salfter
New Member
I've run into a bit of a performance problem with my project. It runs strong for 5-6 miles, but then it starts bogging down and surging. Twisting the throttle doesn't cause it to speed up like it should...sometimes, letting off on the throttle a bit causes it to surge and pick up a little bit of speed. It starts out having no trouble moving along at 20-25 mph, but then it has trouble just limping along at 10. After a check ride today, when I got home and lifted the rear wheel up for a no-load test, it exhibited the same behavior: instead of revving all the way up to speed, it'll go so far and no further. It even stalled out on me.
Adjusting the screw on the side of the carburetor has made no difference. Remounting the engine so it's closer to level (can't get it completely level in this frame) has made no difference. Sealer on the gaskets between the carburetor and the intake port has made no difference. Removing the sheet metal around the cylinder so the engine might run cooler has made no difference.
My daily commute is going to be about 10 miles each way, so getting only halfway there before running into these problems isn't going to cut it. There are a couple of things I haven't tried yet:
1) I've never pulled the spark plug. Once the engine cools down, I'm going to pull it and see what it tells me about how the engine is running. In the meantime, is there something that could be happening with the spark plug (or the rest of the ignition system) that would cause this problem?
2) The fuel line that came with the engine kit was 1/4" i/d vinyl tubing, not much different than I would use to move fluids around when making beer. The hose barb on the carb was 3/16", so I had to add some additional tubing and fittings in between to neck down from 1/4" to 3/16". There are sometimes air bubbles in the fuel line; could this be causing fuel starvation? Also, the clear tubing seems to change translucent after a short time, which would indicate that the gasoline is reacting with it. I'm guessing that a switch to rubber fuel line would be a Good Thing.
Is there anything else that I'm missing? How do I get this thing running right so it's at least a mostly reliable commuter?
Adjusting the screw on the side of the carburetor has made no difference. Remounting the engine so it's closer to level (can't get it completely level in this frame) has made no difference. Sealer on the gaskets between the carburetor and the intake port has made no difference. Removing the sheet metal around the cylinder so the engine might run cooler has made no difference.
My daily commute is going to be about 10 miles each way, so getting only halfway there before running into these problems isn't going to cut it. There are a couple of things I haven't tried yet:
1) I've never pulled the spark plug. Once the engine cools down, I'm going to pull it and see what it tells me about how the engine is running. In the meantime, is there something that could be happening with the spark plug (or the rest of the ignition system) that would cause this problem?
2) The fuel line that came with the engine kit was 1/4" i/d vinyl tubing, not much different than I would use to move fluids around when making beer. The hose barb on the carb was 3/16", so I had to add some additional tubing and fittings in between to neck down from 1/4" to 3/16". There are sometimes air bubbles in the fuel line; could this be causing fuel starvation? Also, the clear tubing seems to change translucent after a short time, which would indicate that the gasoline is reacting with it. I'm guessing that a switch to rubber fuel line would be a Good Thing.
Is there anything else that I'm missing? How do I get this thing running right so it's at least a mostly reliable commuter?