The prologue to this post is the "Died on the side of the road!" thread I started last week, while I was... dead on the side of the road and then having to limp across the state, I'm trying to get the puma going again and needed some input.
Here's the issues-
Bike is a '77 R100S and will start, but the left cylinder sputters and backfires constantly, right cylinder runs fine.
After a few minutes the left header starts to glow from the heat- most have diagnosed this as a lean burn condition. But dammit! what is causing it!!
Prior to it dying (that was caused by a loose battery terminal) it was driving fine, but at higher speeds/rpms I could feel a little hesitation and maybe some small backfires. It felt like I had something in the bowls- The sensation started to get worse after about 30-40 miles. I stopped to check, they were fine, but then it just went to hell... it was constantly backfiring when I started it back up....
So far I have:
- Checked the throttle cable and choke cable, both seem fine.
- Adjusted the pilot screw- seemed fine
- Cleaned the bowls multiple times, removed the jets and cleaned them out- all seemed fine
- Checked fuel levels in the bowls, level is fine, gas is available from the lines.
- Checked and adjusted the valves, (the exhaust on the left side was a bit tight, but not much)
- Checked the plugs- right is (obviously fine) left looked fine, but was wet with gas.... is that normal for what seems like it should be a lean burn? I'm guessing it's just from the cylinder running so crappy that not all the gas is getting combusted..?
- Swapped the leads, spark plugs and coils.. no change.
- Swapped the hoses between the carb and head from side to side to check for airleaks, no change.
- Looked in the front cover to see if water/sludge etc had gotten in there- (I did drive thru a rainstorm the day before everything went to hell), but it's been a week of dry weather since then and everything looked fine inside there. I wd40'd all the connections. But it seems to me that if there was a problem with the points/condenser/timing then BOTH cylinders would be outta whack. But the right one is running strong...
- I'm going to replace my inline fuel filters today, to see if that does anything.. I doubt it because it's getting fuel to at least the right cylinder in appropriate quantities... and the crossover is fine...
- I suppose dissemble the carb... I've already looked at the needles etc.. but could a torn diaphragm cause a lean burn? Not quite sure of what to look for when I'm in there... but maybe something will jump out.. OH- I noticed when I took apart the elbows that gas was getting blown up the elbow towards the airbox.. I guessed that's from the backfires blowing fuel the wrong way- but might that point to anything?
So any help would be greatly, and I mean GREATLY appreciated.