Honda Spree and Elite 50 Forums

I was thinking about documenting my first SYM DD50 build here for several reasons. During the build process I could have your valuable input and suggestions. Also, there will be a place to catalogue and document the build. Would this be something I could do here??? What do you guys think?

Yes, that's what the "Scooter Builds" threads are for! GL with the build!

So here's the base motor I'm going to be using for the build...










I arrived home one day and found this on the bed...





Thanks to my beautiful girlfriend for this piece of hardware.

I dove into the contents only to be disappointed. I actually thought she had purchased the contessa kit packaged in the corsa box. Why you ask. Well, the exhaust port was rough, transfer ports on the cylinder side were not straight, piston did not look graphite coated, spark plug was cheap, etc. After some investigation into the matter, I found I had the correct kit.





So begins the process of getting the parts up to specs.

Here's the exhaust port after a lot of hours working it. Notice it's still really rough. I used a dermal with those fiber sanding discs, hand sand with 2000 grit, and finial polish with buffer bit and some fritz polish. There was also a GP stamped into the side of the exhaust port. Does anyone else have this, or can someone confirm that this is normal?






I was also disappointed with the finish on the head by the spark plug recess. It was rough and had a sharp edge. Out came the wet/dry sand paper. I'm also going to try and smooth out the CNC ridges from the cylinder head surfaces later. I don't know if it will make a difference, but I figure it would make it harder for the carbon to stick to and lower the compression a hair.

I do have a few question regarding the piston. I'm going to try and smooth out the bottom surfaces of the piston as they are sharp and rough.





Does anyone know why the under side of the piston has a thick cast portion on one side and the other side has a thickness roughly half that?






Here's the piston pin. I was scared that it was corroded but the white stuff rubs off. Weird.




Here's a question I have for all of you. I was told to run this spark plug due to it being a colder plug. I was told the plug that came with the kit would run too hot. Does anyone know if this is the correct plug to run? If it isn't what would be the proper plug part number. The plugs are a little different as one sticks out further into the cylinder and the insulators are a bit different. I was going to try and see if NGK had a cross reference chart that I could plug the champion part number into.

my pin in my NEW piston kit came like that too... btw what pipe are you gonna run with the corsa?

Yes, I do understand that removing material, although a very small amount will lower compression a little. This being a high compression setup, a little lower compression ratio might be beneficial for street use. As I will be "smoothing" out both head and cylinder mating surfaces I'm sure it won't be affected too much. I'm also going to be setting squash clearances so that will all be taken into account later.


I have a yms v8 pipe, as well as a upgraded sym pipe to test for now. I was going to try the scorpion, but well see. I did want to ask you guys if anyone has tried the malossi pipe for 72. There is a store with one, albeit it's a $450 exhaust. Is it worth the coin?

never tried the MHR pipe but scorp. is good and i hear arrow it too. v8 isnt good for performance, just good to aviod cops.

Yeah, the whole port and polish corsa is total bs. I just got my mine today also. GP right in the side of the exhaust port and not just that, did you notice the second inner lip on the exhaust port? I spent all morning to wipe out all that meat out and cleaning up all the other ports. You figured since it was ported that meat would all be gone. All the work I did to clean this corsa up, I could have done the same thing with a cheap * Taiwan bore. Waste if money to do all that work. I think i would have been better off spending the money on a polini piston and a taiwan jug.

DorkoElite303 wrote:Yeah, the whole port and polish corsa is total bs. I just got my mine today also. GP right in the side of the exhaust port and not just that, did you notice the second inner lip on the exhaust port? I spent all morning to wipe out all that meat out and cleaning up all the other ports. You figured since it was ported that meat would all be gone. All the work I did to clean this corsa up, I could have done the same thing with a cheap * Taiwan bore. Waste if money to do all that work. I think i would have been better off spending the money on a polini piston and a taiwan jug.

The port timing on the taiwan cylinders are junk. You will be much better off with the italian cylinder

totally agrees with Red..
Buy your taiwan stuff .. You could make it fast but it does take alot of work, the amount of porting work i do on a taiwan bore to even get it close to a polini is crazy. Metal isnt as good quality, transfers are rough and not good in timing and angles .. Easier to start with something proven and work from there..
aloha
D

Anyone ever feel like there in a "rat maze" of this thing called life? I've been busy, but trying to make some headway on this project.

An update on the question I posted earlier. The Polini corsa kit comes with a Champion L78C copper plus plug. You may use a NGK B8HS, B9HS-10, BR8HS, or any of the other derivatives. If you don't mind spending a little more you can get my personal favorite NGK BR8HIX Iridium.

Also to answer another question I had. I'll post this here if anyone needs it for reference. The SYM DD50 has the following gears in the transmission. Gear A: 12 teeth, Gear B: 34 teeth, Gear C: 12 teeth, Gear D: 47 teeth. So stock DD50 ratio: 11.0972 vs the elite s 12 to 1. So the following aftermarket gears would give the SYM these ratios:


DD50
15x42=10.9
16x42=10.2
17x41=9.44
18x39=8.4861
19x38=7.8333

VS.


Elite S
15x41=9.8
16x42=9.18
17x41=8.44
18x39=7.58
19x38=7.0

LOOK CORRECT????? CORRECT ME IF IM WRONG.....

How do you do the calculations? I thought it was B/A X D/C= Ratio. So for 15x42 would be 42/15=2.8 47/12=3.916 so 2.8 X 3.916= 10.9 to 1 NO???? Please help me figure this out.