Urban Express NU50 Fuel Filter trouble

Hadrian Carlsen /

I recently acquired this bike and it has several minor issues but the major one is the fuel filter. The previous owner did some sort of rebuild and it does indeed run like a dream until you put on the fuel filter. Taking its top speed down from around 32 MPH to barely 20 MPH, don't even mention hills. That practically kills the engine.

I'm assuming it's a fuel mixture issue, but I'm not entirely sure how to go about adjusting it, however, I do have a shop manual.

Re: Urban Express NU50 Fuel Filter trouble

Gruff "(OFMC)" - /

sounds like you need a tank, petcock and carb cleaning to me. Check to make sure your gas cap has clear venting (edited)

Re: Urban Express NU50 Fuel Filter trouble

You have fuel flow issues, unless you are mistakenly talking about the AIR filter.

Re: Urban Express NU50 Fuel Filter trouble

Hadrian Carlsen /

Ah crap, I meant the AIR filter not the FUEL filter. My apologies.

Re: Urban Express NU50 Fuel Filter trouble

Hadrian Carlsen /

The engine runs fine with the filter itself, however putting on the cover absolutely kills the engine. It initially revs up pretty high but within a second or two it barely runs unless I let it idle for a bit and breath in more air. I'm a little paranoid for when the rain comes, I don't want the engine sucking in water/mud.

Re: Urban Express NU50 Fuel Filter trouble

If it's starving for air,open the airbox a little.I caan't remember what that airbox looks like,but drilling a coupla half inch holes for more flow should help.don-ohio

Re: Urban Express NU50 Fuel Filter trouble

Does the air filter box contain a plastic retainer grid to keep the filter from being sucked up against the carb air intake as more vacuum is created?

Re: Urban Express NU50 Fuel Filter trouble

It's supposed to.

Re: Urban Express NU50 Fuel Filter trouble

Hadrian Carlsen /

The filter box has a metal retainer to keep the filter pressed up nice and tight against the inlet. I am using a sponge filter so air flow through it shouldn't be to much of a problem, in theory. The frustrating thing with the cover is that it has a lip that goes over the filter box, I was thinking about drilling a few holes in it near the intake but alas I'm still paranoid about the rain, however I'm not sure how justified that fear is. Tomorrow I can take some detailed pictures of what the intake looks like and the box itself.

Re: Urban Express NU50 Fuel Filter trouble

Hadrian Carlsen Wrote:

-------------------------------------------------------

> The filter box has a metal retainer to keep the

> filter pressed up nice and tight against the

> inlet.

The filter should NOT be "pressed up nice and tight against the inlet".

This will limit the volume of air available to the carb.

Re: Urban Express NU50 Fuel Filter trouble

Any updates on this issue?

Re: Urban Express NU50 Fuel Filter trouble

Also sponge flows air VERY badly, and will restrict flow even more causing the bike to be rich. Never just "make" a filter element when it had a specific material to begin with.

Re: Urban Express NU50 Fuel Filter trouble

mike mazzara /

it"s supposed to have a foam filter, I have one and running with no filter made no diff. make sure your intake boot isn"t plugged up, may have a nest in there.

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account