Hello everyone, and thanks in advance for any advice you may have...
I have a 1979 Kawasaki 440 Intruder, engine was recently rebuilt (three years ago). Ran great all last season and this season, up until now.
After running for about 20min at normal trail speeds (not more than 50mph, usually more like 30-40), the engine will start to bog severely, to the point of sputtering and sometimes even quitting. In the midst of the bogging (as I am working the throttle to keep it going), it will surge dramatically for an instant, and then continue bogging. If it quits, it won't start for a few minutes, then will run fine for about 5-10minutes before doing the same thing. If I stop and let it idle for about 5 minutes, it will, again, run fine for a few minutes before bogging/bucking again. This just started happening -- there was nothing unusual about performance until this suddenly started happening.
At first I thought "fouled plugs?" -- I pulled the plugs and they are dry and a nice brown color. With the plugs out, I checked compression, which measures ~160. So now I'm suspecting a fuel flow problem -- it seems as if it is running out of fuel. This one doesn't have a fuel filter, otherwise I'd suspect a clogged filter... Sludge in the fuel tank, clogging the pickup (tank was flushed when engine was rebuilt)? Bad fuel pump? Sticking fuel inlet needle/float arm/floats in the carb (carbs were overhauled with engine...)? Has anyone experienced this, and suggest a good place to start?
Let me know.