Shortcut Method to Bleeding Oil Injection in Urban Express?

The last time I bled the oil injection system in a Honda Urban Express, I did it the way the manual stated. It wasn't hard but it was messy. I have another Urban Express that is going to need to be bled too since it was sitting for years without any oil in the system at all. The tank and the oil lines were totally dry, so I was thinking... to bleed the oil injection system couldn't you just fill the oil tank up with 2 stroke oil and fill the gas tank with 50:1 premix instead of just normal gasoline, and drive the moped till the injection system pumps all the air bubbles out and starts to just pump pure oil? I would think if I ran the moped through one tank of premix that should be enough to bleed the oil system without having to get my hands dirty. Anything risky or wrong with this method? Or am I missing something here? Thanks in advance

Re: Shortcut Method to Bleeding Oil Injection in Urban Express?

So what if it's a bit messy ? Sex is messy , but , I'll bet you handle that without hesitation .

Just do it right and have no worries . Either one . ;)

Re: Shortcut Method to Bleeding Oil Injection in Urban Express?

Sure, I understand that doing it the way the manual states will work great. I'm just trying to understand for my own knowledge if using my other method has any downsides or not. I can't think of anything for certain, besides getting a bit more oil in the moped for about 100 miles since I'd have premix going through it with some of the oil injection system till it pumps out all the air bubbles, so I'm just trying to see if there is anything technically/functionally wrong with running a tank of premix through it to bleed the oil system automatically. I would think that there may even be a slight benefit to running a tank of premix through with regards to getting all the air bubbles out, but maybe I'm wrong. When I bled the oil injection system myself the proper way, I did end up with one air bubble, so maybe the premix method might be even better? I think about this stuff too much lol.

Re: Shortcut Method to Bleeding Oil Injection in Urban Express?

Better a little too much than not enough oil .

It is an OIL pump , not an air pump .

I can see running a bit of oil in the gas if there's an air bubble in the line , as that can act as a flow blockage . But , there shouldn't be an air bubble , if the bleed was done correctly .

I would not try pumping air with an oil pump .

Very likely the exact reason the factory was wise enough to build a bleeder into the pump .

Re: Shortcut Method to Bleeding Oil Injection in Urban Express?

Thanks for the reply, that makes more sense to me. An oil pump may not have the specific tolerances to pump air bubbles out, but can obviously pump oil since that is what it was made for. Good point. You mentioned that there is a bleeder on the oil pump. I did not originally see a bleeder anywhere in the manual when I did the process the first time. I looked at the manual again and I realize I overlooked a step in the bleeding process originally. Are you referring to the oil control lever that you hold open only while the engine is running to bleed the system?

Re: Shortcut Method to Bleeding Oil Injection in Urban Express?

> Amodo Ko Wrote:

> -------------------------------------------------------

> Are you referring to the oil control lever

> that you hold open only while the engine is running to bleed the system?

Sorry for misleading you .

I just did a short study of the urban oil pump .

It doesn't have a bleed outlet , other than the inlet and outlet nipples/ports .

Most oil pumps I've worked with have a bleed screw .

Anyway , the procedure in the service manual seems as effective , albeit , a bit more involved .

Maybe this would work :

Leaving the line connected to the oil tank , disconnect the line from the carb , while leaving both lines connected to the pump . Then lightly pressurize the oil tank while holding the pump control lever at the full open position . Continue that until no bubbles are present in either of the lines . Then reconnect the line to the carb while its oozing oil .

Catch the oil in a bowl or some such .

Seems to me that pushing oil through the entire 'system' would accomplish no air bubbles in a less messy way , with a bit less work .

If that doesn't work , you're left with the procedure in the manual .

Please post which method you used and your results . (edited)

Re: Shortcut Method to Bleeding Oil Injection in Urban Express?

Ok, I will try out your method to see how it goes. Definitely seems easier than the method in the manual. One question though, when you say to "lightly pressurize the oil tank," do you mean to fill the oil tank with oil? Or are you referring to pressurizing the oil tank in some other way?

Re: Shortcut Method to Bleeding Oil Injection in Urban Express?

Of course there has to be oil in the tank .

Just add a little air pressure to the tank when you're ready .

Use your imagination . ;)

Re: Shortcut Method to Bleeding Oil Injection in Urban Express?

I had to do it, I really wanted to try out my premix idea so I thought I'd give it a shot first. I realized the previous owner had installed an improperly fitting oil inlet line, so I replaced that with a clear oil line and while doing that I also checked the port on the oil pump and the port had oil in it so I'm assuming the oil pump was full. I then installed the new clear oil inlet line and left the old oil outlet line alone. The oil outlet line obviously had air bubbles in it since I did not attempt to do anything with it. So I then made sure I had premix in the gas tank and fired the moped up and held the oil control lever open while it was idling. After a second or two or holding the oil control lever open, there were no more bubbles in the oil outlet line (and none in the inlet line, although the inlet line never had any anyways). I'm going to be running premix in the moped for a while anyways and will periodically check the lines, but I think the oil injection system is essentially bled now since I don't visually see any bubbles in either the oil inlet or outlet lines. If I did it the way the manual states, I find that filling the oil outlet line with an oil squirt can is a tad more cumbersome than I like due to the limited space in that area. And the manual obviously tells Urban Express owners to do that because if they just run pure gasoline in the gas tank but have air bubbles in the oil lines, they can starve the engine of oil for sure. So I'm not recommending my premix method obviously, but as of now it at least seems to be working fine. I'll have to check it for a while to see if any new air bubbles form or anything, but I definitely prefer doing it this way over the manual's method.

Re: Shortcut Method to Bleeding Oil Injection in Urban Express?

Cool that it worked, seemed logical that it would, I would not run the pre-mix too long for fear of fouling the plug and coking up the exhaust. One tank or even half a tank should be more than enough.

Re: Shortcut Method to Bleeding Oil Injection in Urban Express?

I agree, I wouldn't want to run more than one tank like that through it. Having a tank of premix in there will give me some time to see if the oil injection system is working properly too, since this moped has not been run in years and at least now I can check to see if the injection system is operational. As of now it seems to be working, but I'll have to check the oil levels in the oil tank to see if they're going down over time to be sure

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