Urban Express won't start

Got a Honda Urban Express for $50 at garage sale. Changed plug. Nice blue spark. Rear brake cable frozen, battery dead, so I locked rear wheel with clamp to try to kick start. Kickstarter works well. Compression seems ok. Drained old gas, primed spark port to see what gives.


What's the next logical sequence of steps to approach the problem? Don't want to start anything else until I figure if it's worth the effort.

Ideas? Suggestions? Anyone with similar bike that can provide novice with assistance?

Re: Urban Express won't start

Don Pflueger /

you need the rear brake cable to move in order to start it. at least on the express you do. i dont think the urban express is much different.

Re: Urban Express won't start

If that does not get it, clean the carb. The jets in a 50cc carb are awfully small and tend o plug up if allowed to sit for a long time.

Re: Urban Express won't start

Leon Swarmer /

Be thankful you didn't get it started. If you had you would have blown out a $30.00 headlight as soon as it reved up.

A charged battery is needed to act as a voltage regulator.

Jax184 did a great guide for garage sale expresses.

do a search. My expresses won't start unless there is oil in the oil tank. You might need to check timing.....


Re: Urban Express won't start

Jonas Quimby /

Coupla pointers. My guide was written for the normal Express, not the Urban Express.

Similar, but not the same.

The Urban Express wont need a good back brake cable to start, but a fully charged battery is definatly a good idea. The UExpress uses a 12v system instead of 6, so remember that for charging/replacing.

From there I highly recommend you tear apart the carb, clean it completly and reassemble it. Make sure to turn the adjustment screws all the way in and write down how many turns it took so you can set them back. Then remove them and clean their passages along with everything else.

That should get you started.

Re: Urban Express won't start

Put some gas in a spray bottle and take the spark plug out and spray some gas in the cylender put plug back in. It might take 20 -30 tries to get it running but it usually works.

Re: Urban Express won't start

Jonas Quimby /

Once the carb is cleaned out, you wont need to gas the cylinder. And gassing it before cleaning the carb will only make it fire a time or two before it runs out of gas.

The Express series is very well known for requiring a spotless carb before it'll run properly.

That and the headlight burning out are the bike's two common problems.

Re: Urban Express won't start

A. J. Souza /

Well. I have to thank (sincerely, wholeheartedly) all who have thus far contributed their opinions.

So far, I have consulted my former mechanic, who assures me that, in order to test the electric system (not run vehicle) any 12 volt moped battery is suitable.

I have spritzed (injected? dribbled? blah, blah) fuel into the spark plug port to attempt ignition.


Though, I admit, I did NOT do it the 20-30 times suggested might be required. Maybe 6-8 times. Didn't want to mess anything further.

Did not even get the "attempted rumble" I'd have hoped for.

I am glad that Jax 184 took time to comment that the bikes were similar, though not the "same." Important to know since I have a manual for the NC 50 and NA 50 and might be otherwise tempted to try those instructions.

I am puzzled about starting the bike: CAN the battery be dead (with no negative repercussions) and the bike still start with the kickstart mechanism as long as the brake cable is in the lock position? I figured this to be okay based upon the former two Hondas I rode (a NX50U Urban SR and a Aero 50), both of which had a locking latch on the left rear brake handle for starting. Even if the brake cable is frozen (as was mine), if I can still position the rear hub using a clamp on the cable (so, in effect, "faking" the bike into thinking that the cable is actually doing its job), would that safely be the same thing? At least as far as attempting to start, if not run, the bike?

So far, I have not had sufficient time or learning or confidence to go much farther.

So, please, don't be shy

Re: Urban Express won't start

Jonas Quimby /

The Express SR uses the same engine as the Urban, just so you know.

Anyway, the brake shouldnt need to be on for the bike to start. So long as the engine spins and you get spark, that means the bike doesnt care what the brake is doing.

I really hope you've cleaned out that carb like you've never cleaned before. It makes a huge differance.

And yes, the bike should start up just fine with a dead battery so long as you use the kick starter. Though if you like you can connect a 12v car/motorcycle battery for the time to test stuff. The electric starter's a lot easier then the kick starter after awhile, so long as you dont burn it out from overusing it.

Re: Urban Express won't start

A. J. Souza /

Thanks for the info, particularly the section regarding the SR engine being the same! This might save one (if not both) of the bikes. I know that the '81 SR was running before but I did not want to spend as much money as was quoted (then) for the redo. If I could get one working, I would prefer the Urban Express, just because I like "bigger" and more durable and stable bikes than the smaller versions. (It's why I am a rare soul in my town who actually WANTS to redo his old Magnum rather than the Maxi).

And, no, sorry, I haven't gotten to the carb yet, but you are among the mechanincs who have said that's where they'd start also. My old guy here recommended same. An upcoming project.

Two other questions: Where can I get a rear brake cable, assuming I actually get it running? And, where is the VIN plate?!!! I looked where I expected it to be based on other Hondas (front fork below handlebars) and found nothing. I looked all over for ANYTHING and found nothing. Is it under some plastic cover plate or what?

Re: Urban Express won't start

Jonas Quimby /

The carb is Definatly your problem.

As for the brake cable, I'ld try calling local Honda shops to see if they still have one in stock. I've been able to get a lot of parts that way.

Otherwise start watching ebay, they'll come up.

I'm as surprised as you are by the lack of VIN tag. I havent worked on a UExpress yet so I dont know where it is.

Have fun eather way.

Re: Urban Express won't start

Start at the gas tank and work toward the carb to see if you have fuel flow. The bootom of the fuel valve should have a hex head that you can unscrew to access a filter that usually needs to be cleaned out. You don't have to remove the fuel valve from the tank to clean the filter

After you clean the filter, reassemble the fuel valve and test for fuel flow in the Both the RESERVE and FULL or ON positions. If you have good flow there move onto the carb. You have to remove it to clean it properly and it has more hoses and tubes running in and out than the Space Shuttle so make sure to make a drwaing and label each hose or tube of what goes where.

The NU50 has oil injection and an automatic choke called a "ByStarter" that works off heat from the cylinder cooling fins. You should see three hoses coming from the heat sensor element on the right side of the fins going back to the carb. Label these also at the carb end so you know what goes where.

When you remove the carb, check the actual fuel intake where the fuel line connects as that can sometimes be clogged with old varnished gas.

If you need an exploded view of the carb , you can find one at http://www.partsfish.com. You have to register but it's free and then ADD a Motorcycle under HONDA and select NU50 or NU50m from the pull down list. Then select CARB from the exploded parts drawings. Order a Gasket kit for $11.99 while you are there. The bike probably won't run properly unless you replce the rubber "O" rings gaskets.

After cleaning the carb also lube your throttle cable so you don't get a run away throttle when you get it started.

Good luck

Re: Urban Express won't start

A. J. Souza /

Thank you to everyone, again. Especially to Jax184 and Zippy. And, yes, you are correct regarding the confounding array of hoses leading to and coming from carb! Have to admit, it made me more than just pause when I checked it out again. Am already registered at partsfish, so I know about their wealth of schematics. Very helpful. I likely will not be getting to this in the next few days (more?) since I am completing a home renovation and that will take precedence. But, at least because of you guys, I've got a clue as to where to REALLY begin .

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