Electrical Issue 93 EX-500

[Dan Mechanical]

Got a doozy of an electrical issue and I'm wondering if you guys can help me out .

This issue is intermittent, so much of my troubleshooting is meaningless .

One cylinder is not firing. I can tell by the sound, lack of power, and strong gas smell.

The tachometer shows near zero rpms and dances around a bit, even at high rpms.

I have deduced that I have an electrical issue somewhere in my ignition system. To prove that it is not the engine or plugs, I have done the following: Run the engine with spark cable disconnected while the issue was not happening (remember it's intermittent). With either cylinder disabled, I still showed correct RPMs. So... the issue is isolated from these components.

I've done the following electrical troubleshooting steps, but since it's intermittent, they are mostly invalid.

- test 12V to each ignition coil
- test omhs on each ignition coil
- test connection (2 wires) between the ignition coils and the ignition coil igniter
- test connection (4 wires) between the ignition coil igniter and the pickup coil
- test ohms on the pickup coil
- reseat all connections in ignition system
- inspect pickup coil by removing generator case cover

The issue seems to appear when the bike is hot. Once I stop riding, it cools off and the issue goes away, making it hard to diagnose. Because the issue is heat related, I am currently leaning towards a problem with the pickup coil because of its proximity to engine heat. Yes, I measured the correct ohms, but most likely when the issue was not happening.

Any advice? Are there any common shorts to look for? Has anyone seen this issue with the tachometer?

 

[sycophuk]

check the carbs,

 

[Dan Mechanical]

The carbs have recently been cleaned. Also, explain how a carb (or any other combustion level problem) can cause the tach to act up. Like I said, I am not able to reproduce the tach issue even with the spark plugs completely disconnected (one at a time). The tach works off of an electrical signal.

 

[Ironbutt]

It's the pulse coil or the coil... the coil is connected to the tach and if you see the tach drop out it's that coil..

Simple diagnostics.. see if the pulse coil is putting out a pulse.. (test light) while cranking it over.. test the coil(s) and make sure it has 12vDC from the battery.. and then do the resistance test to see if the coils have the correct Resistance..

 

[Dan Mechanical]

It's the pulse coil or the coil... the coil is connected to the tach and if you see the tach drop out it's that coil..

Simple diagnostics.. see if the pulse coil is putting out a pulse.. (test light) while cranking it over.. test the coil(s) and make sure it has 12vDC from the battery.. and then do the resistance test to see if the coils have the correct Resistance..

The bummer thing is that it is intermittent, so I can only reproduce after driving for a while. Maybe I can just drive around with a test light hooked up and see if it stops working . I did the 12v check and the resistance check already, but yeah since it's intermittent of course all the tests pass with flying colors.

 

[Ironbutt]

The bummer thing is that it is intermittent, so I can only reproduce after driving for a while. Maybe I can just drive around with a test light hooked up and see if it stops working . I did the 12v check and the resistance check already, but yeah since it's intermittent of course all the tests pass with flying colors.

Yeah... True...

Here's a funny story; I was working on an old Yamaha Venture Royal with the same symptoms at this shop I worked in Cave Creek, AZ.

I was heating that pulse coil with a heat gun, one of the instructors from MMI, Bruce, pops in the shop for his daily beer :30 visit.

I'm sitting at my lift, and he stands in the garage entrance drinking a beer and asks me like he always does.. " What are you doing? "

"Drying the bikes hair" (laughter)

I say, "I'm trying to reproduce the problem.."

He says..

Does the bike have a heat gun heating that part when your riding it around?" (A lot of laughter from the other mechanics)

So much for not parts swapping..

--------------

It's probably the pulse coil.. Have you snipped and reseated the wires? It might be a plug caps too, they're cheap.. There are no bare wires or even slightly jenky wires?

What you really need is a Bruce to make fun for a minute and then take over and fix the problem in like five minutes.. hahah.. It's not always easy..

 

[Dan Mechanical]

That is exactly what I need actually . I can read the schematic and I can do electricity, but I have no intuition about what it "probably is". I love your heat gun approach, I wonder if a hair dryer would do the trick .

I did, in fact, find some loose connections in the beginning, but I tightened those up, reseated, etc (although I didn't cut the wires and reseat them in the actual connector).

So... I'm hoping that once I get my generator case gasket from bikebandit that I can swap out an ignition coil from a friend's 500R. If that doesn't cut it then I'm going to start driving around with a volt meter attached to various points. The pulse itself seems like it might be hard to measure though, seems like you need a o-scope for that. Just need a good Saturday to get it all going.

 

[Ironbutt]

I meant (unscrew the wires from the cap) cut the plug wires just a little bit and then screw them back into the plug connector thingy.. thoes plug caps can go bad too.. They're cheap... Watch them at night.. .you might see a lightening storm..

That is exactly what I need actually . I can read the schematic and I can do electricity, but I have no intuition about what it "probably is". I love your heat gun approach, I wonder if a hair dryer would do the trick .

I did, in fact, find some loose connections in the beginning, but I tightened those up, reseated, etc (although I didn't cut the wires and reseat them in the actual connector).

So... I'm hoping that once I get my generator case gasket from bikebandit that I can swap out an ignition coil from a friend's 500R. If that doesn't cut it then I'm going to start driving around with a volt meter attached to various points. The pulse itself seems like it might be hard to measure though, seems like you need a o-scope for that. Just need a good Saturday to get it all going.

 

[Dan Mechanical]

I meant (unscrew the wires from the cap) cut the plug wires just a little bit and then screw them back into the plug connector thingy.. thoes plug caps can go bad too.. They're cheap... Watch them at night.. .you might see a lightening storm..

Ah yes, I did do that actually - but just as a test I disconnected one plug at a time to see if I could reproduce the rpm thing and it didn't seem to have an effect. So I've pretty much ruled out anything on the high voltage side of the coil.

 

[Dan Mechanical]

UPDATE: I swapped the ignition coils with a friend's ran the bike for about an hour with no problems. I'm going to leave them in for a few days and ride around to make sure, but it looks like I found it finally.

 

[Drag me & C]

heat

Sorry I jest read this, coils handle a lot of electricity they get hot just like the engine and the problem you describe is the breakdown of resistance once the coil gets hot and expands.

Side NOTE/ For those with charging problems that seem intermittent if you have a stator/rotor charging system odds are once the stator gets hot you are losing continuity on one of the leads as the copper winding expands with heat.

 

[CBRMike83]

Got a doozy of an electrical issue and I'm wondering if you guys can help me out .

This issue is intermittent, so much of my troubleshooting is meaningless .

One cylinder is not firing. I can tell by the sound, lack of power, and strong gas smell.

The tachometer shows near zero rpms and dances around a bit, even at high rpms.

I have deduced that I have an electrical issue somewhere in my ignition system. To prove that it is not the engine or plugs, I have done the following: Run the engine with spark cable disconnected while the issue was not happening (remember it's intermittent). With either cylinder disabled, I still showed correct RPMs. So... the issue is isolated from these components.

I've done the following electrical troubleshooting steps, but since it's intermittent, they are mostly invalid.

- test 12V to each ignition coil
- test omhs on each ignition coil
- test connection (2 wires) between the ignition coils and the ignition coil igniter
- test connection (4 wires) between the ignition coil igniter and the pickup coil
- test ohms on the pickup coil
- reseat all connections in ignition system
- inspect pickup coil by removing generator case cover

The issue seems to appear when the bike is hot. Once I stop riding, it cools off and the issue goes away, making it hard to diagnose. Because the issue is heat related, I am currently leaning towards a problem with the pickup coil because of its proximity to engine heat. Yes, I measured the correct ohms, but most likely when the issue was not happening.

Any advice? Are there any common shorts to look for? Has anyone seen this issue with the tachometer?

20-50 bucks GET A SHORT CIRCUT TESTER ...... prob get it online cuz hardly anyone knows what these are!!!!!!!!
If it is a short it will find it

 

[Dan Mechanical]

20-50 bucks GET A SHORT CIRCUT TESTER ...... prob get it online cuz hardly anyone knows what these are!!!!!!!!
If it is a short it will find it

This sounds pretty cool, but I'm not sure it would help me much. You need a known shorting circuit first. I don't have a short to measure. If I did, I would already have isolated the problem. Know what I mean? Sounds awesome for finding a short in wiring though. Don't know if you saw my last post though. Bike seems be working now that I swapped out the ignition coils.

Sorry I jest read this, coils handle a lot of electricity they get hot just like the engine and the problem you describe is the breakdown of resistance once the coil gets hot and expands.

This is about what I had in mind.

 

[Starshooter10]

i had a similar issue...

it was a bad coil.....