Hi All, My 916 has been on a trickle charger for the past few weeks (as is normal and has been during its previous ownership). I took the bike out today for a run. I let it warm up before setting off. This involves holding the throttle open slightly as even with the idle button depressed, the bike stalls at idle when cold (and only very occasionally this continues when it is warmed up). I may need to adjust the idle screw to resolve this. Other than this I've not had any problems with it running poorly up until now. I got the bike up to temp around the 80 mark after a short distance, although it did rise to 100 in traffic. On a few occasions, the bike stalled at idle, refused to start and backfired as it caught then stalled again. The throttle position then seemed to become unpredictable at low revs as I was pulling away. I was able to open the throttle more than the normal amount to pull away with little or no increase in revs, only for the engine speed to suddenly rise sharply to meet the corresponding throttle position. This only happened at low engine speeds. It seemed like something was holding the engine back only for it to clear and allow it to leap back into normal running. The engine also sounded different at these points, like it was running roughly. When I finally managed to coax the bike home I switched off the ignition and the bike let off a loud backfire. The bike has been serviced according to schedule and has been running fine as recently as a few weeks ago. It has the originally supplied termignoni system and chip on it at present. It has had the reg/rec with the heat shield fitted at some stage if this is relevant. I'd appreciate any help in trying to narrow down what might be wrong. In addition, when I got home I looked over the bike and saw that the clutch plates and basket may be worn. This is my first dry clutch bike, so I'm unsure about what constitutes normal or extreme wear etc. The basket tabs look notched where the plates are hitting it and the plate edges have a lip to them. Unsure if this is normal or not? Pics of the clutch attached.
It could be running on one cylinder due to flooding, the backfiring could be the bike chiming in and then burning the fuel in the exhaust. Check for a spark and see if the plugs are ok and showing a good strong spark. I had a similar problem recently after my 748R stood for several weeks, one plug was fouled and the bike exhibited the same symptoms, once cleared it was fine. I also changed the temperature sensor that connects directly to the ECU, which in turn enrichens the fuel when cold, as I suspected it was not delivering a clear signal and the bike was still running rich after it had warmed up possibly causing the plug to get soaked and killing the spark. There is clearly some wear on your clutch plates, the best thing to do is to strip the clutch and check the tangs on both sets of plates are within suggested limits. Is the clutch bell steel or alloy? and do you have matching steel or alloy friction plates. Alloy plates in a steel hub and vice versa can cause more wear on the plates or the clutch outer.
I was so busy concentrating on getting the thing out of traffic and home earlier that I didn't pay a great deal of attention to the difference in the noise the engine made, but now that @Red998 mentions it, it could well have been running on one cylinder very briefly. Would it make sense for the bike to do this as result of flooding if I had been trying to start it several times in a row before moving off? Re the clutch - I believe the parts are all standard with the exception of the pressure plate but can't be sure. It looks like they are probably both similar material as both are showing similar signs of wear.
If it is flooding yes, as the engine picks up it is less obvious and just seems to have lost power. In serious cases bore washing takes place and the cylinder then sees extreme wear as the fuel washes away the oil in the bore. How many miles did you do like this. I know of one bike that had this for 50 miles and the bore was finished. With regard to the clutch check the admissible wear and then see what your measurements are. Hope this helps
Thanks been a great help as what you are describing seems spot on compared with what I experienced this am. I think I did about 4 miles total, otherwise might have gotten it recovered as I had every catastrophic scenario for the engine running through my mind on the way home!
You should be fine, check for a spark on both cylinders as at least it will be burning some fuel. Also check that even a wet plug is sparking I did 5 miles on mine and cleared it by revving flat out to the limiter and then as soon as I moved off it cleared. I use Champion QA55V plugs which are very cold. Might be worth looking at some new plugs. Tuned engines like the SPS need to run at full temperature to not run rich or plug fouling can occur.
Clutch looks a little worn,but have seen a lot worse.Unless its giving you probs,I would ignore that.As for your misfire,I would do the cheap bits first.Plugs being No1 on the list.Good luck.
Thanks for all the advice, have ordered plugs and will go from there. I'll leave the clutch just now as it is functioning fine.
After investigation, the bike was found to be fitted with surface gap racing plugs, both of which were sparking fine. The front cylinder plug was over tightened as indicatedby the crush washer being thinner than on the vertical cylinder. The plug was a bit damp and appeared to have been overheating, causing the engine to then drop onto one cylinder. New pair of Iridium NGK plugs now fitted. I had the TPS throttle bodies and fuelling set up at ERS racing, Knockhill, (where I received excellent service) and the bike now starts, idles and runs as it should and the fuelling has been vastly improved. Fuel system cleaned through as well. Clutch upon inspection is not as worn as it appears and is posing no problems so I will leave that until it requires replacing then may upgrade it for something swankier at that time. Thanks all for the suggestions and advice.
