1982 XJ650 Maxim - Sudden cutting out

I've got an '82 650 Maxim, and have been driving it a bit so far this year. However, it will randomly just cut out completely as if the kill switch has been flipped. I have seen this brought up a few times on these threads, but I wanted to know what you guys think.
It does not bog down or sputter to a stop, its not a fuel delivery problem, I am quite sure it is electrical as it just dies instantly.
It idles nicely when running, but it has gotten more frequent in cutting out so I wanted to figure it out.

The video below is my bike idling nicely, then suddenly cutting off.

Youtube Video Showing Stall (stalls out at 1:52)

Here's what I explored so far:
I checked all ground connections, kill switch connection, fuses, other wiring connections. All are clean and look good.
I figured I narrowed it down to the TCI, so I took it apart and had a look at it.

I also read dave_jacks page on the issue

Dave_Jacks Site

This is my TCI out of the bike:

http://imgur.com/yR4N34D


I checked the resistance across everything I could. All resistors are good. The capacitors were a bit different... I know that using an ohm-meter across a capacitor is not exactly the correct way of measuring them, but I did find something interesting.

There are 6 capacitors on the board: (in the middle of the board)
1 x 2.2uf 50V
2 x .47uf 50V
3 x 10uf 25V

All the capacitors measured very high resistance (as you might expect) except for one of the 10uf ones. It measured relatively much lower resistance. I thought this was good to see, since it had two of the exact same to compare to. So that is where I am at right now. I want to swap out that (what I feel is) bad capacitor with a new one.

Does this process make sense to anyone? Am I doing the right thing? It is an old bike and I figure capacitors do go bad/get weak with age.

I am interested in hearing you guys's comments though.

Thanks

 

Personally, I do think you're on the right track. I read the same page (it's also included on the XJCD set), and when the same problem cropped up on my 750, swapping the caps solved the issue.

It's hard to tell from the angle the picture was taken at, but it looked like two of the caps were bulging on top (although that could be a trick of the lighting). If so, then those caps are indeed bad.

In any event, you're obviously familiar with a soldering iron, and the caps themselves are relatively inexpensive, so it couldn't very well hurt to swap them anyway. Touch up all the other solder joints while you're in there just to be on the paranoid side.

 

Pretty sure you are onto it bud.....

 

Bring a 10-Dollar bill to RadioShack.

Buy 6 Brand New Caps.

Use the change you'll get to buy an Iced Coffee and Donut to energize you as you replace every Cap there is on the Board.

WTF

 

link1
link2
link3

sorry i have no faith in radio shack

 

Just as a follow up, because I always like to see the results of forum questions...plus maybe it helps someone else in that same position that happens upon this thread.
Changing out the capacitors completely solved the cutting out issue.
Also I had a bogging down in the rain issue, that was solved by new Dyna Coils, as many others have done.

I was a little hesitant to start ripping apart a circuit board on a hunch since none of the cap's were visually bad, but it seemed to do the trick, thanks all.
-

I do have one more issue that I just noticed though.

If I run the bike with the petcock turned to on (run by the vacuum line), I can run the bike for a while then it pops/backfires a bit, bogs and feels like it runs out of gas. (I am talking many miles before this happens). I switched it to prime, and have not seen this problem again.
I haven't had the chance to check everything out yet since it just started happening, but if anyone has a suggestion, if this is common, I would start there. I'll scour the forum as well in the mean time.

Thanks,

 

I'd take the Key and open the Gas Tank, look in there with a flashlight to see if it just needs some Gas.

When you get to the point where it starts to act like its running out-of-gas, ...

It probably is!!!

 

Pretty awesome that you were able to diagnose that problem. I am EXTREMELY jealous that you can just push the button and the bike starts!! Doesn't need like 5 throttle pulls to get it going

Nice work man!

 

Next time it starts doing this, pop open the gas cap a bit and see if the problem goes away.....if so, your gas cap (internal) vent is clogged, and creating a vacuum inside the tank that won't allow the gas to "drain".