MOPED ARMY

When I bought the moped in 2008 on eBay, I believe the seller wrote in the description that it needs new piston rings. He just bought the moped in a package deal of Vespas and Puchs, etc, which he restores, and didn't ever work on it, only checked if it was getting gas, had compression, and simple stuff like that.

I actually made a list of what I needed to restore this bike when I got it, which I just looked at today, and the first thing on the list were piston rings.

I'll check the shop manual for the oil pump settings.

I've tried for nearly the past 3 years to get the auto choke working after it stopped working in Dec. 2008, 3 months after I got it. I fixed it once, and it worked until May 2009, then I cleaned it again, worked for a little while, then stopped. I bought another one on eBay and it didn't seem to work. I'm wondering if something else is causing the auto choke to not work properly. I had 2 or 3 threads on fixing the auto choke. After I got the stock pipe last fall, it worked for a little while for some reason, and then it stopped again!

I'll take the choke off again and clean it thoroughly and do exactly what I did last time when it worked after cleaning.

Thanks!

~Adam

http://www.mopedarmy.com/wiki/Auto_Choke. heres a good place to go for the auto choke.

Well if you decide to dump the engine let me know I need the airbox and all the auto choke stuff off it! Good luck. I guess its time for a compression check and rings perhaps. Keep pluggin away though I'd love to hear you get it sorted out.

Well...you do need a compression checker to really know for sure, unless your thumb is calibrated. There is an exhaust gasket, just a ring type that fits up in the exhaust port of the cylinder.

I'll see if I can rent or buy a cheap compression tester. Today I'll try to get the auto choke all cleaned up and maybe the cylinder off. I'm going to find a place that sells the thick tubing, the auto choke tubes, and replace them. The Hobbit gaskets are a little different, but should they still work? Anyone used them on an Express? So are the rings for the Express the same as the Hobbit from Treats?

Thanks!

~Adam

http://www.bikebandit.com/houseofmotorcycles/1981-honda-nc50/o/m9612#sch405190

I agree with every thing that was mentioned earlier, but before looking into a false auto choke or worned piston rings you might look into your muffler. You should not underestimate the possibility that your muffler is simply clogged.

I had the same problems with my Nc50 1981 after my restoration program and the breaking period.

Mine also would started ok, idled ok but would not want to run properly.

I too thought it might be the choke: but no.

Do a simple test:

If you can easily stall the engine by obstructing the muffler with your finger (and a rag), you definitely have a clog somewhere.

To “cook” the muffler may not be enough.

Here’s what I did:

1- Ok, initially “cooked” the muffler.

2- Filled the muffler with a good quality Drano type (industrial) plumbing declogger or any type of carbon “dissolver”.

(follow instructions carefully: usually very corrosive)

The chemical reaction was so intense that I couldn’t hold the muffler with my bare hands.

3- Rinsed the muffler with vinegar to neutralize the reaction.

Rinse completely 3 – 4 times with water to remove any residual chemical agents.

4- Re cooked the muffler to evaporate any remaining water

(I did my cooking on my BBQ) lol

5- Bought/used a long flexible (with right diameter) metal brush to scrape all inner tubes.

6- Reinstalled the muffler.

At first start, I watched all the powdered carbon and flakes shooting out from the back: Very satisfying.

AFTER that, I could finally tune my Card. The Nc50 now runs fine.

For any 30 year old 2 cycle bike (and muffler), this should be a normal maintenance procedure.

around 26mph is normal

I think if you weigh the muffler and post the question in the forum of what a new/ newly cleaned muffler weighs, that should give you a good idea of how clogged it is. Then you can avoid a toxic mess. I did it, and no i did'nt weigh it before or after.

Yesterday, I put on the original auto choke after giving it a thorough clean, but it didn't really change anything. I haven't really rode it much after the issues started happening, but I noticed that once the engine is all warmed up completely, no matter what adjustment there is on the carb, it won't stay idling for more than a couple seconds, and when I give it gas, it accelerates for a second or two and then bogs down and dies if the throttle isn't let go of, but then eventually dies.

I'm ordering the piston rings off of Treats and the gaskets from Cheap Cycle Parts. With band camp 8am-5pm 5 days a week starting this week until school starts, I don't know when I'll be able to work on it. I was thinking of riding the Express to band camp because school is only about 2 miles away, but only if I get it fixed by then.

~Adam

buy a hobbit kit from treats if your going to replace the piston and jug. the hobbit gaskets from treats work fine on nc, na and nu motors. sounds more like a carb problem than a auto choke problem. i removed my auto choke and installed a primer bulb i got from the local hardware store for like 6.00.

I don't think there's anything but steel in the exhaust. Drain cleaner is common lye, which won't hurt steel at all. It's only aluminum you have to worry about with lye. I've spent a lot of time, on this forum trying to explain how to use lye to it's best advantage. It will clean pipes right down to the metal, if done right. Care must be taken to insure you don't hurt yourself, though, cause it will burn your skin & you definitely don't want to get it in your eyes. You will see large chunks of ugly, smelly old burnt oil come out of the pipe. Sometimes it needs to be repeated. Best it it's done in a steel or plastic vat & at high temp 160+ F. Why do you think EPA made it illegal to have 'hot tanks' at shops........ cause it worked! The bastards.

Finally Treats has NC50 head and cylinder gaskets!!! I'm getting them.

Yesterday I was riding around the neighborhood with my friend. Once the bike was warmed up, I ran it at wot for about 30 sec on a straightaway, and it died and white smoke came out of the muffler. Overheating? Caused by piston rings? It starts up after about a minute. Happened 2 or 3 times. Once the gaskets come in the mail I'll change the rings and put the new gaskets on. Then I'll get back on how it works.

~Adam

Before yesterday, I only rode it on 5 min rides, but that can still cause problems. I'm not driving it any more after yesterday until all is fixed. I shouldn't have rode it until then.

Thanks,

~Adam