Honda Twins banner
1 - 11 of 11 Posts

·
Registered
Joined
·
74 Posts
Discussion Starter · #1 ·
What is the best way to test for spark on a 71 cb350. I hooked my timing light up and put the pickup on a plug wire an got no strobe at all. Does that mean no spark??? I'm not super knowledgeable about these old ignition systems considering this bike was built 9 years before I was born. Guess that's what makes them so cool!
 

·
Premium Member
Joined
·
667 Posts
I would think so as long as you had the timing light hooked up correctly. It needs to be hooked to the battery also to work. Another way to check for spark is to put a plug in the plug cap and lay it on the engine to ground it and then kick the bike. Make sure the key is on and the kill switch is on as well.
Don
 

·
Registered
Joined
·
74 Posts
Discussion Starter · #3 ·
Yeah, unfurtunately I tried that. The timing light was hooked up properly and I even took it over to my car and hooked it up just to make sure the bulb was functioning. I did pull the plug wire and tried to get it to spark to the head. Yesterday I had an issue with a leaky petcock, so today I pulled the tank and changed it out, including new fuel lines. I also installed the quick disconnect for a battery tender. I must have done something, but I can't see any wire that disconnected or came apart? I don't know. Maybe it's the fact that I live in Cleveland. Can't win a championship, Lebron left, and I have no spark. :D

 

·
Premium Member
Joined
·
2,386 Posts
Trying to kick the bike while looking for a light on a timing light can be tough. Sometimes it tough to see the spark at the plug while kicking it over too.

I've found the easiest way is take the point cover off and make sue the left point is closed. Remove the plug and connect it to the plug wire then ground it to the side of the cylinder. while holding the plug against the cylinder, use your finger and manually open the left point and watch for a spark at the plug. In this manner the bike isn't shaking and your not trying to do multiple things while looking for a little blue spark. You can open and close the point this way multiple times in succession to look for consistent spark too.
 

·
Registered
Joined
·
74 Posts
Discussion Starter · #5 ·
I was using the electric starter to turn the engine. I will have to try what you said tomorrow. Unfortunately I have a stack of papers to grade tonight. The joys of being a teacher. :) I'm sure i bumped or unhooked something. I think it is one of those things where I'm frustrated and need to set it aside until tomorrow. I checked for spark with the timing light on both plug wires so its got to be the igniion circuit somewhere. Both coils don't go bad at the same time, rigt? Anyway, any advice would be greatly appreciated.
 

·
Premium Member
Joined
·
2,386 Posts
dougqt said:
I was using the electric starter to turn the engine. I will have to try what you said tomorrow. Unfortunately I have a stack of papers to grade tonight. The joys of being a teacher. :) I'm sure i bumped or unhooked something. I think it is one of those things where I'm frustrated and need to set it aside until tomorrow. I checked for spark with the timing light on both plug wires so its got to be the igniion circuit somewhere. Both coils don't go bad at the same time, rigt? Anyway, any advice would be greatly appreciated.
If you've got no spark using the method I suggested then check, using a multimeter, to make sure you have 12v at wire that connects to the point when the key is turned on. Based on what you find there will give us the next step.
 

·
Sensei
Joined
·
27,180 Posts
I'd almost bet you bumped the 'kill' switch....
 

·
Registered
Joined
·
74 Posts
Discussion Starter · #8 ·
That is my guess too. After thinking about it last night, I remember as I was sliding the tank in it caught the wiring harness and I'm wondering if it tugged on it enough to disconnect the kill switch at that bullet connector in the headlight bucket. It's got to be something simple like that. ;)
 

·
Registered
Joined
·
74 Posts
Discussion Starter · #9 ·
Ok, i put a multi meter on and i am getting 12v at the points with the engine swith on an 0.0v win it off. What is my next move? I still see no spark from the plug wire to the head and get no reading with my timing light.
 

·
Premium Member
Joined
·
617 Posts
check the surface of your breaker points.. I was getting no spark on a bike I was working on last week and had to get after the points with a file like a madman.

With the coils powered up, and a new spark plug installed and hooked up to the wire, open and close the points with a plastic wedge or something not metal.. it should spark readily each time you open the points.

If it isn't, you have a short to ground or your points are not conducting electricity right due to being gunked up. They'll pit and deteriorate sometime even when they sort of look like they should be working right.

Even if your condenser is bad, the points should still spark (and the plug should still fire.)

I just swapped coils out on my CB350 for another old set because there was conductivity issues in the plug wires.. this really solved my headaches.
 

·
Registered
Joined
·
608 Posts
read the "How to Use a Timing Gun" post you might have the pick-up clamp facing the wrong way
 
1 - 11 of 11 Posts
Top