XS650 BS34 CARBS

[BACK SHIFT]

Hi,
I sure am in need of some help with my 82 XS 650? I have previously did a couple PM Messages on the forum for some advice. But still have not figured this problem out as of yet. It had been parked 10 years, caught up on lots of maintenance related. It ran great with a tank flush, fresh non alcohol, and some fuel additives, tires, etc. Yamalube engine oil, valve adjustment/timing chain adjustment was spot on and air filters. It ran good for probably 100 mile or so. than an alternator rotor, and a clutch and several other related lot rot parts, and several dollars later, than the dirty carbs caught up with me, which I now realize, I should have gone through earlier.

Went thru both 34 carbs, Ultra sonic tanked, hand cleaned all passages, cleaned all jets, appear to be stock sizes, new floats, set at 22mm, using an external fuel tank vented, no valve to restrict my fuel and am now unable to get any response from the fuel adjustment on either side. I can sync them just fine on my manometer. Have done the clear fuel hose external test, 0K. One cylinder runs a lot hotter than the other out the gate, went back thru both carbs, and then the other cylinder has decided to run hotter? . Great engine compression@ 150psi. Am beginning to think it is something other than a carb/fuel related problem? Have not checked the timing, knowing I should have by now.
Any help will be most appreciated
Thanks,
Backshift

 

[5twins]

When you cleaned the carbs, did you remove the mix screws and, most importantly, the little rubber o-rings fitted on the bottom of them? If they were the originals, they more than likely are in need of replacement. They'll be all deformed by now and probably aren't totally sealing the screw in the hole anymore. That can make mix screw setting difficult. But, even with new good o-rings, the mix screws on the BS34s don't seem to do much until they're really far open or nearly all the way shut. This is because the BS34s are so E.P.A. strangled. They don't respond like the mix screws on the earlier BS38 carbs. On those, going a little past the "sweet spot" in either direction will cause the idle speed to drop off and the idle to start stumbling or running rougher. It's easy to hear this and tune them by ear.

So, on the BS34s, I use a different method for setting the mix screws - small throttle blips. I start with the screws set at about 3 turns out, then start working them in ¼ turn at a time, giving it a couple small throttle blips after each turn in. I keep going until I start getting lean popping as the revs drop back down to idle. Then I work the screws back open (richer) until the popping goes away.

 

[BACK SHIFT]

Thanks once again 5twins, you have been lots and lots of help, just like always.
Backshift

 

[dave_a]

Take your idle fuel screw, washer & o ring and pilot jet out. Wedge something to hold the butterfly open. In the top of the carb throat you'll see three bypass holes and the idle port. If you squirt cleaner in where the pilot jet was and cover the idle screw hole with your finger, you should see fluid coming out all four holes.

If it doesn't, find some fine copper wire to probe each hole until you're sure it's not blocked. Blow any debris back toward the pilot jet with cleaner then with air.

 

[BACK SHIFT]

Thanks for the help on my carb issues, I'm on it as we speak!
Thanks again,
backshift