Motorcycle Repair: 1981 CB750 Custom, petcock, steady stream
Question
right
I recently bought a 1981 CB750 Custom. The speedometer says there is just less than 20,000 miles on the engine. The bike is getting started easily, but the right two cylinders are not pumping. The right two exhausts pipes aren’t even warming up and when the bike continues to run for a few moments it sounds like the right side sputters and then the bike will just die. I’m unsure were to begin resolving this problem. What would you suggest?
AnswerConor, you have to figure out if it's not getting spark or not getting fuel. I'm assuming the engine has good compression but if you aren't sure, it would be good to check it. You can pull the right two plugs and lay them up against the head while you crank the engine. You can see if the plugs spark.
Next try turning off the fuel and opening up the float drains and make sure you have a good steady stream of fuel coming out. It will take a couple of minutes to drain all the fuel out. Once it stops flowing you can open the petcock and make sure the fuel has a full steady stream. If it does, it may just require a carb cleaning to get the cylinders firing.
Regards
Rich
