Pretty in Pink, dunno why
Join Date: Feb 2009
Location: Redondo Beach
Welcome to the forum!
It sounds like it's running out of gas. A quarter mile is about how far you'd get on a carburetor bowl full of gas. After it quits, the fuel trickles into the bowl and it will, I guess, go another quarter mile. Hope I have that right.
There are a couple of things to look at, and they are unusual for a new bike. Logic says you need to look at them, though. Since this problem cropped up right after a service, it would be helpful to know what was done at that service. For example, if valves were adjusted the tank had to come off. That would be a clue.
Let's take them in 'ease of checking' order.
First and foremost, is there plenty of gas in the tank? I'm sure you're familiar with the 'Reserve' position on the petcock, but I have to ask - would switching to reserve cure the problem?
There are some seals in the gas cap that allow the tank to vent, both in and out, yet prevent gas from spilling out when the bike is on its side. Those seals can become stuck and not allow the tank to vent. That prevents gas from getting to the carburetor because a vacuum develops in the tank.
The next time you start the bike, do so with the gas cap open. Go for a ride and see if the sputtering/stalling goes away. If so, the cap needs to be rebuilt. We can help with that.
The petcock on the KLR is vacuum operated. There's a hose that runs from the intake manifold to the back side of the carburetor. If that hose is disconnected no gas will flow. If it is poorly installed there could be a leak that would prevent the petcock from opening fully. Check that the hose is properly installed and in good shape.
The petcock itself should allow a really strong flow of gas to the carburetor if it is working correctly. Disconnect the fuel hose from the petcock and install a longer section of hose, long enough to run into a container set on the floor. Make sure the petcock is turned on and then start the bike, running the bike off of the fuel that has gotten into the bowl (if it won't start, skip to the next test). A good, strong and steady flow should come out of the hose. If it doesn't, then there is something wrong with the vacuum diaphragm on the petcock or there is still something wrong with the vacuum line to the intake manifold.
To test that, remove the vacuum line from the back of the petcock and replace it with one that is a foot long or so. Make sure the petcock is in the 'On' position and have the hose from the previous test installed. Suck on the vacuum line. Fuel should flow from the hose. If it doesn't, the petcock has failed. We can help with fixing that.
Once the fuel gets to from the tank into the bowl, it has to get through the jet and into the engine. There is a carburetor bowl vent that allows atmospheric pressure into the carburetor's bowl and prevents a vacuum from forming (same scenario as the tank). If that vent is kinked or blocked, it won't run very well. The vent line is the pinkish hose that is under the seat. Remove the seat and blow into the line. Don't suck on it. You may not ask me how I know, but if there is gas in that line it don't taste too good. Visually inspect the line from under the seat forward to the elbow on the side of the carburetor to see that there is no visible blockage or kinking. Test the bike.
The fuel gets into the carburetor bowl through a check valve. The floats in the bowl operate that check valve. The valve could be stuck or not opening fully.
On the bottom of the bowl there is a small screw that is a drain. Open that drain to let any gas in the bowl out. Then remove the bowl and inspect the floats (which should be fully dropped) and the valve's needle, which should also be fully dropped. Gently move the floats up and down, feeling for any roughness or binding. I really hope you find the problem before having to go this far. We can help if you're not comfortable with undoing things on the carburetor.
These are the most likely things I can think of, but the problem could be other things.
Let us know what you find and we'll go from there.
Tom [email protected]
“I lit a cigarette and dragged a smoking stand beside the chair. The minutes went by on tiptoe, with their fingers to their lips.”
'How' are words so important they cannot be too often used.”
Sting like a butterfly.
Last edited by Tom Schmitz; 06-02-2015 at 02:22 PM.