Honda NC50 Top Speed Mods

My Honda Express at the time of purchase.

My Honda Express at the time of purchase.

So you want your Honda Express to go faster. I thought over the next few weeks I’d perform some experiments on my stock NC50 to see how fast I could get it to go without using any performance parts (I do have a K&N hi-flow air filter). My top speed now is somewhere around 28 mph. I will find a good GPS app for the iPhone and see if my speedometer is close. Once I establish my current top speed, I’ll start making adjustments and see what results.

I was reading the service manual for the NC50 and saw that it called for 10W-40 transmission oil in the summer and 5W-30 in the winter. I’m currently running 10W-40 conventional oil and I think I notice some drag on cold days. I also read on mopedarmy.com (concerning the Suzuki FA50) that if you went from 20W-40 conventional oil to 10W-30 synthetic oil, you would obtain a 2-4 mph top speed increase. So my first top speed experiment will be to try a lighter weight synthetic oil to see if I obtain a noticeable speed increase. I’d be happy with 1 mph. I think 2-4 mph is a bit optimistic. I’m still undecided on what weight synthetic oil to try. I have 0W-20, straight 30W synthetic, synthetic transmission fluid. I also have conventional 5W-20 and 5W-30 oil. I probably have more if I dig around. Yeah, I’m an oil freak.

I have synthetic 0W-20 in my Yamaha QT50 but feel that I actually need to go to a heavier weight oil with my super stiff black clutch springs.

I’ll make videos of each top speed run and post them here. I’ve got several other ideas but will reveal them one by one as I make progress from test to test.

2/1/16 – Ok, just did a base speed test and hit 29.4 mph. Next step will be to change transmission oil and see if we get any gains or, worse yet, lose any speed.

Ok, I changed the transmission oil to 5W-30 and lost 0.9 mph. Top speed of 28.5. I’m going to look at changing the jetting next.