Hi all I'm trying to diagnose why my 900ss seems to be running unevenly, like on one cylinder. Brief video here - https://www.youtube.com/shorts/lDUMyveQY2A Spark plugs are good, fuel to both, and there is spark on both. I'm now thinking maybe it's the ignition - either the igniters or the coils? I have a spare set of coils from a 95 900ss, but they are different from the standard grey ones, and with MTA plug leads instead of NGK. I was going to swap these over - question I have is are they interchangeable, and would they cause any damage/issues if I were to hook them up? Current Coils =
Simple stuff first, give the battery an hour or two on the charger. Once started can it be revved, or does it still gasp & die?
Yes, simple stuff first. Are leads plugged into the correct ignitors? (Can't quite see your colours in the photo, I got it wrong). Mixture screw setting? Pick-up air gaps? Just a few guesses. Cheers Gaz
Thanks for all the replies Just to answer a few of the questions - Lead connections are all correct (cross checked against another running SS) The carbs settings haven't been touched, but it was running perfectly before layup. Pick up gap was checked previously, as part of an investigation into a separate issue, where the bike will only travel a limited distance before dying and requiring breakdown recovery. Tank has been drained and filled with fresh fuel. The battery is now on charge as it won't even turn over today.
Ignition problems and fuelling problems am can give similar symptoms for info. Does sound like your battery may be ropey for a start. Before you start changing stuff out, check as above and if it still looks like it's ignition, swap the coils round, and then the igniters, to see if the problem moves to the other cylinder. This will diagnose those four components quickly. Checking which cylinder is running by the heat on the exhausts.
Ok, from bad to worse.. Full charge on the battery, and now I get this: https://www.youtube.com/shorts/m16hT5Eg-YQ Swapped the battery out to a known good battery on another SS - same results. So I think we can rule out any battery issues. Also, I now seem to have a massive fuel leak issue, coming from the drain/breather tube on RHS carb bowl. [edit] I've tightened the screw to stop the leak! And while we're at it, let's throw in some dripping oil/fuel mixture from the exhaust manifold on the horizontal cylinder head! See small puddle to the right.
Hey, on that I’d take the plugs out and make sure the engine spins and it’ll blast any fuel out of the cylinders. If it’s still really sluggish turning over with the plugs reinstalled I’d be looking at the starter cables and main earth cable and starter motor. With the roughy running and fuel out of the overflows I’d strip n clean the carbs first before looking at the ignition seeing as it’s obviously firing. Hope this helps
Sounds like muck in the carbs, or possibly a holed float. Strip and clean the carbs and give the floats a shake to see if there is any fuel in one. If it’s really bad you feel the extra weight. My 750 was running, but only just when I got it. I cleaned half the Gobi desert out the carbs when I stripped them.
Thanks again. Quick update, I did remove the plugs and the engine turned over without any issues - fuel sprayed out of the front head. I upgraded the starter leads previously so I know they are good. I have lucky enough to have a spare set of carbs, so I will do a swap over this week when I get chance. I will also do an oil change, bit concerned if that is now contaminated.
I agree - sounds just like muck in the carbs, and this is reinforced by the fuel leak issue where a float might be stuck. Horrible job accessing them, I know, but would suggest it's time for these to be stripped and cleaned - pilot jets would be my first explore!
Update on the above I pulled the carbs and replaced the float valve on the RHS and that seems to have cured the issue. I'm actually getting quite good at the whole process of replacing the carbs, even hooking up the throttle cables seems easy now. It's still not running quite right. Seems to idle away ok but the "unevenness" kicks in again when increasing the revs. Also there is a new issue. Having run the engine for a few minutes, there is oil, or oil/fuel mix, leaking from the join where the exhaust pipe meets the LHS silencer. That's a concern. The pipes are also both emitting some white smoke. It really does seem to be one thing after another atm.
It's possible that with the mixture incorrect there was a lot of unburnt fuel being pumped into the exhaust from one pot which is washing the carbon deposits from the inside of the exhaust and looking like Oil. Have you smelt it?
Just fired it up today, and actually it seems to be running and sounding spot on. Waited a few mins and the dripping started again, and it does appear to be oil. So what am I into now, could this be valve/piston issues?
Keep in mind it was running ok before winter storage, so it can only be down to simpler stuff that is non-mechanical, so highly unlikely to be valve, piston issues. If it is running ok, take it out for a decent ride...then recheck, I've found that the carbies hate to be left stationary. Ps: I also get a smokey exhaust on start up, the valve guides on these models wear extremely prematurely. Mine were noted as shot at 6k. I never bothered to change them.
Whip the plugs out. The only way Oil can get into the exhaust is via the cylinders. If one is pumping that much oil into the exhaust you'll see one of the plugs looking black or even wet with oil. By the way, if one cylinder is pumping that much Oil I'd be surprised it was actually firing.
Saying that, maybe it's worth a valve clearance check anyway...then you can add new valve seals, if not already changed they will need doing by now.
I pulled the plugs and they look OK to me. They are new but even so, not oily. 7.4k miles on this bike. Valves seals sounds like an involved job..
