79F lost power in a puff of smoke and died..POLL!

[Snow]

So the other day I was riding home (hottest day of the year so far, was around 100F) and got to my road when I started losing power as if I was running out of gas and then she completely stall in a puff of smoke. I look down and there is some smoke coming out of my airbox area also. Smoke all looked pretty dark I believe.

The night it happened, I was also trying to re-fix my pickup coil wires... and it has a pretty recent cam chain that I adjusted a couple weeks ago. Also, I have accel coils that I put on a couple years ago.

Now, I am going to test a few things today in order to determine what the problem and solution will be - care to guess what it will turn out to be? Btw, this bike is bored to 1196cc....

[excess11]

Check the plugs

Check to see if you have metalic flakes on your spark plugs. Sounds like you could have burned down a piston. This happens from lean burn and high RPM's. It can actually burn a hole through the piston top. This is of course a worst case situation but I would check it out anyway. Do compression check or leak down test to rule out mechanical failure. This is a good place to start!!!!!!

[Snow]

I hope that's not what happened, but I will be checking compression tonight. I brought over my compression tester but also brought the wrong size spark plug socket :/ Btw, anyone know offhand the right size?

If compression checks out, I'll see if I have spark by letting a connected plug hang on the side of the engine and cranking her over. If that checks out too I'll start scratching my head..

[DiverRay]

Recheck the pickup coils. The "smoke" may have been unburned gas, and the pickup coils could be bad, or shorting inside the case.
I don't think the heat has anything to do with it, as "Daily Ride", a '79 standard, had NO problems at 118F going through the desert last month. I was doing an even 85mph, and it didn't skip a beat.
Ray

[Snow]

Looks like it just might be pickup coils. Got compression (though my compression tester seems faulty), got fuel, and got very richly fouled spark plugs with no fire.

Gonna order a new pickup coil set in a moment. Wish me luck!

[Snow]

BTW, the spark plug hex size is 13/16"

[excess11]

tester

14mm threads, this is the adapter you need

[Snow]

Just an update - I've ordered a set of new pickup coils from Bikebandit - they had a very good price for them. I have no idea if Zanneti's (sp?) even still has them.

I'll update again when I have this new set installed...wish me luck!

[DiverRay]

Snow,
When you mount those new coils, do the following to save them. On the crimp for the wires going to the front coil, DO NOT crimp the wires tight!! That is the reason the wires to the coils fail. What I did was LIGHTLY crimp the cover, so the wires can slide a bit with the vacum advance. This is the "fix" I sent in to Yamaha back in 1978...
Ray

[Snow]

It was the pickup coils! Thanks for the advice DiverRay!