you've probably left the balance pipe nipple covers off
i joined mine together
Good thought, but they're on
Thanks again Dick - I'll take a ride to my local station after work today.
Low rev hesitation?
- Thread starter MattW
- Start date
Good thought, but they're on
Thanks again Dick - I'll take a ride to my local station after work today.
Trullion
Registered user
I shouldperhaps have said that screwing in (clockwise) weakens the mixture. Sorry. Be aware also that after a certain point the adjustment will go back to rich i.e. the adjustment only works over a certain range, then starts over.
I see the whole process as a bit like doing the mixture on an old Amal carb. You need to balance the tickover setting (= adjusting the pot) with the slide cutaway (= adjusting the tps) so that there's a smooth transition between pilot and main (= no surging). I know it's not an exact analogy, but there is a certian similarity, at least on non-cat versions. Closed loop (i.e. cat systems) are a different matter.
It would be nice if we knew what the reistance is supposed to be to give a CO reading of 1.5%. If we knew this we could just remove the pot and set it, using a multimeter (which is how I diagnosed a bad one on my 850 - adjusting it made very little difference, unlike a used spare I got from Motorworks. Still, I don't suppose it's that simple as other factors come into play.
I see the whole process as a bit like doing the mixture on an old Amal carb. You need to balance the tickover setting (= adjusting the pot) with the slide cutaway (= adjusting the tps) so that there's a smooth transition between pilot and main (= no surging). I know it's not an exact analogy, but there is a certian similarity, at least on non-cat versions. Closed loop (i.e. cat systems) are a different matter.
It would be nice if we knew what the reistance is supposed to be to give a CO reading of 1.5%. If we knew this we could just remove the pot and set it, using a multimeter (which is how I diagnosed a bad one on my 850 - adjusting it made very little difference, unlike a used spare I got from Motorworks. Still, I don't suppose it's that simple as other factors come into play.
Well now I'm thoroughly confused (makes a change)
I just took it my local MOT place who kindly let me put it on their exhaust gas analyser (been for a ride first, well warmed up). But, whatever I did, I couldn't get the CO above 0.25% (zero point two five). There is a definite place in the adjustment range where the idle speed picks up and it smooths out but at this 'sweet spot' it still read about 0.25. I could make it drop below this figure but not above. The analyser was working because blipping the throttle took the reading to well above 2 or 3 %. The only thing I can think is that the idle speed was too high (it was about 1200 or so because tweaking the CO pot to the sweet spot had raised it last night and I didn't think to drop it before going out this afternoon).
Back home on the u-tube (again), it took a surprising number of turns (1.5 or so) of the brass air screws to drop the idle back down to 1000 rpm, I can only think that I was 'off the scale' on the air screws and it was affecting the CO reading? (no idea if that's even possible though). Or perhaps my CO pot is knackered like yours was Trullion...
I might buy another pot and see if it helps. Thanks for all the on-going advice - much appreciated.
Matt
I just took it my local MOT place who kindly let me put it on their exhaust gas analyser (been for a ride first, well warmed up). But, whatever I did, I couldn't get the CO above 0.25% (zero point two five). There is a definite place in the adjustment range where the idle speed picks up and it smooths out but at this 'sweet spot' it still read about 0.25. I could make it drop below this figure but not above. The analyser was working because blipping the throttle took the reading to well above 2 or 3 %. The only thing I can think is that the idle speed was too high (it was about 1200 or so because tweaking the CO pot to the sweet spot had raised it last night and I didn't think to drop it before going out this afternoon).
Back home on the u-tube (again), it took a surprising number of turns (1.5 or so) of the brass air screws to drop the idle back down to 1000 rpm, I can only think that I was 'off the scale' on the air screws and it was affecting the CO reading? (no idea if that's even possible though). Or perhaps my CO pot is knackered like yours was Trullion...
I might buy another pot and see if it helps. Thanks for all the on-going advice - much appreciated.
Matt
This is shouting air leak to me... Check your inlet stubs carefully. I normally use brake cleaner and squirt it around the stub / throttle body area - if it gets sucked in anywhere the engine will suddenly surge.
If your co pot was duff I can't see it going slightly out - they're normally ok or not. Can't remember if you said you'd set the tps pot or not. If not, do it now.
Dick
If your co pot was duff I can't see it going slightly out - they're normally ok or not. Can't remember if you said you'd set the tps pot or not. If not, do it now.
Dick
There is no preset resitance setting it will vary bike to bike
The pot does not endstop so be careful
Best way is to set it in the middle with a multimeter as a start point...You can also check the pot works ok at the same time
I could not get mine below 3% even moving the TPS did not help
Matt you could try moving your TPS...Worth a try
My injection system is now on the bench ( good riddens to all the fancy electronics that do a poor job of fueling IMO )
I am sorting the wiring out to fit carbs and a Pazon ignition system at the moment...
I might do a post on the conversion in the future once i have sorted everything out
The pot does not endstop so be careful
Best way is to set it in the middle with a multimeter as a start point...You can also check the pot works ok at the same time
I could not get mine below 3% even moving the TPS did not help
Matt you could try moving your TPS...Worth a try
My injection system is now on the bench ( good riddens to all the fancy electronics that do a poor job of fueling IMO )
I am sorting the wiring out to fit carbs and a Pazon ignition system at the moment...
I might do a post on the conversion in the future once i have sorted everything out
I have checked for air leaks on the inlets with brake cleaner but I'll check again. I also wondered about air leaks in the exhaust - I guess this would lean out the CO reading too.
I check the TPS every time I balance the TB's (which is about twice a day at the moment
). It was at 0.36 but yesterday after reading some stuff on here, I upped it to 0.37.
The upshot of the last few days fiddling is that it now ticks over a lot better than when I started this whole escapade and I can trickle smoothly along through traffic on a steady throttle at 2 to 2.5k rpm with no intermittent snatching. I've no idea what adjustment has caused this improvement - my gut feeling is that (as several have advised) it's a combination of CO pot and air screw setting (possibly with a bit of TPS thrown in...).
I'd still like to get to the bottom of the weird CO reading yesterday but I suppose at this point I should put the tools away and just ride it... The last thing I'm going to do is have a thorough check for air leaks on the inlet and exhaust and I might put a meter on the CO pot and check that it's actually doing something.
It'll also get a conversion to splitter box throttle cables this year. Even with effectively new TB's and a brand new cable, it's next to impossible to get a decent balance - I can see why they changed the design.
Thanks everyone for all the advice and guidance and for having the patience to stick with me - I'll leave you all alone now
cheers
Matt
PS. Garry - I'd be very interested to hear how you get on with your carb conversion. I know Roger and Kenny on here have recently had Steve Scrimminger convert theirs but the all-up cost was a bit eye watering - a more DIY option (even if it involves a dyno run to sort out jetting) would be interesting.
I check the TPS every time I balance the TB's (which is about twice a day at the moment
). It was at 0.36 but yesterday after reading some stuff on here, I upped it to 0.37.The upshot of the last few days fiddling is that it now ticks over a lot better than when I started this whole escapade and I can trickle smoothly along through traffic on a steady throttle at 2 to 2.5k rpm with no intermittent snatching. I've no idea what adjustment has caused this improvement - my gut feeling is that (as several have advised) it's a combination of CO pot and air screw setting (possibly with a bit of TPS thrown in...).
I'd still like to get to the bottom of the weird CO reading yesterday but I suppose at this point I should put the tools away and just ride it... The last thing I'm going to do is have a thorough check for air leaks on the inlet and exhaust and I might put a meter on the CO pot and check that it's actually doing something.
It'll also get a conversion to splitter box throttle cables this year. Even with effectively new TB's and a brand new cable, it's next to impossible to get a decent balance - I can see why they changed the design.
Thanks everyone for all the advice and guidance and for having the patience to stick with me - I'll leave you all alone now
cheers
Matt
PS. Garry - I'd be very interested to hear how you get on with your carb conversion. I know Roger and Kenny on here have recently had Steve Scrimminger convert theirs but the all-up cost was a bit eye watering - a more DIY option (even if it involves a dyno run to sort out jetting) would be interesting.
