'78 Honda NC50 Express almost road worthy.... By rapidrob (Read 1,694 times)

[rapidrob]

I was given this bike a month ago and have made some progress since then. After sitting for 20 years,the last ten in the sun under a pine tree I had my work cut out for me.
The carb had been left with no filter element and unleaded fuel with alcohol in it. The carb was badly plugged which took several hours to clean. Corrosion from the alcohol was fun to remove.
I had to test the engine and see if it would run. The speedo show only 460 miles on the bike. The engine has good compression and no wear in on the cylinder walls ( endoscope used). I was able to start the engine by squirting gas/oil mix into the carb ( all fuel/oil line long rotted away)
Tank had very slight rust in it. Lots of goo from old gas. I solvent cleaned the tank and them acid treated the insides and all the rust came out. 
Only problem is the oil tank cap is loose due to the rubber. A new one is hard to find and expensive.
I added new fuel/oil lines and an inline filter.
Fuel valve is clean and free to turn.
Battery is new. I used expanding foam to make a new battery/ignition "tray". Not as nice as Styrofoam from Honda,but it works.
All of the control cables were rusted and bound up. Soaking in Kroil freed them all up but their too far gone to be safe.
A fellow in England sold me a whole new set of cables made in Japan. All are OEM quality and fit perfectly.
Tires were rotten. A real shame as they looked almost new. I got two new tires and inner tubes and put them on the rims. Rims are like new ( very dry here)
I had to replace the left hand handle bar switch/brake control as the support for the rear break cable was shattered.
Wiring is in very good condition. I was surprised how well it has survived all these years.
Every bulb/lamp was burned out. Common problem I'm told. All have been replaced with LED's  except the headlight( there isn't one yet,LED) so I got a replaceable bulb type.
The plastic parts on this bike are very dry and brittle. I've soaked them in water for a few weeks which seems to have helped. The headlight bezel and bucket were broken but were repaired using JB Weld.
The air cleaner housing is beyond hope. I got a clamp on air filter.
The kick starter lever would not return by its self. The return spring had jumped the retainer. An interesting repair.
NOS Honda seat.
I'm slowly putting all the parts back together. I'm hoping to have it on the road soon.



   

[cyborg]

Great!!!

[rapidrob]

I spent the last ten hours putting all the parts onto the bike and made adjustments as needed to cables and the carb. I hooked up the oil pump to a drill and ran it until there was oil filling the discharge line to the plenum.
That being said, I filled the gas tank with fuel/oil mix just in case.
The bike started right up. After it warmed up for a couple of minutes I adjusted the idle. I do not have a tach so I did it by ear.
I reved u pthe engine and the muffler did not sound right,more than muffled. The engine bogged down and I goosed it again. The muffler belched out a stream of black goo for about ten feet all over my garage floor. 40 years of who knows what,when warm, left the muffler at high velocity.
I ran the bike around my mountain,where on the flats it did about 25. On the hills,not so much.
Two hours adjusting the air and throttle stop unit it ran very well,even with the too oil rich fuel.
I was so happy the old bike I took it over to the guy who gave it to me and he was glad I was able to get it to run. So much so we had a beer to celebrate.
I jumped on the bike to drive home and it wont start. As in after two hours of pharting with it,it will not start or run. Plenty of fuel,hot spark and air. It will not run.
Back to the drawing board.
And the oil pump is no longer pumping oil to the plenum. A good thing I used a mix,just in case.
The spark plug is wet. The carb has to be the fault. Why it will not start again is puzzling.
I will take it all apart and try to find why it will not run. The engine was running like a top when I turned it off. Plenty of oil in the mix.

[cyborg]

Too wet is my guess,, finally got the juices flowing and with the premix you pushed over the efge

[rapidrob]

The plug is wet. I dare not run the engine on straight gas until I'm sure the oil pump is working. The displacement is just a dab of oil about every ten seconds of the running pump.
I cannot find any info on the amount of oil that is to be pumped with the engine running at a set speed.
There is a device at the plenum that looks to be some sort of "injector" that I may need to remove and clean that the oil is pumped to.

[2stroked]

Yup. Maybe killed the plug with oil before the pump died?
Hope you get it sorted soon.

[2stroked]

The pump on the generic Minaralli clones provides a mixed ratio. The higher the engine rpm the more oil in the mix. Not sure about the Honda.
A lot of flks are premixing nad ditchingte injection, but again, am not sure about that engine...
It's probably something so simple thta it's easy to overlook. Good luck

[rapidrob]

The plug is good. Nice blue spark. I need to remove the carb and see whats going on.

[rapidrob]

Since I wrote the above, the engine did start again,but just for a couple of hours. It died as if I cut off the ignition. It would not start.
I tried it again after a few days. Still no start. And then, no spark. The new plug was cracked inside. I've never seen that before. No idea as to why.
I put in the old NGK and it started right up. I ordered new plugs.
The good news is I noticed the oil injection pump was finely moving oil to the intake manifold.
I drained the 40:1 mix and added high test unleaded gas to the tank. The engine started right up and I let it idle making sure the head temp did not exceed normal operating range. Once I was sure the engine would not seize up I took it out for an hour. It ran OK,not great as the carb has worn parts,... wide open it will bog down after a couple of seconds going downhill. On level ground or a rise it runs very well. It has a fixed jet. Neither needle valve Air/Throttle Stop come to a point.
The carb is clean inside. All air tubes and passages are free of any deposits,but the carb does not drop in speed quickly when the throttle it turned down.
The choke moves on/off and seems to seal off but I cannot verify that. Bike idles well and the engine revs up OK,if not just a little slowly.
Still waiting for some lamps from China.

[rapidrob]

The LED bulbs for the Speedo and High beam indicator as well as the tail light/brake showed up today. They took almost a month to show up from China but the wait was worth it. The tail light is very bright even in daylight. The Speedo and High Beam indicator are now a nice Blue color.
Head Light is the replaceable incandescent bulb type. I could not find an LED bulb for the headlight bulb.
Power drain is now only the headlight. Not a huge deal on the little battery since it is only on if the engine is running.
Total cost was less than 8 bucks delivered for the LED bulbs ( got extras just in case )
The old bike is getting closer to being road worthy. I'm waiting for a new kill switch that broke due to dry rot.

[elcamino121]

Would you please let me know all the information regarding the LED's.

I would like to order some for my scoots.

[rapidrob]

The price went up three bucks on these lamps,but they are very bright.
www.ebay.com/itm/2x-6V-1157-bay15d-24-DIP-LED-White-Car-Bulb-Light-Brake-Stop-Tail-Reverse-Lamp-X-/222184993490?hash=item33bb41f2d2:g:rpUAAOSwInxXND78&vxp=mtr

www.ebay.com/itm/2pcs-DC-6V-Ba7s-1-SMD-LED-5050-DASHBOARD-WARNING-SWITCH-BULB-Blue-color-20LM-/222301832875?hash=item33c238c6ab:g:0Z0AAOSwXeJYGVoO&vxp=mtr
blue bulb that fits my Spedo

The third bulb is no longer listed. There are no marks on the LED. It is for the High Beam indicator light.
I'll try to find another that is the same for you.
It does take at least three weeks for the bulbs to show up. Still your getting the bulbs for under 15 bucks now.

[rapidrob]

My last hurtle has been the headlight bucket and bezel. The problem is it is dried out and brittle.
So much so that you cannot put the bezel in the bucket with out chips and cracks forming. After two tubes of JB weld it was getting the the point of having to cover the two parts in fiberglass to make it usable.
I found a better condition complete head light assembly from a "wet" state and I'm hoping it will not be so brittle.

[cyborg]

Good luck ,,, I live in socal,,, the sun is the cause of plastic degradation ,, they get like potato chips if they get any sun at all,,, eBay has been a lifesaver

[rapidrob]

I bought a new complete headlight assembly. The one on my bike was so brittle it had to be constantly repaired.
The "bent handle bars" turned out not to be. The forks were bent. I got a replacement one now.
Bike should be ready to roll for the rest of the summer soon.