I think I am in trouble.....

[yank]

Lots of things can contribute to carb problems like crappy fuel we have these days sitting for long periods of time, trash in your tank ect... your 50 min ride could have knock some trash loose. Sounds to me like you should start from the beginning and do all proper maintenance over to eliminate anything that could have been over looked.

[yank]

Has the other rack been dipped?

[76_Mike_82]

The other rack has been dipped I have a second 850 being slowly brought to ride ready. That is where the spare ignition box came from. I had the drain gaskets but have since stole them for the first 850. I have ordered replacements but they're not here yet. So I will either wait or swap float bowls as I had said.

[dantodd]

Which leads did you switch? The cylinders are numbered 1-4 starting on the kickstand side.

[smilinbrad]

What do you mean "apart for inspection"? The passageways that get gummed up are not visible or at least the blockage is not. Have you cleaned them properly with an ultrasonic bath?

[76_Mike_82]

The leads that were swapped were 2 and 3. Originally #3 was cool enough after a 40 min ride (had to get home) to hold with a bare hand. There was no change other than I started using a thermometer and found both the 3 and 4 cylinders cool. It never moved when swapped.
No I did not ultrasonic clean the carbs I dipped them. They would be the high side carbs and they ran fine for an hour to get to the bike night it was on the way home when the problems started. When I said I had them apart I was looking for any signs of problems, any dirt in the float bowls issues with the float valves and in general condition. I also checked the diaphragms for any possibility of tearing or cracks. My thoughts are if there was any gumming or other dirt in the carbs you should be able to see something in the bowls where the fuel sits. At this point I will swap the carbs and see if the the two cylinders come alive. The new rack is bench tuned but I'll need to do a full tune once they are in but I should see the two come alive even if its not fully tuned. At least I will know if the are the problem or not.

[chuck hahn]

Whatever got sucked into them wouldnt necessarily be seen in the bowls though. AND even a tiny spec that was inside one of then passges came loose and clogged that carb up...who knows for sure. I also would suggest using new fuel line if its old. They do tend to break down and shed rubber specs down to the carbs.

[Grimly]

It did not move after swapping coils. The only difference from when this all started is now I'm using the thermometer (not just my hand) and now I know it's two cylinders not at 100% instead of one dead cylinder.
I guess I'll swap the float bowls over to the other carb rack and try them.

I had similar to this problem with the XJ - cylinders 1 and 3 were colder than the other two (IR thermometer on the headers) and it turned out to be two seperate coil faults.
The PO had fitted a cheap coil to the Left side (1&4), which had a cheese-like HT lead on it which had split and was leaking spark, while the Right coil (2&3) had developed a corroded LT connection at the back of it, hidden under a boot, where the wire sniggled and clamped securely. Too secure, as it turned out, because the moisture loved it in there. The situation was complicated by me doing a carb sync with one of the faults present and that had compensated sufficiently at the time.

[76_Mike_82]

Well gentlemen I am very sad to say that even with a diferent set of cabs the same cylinder is dead. I have tried and tried to tune the new carbs but no matter what I do the #3 cylinder will not pull a vacume. So moving on.....

[Nessism]

Did you check spark on #3 when the issue occurred? For that matter did you check spark on all cylinders?

When you cleaned the carbs did you remove the pilot jets and hold them up to a light to make sure they are open?

Did you adjust the valves yet?

Is the fuel tank clean of rust and debris?

Is the charging system working as it should?

[JTGS850GL]

Did you ever replace the spark plugs?

[yank]

Post 31 and 40.

[76_Mike_82]

Two different set of carbs. Hard to think both sets would cause the same problem.

Charging system is upgraded and working very well.

Valves were done at the begining of the year. Sadly no where near enough time/millage on them to require another adjustment.


Three cylinders are firing one weak but firing.
Fuel tank was professionally sealed and the new carbs have yet to see the tank.

[76_Mike_82]

Hummmm well maybe I do owe you all an apology for not believing..... I would not believe this if I didn't see it myself, the plug looks good (not even discolored more than normal) but has no continuity to the electrode. I'll try it again once I double check my valves (already have the valve cover off).

[Nessism]

What voltage do you have at the coils?

I'd remove the pilot jets and make sure they are open too. I can't tell you how many threads I've seen over the years where the person said the carbs were clean but they weren't.