Upstream exhaust leak?
1100GS pops, bangs and backfires under load or overrun
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No leaks, and it doesn’t have a lambda sensor, so it doesn’t matter if the exhaust leaks in terms of closed loop fuelling as it runs open loop.
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It was very smelly rich on idle, yes, and clearly wasn’t in the idle range because it behaved very oddly.
I’ll tweak to 380mV and test. I have this feeling there’s a dead spot on the lower range of the throttle pot and someone jacked it up to try and stop the stumbling just off idle.
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So tonight, I did some things:
Took the bike out for a ride. Can definitely feel the difference, it's much better, retarding the ignition timing by virtue of setting up the base setting makes the bike much much nicer when starting and cold, it's a lot 'softer' and quieter. It feels much smoother throughout the range, particularly in the midrange.
When it gets hot, there's still a fairly perceptible stumble *just* off idle - the bike kangaroos a bit off the backlash in the drivetrain in the low gears and if gently cruising in fourth or fifth you feel that little stutter as you feed a little throttle in at very low throttle openings. I can provoke it in neutral, if I hold the throttle a very tiny bit open, at the 1400-1900 or so rpm range there's a bit of a wandering misfire/inconsistent feel. It coincides with a deeper clatter from the worn throttle bodies (very high vacuum) too.
I definitely think rebuilding the TBs is a priority now, and I'm 95% there to thinking the TPS is not as it should be in that very sensitive low range of its travel. That said, I probably also need to set the mixture properly with the CO pot, too.
A million times better than I started, and in most cases you can drive around the problem, but I want to work to perfect its running as it's very sweet elsewhere in the range.
To understand what I'm fixing, I'm going to perform changes one at a time, so I'll not replace the TPS until after rebuilding the TBs.
- Made up a Hall Effect Sensor test/setup tool (couple of LEDs, resistors, a 9v battery and a switch in a little box) - and as expected, the timing wasn't right, I repeated the process several times to validate and the sensor backplate sits pretty much centrally in the range of adjustment, the little hole at the bottom is almost exactly inline with the hole in the front cover. Good to see whoever replaced the sensors either can't, or can't be bothered to, set them up properly.
- Set the TPS to 380mV - noticed that it didn't return to that every time when opening the throttle and releasing it.
Took the bike out for a ride. Can definitely feel the difference, it's much better, retarding the ignition timing by virtue of setting up the base setting makes the bike much much nicer when starting and cold, it's a lot 'softer' and quieter. It feels much smoother throughout the range, particularly in the midrange.
When it gets hot, there's still a fairly perceptible stumble *just* off idle - the bike kangaroos a bit off the backlash in the drivetrain in the low gears and if gently cruising in fourth or fifth you feel that little stutter as you feed a little throttle in at very low throttle openings. I can provoke it in neutral, if I hold the throttle a very tiny bit open, at the 1400-1900 or so rpm range there's a bit of a wandering misfire/inconsistent feel. It coincides with a deeper clatter from the worn throttle bodies (very high vacuum) too.
I definitely think rebuilding the TBs is a priority now, and I'm 95% there to thinking the TPS is not as it should be in that very sensitive low range of its travel. That said, I probably also need to set the mixture properly with the CO pot, too.
A million times better than I started, and in most cases you can drive around the problem, but I want to work to perfect its running as it's very sweet elsewhere in the range.
To understand what I'm fixing, I'm going to perform changes one at a time, so I'll not replace the TPS until after rebuilding the TBs.
Following with interest.
Motorworks normally have good stock of used parts and if I remember rightly they warrant them.
He deleted his account.
he took offense to you "following with interest"
said something about "your a nosey bastard!?"
not even a flounce ......
he's way better than the rest of us , he has a diamond file.
he's way better than the rest of us , he has a diamond file.
He deleted his account.
he took offense to you "following with interest"
said something about "your a nosey bastard!?"
Hey! I resemble that remark…
Was hoping someone may have known, even if the OP had disappeared…
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