Wednesday, March 18, 2015

Most Untriumphant

The last month has had many wonderful things happen, but I did have some bad luck. The Triumph blew a hole in the piston at speed on the freeway and Lori had to come pick me up. The Trump has been smoking since the beginning so I assumed the rings didn't seat or the top end was getting too much oil. I decided to take it for one last run before disassembly. I rode to Redwood Rd, had a great ride, and was coming back home when climbing a hill I started hearing that "ting ting" sound in the top end, the sound of a bike running lean. I switched the other petcock on thinking maybe it wasn't getting enough fuel, and within 10 seconds the bike died at 75mph. I looked behind me and saw a cloud of black smoke leave the pipes. I was coasting in heavy traffic signalling to get over. I managed to coast down hill for over a mile on the side street until i was in a good spot to be picked up. When I got the bike home I had no oil in the oil bag, and a hole in the right piston.

After many arm chair mechanics diagnosing the problem, I'm not sure what caused it. Here are the ideas:

A) Timing. The bike is running too advanced, or the mag's lobe is making one plug fire at 38° BTDC and the other isn't. I'm ordering a mag timing light to check this. The mag was professionally rebuilt and I feel pretty confident about my settings, but who knows. It didn't act up until now.

B) Jetting. I'm running a 19 pilot jet, which is one step bigger than stock, and 200 mains. It's accepted that the Bonnies should be running 190 or 200 mains, so I feel I can't be that far off.

C) Air leak. The only air leak I can imagine might be the crossover tube in the intake manifolds. I don't have a clamp on them. Again, it's never been an issue, but something to check.

D) The rings. The theory is the rings were letting in too much oil creating a super-lubricated piston, making the bike work too hard. Climbing the hill made it work harder than it should, creating a super lean condition.

Whatever it is, it sucks. I will probably have to split the cases. But I'm looking at the silver-lining, too. This will give me an opportunity to try to fix some motor issues, change the gearing, and finally take the bike back down to frame to do a nice paint job.

The last picture I took before it all went down.

Waiting in a parking lot.


Davidabl said...

Where do you go to get a mag rebuilt?

Vorhese said...

A few guys do it, I use Doug Poirier in Phoenix.