Hello all. I tried searching but nothing came up that I was looking for thats simular to my fault.The bike is a 748 with a 916 sps motor, ecu, loom ect. I picked it up on saturday. Rode it 20 min and it dropped onto one cylinder and spluttering at around 6-7 rpm at part throttle. Had a look last night and the generator wires had fallen onto the header pipe and started burning through. So I replaced them. And I checked the plugs, coils, relays, connectors, battery and charging voltage ect while I was doing that (only visually). Went out tonight and all was good until about 40-50 miles and it started doing it again. Not every time but its usually around 6-7 rpm at part throttle.basically im just seeing if anyone has had a similar problem before I rip it apart at the weekend and have to go through everythingthanks in advance
Also meant to say it was damp tonight and I did hit rain before the misfire happend. But it was dry on sat when it happened
i had a very similar prob with mine. it turned out to be a faulty injector. as you know they have twin injectors per cylinder and the second one comes in at around 6-7k..its deffo worth checking out..it took about two years to get to the bottom of it and i nearly cashed my chips in once doing a chancey overtake when it decided to pack in..
i thought only the 996 onward had twin injectors?? (maybe some of the 916 sp's did as they were 996 anyway??) i had similar prob on mine and replced the HT leads for some performance ones (magnecor)
I thought only the 996 had twin injectors also? I had a similar issue a long time ago on my 2002 748. Mine was miss-firing then cutting out completely. The only thing that solved it was swapping the ECU, which actually turned out to be where some damp had got into the standard one where the exhaust chip had been changed and I had washed the bike so some had got in there. I would start at the ECU; then the Injectors, and then maybe look at the HT leads as it could be an issue when there is 'high load' going to them.
no mine has twin injectors, I was going to check it out this weekend but I went out on Wednesday night and the oil cooler decided to start leaking so I replaced that this weekend and didn't have time to get deep into electrics. tried to go out on sunday and made it 10miles before it decided to pop the fuse near the ecu (I believe its the live for the I injector and coil relays which is blowing). so I robbed my high beam fuse which got me about a mile further down the road before it went again, so I turned around to head home. 7 fuses later I made it back and just stuck it in the garage. i am going to check the wiring for the fuse blowing first (could be related to my fault of the misfire if its a coil wire shorting or injector wiring shorting) and once ive sussed that out im going to check the injectors, clean the filters in them, check coil resitances, replace the ht leads ect. So thanks for the pointers, if anything im going to say riding it at a higher speed this weekend it felt like it was bogging and starving of fuel when i got to around 120/130mph (on my private driveway) so im thinking more along the lines of injectors and as previously stated they kick in around 6-7k which i didn't know and where my problems start. Thanks again folks
Lets us know how you get on James..i will be personally staggered if a piece of technical information ive given actually ends up being some use to someone!!
Well I managed to get 15 min to look at the bike today. And after a bit of thinking. Looking at wiring diagrams and having a little mess around with it I think I may have a short/broken fuel pump live which is blowing the fuse. And also could be causing the misfire feeling when riding if the fuel pump is kicking in and out. So im going to lift the tank up when I get chance in the next few days
Yep, sounds like it is a good place to start, when I had issues with mine I could here the fuel pump re-priming intermittently and sometimes only getting halfway through, sounds similar even though drying my ECU seemed to fix it I sold the bike not long after so will never know if it truly was the fix.
Well I had a bit more of a look this afternoon and sure enough as I thought there was a chaffed wire and it was the pump live and it looks as though it was in a position to touch the cylinder head which could of been blowing the fuse. So I sorted it and took it out for a 10min blast and It didnt misfire or blow a fuse and had top end power. I cant say it is 100% the cause because i was jiggling the wiring everywhere after to see if i could get the fault up so it might be hiding the fault if ive moved something back into place but only time will tell. But its a problem that no doubt would of cropped up at some point do its not wasted time. So lets just hope and see if it remains faultless
