Spree will not start

[bgirton]

I've got an '86 NQ50 with about 1500 miles on it. At one time, it was running well enough for me to ride to work 20 miles each way, at up to 32 mph, getting about 65 mpg. The only funky thing was warm-up; it often stalled about a mile into the ride, but would restart after a few good kicks. Over time, it gradually lost power, especially on hills, and became more difficult to start when cold. Now it does not start at all.

I spent most of a couple of days working on it. It cranks over vigorously, but does not even sputter. The carburetor is microscopically clean inside, all ports and pathways are clear. Both fuel and oil are reaching the carburetor. The air filter looks clean, and all of the air intake connections seem to be tight. The auto-bystarter warms up and moves when energized. The auto-bystarter and throttle needles appear fine. The throttle adjustment appears to be in factory spec. The ignition seems to be okay; the spark plug shows a bright white spark when the engine is cranked. The reed valves appear normal. All other components appear to be in good condition and functioning normally.

The only other possibility I can think of is loss of compression: maybe the rings are shot or stuck. I don't see any sign of head gasket leakage (although I am not sure what I would see if there were some.) I don't have a compression gauge, and am loathe to purchase one, as I will not likely have use for it again for years. Does anyone have any suggestions for me? I sure would appreciate it. I'm out of ideas.

[kingearwig]

take the plug out and put your thumb over the plug hole. you should not be able to hold the pressure with your finger when you crank the motor over... it should blast your thumb off of the hole. if you can hold the pressure with your thumb then you for sure have lost compression. Not the most accurate way to measure compression but it works if the compression is really weak.

[bgirton]

Thanks for the suggestion, kingearwig. I was not able to keep my thumb pressed tight over the spark plug hole when cranking. I guess I will have to rent, buy, or borrow a compression gauge to completely eliminate compression as a possible cause.

Any other comments or ideas would be most welcome.

[kingearwig]

I think your issue is fuel. Take the airbox off and spray ether directly into the carb with the throttle wide open and see if it will fire at all. my guess is that it will.

The carburetor is microscopically clean inside, all ports and pathways are clear. Both fuel and oil are reaching the carburetor. The air filter looks clean, and all of the air intake connections seem to be tight.

Is there fuel in the bowl?
What is the condition of the float needle and seat?
Are you getting too much fuel?
Is the plug wet?

I've got an '86 NQ50 with about 1500 miles on it. At one time, it was running well enough for me to ride to work 20 miles each way, at up to 32 mph, getting about 65 mpg. The only funky thing was warm-up; it often stalled about a mile into the ride, but would restart after a few good kicks. Over time, it gradually lost power, especially on hills, and became more difficult to start when cold. Now it does not start at all.

Is the plug fouled? Try another one.
When all else fails I generally clean the carb again no matter how "microscopically clean" the carb appears. Put a wire through all orifices and polish the float needle seat again.

[Bear45-70]

NO ETHER!, if you have a back fire you can blow the reeds out of the motor. Get an squirt style oil can and put some gas and oil mix in it and use that as a primer. I agree it is most likely a fuel issue. If it runs with fuel primed thru the intake the it is definately fuel. The old saying still applies, "Clean the carb, clean it again and if necessary clean it again."

[bgirton]

I cleaned the carburetor again and bought a new plug. I was actually putting it back together to try it when a couple of mechanically-inclined youths appeared in my driveway with a pickup truck and $300. I sold it on condition that they not tell me if they got it running.

[Storm]

Ignorance is bliss eh? You should have made them promise to do a repaint so you wouldnt accidentally recpgnise it putting past you on the roads