_Sorry for the lack of pics, I didn’t have a camera available at the start of the project._
First impressions : Kit comes is a small box, minimally packed, but sufficient; all gaskets, wrist pin, and clips included; no instructions. My single piston ring was broke upon delivery, but benji hooked up another well before I was ready for it. There are some rough spots from molding on all the transfers and ports; the exhaust port has an offensive lump and de-compression port both of which will need to be eliminated. Impressive port map, overall exterior finish is nice, cylinder wall finish is also nice. Transfer and ports are noticeably larger then the Malossi kit and stock cylinders.
Install : I was in a hurry and really didn’t feel like rebuilding the Express drive train so I took the lazy man’s approach to case matching. First I lined the crank webs and bottom of the case with tissue paper just enough that nothing could get in there; then I took a small amount of play-dough lined the bottom case tightly with about a 1/8" thick layer. Then used some short 6m bolts to hold down the base gasket, once lined up I marked my cuts. All three transfers needed a good amount of work. I used a pointed tungsten bit to do most of it and finished with some red grinding stones.
The cylinder studs were bit smaller then the holes on the kit, I was able to shim two of them with brass tubing from Ace which got it centered pretty well.
The piston went on as smooth as could be, with a nicely lubed pin.
After lubing the piston and cylinder with some 2 stroke I installed the cylinder, making sure the ring stayed aligned on its pin. I installed the head gasket, and then a stock 77 NC50 head, and tightened it up in a crisscross pattern while turning the fly wheel. I finished up the install with a BP7HS plug.
Carb : Now after having the kit on a really seeing the potential of this cylinder I took a step back and decided to rethink the carb situation. The stock 12mm was just not going to cut it, not mention the silly jets (this had a later model carb with the o-ring style jets). So I had 15mm del knock off with an intake sitting around and started brain storming. This is what I came up with.
I took an intake manifold from an 80 NC50 and sawed off the top almost right thru the middle of the stock opening. Then I lined up the Del intake so that it was as centered and lined up to be matched to flow well, then drilled the needed mounting hole to bolt the intake to the other intake. For the top of the intake I took a piece of copper pipe that was about 16mm OD and bent the ends to match the shape of corresponding intake, put it in a finger tip of a rubber glove and stuffed it with paper towel until it had the shape I wanted my intake passage to have. Then I put the plug in place and molded Quik Steel tm tightly around the plug and against both intakes. I let the Quik Steel set for about 5 minutes and then removed the Del intake and the plug, then I let the Quik Steel set over night. The next day I planed out my intake design and went to town with the Dremel. I wanted to add some volume to the intake and I wanted to improve the flow thru the corner, as you can see in the pictures below I think I accomplished this rather well. After getting everything matched up I put it all together sealing all mating surfaces with blur RVT and allowed it to set another 24 hours.
Installing the carb was straight forward, removed the old intake installed the new intake. The stock throttle end was a little big for the Del, I simply trimmed about 1/16" off the end of the knarp and it worked perfect. As for jetting I guessed; I went with a #63 orifice drill. As for a filter I used a shimmed up uni-pod from one of my old RD 34mm Mikuni carbs.
Exhaust : The stock exhausts on any Express are junk in my opinion so that was clearly not an option. At my disposal were 3 clear choices; first there was the Leo Vince Circuit, a very nice pipe with the most impressive header of the bunch and great reputation but sadly no stand clearance; next was the Proma Lowboy Polymer, by far the lightest of all of them, close to stock header and not that impressive of a chamber, but no clearance issues but needed to a support bracket made; and the final option was a pocket bike exhaust that I had already modified to fit on the NC which has huge chamber, stock header and known performance qualities.
I went with the last as it was the easiest and I felt it matched the bike the best.
I did forgo the exhaust studs for some allen head bolts instead.
First start/ride : I turned on the fuel, put on the choke, wound it up, pulled the rear brake, and it turned over smoothly but no fire. So I wound it up again, pulled the brake and instantly she fired up; I quickly popped the choke and she began to idle perfectly. I instantly began checking for air leaks, and thankfully found none. I then did three 10 minute heat cycles. After rechecking all nuts and bolts I took it for a 10 mile cruise at