Kymco SC10 motor build 81cc Phongeer Tri-port Aluminium AC

[oldgeek]

I picked up this kit a while back and have been itching to build a motor using it since I got it. It looks to be pretty well made. It should not take me forever to build this one because aside from some minor port matching and opening up the intake a bit, the cases do not need to be highly modified like they do if you are building a big stroker motor.

[oldgeek]

Here are some of the parts I rounded up for this build. A Malossi RHQ crankshaft, standard 41.4 stroke. A stock reed block that I modified (on the left) by taking out the metal reed and 2 center vanes, then installed one large CF reed. A totally stock Kymco intake, with a shiney Malossi PHBG carb adaptor bolted to it. The carb will be a Dell PHBG clone 19mm or 21mm. And finally the exhaust will be a Phongeer PG short or the V8 I got from Autotech on Feebay a long time ago.

[oldgeek]

I installed the Malossi crank into a stock set of Kymco SC10 cases, using slip fit bearings. Then I tried to install the cylinder but the cylinder skirt was hitting the cases. So I used the fine wheel on the bench grinder to carefully grind the corner of the skirt off.

The base and head gasket supplied with the kit...

...did not set up very well. It's hard to see in the BDC picture, but the piston is still well above the transfer floors.

At TDC the piston is way out.

Added a thick base gasket I had along with the other gasket.

Now it looks much better. BDC

And TDC

Thick gaskets compress, so I cut out a base spacer on the scroll saw table from a piece of 1.35mm aluminium sheet.

You may have noticed the dowels for head alignment. I had to put them in because the piston protrudes from the cylinder into the recess of the head. I used a step drill bit in the drill press to oversize the hole in the head and the cylinder. I cut a spare carter dowel in half to make the dowels for the head. Considering the tools I used it came out really well, almost lined up perfect. The step bit does a pretty good job centering itself when enlarging an existing hole. If the original hole is accurately spaced, then the hole I enlarge should be good.

The port timings should end up ex186 xfer130  Squish is .51mm - .62mm without any sealant. By the time I seal it up, squish will end up around .7mm - .8mm depending on how much sealant and copper spray gets used.

Looks like some light port matching would help.

The intake windows definitely need help. The stock Kymco SC10 windows are much smaller than the stock windows in the Honda AF16 motors.

I also need to delete the oil pump hole. I think I will just use a plug instead of doing the epoxy thing this time, at least for now.

[repherence2]

I'm happy for you Oldgeek. I seen that bore on e-bay but even though it ships from Honolulu, I don't think the seller wants to mail it for people on Oahu. the note on his e-bay listing says to check local shops on Oahu...but none of the shops I have been to stocks them.

I went to Qwikfix Garage to see if they had the PG 50mm bore in stock. the owner said that he could order it for me. I ended up leaving the shop with a MHR replica instead. for the price listed on e-bay, I really wanted to get that PG bore kit. I will probably just order one through Qwikfix Garage and save it for another engine build.

my idea was to port it to the same durations as a Corsa and match it with a Scorpion pipe.

I am excited for you. I can't wait for you to finish this build and to hear your opinion of the PG's performance.

[oldgeek]

Oct 16, 2019 20:43:33 GMT -5 repherence2 said:

I'm happy for you Oldgeek. I seen that bore on e-bay but even though it ships from Honolulu, I don't think the seller wants to mail it for people on Oahu. the note on his e-bay listing says to check local shops on Oahu...but none of the shops I have been to stocks them.

I went to Qwikfix Garage to see if they had the PG 50mm bore in stock. the owner said that he could order it for me. I ended up leaving the shop with a MHR replica instead. for the price listed on e-bay, I really wanted to get that PG bore kit. I will probably just order one through Qwikfix Garage and save it for another engine build.

my idea was to port it to the same durations as a Corsa and match it with a Scorpion pipe.

I am excited for you. I can't wait for you to finish this build and to hear your opinion of the PG's performance.

Is it ok to port an aluminum/nik cylinder? I would be scared of screwing it up. I was hoping the EX duration would be a little higher than 186. It would be nice to be able to bump it up a bit!

What do you think would work best with this cylinder pipe wise?

[repherence2]

I ported my Taida 54mm aluminum/nik bore on my chinarelli, raised the exhaust port. I never encountered any problems with it. im planning on porting the MHR replica bore that I just picked up. the casting of the port windows is not so straight, as in the transfer and boost port roofs. exhaust port roof to top of the bore I got 25mm. from my minarelli experience that seems fairly low. my math estimate is 175 exhaust duration on this MHR replica.

as far as pipes, I wouldn't know what to really recommend. it will depend on the duration of the ports as well as how obnoxious you want to be. the PGs are loud. I like running V8's on my minarelli because it's more on the quiet side. I am going to run the Arrow because I was told by a builder that it was the best all around pipe. he also said that the Scorpion is a pipe for top end screamer.

im just getting into this Honda stuff so I pretty much walked into Qwikfix Garage and told the owner, "I am a minarelli guy. I feel that I have achieved what I wanted out of the minarelli platform. I just picked up a SYM dd50 engine and I want to build it. I have an Arrow pipe. what do you recommend?" I walked out with the MHR, a stock stroke Taiwan crank and Taiwan bearings. I asked him about the PG 50mm bore. his response favored the Italian products as far as bores, a Taiwan versus Italy comparison.

gathering parts has been a neat experience. basically going to the "known" moped shops and asking the owner/tuner what they would build.

the tuner at Glenn's Cycles said mini stroker Corsa.
the owner of Qwikfix Garage sold me a MHR replica and a stock stroke crank.
the owner of 808Cycles said, "Stroker all the way!"

all I know is that I will be using a Degree Wheel for the first time on my build. I have no clue of what kind of port timings to expect with this Honda stuff.

[pitobread]

Use the diamond burrs, less likely to chip the nikasil.

[oldgeek]

Spent a little time today on the intake windows in the cases. I decided to do only a minimal amount of work since I am sticking with a stock style reed block and intake. I couldn't see where doing a bunch of cutting would help the flow much in this build. I did cut a spacer to go under the reed block, and raised the top of the windows a bit.
Before

After

[Lucass2T]

Lookin good OG!
Nice cylinder too.

[90GTVert]

I haven't used a scroll saw since middle school, but you're making me want one with that spacer work. I have a feeling you're making it look easy. I'd prob have some abstract art versions of spacers if I tried it.

[oldgeek]

Oct 18, 2019 17:58:11 GMT -5 90GTVert said:

I haven't used a scroll saw since middle school, but you're making me want one with that spacer work. I have a feeling you're making it look easy. I'd prob have some abstract art versions of spacers if I tried it.

It really is easy, saw speed, feed speed and let the blade do the work. My issue is poor eyesight. I can hardly see the lines I scribe. I rubbed the reed spacer with a black sharpie then scribed it and still could not see it much better.

If anyone tries it, I have found it's best to lay it out, drill the holes, cut the center out and then cut the outside.

I like tools, and got lucky when I found that saw for $20 I think it was. Sears brand with a fairly heavy cast iron base. The right tool can make tough jobs easy. My hands started hurting pretty bad today while filing away at the intake with diamond hand files. I went looking and I just ordered a pneumatic file Hoping it will make things easier.

[aeroxbud]

I'm liking this build already 👍

[oldgeek]

After helping a friend move for four hours this morning, I spent 9 hours at Scootopia, mostly working on this build. Where does the time go! I did some port matching and opened up the boost port quite a bit. I was not going to cut on the cylinder skirt or the piston any, but like I said, I was there 9 hours. When you are trimming the cylinder skirt or the piston it is soooo easy to cut more than you wanted to. I dont think I cut all of the fast out of the piston!

[oldgeek]

Poor weather and I am not on call for work this weekend = all day at Scootopia!
All new gearbox bearings, shock bushing, and motor mounts.



Oil pump delete plug done.




I would like to do the crank next, but I need the lift and the Naked Kymco is currently on the lift waiting for me to put the intake back on.

[oldgeek]

I got the crank installed this evening using the puller, after 2 fails yesterday using the hot cold method. I am not sure what was going on with the hot cold method, I usually get it done easily with my setup.

I actually had to file the ring end gaps to get them to spec, not used to having to do that! Did a final check on the cylinder and base spacer, then cleaned them up. I hope to get it sealed up and installed tomorrow in between jobs at work.