TS250 Joy, Then Sadness

[Weldangrind]

I finally sourced the parts I needed to make our Suzuki TS250 run properly (or so I thought). The original carb was missing the idle screw, and the float pin hinge bosses were completely worn out, which allowed the float to sit crooked. I put the carb aside and bought a China copy on eBay, but Son of Weldangrind and I could never make it run without the choke, despite trying different jet sizes. I imagine that we could have beat it eventually, but it had a goofy choke mechanism, and it lacked the necessary oil injector tuning hole. The stock carb has a plug that conceals a dimple in the slider; once the dimple comes into view, the timing marks on the oil injector should line up. For the uninitiated, the Suzuki TS bikes are two stroke machines.

All that said, I decided to resurrect the stock carb. I read a tip about using JB weld to rebuild the float hinge pin bosses. I used Permatex Cold Weld, because it actually claims to be compatible with gasoline, whereas JB Weld does not. I cleaned the bosses, applied the Cold Weld, filed it square and drilled the pin hole. It worked! I installed the new idle screw, spring and o-ring that I bought from Bike Bandit, and a new air screw and float valve from www.jerryscycles.com. I was disappointed to find that neither the float bowl gasket from Bike Bandit nor Jerry's Cycles was a match. the carb is from a late year model, so the carb on the fiche for the '79 is wrong. The carb on the '80 looks to be correct, but not the float bowl. Undaunted, I coated both sides of the original gasket with grease and installed it.

I didn't want to perform a complete restoration at this time, because it's insured until August. We wanted to ride! Instead, I cooked the nasty old oil out of the expansion chamber and muffler, then painted it with VHT semi-gloss high heat paint. Here are the bits:



I bought a NOS side cover on eBay and painted it with Krylon Fusion red Pepper. It looks good enough for now. I'll paint the rest of the plastics and tins eventually.







I bought some bulk Uni foam from Bike Bandit, and cut it to fit the stock filter cage.





I have a new seat cover for it, but I'll install it later. Gorilla tape will do for now. Here's the assembled bike:







After a couple of kicks, it fired right up! I took it for a couple of victory laps that day, and then Son of Weldangrind and I went for a ride after work the next day. With the tuned oil pump, factory airbox and cooked exhaust, it smoked much less that before. It also ran beautifully without the choke. It had a slight off-idle bog, but I'm sure that's just an air screw adjustment.

With Son of Weldangrind on my tail through the twisties up a neighbourhood mountain road, the joy suddenly stopped. The engine came to an abrupt halt at 6000rpm, followed by a long black stripe from the back tire. Crap. Son of Weldangrind took my bike home and returned with his Ranger and a ramp. Once I got it home, I began the post-mortem. Here's what I found:



Any guesses as to the cause?