Hope its OK for me to ask for advice on a bike thats not mine, please delete if inappropriate. 93 900ss carb on a good 30 mile ride with me on my 888. We parked up on a hot ( 29 degrees ) sunny day and he had big misfire and dying as we rode away. He says it just ground to a stop after a couple of miles of this, fired up then ran perfectly after that ( I went home to get my trailer if needed ). Says he has been having problems like this for a while, very intermittent. We both thought fuel issue from the heat under the tank. But he's checked the filter & breather already. I thought about a coil breaking down in that heat and zero cooling .... but he says he has swapped them and it has not cured it. Anyone got an idea if that sort of heat can affect a reg/rec that's failing or even a battery on a 900ss? Are the Mikunis prone to problems with that sort of heat? Is there any other suggestions as to something that sort of heat with zero cooling air could affect ..... of course is could all just be coincidence but I thought I would ask as there is a wealth of experience on here.
so ok on start up from cold but misfire when warmed up/even worse with higher ambient temp, and slowly getting worse? firstly:- both cylinders or one? this will help a lot with diagnosis as if one cylinder then you can try several "trial and error" swaps of coils/exciter boxes etc before focusing on the Elefant that might be in the room that is the ignition pick-up. Can be the pick-up itself breaking down (symptoms fit) (non O.E.M. Electrex units work well, O.E.M. available at much higher price) or the connectors going intermittently open circuit, or shorting out, latter more common of the two.
Yep, all of what Chris said with the electronics. Could also be fuel starvation. Does the bike have the tap to divert hot oil through the float bowls in cold weather? If that's been left on the fuel could be evaporating in the bowls under some circumstances. Also worth checking all the various breather hoses are routed where they should be and not kinked. I ended up replacing the breather boxes on my M900 that a previous owner had removed, the carburation was instantly better and it no longer stalled on shutting the throttle down quickly. Nasher
Thanks guys. Will pass these things on to give him more to try and check. I shall lay awake tonight praying that I don't suffer the watercooled brommbah broombah urgh... Pfft psst phone affliction ...... at least for a while.
