Rough running low down and high idle when warm - Page 4

FrankenDesmo · 20-03-2020, 09:43 PM

I appreciate the the write-up utopia, always good to hear from those that have been there and done that a few times. This was my first time doing a valve clearance check on any vehicle, and I'm fairly sure it's the first time I've ever use feeler gauges in anger. I know that the principle is for there to be a small amount of 'drag' and for the feeler to go in without being forced (or even encouraged), but you know what they say about theory and practice. I'll go through the checking process again tomorrow. Also I can't believe I didn't think of a mirror! I ended up getting what would seem to be a very flat tile from B&Q but a mirror has a much better chance of being true.

I am, however, very tempted to leave them well alone for now - if the impact is on efficiency and less than perfect low RPM running, then I'll take the hit for now while I sort out the more acute low-RPM running issue I've been facing (which I don't think is likely to be caused by valve clearances given it wasn't anywhere near that bad before being parked up over winter). I think at this point I run more risk of getting it wrong, which puts the bike out of action for longer. Whereas over the winter I can take my time with it (and possibly get a shim kit ready from emc ahead of time). Also - I really, really want to ride the bloody thing! I've owned it for 6 months and have barely ridden it - I'll happily do the things that require attention right now, but I am willing to put off those tasks that aren't a pressing issue at the moment.

Going off of the link that flip has shared, it seems that I should be aiming for the assembly tolerances? I do want this bike to last 'forever', however that would mean a full re-shim if my measurements are correct. I think I'd like to take the heads off for that, and do it in the off-season.

Am I being too impatient? Is it silly to leave the valves as-is (for now) if my measurements are correct?

FrankenDesmo · 20-03-2020, 09:48 PM

flip - with the battery, I'll see how it goes once I've got the carbs back on. If I've still got the exact same problem, then that's probably the only 'cheap' bit remaining to replace before I start looking at more serious bits.

manwithredbike · 20-03-2020, 11:03 PM

Would agree with Utopia about rubbing down shims manually, though i think when you consider the effort in re-ordering/waiting time/price etc, it's almost inevitable that you'll try it. I done mine a few years ago after changing the cams and brought my closing shims down a few thou as they were a bit tight. Eventually got them turning sweet, as close to zero as you could get but my first attempt left me with two uneven shims even though i though i was rubbing it flat. Second go, i'm sure was as close to as flat as could be done manually but prob as much carefully slow/luck as tecnique. I had my heads on the bench as well as having a few spare shims to play around with which makes it much easier.

Darren69 · 21-03-2020, 04:41 AM

Yea, I'd get the carbs sorted and bike running sweet then worry about valves. It is unlikely that is the main problem imho from what you've described is most likely fuelling set up or less likely an electrical ignition issue.

jerry · 21-03-2020, 09:24 AM

Problem with shims is that the ones ducati sell u are often a few thou out of spec , so grinding them becomes a chore , also when reassembling the adjustment can change when u refit the collets a different way round from when
they came off ,, im very fussy about this so it takes more time,,

Dukedesmo · 21-03-2020, 09:53 AM

Quote:

Originally Posted by FrankenDesmo

However, I've just done the valve clearance checks...

Vertical Inlet Open: 0.04mm (0.05 required a tiny amount of force)
Vertical Inlet Close: 0.14mm
Vertical Exhaust Open: 0.04mm
Vertical Exhaust Close: 0.09mm
Horizontal Inlet Open: <0.04mm (didn't have a feeler gauge smaller, 0.04 required a tiny amount of force)
Horizontal Inlet Close: <0.09mm
Horizontal Exhaust Open: <0.04mm (same as Inlet)
Horizontal Exhaust Close: <0.09mm

Unfortunately your readings are essentially 'inverted' as in you want the closers tighter and the openers looser, but that's what happens as they wear - the openers close up and the closers open up due to wear and you basically need to move the clearances by adding whatever you remove from one to the other.

I aim for 0.1 - 0.12 openers and for the closers to be as tight as possible without binding but definitely under 0.1, 0.05 is good IMO.

My advice is fit MBP retainers rather than the half-rings as much of the wear/variation comes from the rings, just re-fitting them upside-down can change the readings significantly.

I was checking the clearances on my 916 this week and I only needed to change one opener shim on all 8 valves (I didn't really 'need' to change it either as it was only at 0.14mm!) and that is the first one I've changed in probably 5 years. This is a huge benefit on a 916 as the exhaust clearances are tricky to check due to access, especially the rear cylinder as the rear suspension/subframe is in the way, plus there are twice as many valves/shims as a 2v and changing them is trickier.

I reset the Monster clearances last year as I had the heads off and they were unchanged this time round.

General rule of feel is that you can't 'feel' a clearance of 0.05 or less by hand so you can get get an idea even without gauges.

BTW, I don't know where Haynes get their clearances from? - at least for the 4v...

FrankenDesmo · 21-03-2020, 08:10 PM

Thanks for the input everyone. I'm going to leave the valves and aim to shim them all back into "assembly" tolerance next winter - I'll aim to get myself a kit from EMS duc (incl the MBP retainers). Or maybe just individual shims since a kit w/ MBP retainers will set me back around £430 once shipping and customs is factored in

The kit is probably the better investment in the long run given I don't intend to get rid of this bike (and may end up with more 2v 900 powered Ducatis in the future).

Anyway I've started the reassembly - carbs are seated with cables & hoses re-attached. Unfortunately the throttle is not snapping back, so I must have messed up the routing and/or adjustment of the cables - but that's tomorrow mornings first job.

I've got the oil cooler off and laying on the front tyre, I'll leave the heater disconnected and attempt to rig the bike up in a running state without the airbox on (though that might not be possible given I need to get the battery box w/ igniters & coils back on - maybe I can sit it on the bike backwards?), so that I have a chance in hell of getting a screwdriver at the sync screw (my regular philips will do it if I can see what I'm doing, the long one that I purchased is too long

). Really hoping that the sync/adjustment part of this process isn't going to be too much of a saga!

FrankenDesmo · 21-03-2020, 08:11 PM

Quote:

Originally Posted by Dukedesmo

BTW, I don't know where Haynes get their clearances from? - at least for the 4v...

Chris Kelly recommends using a Haynes manual on his valve adjustment page, though he doesn't specifically say to use it for the numbers (but then again he doesn't specifically say not to, either...).

FrankenDesmo · 22-03-2020, 12:10 PM

Had to reconnect the heater as it started pumping out oil while cranking the motor. Looks like the tap doesn't do a hell of a lot at the moment as all I could manage was shutting off the line directly attached to the tap, however the line I assumed was the return was also pumping out oil so I have no idea what's going on there (possible connected to the wrong side of the oil cooler? it's bolted to the same side as the 'inlet' heater pipe). I've got the battery/airbox sitting on top of the bike rather than seated/bolted in, so I should still be able to get at the carbs for sync/adjustments.

Just waiting for the battery to charge as I had drained it a bit cycling the engine without the plugs in to prime the carbs.

BTW while cycling the engine, when I'd let go of the starter there is a ratchet-like noise as the starter spins down and stops - is this normal or is it something like the sprag wearing out?

FrankenDesmo · 22-03-2020, 07:31 PM

And it's alive!

Ended up jumping it off the car since I was too impatient to wait for the battery to get enough charge. After I'd dialed down the idle and let it warm up, I put the carbtune on to find that they were both more or less in sync, but I did fine tune them a wee bit - managed to get them within 1cmHg. In the end, having the airbox off the carbs (but still sitting on top), I could use the mounting holes to get a sight to the sync screw and get a small screwdriver in there (pain in the arse but once I had it lined up it was easier to get it back there between throttle blips).

Idles beautifully at around 1100-1200rpm, pulls away nicely up to past 9k rpm.

When part-throttle cruising at around 4k, it does pop a wee bit, and if I go from part to full throttle (chopping down a gear as well, usually), there is a decent hesitation for a second or two before it pulls away. So something to smooth out (unless it turns out to be due to the valve clearances, in which case it'll wait till winter...).

All in all the bike is running pretty damn nicely and is perfectly rideable as-is. I'm going to take it for a longer ride tomorrow for more of a shakedown.

Edit: This is my 69th post. Nice.

Flip · 22-03-2020, 08:20 PM

Glad you seem to have ironed out most it’s issues- a little odd if it’s popping about on a part throttle while cruising though but could just be it clearing its throat after getting going again. Did you check the diaphragms after all the disassembly?

It’s nice to know it reaches maximum revs reasonably cleanly but pressing on by revving it to 9k through the gears is kind of missing the point of the old 2v 900 as that’s way past peak torque which the wave you want to be riding to enjoy the bike at its best.

FrankenDesmo · 23-03-2020, 09:11 AM

Quote:

Originally Posted by Flip

Glad you seem to have ironed out most it’s issues- a little odd if it’s popping about on a part throttle while cruising though but could just be it clearing its throat after getting going again. Did you check the diagrams after all the disassembly?

Do you mean the diaphragms? They're in tip-top shape, so no worries there.
'popping' might not be the best description. I'll be cruising at part-throttle, and around 4k seems to be the place with the biggest problem (possibly 3-4k), and it'll start to hesitate a wee bit if I 'adjust' the throttle - then if I chop a gear and open it up, there'll be a noticable hesitation right before it picks up and pulls as normal. Taking off from idle is fine, it's just that troublesome part of the rev range at part throttle.

Quote:

It’s nice to know it reaches maximum revs reasonably cleanly but pressing on by revving it to 9k through the gears is kind of missing the point of the old 2v 900 as that’s way past peak torque which the wave you want to be riding to enjoy the bike at its best.

The note about it pulling strongly past 9k was really just a test, I don't go thrashing it whenever I'm out! But I had to put it through its paces after stripping the carbs

Flip · 23-03-2020, 12:38 PM

Quote:

Originally Posted by FrankenDesmo

Do you mean the diaphragms? They're in tip-top shape, so no worries there.
'popping' might not be the best description. I'll be cruising at part-throttle, and around 4k seems to be the place with the biggest problem (possibly 3-4k), and it'll start to hesitate a wee bit if I 'adjust' the throttle - then if I chop a gear and open it up, there'll be a noticable hesitation right before it picks up and pulls as normal. Taking off from idle is fine, it's just that troublesome part of the rev range at part throttle.

I did indeed mean ‘diaphragms’ - damn that auto fill!!!

Ok next thought then- are the two little ‘air boxes’ still fitted to the frame?

Some people remove them to clean up the look of the frame (the fuel injected bikes don’t have them by default) but if the tubes from the carbs are not tucked into a still air space when riding on a steady throttle it can have the effect of blowing over a bottle neck and make the carb slides rise and fall as the pressure changes resulting in a kind of pulsing/hesitating sensation.

FrankenDesmo · 23-03-2020, 08:10 PM

If you mean those wee pods on either side of the front of the frame, they're still there (for now).

I have had one or two backfires on deceleration, would I think suggests a bit of a lean condition. My suspicion is that this is something to be fine tuned via the pilot screws, and possibly the needle clip, but I'll do some more reading. Unfortunately now that we are in lock down, test runs will be limited to shopping for essentials (though I'm sure I can include the M77 in my route to/from the shops).

After my riding today I think the area where this is occurring is more 4-4.5k rpm, and it is definitely ony under partial throttle (I think up to about 1/4-1/3). From memory of reading lots of posts, this is the typical trouble area for these motors/carbs. Skim reading the sigma performance link you've provided earlier also suggests that the valve clearances could be playing a part.

It's a problem that seems to 'build up' while cruising, too - if I'm constantly up and down the rev range then it barely even coughs, after a wee bit of cruising I'll get a slight hesitation, but after a few minutes of cruising it'll bog down/hesitate quite badly for a couple of seconds before pulling away.

Luddite · 23-03-2020, 08:31 PM

Quote:

Originally Posted by FrankenDesmo

It's a problem that seems to 'build up' while cruising, too - if I'm constantly up and down the rev range then it barely even coughs, after a wee bit of cruising I'll get a slight hesitation, but after a few minutes of cruising it'll bog down/hesitate quite badly for a couple of seconds before pulling away.

Could it possibly be carb icing? Utopia has plenty of experience of this phenomenon so perhaps he can offer an opinion?

20-03-2020, 11:03 PM	#48
manwithredbike aka Phil Join Date: Nov 2005 Location: derry Bike: M900 Posts: 376	Would agree with Utopia about rubbing down shims manually, though i think when you consider the effort in re-ordering/waiting time/price etc, it's almost inevitable that you'll try it. I done mine a few years ago after changing the cams and brought my closing shims down a few thou as they were a bit tight. Eventually got them turning sweet, as close to zero as you could get but my first attempt left me with two uneven shims even though i though i was rubbing it flat. Second go, i'm sure was as close to as flat as could be done manually but prob as much carefully slow/luck as tecnique. I had my heads on the bench as well as having a few spare shims to play around with which makes it much easier. __________________ .. ~

21-03-2020, 04:41 AM	#49
Darren69 Transmaniacon MOC Join Date: Sep 2013 Location: Sutton In Ashfield Bike: Multiple Monsters Posts: 6,022	Yea, I'd get the carbs sorted and bike running sweet then worry about valves. It is unlikely that is the main problem imho from what you've described is most likely fuelling set up or less likely an electrical ignition issue. __________________ Roast Beef Monster! Termignoni and Bucci - Italian for pipe and slippers! S4 Fogarty, S4R 07T, 748, Series 1 Mirage

21-03-2020, 09:24 AM	#50
jerry Old Git Join Date: May 2006 Location: Cricklade Bike: Multiple Monsters Posts: 2,803	Problem with shims is that the ones ducati sell u are often a few thou out of spec , so grinding them becomes a chore , also when reassembling the adjustment can change when u refit the collets a different way round from when they came off ,, im very fussy about this so it takes more time,, __________________ MONSTERMAN

21-03-2020, 08:10 PM	#52
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	Thanks for the input everyone. I'm going to leave the valves and aim to shim them all back into "assembly" tolerance next winter - I'll aim to get myself a kit from EMS duc (incl the MBP retainers). Or maybe just individual shims since a kit w/ MBP retainers will set me back around £430 once shipping and customs is factored in The kit is probably the better investment in the long run given I don't intend to get rid of this bike (and may end up with more 2v 900 powered Ducatis in the future). Anyway I've started the reassembly - carbs are seated with cables & hoses re-attached. Unfortunately the throttle is not snapping back, so I must have messed up the routing and/or adjustment of the cables - but that's tomorrow mornings first job. I've got the oil cooler off and laying on the front tyre, I'll leave the heater disconnected and attempt to rig the bike up in a running state without the airbox on (though that might not be possible given I need to get the battery box w/ igniters & coils back on - maybe I can sit it on the bike backwards?), so that I have a chance in hell of getting a screwdriver at the sync screw (my regular philips will do it if I can see what I'm doing, the long one that I purchased is too long ). Really hoping that the sync/adjustment part of this process isn't going to be too much of a saga! Last edited by FrankenDesmo; 21-03-2020 at 08:12 PM..

22-03-2020, 08:20 PM	#56
Flip Registered User Join Date: Mar 2010 Location: Beachtown Bike: M900 Posts: 2,188	Glad you seem to have ironed out most it’s issues- a little odd if it’s popping about on a part throttle while cruising though but could just be it clearing its throat after getting going again. Did you check the diaphragms after all the disassembly? It’s nice to know it reaches maximum revs reasonably cleanly but pressing on by revving it to 9k through the gears is kind of missing the point of the old 2v 900 as that’s way past peak torque which the wave you want to be riding to enjoy the bike at its best. __________________ You're perfect, yes, it's true- But without me you're only you! Last edited by Flip; 23-03-2020 at 12:34 PM..

20-03-2020, 09:43 PM	#46
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	I appreciate the the write-up utopia, always good to hear from those that have been there and done that a few times. This was my first time doing a valve clearance check on any vehicle, and I'm fairly sure it's the first time I've ever use feeler gauges in anger. I know that the principle is for there to be a small amount of 'drag' and for the feeler to go in without being forced (or even encouraged), but you know what they say about theory and practice. I'll go through the checking process again tomorrow. Also I can't believe I didn't think of a mirror! I ended up getting what would seem to be a very flat tile from B&Q but a mirror has a much better chance of being true. I am, however, very tempted to leave them well alone for now - if the impact is on efficiency and less than perfect low RPM running, then I'll take the hit for now while I sort out the more acute low-RPM running issue I've been facing (which I don't think is likely to be caused by valve clearances given it wasn't anywhere near that bad before being parked up over winter). I think at this point I run more risk of getting it wrong, which puts the bike out of action for longer. Whereas over the winter I can take my time with it (and possibly get a shim kit ready from emc ahead of time). Also - I really, really want to ride the bloody thing! I've owned it for 6 months and have barely ridden it - I'll happily do the things that require attention right now, but I am willing to put off those tasks that aren't a pressing issue at the moment. Going off of the link that flip has shared, it seems that I should be aiming for the assembly tolerances? I do want this bike to last 'forever', however that would mean a full re-shim if my measurements are correct. I think I'd like to take the heads off for that, and do it in the off-season. Am I being too impatient? Is it silly to leave the valves as-is (for now) if my measurements are correct?

20-03-2020, 09:48 PM	#47
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	flip - with the battery, I'll see how it goes once I've got the carbs back on. If I've still got the exact same problem, then that's probably the only 'cheap' bit remaining to replace before I start looking at more serious bits.

22-03-2020, 12:10 PM	#54
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	Had to reconnect the heater as it started pumping out oil while cranking the motor. Looks like the tap doesn't do a hell of a lot at the moment as all I could manage was shutting off the line directly attached to the tap, however the line I assumed was the return was also pumping out oil so I have no idea what's going on there (possible connected to the wrong side of the oil cooler? it's bolted to the same side as the 'inlet' heater pipe). I've got the battery/airbox sitting on top of the bike rather than seated/bolted in, so I should still be able to get at the carbs for sync/adjustments. Just waiting for the battery to charge as I had drained it a bit cycling the engine without the plugs in to prime the carbs. BTW while cycling the engine, when I'd let go of the starter there is a ratchet-like noise as the starter spins down and stops - is this normal or is it something like the sprag wearing out?

22-03-2020, 07:31 PM	#55
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	And it's alive! Ended up jumping it off the car since I was too impatient to wait for the battery to get enough charge. After I'd dialed down the idle and let it warm up, I put the carbtune on to find that they were both more or less in sync, but I did fine tune them a wee bit - managed to get them within 1cmHg. In the end, having the airbox off the carbs (but still sitting on top), I could use the mounting holes to get a sight to the sync screw and get a small screwdriver in there (pain in the arse but once I had it lined up it was easier to get it back there between throttle blips). Idles beautifully at around 1100-1200rpm, pulls away nicely up to past 9k rpm. When part-throttle cruising at around 4k, it does pop a wee bit, and if I go from part to full throttle (chopping down a gear as well, usually), there is a decent hesitation for a second or two before it pulls away. So something to smooth out (unless it turns out to be due to the valve clearances, in which case it'll wait till winter...). All in all the bike is running pretty damn nicely and is perfectly rideable as-is. I'm going to take it for a longer ride tomorrow for more of a shakedown. Edit: This is my 69th post. Nice.

23-03-2020, 08:10 PM	#59
FrankenDesmo Member Join Date: Sep 2019 Location: Glasgow Bike: M900 Posts: 108	If you mean those wee pods on either side of the front of the frame, they're still there (for now). I have had one or two backfires on deceleration, would I think suggests a bit of a lean condition. My suspicion is that this is something to be fine tuned via the pilot screws, and possibly the needle clip, but I'll do some more reading. Unfortunately now that we are in lock down, test runs will be limited to shopping for essentials (though I'm sure I can include the M77 in my route to/from the shops). After my riding today I think the area where this is occurring is more 4-4.5k rpm, and it is definitely ony under partial throttle (I think up to about 1/4-1/3). From memory of reading lots of posts, this is the typical trouble area for these motors/carbs. Skim reading the sigma performance link you've provided earlier also suggests that the valve clearances could be playing a part. It's a problem that seems to 'build up' while cruising, too - if I'm constantly up and down the rev range then it barely even coughs, after a wee bit of cruising I'll get a slight hesitation, but after a few minutes of cruising it'll bog down/hesitate quite badly for a couple of seconds before pulling away.