Won't start

[Mike Horton]

Picked up my bike ( 1973 Jackpiner with Bing)today at Forward Air in SF. The bike looks great and is in excellant mechanical shape. The only problem is that I can't get it to start. If you let it set for awhile it will hit and run for about a second. After that nothing. I checked the plug and it was dry. If you continue to kick start, gas appears below the carb on the crankcase top. Let it set again and it will run again the same as before. I have tried the choke in all positions, doesn't seem to matter. Not giving it any throttle at start . Since all the gas was drained for shipment, could the float be stuck or the needle jet ?? Any ideas and how to go about it. I am a novice - its been 30 years.

Thanks Mike

[hrbay]

Mike, it sounds like the gas flow is intermittant, as you suspect,  consider pulling the bowl and cleaning the needle jet and bore. Good luck on the nice find.

GC

[tmc3c]

Hi Mike,Try taking your gas cap off when it is sitting there running. Keep us up to date on the results.

Thomas Carmichael

[cubfan1968]

Get in to the "Search the message board" section. Type in "Won't stay running" You'll get my post. I got a lot of great information, used it like a laundry list. Now the bike runs pretty good. Alot of knowledge in this group.

Rod Whitman

[Doug Wilford]

Mike;
It sounds like the choke is on.   The choke is in the slide and has to be held up to be off.  The lever on the handlebar should be at a 90 degree or back  or down so you are holding the choke open.   Good luck.  and have fun.

[Mark Annan]

It could also be your ignition.  I had a bike exhibit the same problem.  Did all the usual checks.  I'd get a spark if I pulled the plug and gave the motor a swift kick.  But, the bike would only run for a few seconds then shut off.  I finally figured out it was the motoplat dieing.  Pull the sparkplug out.  Put a known good plug in the plug wire and then ground the plug to the motor (I clamped it onto a cylinder fin with a vice grip).  Then put the bike in gear and push it a ways.  I bet you'll see a good spark at the beginning and then it will fade away and quit.

Mark

[cardojr]

mike-check the basics first (air-fuel-spark).
1) air is pretty easy-also check your compression (rings) and your case seals -a cold engine may start, then puke when it heats. lastly, check that the horn toads haven't nested in your pipe and filled it up with stuff.air flowage is good.

2)fuel -start with good gas- remove the carb and pop the bottom off to access the jets-often poor starting is related to a plugged pilot jet. check the gas flow to the carb and verify that the float floats (more a problem with brass than plastic). finally check your choke assy  and carb slide for smooth movement. on bikes that have been languishing the answer is clean,clean,clean. what happens when you throw a shot of fuel down the plug hole and then kick it over-this may tell you a lot about the system

3)motoplat electonics are always suspect. Mark is right on with the test. I use a briggs and stratton ignition tester in place of the vise grips. it clips on the cylinder and has a view window to see the spark-if the spark jumps the electrodes in the tester then it should fire. do the push test out of the sun & preferably on a hill.
also check all electrical connections,the kill switch and the 'plat timing. blowback from the carb is often a sign of a weak or poorly timed ignition.

this should give you a start. follow-up to the basics is always a quick top end check of rings and piston skirts.
good luck--rob