cylinder temps

[pahako]

This bike really making me appreciate my xs650.
So I took out the mix screws just to see what kind of shape they were in, and it turns out that there where no springs under them. I guess that is why they were screwed in so far. If I turned them out 2.5 turns they were loose with nothing to hold them in place. So for a temporary fix I found a couple of pens and stole the springs out of them. They happen to be the right diameter, I just had to cut them down short enough to work. Got the screws 2.5 turns out and thy seem to be holding tight. I'm surprised the head pipes weren't blue from this thing running so lean. Anyway, this did help the throttle to come down faster. So I'm thinking that I am getting close to having this thing running right. Took it out for a test ride and it is bogging down again. Cylinders 3 and 4 are running very cool or not at all again. Any wisdom would be appreciated.

[motoman]

This bike really making me appreciate my xs650.
So I took out the mix screws just to see what kind of shape they were in, and it turns out that there where no springs under them. I guess that is why they were screwed in so far. If I turned them out 2.5 turns they were loose with nothing to hold them in place. So for a temporary fix I found a couple of pens and stole the springs out of them. They happen to be the right diameter, I just had to cut them down short enough to work. Got the screws 2.5 turns out and thy seem to be holding tight. I'm surprised the head pipes weren't blue from this thing running so lean. Anyway, this did help the throttle to come down faster. So I'm thinking that I am getting close to having this thing running right. Took it out for a test ride and it is bogging down again. Cylinders 3 and 4 are running very cool or not at all again. Any wisdom would be appreciated.

Likelyhood of broken UNSEEN pick-up coil wires under left-side ignition cover would be a good place to start. That means not LOOK at them, pull each wire with two hands every inch looking for insulation stretch, which equals broken wire internally.

[pahako]

OK, so I checked the wires as far as I could in both directions, pulling, but not getting any stretch on any of them, and the advance seems to move freely. I am aware of what a broken one acts like, because I have had to fixed one before. Three of these wires had been fixed at one time. 2 from a po, and one from me, but all solder joints are still good. If there is a break, I can't find it. Cylinders 3 and 4 still running cold so I decided to check all for spark. All 4 have spark, but what surprised me was how black the plugs were in all 4, like it had been running to rich. The plugs are new and I had only had the bike out a few times for test rides. I double checked the float heights, and they are all within specs. Not sure where to go from hear.

[Ken Talbot]

...Cylinders 3 and 4 still running cold so I decided to check all for spark. ...

At the risk of sounding like a broken record, I'll suggest again that the one thing tht cylinders 3 and 4 have in common is a fuel supply. Have you found the diagram of the convoluted fuel line routing diagram for Specials, and have you confirmed that yours is plumbed correctly? I do not see confirmation of this anywhere earlier in this thread. Pictures would still help!

You should be able to disconnect the fuel lines from the two lower "T"s, turn both petcocks to "ON", apply vacuum to the octopus, and see fuel flor out of each line. You should also be able to get flow from both lines by releasing the vacuum from the octopus, and switching each petcock to "PRI". You should also confirm the the hoses coming from each of the upper "T"s, which are float bowl vents, are both in fact open to atmosphere.