Modern Vespa

Cleaned up the intake, put in Boyesen reeds to help with the intake. Already have a Mazzi crank, new bearings nd a Sito + exhaust installed. Now moving onto the DR177, it is already installed. I want to optimize it for riding a 55mph road with small hills. Going to remeasure the squish to verify what I have, want to get to 1mm. Clean up the cylinder ports, any pictures of the DR177 and what exactly I should clean up? How about optimal timings? Going to get a degree wheel also, what do I need for mounting, what’s the largest diameter that will fit?

More questions to come!!

If you can do it, try to get your port timing up to 124TD/172ED. That'd match a Polini 177. You'll probably find that's not possible without altering the ports in the cylinder. I have some blown up DR's on the shelf. I'll get some measurements and see what they might look like by default.

You'll also want to cut the bar out of the reed cage and possibly widen it. Then, blend/flow all the channels. Carb to airbox, airbox to reed block, reed block to case, cylinder ports to case. This would be the time to open it all up, too, especially the ports on the DR.

You're already into my Porting 101 thread, which covers a lot of this.

Once you have your port timings sorted and everything flowed, then you can worry about squish. I've always found that squish on the DR by default is in the neighborhood of 2.5mm by default, so be prepared either have the cylinder or head milled down, or spend some quality time lapping the head.

You're using the stock ignition, right? You'll need to adjust timing to 18 degrees BTDC, too.

Good luck!

I'm using the stock ignition for now, I cleaned up the intake path, opened it up so all the pieces flow together better, cut out the center support in the deadlock and put in Boyesen reeds. The reeds seem really stiff, but I did leave out the metal support since Boyesen says it's not needed. I would say my squish is in that 2.54 area where I measured it. I don't know what the head looks like yet, thinking of going out and taking a look and getting a few pictures of what I've got.

There was no head gasket is there supposed to be one in this setup? The base gasket is 0.25mm thick aluminum, the piston dome is above the top of the cylinder. The cylinder and piston look to be in good shape. The stroke measure around a 57mm.


Should I take off the front red line, non exhaust side, as part of the porting?

The base side red marking is what I would need to remove to match the cylinder to my case ports.

Does it do any good to open the cylinder ports beyond the hole in the piston ? If I open up the non exhaust side the port will align with the piston. If I open up the rear or exhaust side the opening would be larger than the piston hole.


The red on the front non exhaust side is what it looks like I can open up to make it line up with my Stella case.

The red on the exhaust side of the port is what would need to be removed to open it up to match my Stella case.

Random pictures

Opened up the two intake ports on the side, now they are about the same or a little bigger than the piston. Just took a look at the third port in the front. The DR port is 25mm wide factory and the case port is 20mm. Going to open it up a bit to 25mm looks like there is plenty of casing there and looking at other people who opened up their third port it shouldn't be an issue.

Working on assembling a 10.5" degree wheel so I can try and measure my exhaust port timing and anything that would be good to check while I'm not in a hurry. I need to find a port measuring for dummies video. Trying to read and watch videos to get an idea of good touring settings.

https://www.scooterhelp.com/tips/timing/timing.disc.pdf

degree wheel with only the use of a printer and some scissors to cut it out / paste it to some cardboard.

I feel like I get better accuracy from using vernier calipers, myself, but different 2-strokes for different 2-folks

yeah verniers for port timings, wheel for ignition timing

does this cylinder have 3 exhaust ports?

My $.02
I found that using the ring method he shows was the most consistent.
Gave me a level of certainty I could not achieve with other methods.
Used magnifying reading glasses - a flashlight - and a pic tool to tell when I had the ring truly flush with the top of the port - (pick tool to feel if there was any edge or if I was totally flush).
Used an old set of rings and his gluing method to hold in place when I did the grinding - really allowed .05 type accuracy I could not have managed without.
Broadly (and regularly) recommend this method having tried a range of them:

Yes, a large center one and two smaller auxiliary ports.

Opened up the two larger intake ports on the cylinder to match my LML case. Measured the smaller third intake port in the case, mine is 20mm wide, the DR177 stock port is 25mm wide, going to open up the port in the case a few mm on both sides to match. Looking at videos and pictures it shouldn't be an issues breaking out of the case side.

Christopher - one other thing I found helpful.
Use a sanding drum on your Dremel tool whenever possible - rather than a grinding burr.
It is way way more forgiving - and gives a very nice finish.
Kinda helps make it look like you know what your are doing - which in my case - I didn't.
Bought a set off amazon for all of about $10.00, that had three different sizes. Found them very helpful.

Measured up the oblong exhaust port today, measured it at 60% of the diameter, believe that is a good size. The small side ports don't have much to them.

Rough cut the openings now to get out a small stone and Dremel to clean them up. I've been looking at this video and opening up the two larger side ports. I keep losing my orientation, in the video, the more I watch it the more it looks like more than one area was built up with epoxy.

https://www.google.com/search?ei=Fy7tXZzdKNDUsAXruYyIAw&q=dr177+lml+case+porting&oq=dr177+lml+casecporting&gs_l=mobile-gws-wiz-serp.1.0.30i10.2509259.2515177..2517553...0.1..0.236.2089.0j11j2......0....1.........0i71.l4xFffq5qag

I can't get the link to work for me, the video was s freak moped in the search engine link, FMP guide in the video title.


https://m.youtube.com/watch?feature=youtu.be&v=bcki-q6ORPY







The green is the front or non exhaust side if I'm looking at it correctly.

About 35 seconds in it look like he tried opening up the side port further forward and broke through the casing and had to fix it.

About 54 seconds in the repair or build up is on the front outside and rear inside?

About 1:41 there are circles and XX, the circle area looks like it has a repair also, did he take to much off the first time? Not enough material there to open it up? What is he trying to show?