1980 gs850L cool 2nd exhaust pipe

[Scudder]

Got the gs850 started yesterday. This is what I've done.
1. Por-15 Tank
2. New manifold boots
3. New airbox boots.
4. rebuilt carbs (used the kit jets, etc. because several jets were so jacked up the twisted off).
5. Sealed air box with weather stripping
6. New air filter
7. New petcock
8. New plugs
9. New spark plug caps

I haven't adjusted the valves yet.

It starts right up. Reluctant to rev but idles find. No real power. And... cylinder #2 doesn't fire apparently, because the second pipe is cool and #1, #3, & #4 are very hot.

Any ideas before I head down this slippery slope?

Scudder

The plug has spark. I haven't adjusted the valves ye

[mike_of_bbg]

valve adjustment is very important. The valves wear tight over time and they can actually hang open and lose compression.

Did you bench sync your carbs? Maybe carb #2 is fully closed at idle? You should wait to vacuum sync until after the valve adjustment (or do it again after valve adjust).

Idle circuit or pilot jets might be blocked (yes I know you just cleaned or replaced them, but it's not unheard of).

Does it heat up off-idle?

[Scudder]

The pipe doesn't heat up at all. Doesn't matter if I rev the engine or not. Even if I give it the gas, I can feel the lack of power. I had the same issue with a gs750 last winter. I adjusted the valves an the power was awesome after that. I suppose I'll not escape adjusting the valves of this 850. I didn't bench sync, but I'll pull them off and do it this weekend. Maybe that's the issue. The power or lack there of I suppose could come from it running on only 3 cylinders. I'll bench synch and then then adjust the valves. I guess there are no short cuts, huh?

Scudder

[BassCliff]

Hi,

Check the #2 carb for proper assembly. Did the rubber pilot jet plug fall out? Is the float bowl gasket configured properly?




Thank you for your indulgence,

BassCliff

[Scudder]

I salvaged the OEM gasket. But I'll check the plug tomorrow.

Scudder

[Smellii]

I recently had the same problem with cylinder #1, exhaust header wasn't getting hot and vacuum was messed up and pushing fuel/air mixture backwards to the airbox. I got a compression tester for like 12 bucks at an auto parts store and had zero compression. Ended up being a bent valve but I took the engine to a mechanic to repair. I wouldn't have found it myself. He sprayed some aerosol stuff on one side of the valve and watched it leak out the other side of the seated valve, engine was taken apart of course when he did it.

[GateKeeper]

Bad spark plug ?