XS650SK bad miss

[jetmechmarty]

I had a free hour this afternoon and the sun was shining although it's about 50 degrees. I dug out the XS650SK Heritage Special. It has almost 60K miles and I bought it new in 1983. OK, so it started on the 1st kick as usual. I let it warm up at idle while I suited up. I took off on a spirited ride speeds up to maybe 65 mph. After 15 mile or so, it developed a bad miss. Hard bucking. Throttle to the stop, I can go 50 mph. I'm pointed toward home because I have another obligation this evening. When I slowed for a left turn I noted that it runs fine with the throttle closed. After the turn, I stopped. It idles just fine. Goose throttle in neutral, it's fine. I put it back in gear, make it go and the bucking bronco ride starts again. Bad miss. This went on for about 10 miles. Without warning it cleared up. When it did, the left turn signal light came on steady for a second or three, twice. It ran fine for a few miles and went bad again, but this time I had a sweet spot in the throttle and got home to the barn. Shut down. Restart fine. Idle fine. I checked the battery connections and put it away.

What say the experts?

 

[Jim]

You running the original TCI iggy system?

 

[jetmechmarty]

You running the original TCI iggy system?

Yes, that's right. Everything but the wheels is as original.

I'm thinking about this and it has been a very long time since I had a look at the alternator brushes. It's going to be after the holiday weekend before I can dig into it.

 

[Jim]

I was thinkin' more the TCI box. Here's a cut and paste from my resto thread when my TCI box went south...

Bikes been running great since I re-cleaned the carbs. Started out this morning for Clark Tools (my favorite store). About halfway there it started sputterin' and backfiring. So, after a little test riding... here's the symptoms: Idles good, accelerates good...'till about 2200 revs then it starts popin' and sputtering. About 3 grand it goes (quickly) back to running smooth. When it acts up, I can back off the throttle and reapply power and sometimes that works, sometime it just keeps acting up. Other than that, throttle position has no affect. It's fixed now.

Swapped in my spare TCI box and it's run fine ever since.

 

[jetmechmarty]

Swapped in my spare TCI box and it's run fime ever since.

Great! I have somebody in Georgia who fixes them. Maybe it's time to look him up. Thanks!