UK Monster Owners Club Forum .: Technical :. Engines, Clutch, Gears » Unpleasant jerky lurchy ride sensation

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Old 13-03-2020, 08:41 PM   #1
MrsC_772
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Unpleasant jerky lurchy ride sensation

I fear Primus, my 10 1/2 year old 696 is once again punishing me for its lifestyle of year round commuting and big mileages. (Current indicated mileage 77756, though it has done around 1000 more due to the 3 times when the speedo sensor failed and didn't record every mile!)

Since Christmas, I've needed a new throttle cable (after a slightly scary ride into work when the revs started running away with me even when I closed the throttle), it had a major service (including valve clearances, belts, and also needed belt tensioning bearings replacing for the 3rd time in its life). Then on the ride home from Snells after the service, the engine warning light came on, which turned out to be due to the throttle position sensor having failed. An after market TPS was then fitted (due to the official Ducati one costing at least 4 times the price of an aftermarket one from a German company via eBay).

Two weeks of happy riding were then followed by a horrible feeling of seasickness on board. It feels like I'm lurching backwards and forwards. I must look like a dashboard nodding dog! I'm not getting smooth power delivery through to the wheels. It's a bit like the jerky feeling of trying to ride at 10 mph without holding the clutch in, but at all speeds, in all gears, at all rev ranges. The sensation is not just when I wind open the throttle, but when I'm holding it at steady throttle, or even fully off and decelerating. The indicated revs don't seem to be going up and down in line with the lurchiness.

I'm getting some vibes through my feet - I did wonder whether it might be chain & sprocket related (vibes through feet having been a symptom of a saggy baggy chain in need of replacement). While the C&S are well worn, and will need replacing next time round, I've seen worse (as have some of the UKMOCers on here who saw the state of my chain at a previous Weekender).

It misbehaved in this way for about 3 days, then behaved again for another couple of weeks, and then I had a ghastly day's commute on Wednesday with it worse than ever.

Someone Andy spoke to wondered whether could be fuelling related - maybe the fuel pump is on the way out or fuel filter is blocked? But the fact it behaves like a bucking bronco even when I'm not winding open the throttle made me query this.

The problem did not start immediately after filling up (so I don't think it's a dodgy tank of fuel). It had started before I filled up, and continued after, went a way and then came back halfway through a later tank. Normally it gets Shell ordinary, with the odd tank of Tesco or Texaco, depending on when the light comes on. It has never been happy with super unleaded.

While fuel economy hasn't been great of late, it hasn't developed the same horrible thirst as when the vacuum hose on the throttle bodies split. There is a faint whiff of petrol around the bike.

Any suggestions as to what might be going on and what can be done about it gratefully appreciated. I don't like getting my hands oily, but I'm also getting fed up with large garage bills draining my savings. My dream of getting it to 100,000 miles is starting to look more distant.

I'm starting to think I may no longer be the right owner for this particular bike, and it might be time to find it a good new home with a keen amateur mechanic who would like a cheap Monster and who would be happy to do all their own servicing & maintenance, tinkering and troubleshooting. I doubt anyone looking for a Monster on eBay would ever choose mine if there were any others out there on sale. (If it isn't the highest mileage Monster, or at least 2nd generation Monster, in the UK, I'd love to hear from whoever has a higher mileage one!) I still have, and today enjoyed riding, Secundus, my 7 year old shiny low mileage 696 - I could never be happily Monsterless, but Primus is starting to try my patience and bank balance.
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Old 13-03-2020, 08:47 PM   #2
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check the plugs, maybe change them if that doesn’t help try the coils and ht leads from secundus
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Old 13-03-2020, 09:00 PM   #3
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Thanks Slob. Plugs were replaced at the service in January, since when it has done only 600 miles.

Given that both Andy & the mechanic at Snells who serviced the bike in January commented on how horrible, swollen & corroded the front coil is looking, sounds like it's worth investigating the coils as a starting point.
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Old 13-03-2020, 09:09 PM   #4
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looking at the plugs costs nothing and might show a problem on one cylinder. the front lead and cap are in the firing line for a lot of water and other crap. having another identical bike makes substitution of parts a cheap (if time consuming) way of eliminating problems. snells are reputable, so won’t have skimped on fuel filter changes. fueling and ignition can be hard to differentiate from symptoms. previous models had problems with igniter circuits failing due to vibration on marelli 5.9 ecu but i’ve not (so far) heard of similar problems on the siemens units on 3rd generation monsters.
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Old 13-03-2020, 09:30 PM   #5
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Although you've just changed the TPS, I wonder if it's nevertheless worth performing a 'hot' TPS reset. Start the bike from dead cold and allow it to warm up until three bars show up on the temperature gauge without touching the throttle. Then turn it off.
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Old 14-03-2020, 09:25 AM   #6
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Rob's suggestion of substitutions to eliminate the plugs, leads and coils is definitely the way to go, but only one thing at a time, or you won't know which bit was faulty.
I would be very suspicious of the TPS as Luddite suggests. I think a TPS fault could well produce the symptoms that you describe, but I would not try and substitute that from your good bike, rather try everything around it to isolate it as the culprit... You don't want to be messing up your good bike after all.

Thinking on.. It could also be a dirty or faulty injector(s)
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Old 14-03-2020, 06:01 PM   #7
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The swollen coil seems ominous too ??
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