Bike Lurching/Surging/Coughing Problem - Help!!
 

So my 2002 900ss is playing up big time.

It has developed what can only be described as a surge or cough when under power. No other way I can describe it really. Usually, whenever the revs get close to 5,000rpm and above, there is a sudden, short loss of power, then it picks up again. Sometimes this will happen once in a while, every mile or two perhaps. Other times it happens almost constantly.

I've tried to figure out if it happens when hot or cold, doesn't seem to matter. Tried to figure out if it's with full or empty-ish fuel tank, doesn't seem to matter. Tried to figure out if it happens at different rev ranges and usually it is between 5k and 6k rpm, but this morning it was particularly bad and happened all the way from 3,000rpm upwards.

So far I have done the following:

- drained the fuel tank totally. And there was a significant amount of water in the bottom - about 1 inch in the bottom of a 1 litre plastic drink container.

- change the fuel filter. Did both of these at Cadwell on Tuesday. I had 15 trouble free miles on the way home, before the problem started again.

- Changed old spark plugs for new. Fortunatelly my 900ss and my DD bike use the same plugs and I had a spare set.

- Put the standard pipes and airbox back on. The problem was still there, just that the "buck" of the bike didn't seem so bad with the standard pipes on.

All of the above has been to no avail. Problem still happens.

Someone suggested that it could be my potentiometer, but the SS ECU doesn't have one.

I'm supposed to be riding to Normandy on Friday evening for the bank holiday weekend. However, at this stage I'm not sure the bike is up for it. Looks like my weekend could be stuffed.

Any ideas? I guess it's too late to get it into a workshop now, but is there anything else I might try?

Help!

Fuel tank breather partially blocked??

Now there's an idea........

I had this blocked once before and it caused this:

http://www.kapital-sales.co.uk/desmo...Tank%20001.jpg
http://www.kapital-sales.co.uk/desmo...Tank%20009.jpg

I'll check the breather pipe because I did notice this afternoon a "hissing" coming from around the fuel cap. I did think perhaps it was something I'd done in not putting it back together correctly after changing the filter.

Any thoughts on the best way to clean/clear the breather?

Cant remember how the breather is routed on the I.E bikes,but when my wife had a carbed SS,I cleaned out a blockage by pushing a lengh of 4mm electrical cable down it.

Oh yeah,I remember those pics.Incredible!

Errrrr...you weren't copying me were you?

I had exactly the symptoms you described on my ST2 for the whole of the first morning at Cadwell.

I changed the fuel pump, fuel filter, spark plugs...cleaned up the usual green connector suspects, drained the tank etc... almost exactly what you did.

I checked all the breathers as well, Still can't crack it :(

Pity, cos when it clears and pulls hard it's going like a train, better than I remember it ever going before.

thought about the TPS, but like your problem it seems to happen across the rev range not at a specific spot.

I'm gonna replace the battery next, because the battery is not holding it's charge. It's OK when you take it off charge, it'll start the bike no problem and it'll start the bike all day after that, but leave it overnight and the solenoid is clicking...I have a theory that if the battery or charging circuit is stopping the right voltage to flow across the TPS, or not providing enough voltage to the ECU then all sorts of crazy stuff could be happening to the fuelling or the sparks.

Don't know if this theory would explain why it's worse round right handers though :puzzled:

OK, maybe I'll try a twisted piece of lock wire or similar. Thanks for that.

I should also mention that I spent some time this evening checking that the fuel line wasn't kinked anywhere, thus reducing the flow of fuel.

Any further ideas?

how about getting it plugged into a diagnostic machine in case its a sensor of some kind.
The guys from MotoRapido were kind enough to plug theirs in to Dallas's bike on Monday at the trackday and it revealed a rpm sensor fault.

I dunno about SSie's either but on the ST the breather is a little round can about the size of a 10p piece and about half as deep with an air inlet sticking out the side. It's a one way valve and it sits on the bottom of the fuel pump assembly.

Bugggerit...if I'd known they had one of those at the trackday :( :( :(

Well, I was hoping you'd reply with the solution ;-)


After I'd changed the plugs the engine somehow seemed to sound "crisper." Might have just been my imagination though.


I'll be honest, put my hand up and say I've tried changing the TPS (Yes I am that desperate) - quarter of a turn one way, quarter of a turn the other. No change to the overall problem, so the TPS is back where it started now.


My battery seems to be holding charge, as I don't have any starting problems. I did check that the connections were all fine though. Maybe I should try and find another battery just to check. Could be a busy day tomorrow....


Mine happens mostly in a straight line, but then again I'm extremely tentative in the corners at the moment because I don't want to get thrown off the bloody thing!

Had similar issues before on a 900SS was an HT cable breaking down under load, finally traced it by spraying water onto leads via a greenfly killer in the garage in the dark and seeing the break down, I know 'how those long winter evenings must fly by', but bl**dy found it eventually !!!

Yeah, I've just had a little swear too.

My main problem is that I don't have the time to get it to anyone with a diagnostic machine before I'm due to catch the Eurotunnel on Friday evening. So, I'm prepared to try everything I can myself at this stage!

Maybe a diagnostic machine is the only way to go......

Perhaps I'm being ignorant - very possible - but I don't quite understand. Please excuse me, but what is an "HT cable" and how did spraying water on it in the dark help you to see the break down?

HT cable is cable that goes on spark plug, you can see it arcing to heads or frame depending where the insulation is breaking down, hence it discharges there and no spark at plug = misfire tends to happen under load and more if damp.

OK, great, now I understand. I'll check the insulation around them tomorrow at least. Thank you

I know this may sound bizzare but:

If you can take it for a ride in the dark with the side panels off you will see the arcing very easily if the insulation is breaking down, alternatively as a very short cure bind the HT cables with insulating tape, but the tape will also fail soon if the cable is breaking down.

Also had this happening with a Subaru when under full boost, more difficult to see in the dark tho'.....lol

Cheers

If it works for 3 days over the weekend in France, I'll be very grateful. So, I'm going to try this anyway.

Someone has suggested to me that the problem might be the engine temperature sensor on the front cyclinder. They only knew about Monsters but thought Supersports might be the same. Apparently this sensor can be "fiddled" with to run a richer mixture.

Anyone know more about how to do this? Or if indeed it's worth doing?

OK, so I took my bike into the Ducati Proteam and Wimbledon. I needed to get things fixed quickly and I wanted somewhere close to home, so I chose these guys for the first time.

Just been on the phone to them and apparently my "trimmer" was set to -55 which has leaned the mixture right out. They've reset it to -10 (factory setting is 0 I believe) and the bike is running fine.

Can anyone tell me what else a "trimmer" might be called and what it does/how it's set etc???