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Hello all,
Finally took the bike out for it's first little trip. Met some friends in Dubuque, IA and headed south out of town, eventually riding along the Mississippi for a while. She rode pretty good, tooling along at about 5,000 - 5,500 RPM for most of the time. Made it 41.1 miles out and she starts backfiring....popping through the carbs.....losing power.....not a good thing. Out of nowhere....flat grade at 5,000 rpm. Ending up trucking her back. The guys we were with thought it was a plug problem, but I though carbs, since they have given me the most trouble of anything on the bike. So, I took the carbs off the bike, dropped the float bowls, found no evidence of dirt or junk in them, and sprayed them down w/ carb cleaner.....sprayed through fuel passages, jets, so on and so forth. Anything I could hit with them still on the rack. Put them back together and back on the bike, fired her up, and she ran fine. Hmm. Ok.
So we head out into town that night. Made it about 10 miles or so, and it resumes doing the same thing it did before. Really *@%^$*@%^$*@%^$*@%^$ed me off now. Left her in a grocery store parking lot til the next night. Came back that night, and just for the hell of it started it up before pursuing the possible dead plug theory, and lo and behold, it fired right up. Ok. Makes no sense. Rode it maybe 2-3 miles down the road to the local Wal-Mart to try and buy a plug just in case it resumed it's problem on the way home. Park it, shut down and run inside. We're in there for 5 mins at most, come back out, fire it up, and it immediately runs like crap. Argh!
Determined all the plugs were firing just fine, and after more deduction figured out that the number 2 cylinder is not getting gas. This was the same cylinder, if I remember correctly, that was not getting gas when I was prompted to completely disassemble and clean out the carbs last winter. It's been running absolutely fine since then. Until now.
My current theory is that there might be some sort of junk from the tank that is clogging some internal passage in the #2 carb. I don't think it's in the main fuel passage, as the number #1 carb is downstream and wouldn't get any go juice either. If there's crap floating in the tank, that might possibly explain why it will go 40 miles and lose cylinder #2, then after being cleaned out go another 10 miles before another piece gets stuck, and then after sitting all night run for a little bit before failing again. Why the #2 carb would be the victim every time is puzzling, since the blockage could just as easily go to the right side, and into #3.
If that's not the issue, then I don't understand why the carb would just all of a sudden fail like that. Just makes no sense. If anyone has any idea or suggestions I would be most appreciative.
One other quickie. It's a 77 GS750. What should she cruise at, roughly. I think at about 65-70 mph (speedo's a little off) it was running at roughly 5,000 rpm. Sometimes 5,500. Redline is 9,000. Is that about where it should be? Thanks for the help as always,
Ryan
mueller@xta.com
Finally took the bike out for it's first little trip. Met some friends in Dubuque, IA and headed south out of town, eventually riding along the Mississippi for a while. She rode pretty good, tooling along at about 5,000 - 5,500 RPM for most of the time. Made it 41.1 miles out and she starts backfiring....popping through the carbs.....losing power.....not a good thing. Out of nowhere....flat grade at 5,000 rpm. Ending up trucking her back. The guys we were with thought it was a plug problem, but I though carbs, since they have given me the most trouble of anything on the bike. So, I took the carbs off the bike, dropped the float bowls, found no evidence of dirt or junk in them, and sprayed them down w/ carb cleaner.....sprayed through fuel passages, jets, so on and so forth. Anything I could hit with them still on the rack. Put them back together and back on the bike, fired her up, and she ran fine. Hmm. Ok.
So we head out into town that night. Made it about 10 miles or so, and it resumes doing the same thing it did before. Really *@%^$*@%^$*@%^$*@%^$ed me off now. Left her in a grocery store parking lot til the next night. Came back that night, and just for the hell of it started it up before pursuing the possible dead plug theory, and lo and behold, it fired right up. Ok. Makes no sense. Rode it maybe 2-3 miles down the road to the local Wal-Mart to try and buy a plug just in case it resumed it's problem on the way home. Park it, shut down and run inside. We're in there for 5 mins at most, come back out, fire it up, and it immediately runs like crap. Argh!
Determined all the plugs were firing just fine, and after more deduction figured out that the number 2 cylinder is not getting gas. This was the same cylinder, if I remember correctly, that was not getting gas when I was prompted to completely disassemble and clean out the carbs last winter. It's been running absolutely fine since then. Until now.
My current theory is that there might be some sort of junk from the tank that is clogging some internal passage in the #2 carb. I don't think it's in the main fuel passage, as the number #1 carb is downstream and wouldn't get any go juice either. If there's crap floating in the tank, that might possibly explain why it will go 40 miles and lose cylinder #2, then after being cleaned out go another 10 miles before another piece gets stuck, and then after sitting all night run for a little bit before failing again. Why the #2 carb would be the victim every time is puzzling, since the blockage could just as easily go to the right side, and into #3.
If that's not the issue, then I don't understand why the carb would just all of a sudden fail like that. Just makes no sense. If anyone has any idea or suggestions I would be most appreciative.
One other quickie. It's a 77 GS750. What should she cruise at, roughly. I think at about 65-70 mph (speedo's a little off) it was running at roughly 5,000 rpm. Sometimes 5,500. Redline is 9,000. Is that about where it should be? Thanks for the help as always,
Ryan
mueller@xta.com
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