CA78 running on one cylinder

garncarz · Post by **garncarz** » Sun Jan 26, 2014 9:49 am

I just replaced the O-rings on both sides of the carb insulator. The bike started instantly and ran for about 5 minutes and then stalled. When I started it up again it was only running on the right cylinder. Removed the left plug - clean but wet with fuel. Looks like I have a good spark on both plugs. I am going to recheck the points but if one side is working they both should be.

Any thoughts on troubleshooting? Thanks in advance.

Hoosier Tom · Post by **Hoosier Tom** » Sun Jan 26, 2014 4:38 pm

Have you checked and or adjusted your valve tappet clearances?

HT

garncarz · Post by **garncarz** » Sun Jan 26, 2014 5:06 pm

Hoosier Tom wrote:Have you checked and or adjusted your valve tappet clearances?

HT

No, I haven't. I am not sure I understand how to tell which "valves are not in the opening stroke....." , per the owners manual. Does anyone have a procedure/walk-though on valve tappet adjustment for the CA77/78?

cadman · Post by **cadman** » Sun Jan 26, 2014 6:29 pm

Valve clearance doesn't happen suddenly - since you were messing around the carb I would check that first. Possible the float in carb was stuck in conjunction with a weak plug or plug wire dumping fuel on to the cylinder. Rotate a few times with the plug out to clear the cylinder. You could try temporarily shutting off the gas when you start. I would also consider trying a new plug - a defective plug will fire outside the cylinder but not when installed.

garncarz · Post by **garncarz** » Sun Jan 26, 2014 6:32 pm

cadman wrote:- a defective plug will fire outside the cylinder but not when installed.

Really!?! I did not know this. I'll replace the plug and give it a try. Thanks for all the help.

Hoosier Tom · Post by **Hoosier Tom** » Sun Jan 26, 2014 11:14 pm

Here are adjustment procedures copied directly from the owner's manual.

http://www.flickr.com/photos/113195568@N08/12165387603/

http://www.flickr.com/photos/113195568@N08/12165834736/

http://www.flickr.com/photos/113195568@N08/12165859246/

HT

garncarz · Post by **garncarz** » Tue Jan 28, 2014 8:07 am

garncarz wrote:
cadman wrote:- a defective plug will fire outside the cylinder but not when installed.
Really!?! I did not know this. I'll replace the plug and give it a try. Thanks for all the help.

Replaced the plug with a new D6HA and now both cylinder fire. Who would have thunk? Thanks. I still neeed to adjust the tappets, though. Thanks for the help.