The Last Little Thing
Posted: Fri Oct 07, 2005 2:20 pm
Bought a 1999 Triumph Trophy 1200 last spring that wasn't running real good and I've put close to 7000 miles on it and sorted out a bunch of problems. Although it's never left me stranded, there have been a number of serious PITAs. The pickup coil has been replaced. The fuel system revamped from some previous erroneous repairs and the evaporative system has been scraped (the open-ended evap hoses are still in place since the gas cap doesn't vent). The throttle cable has been rerouted so the throttles close. The carbs have been balanced. A can of Seafoam has been run through it. The petcock has been replaced and, finally, it's got new plugs.
Runs pretty good now except it'll still give me some trouble after running for about 20-25 miles. One thing it'll start doing is sputtering and bucking around 2000 rpm, typically accelerating away from a stop, etc. It's almost like the torque curve has fallen off at low rpms and when you accelerate, it's lugging. Sometimes, if I don't really give it much gas, it'll go up through that range without a hitch. But any normal pull and it bucks and can stall. Sometimes it'll just stall while waiting for a light.
Another thing it'll do is if I'm on the freeway at 70+ mph for 20 miles or so, it'll start to drop out and can even stall when I finally get off the freeway. The petcock was causing this real bad and it's better now, but not gone entirely. If I stay on secondary roads, I don't have problems at speed.
Now both of these problems seem to show up and then, quite often disappear, making diagnosis tough.
Other things I've noticed is the idle doesn't seem terribly stable. Not bad, but you can kind of feel a miss every now and again. Also, the choke makes it run while cold, but it seems to exacerbate the instability.
A couple of my thoughts would be that the Autolite plugs I put in are crap and should be changed again. Or maybe the valves need adjustment (they probably could use it anyway, but it's a pain on a 16-valve faringed(sp?) bike like this one). Or maybe I just need to pull the carbs entirely and rebuild them.
Any good ideas from the collective experience? I'm so close I can taste it.
Runs pretty good now except it'll still give me some trouble after running for about 20-25 miles. One thing it'll start doing is sputtering and bucking around 2000 rpm, typically accelerating away from a stop, etc. It's almost like the torque curve has fallen off at low rpms and when you accelerate, it's lugging. Sometimes, if I don't really give it much gas, it'll go up through that range without a hitch. But any normal pull and it bucks and can stall. Sometimes it'll just stall while waiting for a light.
Another thing it'll do is if I'm on the freeway at 70+ mph for 20 miles or so, it'll start to drop out and can even stall when I finally get off the freeway. The petcock was causing this real bad and it's better now, but not gone entirely. If I stay on secondary roads, I don't have problems at speed.
Now both of these problems seem to show up and then, quite often disappear, making diagnosis tough.
Other things I've noticed is the idle doesn't seem terribly stable. Not bad, but you can kind of feel a miss every now and again. Also, the choke makes it run while cold, but it seems to exacerbate the instability.
A couple of my thoughts would be that the Autolite plugs I put in are crap and should be changed again. Or maybe the valves need adjustment (they probably could use it anyway, but it's a pain on a 16-valve faringed(sp?) bike like this one). Or maybe I just need to pull the carbs entirely and rebuild them.
Any good ideas from the collective experience? I'm so close I can taste it.