bike still won't run, and I'm going nuts... HELP!

RedBaronX

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Poops out after 15 min: Opinions?

OK... I got my new MB running for the first time yesterday after LOTS of pedaling and silent cursing. I have ridden it twice today, but each time was no more than about 15 minutes, because after that, it poops out.

I prime the carb with five or six pumps (less and it will not start). Idle screw is all the way in or else it won't idle at all. This morning's ride, it was idling pretty good. This afternoon, not so much.

It won't start with the choke closed like what is recommended for starting it.

I do have a fuel leak at the fuel cock. It's a slow leak, but bits and pieces do get wet.

It doesn't seem like fuel is flowing that well-- when I went to ride it this afternoon, the filter was full of gas, but by the time it pooped out, the filter was not very full and I couldn't get more to flow into it. Could there be too much pressure in the tank which is keeping fuel from flowing?

What should I be looking for? Any guesses on why it's pooping out after about 15 min? Yes, I am still in the initial break in period and I shouldn't ride for long periods, but it's pooping out because something isn't right.
 
I'm going to "ASSUME" you are working on a HT...right? First, cut fuel off at tank, remove fuel line from the carburetor. Take a small container, insert hose and open the fuel valve. The valve handle will be inline with the hose when open. Check for flow..remove gas cap check for flow. If you don't have good flow, remove the cut off valve from the tank and check for trash both on the filter screen and in the tank. This seems to be a common issue. These tanks are vented, if pressurized the fuel would flow faster.
 
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yup, HT.

the tank and cock are not HT stock, though. It's Whizzer. The lever is marked "C" and "R" and are 180 degrees away from each other. . "C" is definitely "closed", but it was in the "R" position when I first added oil and the oil flowed into the filter... so I've been assuming that "R" is open, though I don't know what "R" stands for.

When I take off the cap, there is enough pressure in the tank to make the fuel splatter out a bit even when I open it carefully.
 
yup, HT.

the tank and cock are not HT stock, though. It's Whizzer. The lever is marked "C" and "R" and are 180 degrees away from each other. . "C" is definitely "closed", but it was in the "R" position when I first added oil and the oil flowed into the filter... so I've been assuming that "R" is open, though I don't know what "R" stands for.

When I take off the cap, there is enough pressure in the tank to make the fuel splatter out a bit even when I open it carefully.

"R" most likely Reserve, these carburetors need a tank that is vented. Non vented can create a suction and inhibit fuel flow. Always mix oil to fuel in a different container then the tank. Remove hose so fuel can flow, move lever into different positions and observe the fuel flow.

So your cruising down the freeway and all the sudden your motorcycle starts to lose power. Its still chugging chugging chuggin along until finally you are forced to pull over and the motorcycle dies. We have ALL been there before, and the lucky ones of us know that its a simple problem of flipping the fuel tank petcock, but for the new rider it can be very confusing and intimidating.

Since most motorcycles do not have fuel gauges the kind engineers that designed our bikes decided to include a reserve fuel tank inside the main fuel tank. That way you don't have to keep opening your gas tank every time you go out to see how much fuel you have left. Basically the reserve switch for most bikes I have been on will be right below the gas tank/seat area either on the right or left hand side. It will be a little flip that usually says "On, Off, and Reserve" or something like that. This little switch is called the Fuel Petcock, the "on" position is what it should be set to when you are regularly using your motorcycle. If your motorcycle dies on you like in the above situation the first thing you should do is flip it to the Reserve position and see if that fixes things, which it will if its a fuel problem. The Off position should only be used when the motorcycle is going to be sitting unused for a very long time, like in the winter for storage.
 

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I actually just uploaded some pictures to my facebook account, including this one which shows what the petcock looks like. The lever is in the "R" position right now, with "C" being 180 degrees away.

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs304.snc4/40562_456049091150_500921150_6849848_7439363_n.jpg

so... down is always "on"? we are about to get big thunderstorms, so I won't be working on it at all again today. I know people ride these in the rain sometimes, so I'm going to have to hope for the best that it's going to be safe sitting in the rain (I have no cover yet)
 
If your tank is getting pressurized that is not good either. These carburetors run on a gravity fed principal. The float valve is not designed to deal with a pressurized input such as what is found in a car or some motorcycles.
The next time the engine acts up, crack the cap, wait a minute, then try to start the engine again. Do not ride with the cap loosened though. That is asking for a potentially painful mess.
 
If your tank is getting pressurized that is not good either. These carburetors run on a gravity fed principal. The float valve is not designed to deal with a pressurized input such as what is found in a car or some motorcycles.

which is why I mentioned that there is pressure in there...

I had just assumed that the "R" position was the "on" position because when I put straight oil in and the oil went into the filter, the valve was in the "R" position.

When I empty the tank, I'll have a chance to play with the valve positions. I have to fix the leaking fuel cock anyway. Teflon tape was just not good enough, so on to gasket goop... and yes I was using gas-resistant tape. I didn't know it existed until I couldn't find my plumbers' tape and had to buy more anyway... and there it was in all it's yellow glory...
 
I agree with Gearnut. It sounds very much like you're getting a vapour lock from a badly vented cap.
When it starts to die, stop quickly then open the cap and see if the engine suddenly picks up.
 
I agree with Gearnut. It sounds very much like you're getting a vapour lock from a badly vented cap.
When it starts to die, stop quickly then open the cap and see if the engine suddenly picks up.

hmmm... so what do I do about a poorly vented cap?

The tank is a Whizzer tank, and I would have assumed that fuel for them is also gravity-fed (or else why would there be an on/off fuel cock?) Obviously I could be wrong about that...

I'm unfortunately not going to have the time to really look at anything until Monday
 
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