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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Dovafish on June 14, 2026, 11:42:16 AM
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Hello there, I am the (somewhat) proud new owner of a 1999 Ex police K1100LT here in the UK, with 39k miles on the clock. The fellow I bought it from had it sat idle for the past four years or so, however kept up with replacing filters and fluids yearly as he knows being sedentary is bad for a bike. About six months and 200 miles before I purchased it, it had new: Plugs, brake fluids, coolant, oil, oil filter, air filter, back tyre and battery. seeing the mileage, I asked if he had lubed the clutch splines, which he hadn't, but the previous owner had.
Reason for writing is that the first time I took the bike out for a proper run (two days after purchase), after about two hours on the road, it started cutting out under power at certain rpm ranges. I first noticed it when giving it the beans in second, when it hit 6k it kind of 'coughed' and removed all power for a second, then carried on, albeit with the brake light warning triangle illuminated. Ever since this, it has been spluttery between 3k and 4k revs, with the tach needle dipping whenever the engine has a momentary loss of power. Other than this, no other electrics seem to have been freaking out, other than the red warning triangle, which now won't go away when I touch both brakes, and will stay on until I bring the bike to a halt and power cycle it. In some hears (mainly third), it will lose power over 6k rpm, almost like it's hitting the limiter, but rougher. Whenever there are these dips in power, some mighty backfires will come from the exhaust... I've had a look at the fuel filter which is dated 2007, and ordered another out of principle - however unsure if it could be a fuelling issue over an ignition problem, the backfiring suggests an inconsistent spark to me.
Here are two videos of it happening, firstly of me in fifth gear maintaining between 3k and 4k, notice the needle dropping and the camera shaking as the bike lurches. I am under a constant cruising throttle here.
https://www.youtube.com/watch?v=Soa6iAfUXAE
The second video is of me in third gear, then giving it wide open throttle, as if on a motorway slip road or overtake, before the engine tops out at 6.5k rpm, stops giving power and backfires loads.
https://youtube.com/shorts/50psWyUDWXo
It isn't in every gear that power delivery tops out at 6.5k, first and second hold on a bit higher before the issue comes into play. (didn't test how high fourth and fifth would go for obvious reasons)
I'm baffled as for the first two hours of this ride it was performing perfectly, it seems a rather large issue to just come on out of absolutely nowhere. I let the bike fully cool down in a Tesco car park before limping it home to test if it was an overheating hall effect sensor, which made no difference. As far as I can tell from the manual, the red warning triangle on the dash is solely for brake light or ABS failure, both of which I tested to be working fine while the lamp was illuminated.
The seller was a genuine bloke and had MOT evidence to show that the bike was suffering severe lack of use compared to his other bikes, and that it had been taken care of as much as was reasonable for a garaged bike.
There seems to be other people having similar issues, although none identical to mine, and they all seem to have vastly different solutions, even down to something as unrelated as the sidestand switch. This is my first bike with any kind of technology on it so I'm in pretty far over my head.
Any help welcome
Tom