1983 Honda NC50 bogs and dies after motor is warm

Dustin Schings /

So my 83 Honda Express was running like a dream for the past couple of months, then one day it was messed up. It bogs down and then dies at WOT once engine is warm.

Bike is stock except the airbox is removed, no filter ATM and upjet from 75 to 80. Has been running very well like this for most of the summer.

I have cleaned the carb VERY well and it is perfect. Plunger needle is coned and not bulged or mis-shaped. Jet is also brand new.

I have replaced the spark plug with a brand new one and properly set the gap.

Fuel is freely flowing from the tank and thru clear fuel filter. Petcock is new as of April I believe. Does NOT appear to be a fuel delivery issue.

I read on one forun that it could be the ignition coil acting up under heat, but it is mounted in front of the head on the frame, and I am not sure that would be it, but open to suggestions.

I was also told it could be piston rings just getting worn out dues to mileage (~6000 miles). This could be it, but from perfect one day up until I parked it and then crap all over 1 night?

Any help is appreciated. If you need any more info, please let me know!

Thanks in advanced.

Dustin

Re: 1983 Honda NC50 bogs and dies after motor is warm

Dustin Schings /

Turns out the 80 jet I ordered was actually a smaller hole than the stock 75 jet I had, and WAY smaller than the 86 jet that I initially upjet to. I took it out and put the 85 back in with a panty hose filter and G2G. Note sure whats up with the 80 jet I got from treats. It was either misdrilled and made too narrow, or BOTH of my thought to be STOCK 75 and 85 jets were drilled out. Not sure which..

Re: 1983 Honda NC50 bogs and dies after motor is warm

There are some jets from different companies with different numbering. for example some mikuni and dellorto jets are interchangeable size wize but numbers are off, one sizes by the diameter of the hole (i.e. 85 =0.85mm roughly) and the other sizes by a flow rate (like 0.85 ml per sec at some given pressure or something)

Re: 1983 Honda NC50 bogs and dies after motor is warm

Dustin Schings /

I suspected that was the case. IDK, I have a stock carb on my 83 NC50 and ordered this jet in a size 80 and it was a tine hole. Way smaller than the 75/85 jets.

http://www.treatland.tv/OEM-honda-EXPRESS-keihin-carburetor-jet-p/oem-express-keihin-main-jet.htm

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