Grand Prix 125
Main Motorcycle: 1995 Triumph Thunderbird
Join Date: Jun 2011
Location: Temecula, California
Tuning Carb on 1995 Thundebird
I bought a 1995 Thunderbird w/ 11K miles from a dealer, got it home and it wouldn't stop backfiring. Took it back and they told me the injection coils were bad. So they fixed them for free. I moved, and couldn't find a mechanic within 65 miles who would even change my tires, and I was having issues with not having any power over 70 mph. So I got a Haynes and started going over the engine. I found pieces missing. The biggest issue I found was that the airbox and aux airbox were cracked, and there was no hose connecting them. I glued the cracks back together and replaced the hose, and the bike appeared to be running much better for about two weeks. Then I noticed some performance issues.
Sometimes when I start riding, there doesn't appear to be any horsepower (I've almost fallen off a couple times when the expected acceleration wasn't there and I lost my balance). This occurs all through the RPM range from 1k through 6K. However this usually only happens in the afternoon (I ride to a carpool about 7 miles from my house twice a day). However, the most pronounced time was when I rode 65 miles to work in the morning with no problem. It sat in the shade all day, then I rode home. Six miles from my house, the engine died, with all the symptoms of running out of gas (it had half a tank, however).
The only way to get it started was to apply 3/4 choke, and it fired right up. Took off the choke and rode home. It tried to die on me again, but I just feathered the throttle at high RPMs (I was doing 75 on the freeway) and it stayed alive. However, I noticed the drop in power once I got onto surface streets and was hitting light after light. The only other thing I have noticed is twice, when pulling out from a stop, I could swear I heard a "pop-psss" like a popped tire just as I'm pulling away. I can't find any holes or anything in the hoses, I've talked to engine fellas I know, and I'm at a loss. And, like I said, the local mechanics won't even look at my bike. I'm wondering if anyone has had a similar issue (I've got Mikuni carbs), and a solution that doesn't require jet adjustment or the like, since this is way above my skill level.
Thank for any sharing any info