1989 900 Supersport running on one cylinder

[Mc tool]

and what ever else the kids have stuck in there over the last 12 months.
Nick.

Ha ha my Dad bought his 1st brand new car................ and I ( as a 4 year old ...............yeah , I started early ) managed to get most of the gravel off the drive way into the tank , my next brother , some time later filled it with grass cuttings , and the youngest put the garden hose in there when it was his turn. Dad still changes colour when we bring this up

[ducinthebay]

If you ran the tank almost empty, then you may have picked up some water out of the tank and put it into the carb. Can you drain the carb? I don't have a Weber to see if there is drain plug. Follow with a bit of Sea Foam and go for a hard run.

Cheers, Phil

[Derek]

If you ran the tank almost empty, then you may have picked up some water out of the tank and put it into the carb. Can you drain the carb? I don't have a Weber to see if there is drain plug. Follow with a bit of Sea Foam and go for a hard run.

Cheers, Phil

Worth draining the carbs anyway but running the tank near to empty wouldn't have made it pick up water any more that if the tank was full. Water is heavier than petrol and sinks to the bottom.

[Mc tool]

Yeah but , as the level gets real low the remaining fuel starts to really slosh around stirring up all the shit ( inc water ) , mixing it all up and it goes out with the fuel

[bmw851]

Can you clarify that a bit more, as I'm reading it, if you leave the choke on it continues to run on 2 cylinders? and only cuts to one when it shut off.

Again I say fuel starvation, and what all the boys are saying in various ways, is clean out the carb, jets needles, float bowl etc. before paying someone what may unnecessarily do what is a fairly I think on a webber simple bit of maintenance, fella's is it?

Cheers

Peter

[Mc tool]

Yup , probly got a lump of shit in one idle jet .

[ducinthebay]

Yeah, Pull it apart, clean things up, probably needs a new fuel filter anyway. I'll go with the clogged idle jet. Runs really bad with that clogged.

Cheers, Phil

[paso750]

if it runs on both cylinders at higher rpm it`s not a clogged jet. Usually that`s due to a voltage drop at the coils. As soon as you raise rpm and voltage increases the non firing coil starts working and the second cylinder kicks in. My bet would be on that.
I`d rule out the simple things first before taking the carb apart.

[TheDuctor]

Thanks for all the advice guys. The bike went into the shop yesterday as I dont have the space at the moment to work on it myself. Its all sorted now and the diagnosis was........drum roll..............water in one of the carbs. The tank was drained, but no water was found in there and the carbs were cleaned out fully aswell and everything is hunky dory.

[paso750]

water in one of the carbs

So you don`t have the original Weber ?

However it`s good it`s working now

[TheDuctor]

They did specifically say it had the original Weber

[TheDuctor]

Well guys, turns out everything wasn't as hunky dory as first thought. I picked the bike up last week and as soon as the mechanic bought the bike out it was clear that it was still running on one. I was assured it was on two and that it just needed a good run to bed in and the 25 miles back home would sort it. Despite having paid out to have the carbs drained, cleaned and balanced. At 4000rpm and a steady throttle it was misfiring and coughing and splutteting like a pig, but at higher revs and a good crack on the the throttle she flew. So I got home, removed the rear plug cap and she cut out. Statted her up, removed the front cap and she still ran. Rang the shop up and was told maybe we shouldve taken it out for a test ride! This from a Ducati main dealer!! So, my finger is pointing squarely at the coil, but can anyone tell me please what model is compatible with my old girl as trying to find one is proving to be a nightmare. Thanks again guys.

[paso750]

I did wonder about that repair as the Weber has only one float chamber and water in it wouldn`t explain why the bike runs only on one cylinder.
However, swap the coils to see if one is really defective and do finally measure the voltage at the coils !

G.

[TheDuctor]

Thanks G. I'm going to nip out to the shed once the rain eases up (good old English weather lol) and take a look. Unfortunately I dont have anything to measure the voltage but I'll try swapping the coils over.

[lane1feathers]

Rang the shop up and was told maybe we shouldve taken it out for a test ride! This from a Ducati main dealer!!

...and this is why I fix mine myself (and why I rely so heavily on this forum )