CB 360 problems

Nathan Hampton · 08-09-2011, 10:01 PM

My 74 CB360 is showing 60 psi on the left cylinder and 130 on the right when the throttle isn't opened, and 150 on both when it is opened. The bike starts and idles very well, but the left cylinder cuts out when the engine is revved. The guy I bough it from said that the points were probably bad. Any help is greatly appreciated.

slumlord · 08-10-2011, 10:24 AM

google the above and you will surely come up with dan's motorcycle repair course.
Find the section on engines and topic 73 and 76 deal with compression and compression leak testing. After you have concluded the testing,you should know if your compression problem is caused by the rings, intake valve,or exhaust valve should be revealed by the leak down test
I really like dan's site as it is advice that is easy to understand.

Nathan Hampton · 08-10-2011, 02:03 PM

Thanks for the link. I do not have the tools necessary to do a leak down test. I put my hand over the carbs to see if they were creating suction, the right carb felt good, but the left carb had no suction until I gave it throttle. Also, I sprayed gas into the left carb while it was running, but there was no effect. Am I looking at valve problems? It doesn't backfire but it does pop from the left pipe.
I'm hoping there might be an easy fix. I really don't feel like taking the head off. I guess I should have considered that before I bought a motorcycle for 300 dollars at a yard sale.

LWRider · 08-12-2011, 09:50 AM

First thing I would do is set the valves correctly, then do another compression test. Adjusting the valves is pretty simple.

Cheers,

Mike

slumlord · 08-15-2011, 07:58 PM

Put a teaspoon of oil in the 60 PSI side. If the compression stays up,then you are talking about a ring problem.
Look around on Dans some more. That place is full of how to diagnose problems without using expensive tools.

08-09-2011, 10:01 PM	#1
Nathan Hampton Newbie Join Date: Feb 2011 Posts: 5	CB 360 problems My 74 CB360 is showing 60 psi on the left cylinder and 130 on the right when the throttle isn't opened, and 150 on both when it is opened. The bike starts and idles very well, but the left cylinder cuts out when the engine is revved. The guy I bough it from said that the points were probably bad. Any help is greatly appreciated.

08-10-2011, 10:24 AM	#2
slumlord Senior Member Join Date: Dec 2008 Posts: 1,548	dansmc google the above and you will surely come up with dan's motorcycle repair course. Find the section on engines and topic 73 and 76 deal with compression and compression leak testing. After you have concluded the testing,you should know if your compression problem is caused by the rings, intake valve,or exhaust valve should be revealed by the leak down test I really like dan's site as it is advice that is easy to understand. __________________ Pull off the Band-Aid. Eat our peas. Just do it.

08-12-2011, 09:50 AM	#4
LWRider Challenged Mechanic Join Date: May 2009 Location: Lake Wales, FL Posts: 2,344	First thing I would do is set the valves correctly, then do another compression test. Adjusting the valves is pretty simple. Cheers, Mike __________________ To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

08-15-2011, 07:58 PM	#5
slumlord Senior Member Join Date: Dec 2008 Posts: 1,548	Put a teaspoon of oil in the 60 PSI side. If the compression stays up,then you are talking about a ring problem. Look around on Dans some more. That place is full of how to diagnose problems without using expensive tools. __________________ Pull off the Band-Aid. Eat our peas. Just do it.

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08-10-2011, 02:03 PM	#3
Nathan Hampton Newbie Join Date: Feb 2011 Posts: 5	Thanks for the link. I do not have the tools necessary to do a leak down test. I put my hand over the carbs to see if they were creating suction, the right carb felt good, but the left carb had no suction until I gave it throttle. Also, I sprayed gas into the left carb while it was running, but there was no effect. Am I looking at valve problems? It doesn't backfire but it does pop from the left pipe. I'm hoping there might be an easy fix. I really don't feel like taking the head off. I guess I should have considered that before I bought a motorcycle for 300 dollars at a yard sale.