please help me

[realgraverobber]

Problem with my 1984 Spree, in great shape.

Once I start it, it will go about 40 feet and start bogging. Initially a slight bog, and will get worse and eventually kill the engine UNLESS I let it idle for 10 seconds or so -- then it will perform fine for another 40 feet.

Sometimes if I hold throttle at 1/4 or 1/3 open it will run fine and get around until an incline occurs then it'll not go up the hill, bog, etc (see above).

I have done the following with NO results:
changed the:
vacuum-operated fuel valve on the tank
fuel filter in the gas tank (white plastic one)
fuel lines
cleaned the carb twice
unplugged the electric choke thing and had no change, plugged it back in
adjusted the air screw for the idle circuit (willing to try any ideas now)
cleaned the spark plug
new gasoline

Note:
-battery is dead as heck, I use jumper cables to start the Spree (will but a new battery once it proves itself as reliable.
-didn't gap the spark plug, assuming it would be close enough to work. Waiting for 10 seconds allows Spree to work perfectly, until 40 feet later.
-Took an old fuel petcock and drilled it out, allowing fuel to free-flow through into the carb, plugged vacuum lines for this try.
-Ran the bike with no fuel cap to check for a vent-into-fuel-tank cause. no change happened.
-When the current battery was new this bike did the exact same thing.

I want to keep this bike, please lend your advice!

ANY IDEAS? Running out of time on this one.

[Kenny_McCormic]

Check bystarter for proper operation, I bet its jammed open and your running rich once it warms up.

[realgraverobber]

Good idea! When I take the bystarter out of the carb, the tapered inner (?) part should be able to move freely.

I hope this works. This is the only part (the bystarter) that I DIDN'T CLEAN, and the bike did have some gunky fuel in it for longtime.

Hope this works. If it doesn't this bike is history (nice 84 Spree with 3,000 miles total).

[Clivester]

Don't try forcing the parts on the bystarter to check it - you could damage it. Attach the contacts to a twelve volt battery. After 5 minutes the tip should extend a few mm. You'll need to measure the distance with a rule before and after because its not easy to see.

What is the compression on your cylinder?

Clive.

[Clivester]

By the way, if you remove the bystarter on a nicely tuned bike it will run like crap unless you block the hole. That makes me suspicious that the bystarter passages may not be as clean as they should be.

Any clues as to the fuel mixture condition from the color of the plug?

Clive.