Elusive electrical problems (solved)

[Bjorn]

Hehe you guys dont miss anything. Dont worry, this was just an impression photo. The rubber plugs are in there .

I see you're using a Honda MP08 coil? Those are supposed to be very dependable, but shit happens, lol. Bring a spare spark plug along on your next test run. If the bike quits, stick the spare plug in one of the plug caps, ground it on the motor cooling fins and check for spark. That should point you towards electrical (possible coil failure) or fuel issues.

When you say ''dependable'' what are you referring to? I bought these coil are they were recommended here on the forum...

 

[5twins]

By dependable, I was referring to that coil. Several guys here have used them with good results. I plan on trying one myself eventually. It will allow me to install new silicone plug wires. The '80-on stock TCI coil has the plug wires molded in and they can't be replaced.

 

[Bjorn]

Dependable on input voltage you mean? O talking about plug wires, I also got some new ones for that. Just to be sure...and they are not that expensive.

 

[mrtwowheel]

That MP08 Honda coil has a good reputation for being reliable. The Honda coil that was used before the MP08 has earned a bad reputation. It has become common practice to replace the earlier Honda coils with the MP08's for TCI ignitions. With points the MP08 can be used with (or sometimes without) a ballast resistor.

Scott

 

[Bjorn]

Hi Scott, what is this resistor? And should I use one? My coil is gets the inpit without an resistor...

 

[5twins]

No, you don't need or want a resistor on your coil. That is only used if you have a points ignition. It raises the primary resistance on the coil from 2.5 or 3 up to 4 or 5. A 2.5 to 3 ohm coil will burn up points quickly.

 

[mrtwowheel]

Yep, listen to 5twins, follow his advice.

Scott

 

[Bjorn]

The hardest electrical issues to solve are..................................fuel issues....

Last weekend i worked on the bike together with a friend. We replaced the old vacuum petcock with a manual one. After messing with the fuel routing and a leaking 90° elbow we finally found a routing straight to the T of the carbs. The next day we did a test ride, the weather was cold but the bike worked perfect for 30 kms. At that moment i still suspected the coil and thought that the cold weather made it work longer. So i decided to do some additional highway riding. After a few kms on the highway the bike started to misfire, sputter and within half a km die. I managed to make it to the nearest exit. We looked an the fuelfilter.......it was dry... Could it be that simple? We flipped to reserve and within seconds I could restart the bike and drive off again.

I believe that my efforts aimed on the electrical issues have worked (new ground wires, additional grounds, new coil). However my focus has always been on the electrical side, making me blind for signals relating to fuel. I even believe that the last two times i stranded, it could very likely have been solved by switching to reserve. The fact that the bike seemed to die after 10kms of riding could just be a coincidence. since i never topped off the fuel tank (because i needed to take it off all the time) and never paid much attention to the fuel level. Funny how the brain works

Last Sunday I did another 100 kms without any issues. Im super happy the bike is working again. Thanks everybody for the help, couldn't have done it without you guys!

 

[MaxPete]

Excellent! Don’t beat yourself up Björn - I’m sure we’ve all had those forehead bangers in our day. I always recall my old auto shop teacher telling us that an engine needs three things to start and run:

• SPIN (it must turn over reliably)
• SPARK (the spark must be strong, reliable and properly timed)
• SPIRIT (the must be fuel and it must get to the spark).

It is perhaps a bit simplistic, but keeping those three S’s in mind has saved my bacon a few times.

Pete