Then sanded more off the adjuster itself.

The bend is a right fit to get the cable fitting through. Took it apart and slid each part on and it all fit together good.

I think there is a fuel pump in my future, I poured a gallon of fuel in before fuel ran into the carburetor. The fuel comes in the top of the carburetor, the bend coming into the top is to high I think. Not much I can do about that. Removed the oil tank for now. This allowed me to have enough fuel line since I wasn't trying to go around the oil tank. I have the petcock on reserve so thats not the issue.

Anybody ever try one of the small electric pumps? Thinking I have plenty of room in the area under the tank for one now.

Will a vacuum fuel pump work If I tap into the adapter under the carburetor on a rotary valve motor?

https://www.mrp-racing.de/MRP-30mm-rotary-valve-intake-largeframe-Vespa-PX-T5-Sprint-Rally-VNB

If you're not using the air bellows anymore, you can always run your fuel line through that large opening. It will at least get rid of that loop in the fuel line. Another trick is to use a longer rear shock bolt spacer, so that it will effectively lift the fuel tank higher up from the carb.

Why does the inlet manifold need the big block underneath it? Seems excessive and almost as big as a reed block. Can you not just use one of the Malossi manifolds, which would lower the carb and improve fuel flow?

https://www.sip-scootershop.com/en/products/intake+manifold+malossi+for_22158000

Just a guess, I was thinking the same thing. The carburetor sits tipped a bit currently, the fuel bowl is touching cylinder plastic engine shroud. If the carburetor sat any lower the top would be worse. I

I'm also thinking about a molded plastic 45°, that would take the loop over the carburetor completely out. If I were really good I'd find a fuel fitting with a female end I could slip over the carburetor fuel inlet to reduce height even more.

Something like this maybe, I could cut out a molded curve.

https://www.amazon.com/Universal-Molded-Fuel-Line-Rubber/dp/B07C8YTNPF/ref=pd_bxgy_2/141-5445264-3280506?_encoding=UTF8&pd_rd_i=B07C8YTNPF&pd_rd_r=47029597-26c2-4f37-8da6-ec41c1f472e0&pd_rd_w=3DCbw&pd_rd_wg=Cw42m&pf_rd_p=ce6c479b-ef53-49a6-845b-bbbf35c28dd3&pf_rd_r=ZCJ9FWW69V1PG10VG0ZC&psc=1&refRID=ZCJ9FWW69V1PG10VG0ZC

Last edited by Christopher_55934 on Sun Sep 06, 2020 2:58 pm; edited 1 time in total

It runs, a few videos.


[/url] [/url] [/url] [/url]

Christopher - lookin good.
Been through this dance myself.
Different carb - and a bit risky - but my solution was to angle the carb more aggressively.
You can probably find specs for your carb's max tilt angle online.
Mine was supposed to be 20 some odd degrees - but it went to 45 without issue.
I had to adjust the float level.
Many of these carbs are put on motorcycles and tilt pretty heavily down.
The tilt allows it to clear the cylinder on our scoots.
I then got brave and cut my expensive intake manifold kit down to nothing - getting rid of the block entirely.
You can see I drilled holes for the direct mound to the cases - and reshaped the footing.
I also "reshaped" the manifold tube - if you wanna call band-sawing it off reshaping.
TBH - not sure I would recommend unless you can find how steep you can go with the angle of the carb. Also - you have to cut your intake manifold kit down to a nub... Super happy with yow mine came out - but coulda been a disaster.

I also pulled the fuel inlet all together and replaced it with a brass elbow from the hardware store.
This I would recommend - and suspect you can do even better as there will be options online for your Mikuni.
Mine had a pressed in one from the factory (not screw in).
To pull it - you screw a drywall screw in to to the brass inlet - put a vice grip on it - and use a small hammer to tap it out.
I put a new one in that was an elbow - and used JB weld to assure it would stay.
Ugly but functional in my case.


You can buy these for $5 in or close to the size you need.

Mine is bonded in with JB weld.

This is the manifold after a few adjustments

Shaped to match cases

I added holes so I could use the studs and go directly on to the cases without the block - considerably lowering the carb.

Posted elsewhere - but here for reference - you can see the approximate angle needed to clear everything.

Hey - Awesome!
Just saw your vid after I posted...
If your carb hits the frame when you go over bumps, you can twist it a little to help it clear.

Good ideas, I have a 54 mm or whatever the longer spacer in there already. I hope to use that hole for an intake hose to pull air from under the seat.

Went out and measured, the fuel tap and carburetor fuel inlet are the same height. Getting that bending loop out I should be able to run to empty almost.

I have no experience with the TMX carbs, but a PHBH 30 would work fine with the Malossi manifold and a ~45 degree tilt. No fuel pump required, at least with the Pinasco level of tune. The other feature of the PHBH is an adjustable fuel inlet/banjo and a choice of float valves. I think I swapped out the 200 for a 300 on mine (need to look back at my notes), in order to sort the flow with no pump. Not much use to you as you have the Mikuni and MRP manifold, but good to document nevertheless

I run a PHBH in my 70cc scooter, I like them. This came running with the TMX 30 with a power jet. I want to give it a try. The TMX is a 2 stroke carburetor by design. It does have two needle and seats options that I know of 2.5mm for gravity and 1.8 for fuel pump. Going to try the 2.5mm to start with. Just need to keep, the bowl full and I'm running some large id fuel line also. Just need to get rid of that loop, to start with.

Checked the voltage out of the stator and at higher RPM it gets to 14+ vac. Purple lighting wire is still hanging around doing nothing. Battery voltage did go up 0.2 volts after riding around, so it works for now.

Installed my AFR sensor and took Stella for a short ride. That TMX 30 looks to be pretty darn close to dialed in for short around town riding. AFR is about a 13.4 at idle and goes to about a 11.8 under throttle. Interestingly enough the AFR is stable with this setup. No real bouncing around, it is easier to read. Need to mark the throttle positions and see what I get at 1/4 , 1/2 , 3/4 and wot.

Temperature stayed under 200°f or 93°c around town.

Need to install my SIP 2.0 speedometer, with tachometer and temperature then see what happens. Need to run the wiring from the headset to left side cowl for power and tachometer input.

Just from my short ride a few miles around town, Stella has more torque. Felt like she wound out quickly but who really knows until I get a tachometer hooked up again.

Then I'll build a GSF Board and see where Stella is for a baseline.

Well - I have certainly gotten good stuff outa my GSF board! (nicely done).
Sounds like you are pretty close - perhaps a little rich - based on temp and sub 12 AFR.
Interesting that it seams more stable (AFR).
I wondered if the bouncing I saw was actually a good reflection of changing AFR based on SI (perhaps it has variation).
Will be interested to test my Smart Carb and see if I get less movement.

Suspect you will have no trouble pulling along at 60-65 with this set up.
Look forward to seeing how you like it on the open road.

So far Stella has been running fine with the P200 motor, she does have a TMX30 carburetor and AFR meter. AFR Meter says a little rich with about a 11.8. She starts on 1st kick cold without the choke on, the idle is high then slows down to a low idle after about 20 seconds. My question is do you guys think I should reduce the pilot jet size since it starts cold easily even after sitting for three days? The meter saying rich and easy cold start makes me think I should down jet the pilot a size.

The best test to check the pilot jet size and air screw setting is to open the throttle wide on the stand, then quickly close it. The engine should instantly rev up high (like 6000). After should fall to tickover quickly and not stall.

If the jet or screw is too lean the rev up will bog flat and not rev so high. If too rich on the jet or screw it might splutter on the way up or stall on the return.

When you get this right it really helps with adjusting the needle, while making it nicer to ride.

I'll have to get a video of it once I close up my headset. I don't have anything to compare it too, to make that judgement.

The cold start video didn't work, this is a warm start.

https://youtu.be/-Vmaelxfs2o

Another short video.

https://youtu.be/nZMSkcTroM8

Would a P200 normally top out at 7000 RPM? It has a Ducati blue CDI, also has a Kytronik module. The Kytronik is set to curve 6.

I think my next step is going to be to verify the timing. No reason to second guess it, everything has been correct so far.

The temperature never gets above 200F, really rich or timing off? This is with two meters so it isn't the meter.

Christopher - just catching up - looks good.
From what you have posted - looks well rich to me.
- 215CC
- 30MM carb
- 60MM crank
- Big box exhaust

I would expect you to be churning out 20HP plus.
Additionally - you are peaking at under 5K RPM.
Looks from the chart like you are just not able to rev out because it is too rich.
The sub 200° temps suggest the same.

With a resonate pipe - the heat is an important part.
To me - your chart looks like it is running with the choke on.
Wouldn't be surprised if you saw spluge coming out of the connection from pipe to head.

Are all the colored lines the same jetting run back to back?
Think you'll find a world more power out of this as you lean it.
Of course - not a terrible idea to double check your timing - but my money is on fuel.
-CM

I would have thought 16/17hp would be achievable with your setup. Certainly more than 11hp. Remember that the Pinasco 215/225 is considered by many to be a big bore alu version of the stock P200 top end. It retains the single case <> cylinder transfer port, with some elaborate splits inside the cylinder to give you multiple transfers. Whilst it is a good solid performer in my experience, it's not a Malossi 210 Sport.

I would agree that carb tweaking is most likely where you'll find the missing 5hp and I would question if a SIP XL was the right exhaust for a Pinasco. They suit a higher revving engine, bit like a BGM BB Sport. What did you set the static timing at?

Did you say this carb was a power jet? Do you have a good selection of jets and needles?

I agree from what I've read and seen on the XL exhaust it likes a higher rpm. I had nothing for a 0200 and bought it used with the motor, it was a place to start and see how it runs. I was thinking a BGM big box touring eventually.

I didn't set the static timing bought it used with 150 miles on it. Another Chris was moving on to another project. I was thinking 24° static with the Kytronik, then around 6° retard to 18°. It might be there now I just haven't verified it with my own eyes and timing gun.

Yes, that is correct Mikuni TMX30 power jet.

I was waiting to see what I ended up with before buying a bunch of jets. Looking at my jet stash I have the large round jets, not the large hex that is in this carburetor.
I have a size smaller and larger main and power jet, the needle is in the center slot so I have some adjustments to lean out the top end and midrange. With only 175 miles on this motor not going to go to wild, running rich isn't bad. Would be nice if it warmed up a few more degrees. Just going to start making small moves and working towards a little more heat and power.

I have a local motorcycle shop also, I've bought parts from the before. We will see what they have for Mikuni jets. The only issue I run into is the jetting for the scooter is so small they don't have them sometimes. Sometimes they have new jets that have never been out of the bin in 10 years also.

Running way over rich does damage too. Different damage but still.

Need to aim for 280F for running in. Around 240F cruising around at 1/4 and 280F up around 50mph.

Going to need a lot of jets and a few needles. The power jet is an added complication that you may not need. Could just block it off for now.

I'll work on the timing and leaning it out a bit. I'll have to hook up the AFR meter and see how rich I am at WOT in third. I have an 80 power jet in there now and a 70 sitting in a bag. I'll have to see where that gets me. I'll just keep making slow adjustments, keep notes and see what happens. I ordered a few smaller main jets also, need to mark my throttle and see where I am at each mark.