I’ve kind of picked this up late in the process but I figured I would document my NCU50 Hybrid Express progress. I bought an Iowa Urban Express engine and after getting it running, I realized I had an NC50 frame hanging around. I decided to mate the engine with the frame and create the NCU50 Express Hybrid. Others have done this so it’s nothing new, and it’s been a fun project. I finally got the wiring all worked out and have experimented with several different exhausts (mlm people’s side bleed, tomos A35 tecno boss pipe, and an Estoril side bleed pipe). Currently the Estoril is on it and seems to have superior low and mid range but I haven’t matched or surpassed my 39.9mph run obtained on the tecno pipe. The Estoril pipe is amazingly quiet and much quieter than the MLM pipe.
I recently upped the compression from 160psi to 180psi and down-jetted from a 75 main to a 72.5 main. I think it is still running too rich so I may go down to a 70 jet (I’m using a Dellorto SHA clone carb). I’ll report soon with an update on where I stand after those changes. I have also installed the Malossi racing gears but it seems like the stock Iowa Urban engine can’t turn that steep a gear. I will probably swap back to the original gears.
Future changes may include opening up the tiny Iowa exhaust port; tucking in and hiding the wiring; adding a mudflap; experimenting with different drive belts; changing length of the boss; and more.
11/14/18 update:
So I decided to open up the tiny exhaust port.
So here’s an Express cylinder with basically the same tiny exhaust port as was on my Iowa Urban cylinder. I didn’t get a before picture of the Urban cylinder.
This is an after pic of the Iowa Urban cylinder. I only raised the exhaust port inside the cylinder chamber 1.5mm or so. I did open up the exhaust port everywhere else quite a bit. I’ll install it soon and report back with the results. I also cleaned up the exhaust threads and sanded down the cylinder head mating surface for a better seal.
Here’s another shot of the urban cylinder after I had finished it and it has the exhaust gasket in it. I took it for a spin after re-installing it. Initial take off is slower but acceleration from 15-30 mph is much faster, and I will verify later, but I think I have a new top speed around 40 mph. It’s also a little louder as well.
11-19-2018 update:
I finally swapped the Malossi racing gears out of this bike and but them in to the black Urban Express which will be better able to take advantage of them. As a result, I lost some top speed and am back to about 36 mph but my acceleration is way better. I may try the bx31 belt without a washer next to the boss and see if acceleration remains acceptable. That should get me a little more top speed. I think raising compression to 180psi definitely helped with acceleration.
I added a USB phone charger (12v) as well.