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

Discussion in '2-Stroke Engines' started by RedBaronX, Aug 20, 2010.

  1. RedBaronX

    RedBaronX Member

    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.

  2. Al.Fisherman

    Al.Fisherman Active Member

    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.
    Last edited: Aug 20, 2010
  3. RedBaronX

    RedBaronX Member

    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.
  4. Al.Fisherman

    Al.Fisherman Active Member

    "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.

    Attached Files:

    Last edited: Aug 20, 2010
  5. RedBaronX

    RedBaronX Member

    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.

    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)
  6. GearNut

    GearNut Active Member

    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.
  7. RedBaronX

    RedBaronX Member

    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...
  8. AussieSteve

    AussieSteve Active Member

    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.
  9. RedBaronX

    RedBaronX Member

    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
  10. Al.Fisherman

    Al.Fisherman Active Member

    First test to make sure that the cap is the issue. Follow Steve's lead.
  11. RedBaronX

    RedBaronX Member

    well yes, it might not be the cap at all. Amongst everything else, there is already a good amount of gook in the filter... there could be blockage in the tank itself. I have to empty the tank anyway to fix the leaking fuel cock...

    I guess my question would have been better phrased as "if the problem is that the cap is not vented well enough, can the venting issue be fixed without buying more fuel caps?"
  12. Al.Fisherman

    Al.Fisherman Active Member

    In one short word "YES" but we can address that issue later if it needs it. It has been discussed before.
  13. RdKryton

    RdKryton Active Member

    Whizzer caps don't breath the way they should and they will build up a lot of pressure. I have had to take the center out of the two caps I have and drill a very very small hole in the white plastic piece to solve my problems. Now it does not build up pressure or pull vacuum. I am using one tank on a Whizzer and the other with an EZM Q-Matic with a Harbor Freight engine. I tell you this because the caps caused problems on both setups.

  14. RedBaronX

    RedBaronX Member

    the first time I opened it after riding and saw how much it splattered, I had a feeling the pressure might be a problem.

    I'll do some trials and tests to make sure that the pressure is the problem, but feel free to posts details and/or pictures of what you've done to alleviate pressure problems. I have no desire to go drilling holes into my gas cap unless I really have to
  15. Al.Fisherman

    Al.Fisherman Active Member

    If that happened you will most likely have to first vent your cap, by either drilling a hole and possibly running a tube out of it like a dirt bike, or find a vented cap that will fit. Also I'd bet you will have to go into the carburetor and readjust the float, as the pressure might of bent the float tab. So once the cap is vented be aware of the float situation.
  16. motorpsycho

    motorpsycho Active Member

    If you find that you do have to drill a hole in the cap, just do what i did.
    I built my own gas tank, and i made my own fuel cap. the fuel cap that i used is just a chrome push in oil cap for a car valve cover. ($4.99) I drilled a small hole in the center of the cap for a vent, and then i added a small pewter skull & crossbones to the cap to cover the hole. The eyes in the skull are open and the back of the skull is hollow, this allows the vent hole to still work, while covering it up at the same time.
    keep it simple man, and don't be afraid to think out of the box.
    The pewter skull & cross bones cost me $1.49.

  17. RedBaronX

    RedBaronX Member

    Monday, I had to fix the leak of the less-than-perfect fit of the threads of the fuel cock, and I am still waiting for the gasket maker goop to fully cure (teflon tape was just not enough...) but when I came home from work Tuesday, I was playing with "how closed is closed enough" with the cap, and there is a "step" between the tightening stage and a "locked" stage. When I finally put gas back in the thing, I'll try out these cap positions
  18. Al.Fisherman

    Al.Fisherman Active Member

    Although I'm not a skull and crossbones type of guy, that was very ingenious. Other things can be used, but you had the idea there.
  19. RedBaronX

    RedBaronX Member

    so basically, if the problem IS too much pressure in the tank, the solution is-- drill a small hole in the cap and then fashion some sort of rain cover?

    Wednesday, after fixing the leaking fuel cock on Monday, I finally put fuel back into it. No leak, so that's good, but just opening the fuel cock as well as turning the crank a couple times (while adjusting the clutch control arm) that was enough to build up enough pressure in the tank to make it spatter when I opened the tank again.

    I will do some actual running tests on Sunday when I have the whole day off to play with it, but the signs are pointing more and more towards "too much pressure".

    I've already picked up some JB Weld since I was at the hardware store today anyway, but then it's a matter of picking a "cap"... again, if that IS what the bike needs...

    Suggestions of things that can be found at a hardware store? I'm even thinking just a lock washer, split open further around it's circumference, and then capped with a chunk of flat metal... or an acorn nut...

    and for the actual hole in the cap-- what is the smallest I can go that would still be big enough... would be nice if I can go just as small as "the smallest drill bit you can find"
  20. GearNut

    GearNut Active Member

    If you can find a drill bit sized 1/32" that would be enough. A dinky, teeny hole is all that is necessary.