I’ve been desperately trying to troubleshoot my 650’s performance issues for the better part of a week now. I go the bike tuned and running great for a couple of days. It starts fine, idles decent but all of the sudden it has started sputtering out at 3k RPM every time. No matter how rich or lean the mixture is it starts to die right at 3k. Just to be safe I rebuilt and thoroughly cleaned the carbs (twice), and put on a new fuel hose so I don’t thinks its either of those. Tested ignition coils, spark plugs, spark plug wires and caps, battery, pulse generator, reg/rec and everything is within specs. I did check the timing however (I’ve never done that before) with a light gun and it showed that the “f” mark was just a little bit behind where the indicator arrow was on the casing. So then I start trying to figure out how to adjust the timing on this bike only to discover I can’t! Apparently this is all controlled by the “Spark Unit” box (some have called it a CDI but I don’t think its a true CDI)?? But just to make things even more interesting....apparently there is no way to test the spark unit. Can anyone confirm that a bad spark unit would cause this kind of performance issue? It’s honestly the only thing left that I think could be the problem unless I’m missing something.
1984 CB650 PERFORMANCE ISSUES
- Thread starter tdphoto
- Start date
Thanks for the reply!
It revs seemingly fine while on the stand in neutral. No sputtering at all.
It's only when I'm actually riding under load that it does this. Do you still think the spark unit could be the culprit?
Also...I was watching the digital tach I have on the bike while letting it idle and I noticed it jumping from 1040 to 1210 very erratically. Is this normal? I've never had a digital tach so not sure.
I'm in Wichita KS and I'm guessing you live anywhere but here because why in the world would anyone live in Kansas that loves to ride lol.
Thanks again for the help.
It revs seemingly fine while on the stand in neutral. No sputtering at all.
It's only when I'm actually riding under load that it does this. Do you still think the spark unit could be the culprit?
Also...I was watching the digital tach I have on the bike while letting it idle and I noticed it jumping from 1040 to 1210 very erratically. Is this normal? I've never had a digital tach so not sure.
I'm in Wichita KS and I'm guessing you live anywhere but here because why in the world would anyone live in Kansas that loves to ride lol.
Thanks again for the help.
