Intermittent spluttering

Mistacat said:

The easiest on the road temp bodge on the SS switch is to open the outer sleaving on the frame downtube and use a scotch lock to connect the 2 wires that it showed on the video that you said you watched.
I hate scotch locks but in this instance they are handy and it makes it easy to return to stock.

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I’ve had a good wiggle of the side stand, running in 1st and no change - running okay at the moment.
I just had a look at the air filter and it’s not dusty but it looks a bit oily - I’m usually up front so could sitting behind Smokey trucks clog it up? My filter needed changing after 6K miles , the Himmie looked brand new after 12K but we changed it anyway.

Chances are the oil is on the inside of the air filter , if the oil is filled to the top of the sight glass they tend to breath quite a bit of oil into the airbox.
I doubt that the air filter would create the intermittent fault described.
With the side stand operating a potentiometer rather than micro switches it normally has to move quite a long way before the ECU notices a change of position unlike micro switches.
A dirty track on the pot can throw up all sorts of problems. Not saying this is your problem.
It is very hard to diagnose an intermittent problem, when you get to a mechanic and he downloads the fault codes and how many times the fault has occurred the problem may be more obvious.

Mistacat said:

Chances are the oil is on the inside of the air filter , if the oil is filled to the top of the sight glass they tend to breath quite a bit of oil into the airbox.
I doubt that the air filter would create the intermittent fault described.
With the side stand operating a potentiometer rather than micro switches it normally has to move quite a long way before the ECU notices a change of position unlike micro switches.
A dirty track on the pot can throw up all sorts of problems. Not saying this is your problem.
It is very hard to diagnose an intermittent problem, when you get to a mechanic and he downloads the fault codes and how many times the fault has occurred the problem may be more obvious.

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Thanks again Chris.
What do you mean by ‘a dirty track on the pot’ ?
Yes intermittent problems are the worst
I’m not sure we will find a mechanic with motorcycle diagnostic equipment around here.

Update:
Rode into town this morning, a 30 mile round trip, in torrential rain - no splutters. Bike started and ticked over fine, ran okay when accelerating but running at 50mph it didn’t feel 100%, nothing major just not quite right.
So, for around a month we’ve been riding down the Pan American Highway. Apart from 4/5 days in the desert it’s been a steady 58mph (Himalayan speeds). Perhaps this is not good for the bike? It had a full service 6K miles ago, which should have included valve clearance and throttle sync - but perhaps not?

If the valve clearances needed doing would that cause intermittent spluttering?

At 80k miles I would be surprised if the valve clearances had closed up enough to cause a problem. ( My TC has had one valve close by one thou in 85K miles).
Unlike pushrod engines overhead cam engines tend to tighten the clearance. Then again it would not be intermittent.
Poor throttle sync normally manifests as a flat spot when the throttle is opened gently off idle. Again not intermittent.
I think it needs a good thrashing.

Mistacat said:

At 80k miles I would be surprised if the valve clearances had closed up enough to cause a problem. ( My TC has had one valve close by one thou in 85K miles).
Unlike pushrod engines overhead cam engines tend to tighten the clearance. Then again it would not be intermittent.
Poor throttle sync normally manifests as a flat spot when the throttle is opened gently off idle. Again not intermittent.
I think it needs a good thrashing.

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I think you might be right.
We’ve found a local mechanic. When we got there it was a shed full of out board motors, chainsaws, lawn mowers and a few old trail bikes out the back . Having said that we have found, in the past, that ’bush’ mechanics can be very good as they have to fix everything from lawnmowers to 20 ton trucks - no BMW diagnostic computer though

Our plan is to keep going, if things get worse I’ll do the SS switch bodge and hope for the best.
Thanks for everyone’s input, keep making suggestions, it’s all good info.
I’ll keep you posted
🏍

I had a problem with the side stand switch thinking that the stand was down all the time, so the engine would cut out as soon as I engaged gear. I was 150 miles away from home on a Sunday so not the best time for it to play up. I did a quick search on my phone and found the wiring to the switch. I cut the wires and twisted two together so by-passing the switch. Now the bad part, I can't remember what colours I joined! Sorry. But if you do suspect the side stand switch then it can easily be taken out of the equation. Good luck.

dashfixer said:

I had a problem with the side stand switch thinking that the stand was down all the time, so the engine would cut out as soon as I engaged gear. I was 150 miles away from home on a Sunday so not the best time for it to play up. I did a quick search on my phone and found the wiring to the switch. I cut the wires and twisted two together so by-passing the switch. Now the bad part, I can't remember what colours I joined! Sorry. But if you do suspect the side stand switch then it can easily be taken out of the equation. Good luck.

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Thanks, it’s the tan and white wire.
All has been okay for a couple of days, I’ve got 1200km of unpaved road coming up so that should give it a decent test

Update:
So after the mechanic looked at it the bike had a day’s ride in the sunshine and all was fine. The next ride started in light rain which turned into glorious sunshine there was a few short instances of spluttering but mostly fine. Bike then sat in 4 days of torrential rain whilst we holed up in a hostel. Next ride was sunny but cold. We rode for the morning and the bike was terrible. At lunchtime we turned around and went back to the hostel for a switch bypass.
Next day was a cold but dry start and the bike seemed fine. In the early afternoon we rode up to over 1000 metres and rain - the bike started playing up quite badly. Later in the afternoon it became sunny but cold. The bike recovered and ran fine for an hour or so so I began to think it was rain related. However, just before we reached our next stop it suddenly became worse than ever and I limped into town.

When it’s bad it doesn’t last long and if I accelerate hard it doesn’t happen so I end up accelerating for a bit, slowing down then accelerating etc until it smooths out.
Trouble is that’s not ideal on unpaved roads.

At the moment it’s okay for much longer than it’s not and we’ve, hopefully, got 6 days of dry weather to do this unpaved section so I’m going to keep going with fingers crossed.
But I would be very grateful for any ideas.
Many thanks
D

I had similar symptoms on my R1200RT which I eventually traced to a failing ignition coil. It would misbehave in the rain, but would be fine after it dried out.
Replacement was obtained from sparkplugs.co.uk at a good price and this solved the problem.
They used to sell the Champion equivalent coils which are the same as the Beru but cheaper. However I don't see them on their website any more!

Another thing to consider if you have Afxied fuel control units fitted. These can also fail giving similar running problems. Just disconnect these.

Hope you can get to the bottom of this,

Best regards...

Check that your fuel filler cap is sealing tightly when closed and not letting a few drops of rainwater into the tank or accumulating rainwater around the filler if the drain is blocked. Check that the filler neck drain holes around the fuel flap and its associated drain pipework are not blocked with congealed dust etc. If you can find an airline at a petrol stop maybe blow through the drain line.

gspod said:

Update:
So after the mechanic looked at it the bike had a day’s ride in the sunshine and all was fine. The next ride started in light rain which turned into glorious sunshine there was a few short instances of spluttering but mostly fine. Bike then sat in 4 days of torrential rain whilst we holed up in a hostel. Next ride was sunny but cold. We rode for the morning and the bike was terrible. At lunchtime we turned around and went back to the hostel for a switch bypass.
Next day was a cold but dry start and the bike seemed fine. In the early afternoon we rode up to over 1000 metres and rain - the bike started playing up quite badly. Later in the afternoon it became sunny but cold. The bike recovered and ran fine for an hour or so so I began to think it was rain related. However, just before we reached our next stop it suddenly became worse than ever and I limped into town.

When it’s bad it doesn’t last long and if I accelerate hard it doesn’t happen so I end up accelerating for a bit, slowing down then accelerating etc until it smooths out.
Trouble is that’s not ideal on unpaved roads.

At the moment it’s okay for much longer than it’s not and we’ve, hopefully, got 6 days of dry weather to do this unpaved section so I’m going to keep going with fingers crossed.
But I would be very grateful for any ideas.
Many thanks
D

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Certainly sounds like water is getting in somewhere, can you get WD40 or similar over there. Next time it does it try spraying on different electrical components to see if it cures it. It might at least give you an idea of what to replace/check.

I thought it was normal for a TC to drop an exhaust valve or more around the 100,000 mile mark - and usually after the valve started to burn out ?

Thanks everyone. Well it’s been 2 dry sunny days and nothing’s changed. I’m not sure it’s the coils as it’s not a 1 cylinder problem - would the symptoms be getting worse by now? It’s not getting worse or better. Would the unpaved road make things worse.
Filler cap and breather pipe seem fine.
Not sure what drop an exhaust valve is. Would it be getting worse by now if it was?
Thanks again

gspod said:

Thanks everyone. Well it’s been 2 dry sunny days and nothing’s changed. I’m not sure it’s the coils as it’s not a 1 cylinder problem - would the symptoms be getting worse by now? It’s not getting worse or better. Would the unpaved road make things worse.
Filler cap and breather pipe seem fine.
Not sure what drop an exhaust valve is. Would it be getting worse by now if it was?
Thanks again

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Kind of rules out the water getting in somewhere then. I hope you get it sorted soon.

Thanks. As it is it’s okay to ride but we’re getting further away from a tow truck if it stops running

with modern vehicles and german's especially on cars going all in on posh diagnostics on the end of an electrical socket (note these aren't posh) - almost everything on the road does at least this much. we often forget the basics

a compression test gives a really simple, low cost view of the mechanical state of the engine. Of course you are saying its seemingly intermittent, so mechanical things awry are less likely, bit not impossible

it will check for issues with the valve train not operating correctly, holes in pistons, destroyed rings, dodgy head gaskets etc. It should cranking a cold engine within 5 to 10 seconds hit (I guess) around 150psi on each cyl, (do one at a time all plugs out, throttle wide open), if its not something's wrong. If you get a big disparity >30PSI between pots that's not good, if one gets nothing or <90 PSI there is a big mechanical issue on that cylinder and you are going to need to understand and fix it.

Not saying this is your issue - but worth knowing and thinking about - a dropped valve means the thing has burnt out with continued use got worse and fell off or its just snapped off the end of the tulip valve due to stress (common on these at high miles). Most 4 stroke motocross bike's will snap off a valve in 1200 miles of use. It makes a horrible mess. You could have a slight bend and or a sticky valve that would get an intermittent issue. Likely I guess driven from a valve that's starting to fail

check this out (yes they are more highly tunes and with wilder cam opening but the idea is the same....) Note 50hrs use is about 1000 miles....

"Some motocross bikes can go a couple hundred hours with the valves still in spec, but that is very unlikely if you are racing. I suggest you replace the valves around 40-60 hours. Hard starting is a common indicator of at least a valve adjustment because they are tight and out-of spec."

I would be doing a compression test for piece of mind, and replacing the TPS they seem to last 30k miles each. And another common one could be a tired fuel pump and wandering fuel pressure