Very odd problem

[Brett]

While taking my bike (94 ZXR250C) out for a ride tonight, i noticed something odd. Well it was acutally hard not too notice.
In first gear ( and ever so slightly noticable in higher gears) if i open the throttle while at low rpm, i.e pulling off form a set of lights at full throttle, i get to about 4000rpm and the thing starts miss firing like its gonna blow up, then once it hits 10000rpm it pulls off like it has a rocket up its ass.
So...missfiring low end, and then insane top end. I havent yet pulled anything apart to have a look, but is there anything in particular to look for?
The bike sits outside so gets rained on, could it be due to water damaged electrical points??
It started all of a sudden, i rode it yesterday with no probs, but today all of a sudden it did it.
Sucks, cause i can't safely lift the front off the ground on my favourite bump now!!
Any help would be great.

Cheers,

Brett

[FROSTY:Me]

water in the electrics.crap in the carbs

[Lou Girardin]

water in the electrics.crap in the carbs

You sure it's not carp in the carbs? There's a bit of it going around.

[WRT]

Does sound a little fishy

[Brett]

Yeah i am not too sure. It appeared to be a bit better this morning, but is still there.
How easy are carbs to clean without messing the settings up?

[Sniper]

I had that problem with the CBR, I went to the extreme though and changed my plugs and that sorted it out. It may be a lead or anything like that.

With carbs, buy carb cleaner and spray it into the carbs while trying to avoid all rubber seals ect.

[N4CR]

I usually get that problem running 91 or a 96/91 mix with too much 91 or when the fuel gets low and the shit vacuum system on the zxr goes nuts, (eg start running out with 2L left) ask John about that problem as he has figured it out.. It goes away after a while usually. Mine happens around 8k and then at 10k, then it will go. It has happened mabey 15 times ever.

Could also be crap in the fuel.

[Brett]

I generally only run 98 in the bike...i suppose it could well be a crap batch of fuel. It is at the tail end of a tank of gas, probably about 2/3 litres left, so i might go fill up and see if that helps.
Sniper - i think that you might have a good point, will have to check the spark plugs and leads too.
I will pull the fairings off later on and see what may be up.
I dont think it can be crap in the carbs, i have only run it dry once, and that was months ago...but hey, you never do know do ya.
The odd bit about it was the amazing amount of top end suddenly developed...it has never revved that well before now...

[N4CR]

I generally only run 98 in the bike...i suppose it could well be a crap batch of fuel. It is at the tail end of a tank of gas, probably about 2/3 litres left, so i might go fill up and see if that helps.
Sniper - i think that you might have a good point, will have to check the spark plugs and leads too.
I will pull the fairings off later on and see what may be up.
I dont think it can be crap in the carbs, i have only run it dry once, and that was months ago...but hey, you never do know do ya.
The odd bit about it was the amazing amount of top end suddenly developed...it has never revved that well before now...

It probably got starved so ran a little leaner and went quicker, mabey it is running a little rich. Is your fuel economy very good? Eg at least 17km/l or so?

[WRT]

Check your oil level as well. On my old GSXR400 when I got it back from the mechanic after a service it was going like a cut cat. Couldnt believe how well it was going, turned out the dude hadnt put in enough (possibly any) oil . . .

Needless to say, it wasnt going so well for very long. Cant have been cheap for the poor bastard to fix either . . .

[FROSTY:Me]

drain ya carbs in place-just undo the drain screws.
Id be checking the plug leads and ignition pickups for water in em.

[Ixion]

Water in the works.

[Brett]

Well, i am led to believe that it was the fuel vacuum thing, tho it has never happened before.
Was riding home from work, when it decided to splutter and die going up pakuranga rd there by the mobil. Turned into a side road and wheeled down to the servo thinking perhaps i was out of gas, but no...had 3 litres or so left. Once i filled up, i pulled onto the road agan, and what a difference...no spluttering and has run sweet since...most odd. I think it may have something to do with running it with reserve open or shut, i normally ride with reserve open and just remember when i need to fill up, but i was experimenting the last few tanks of gas with reserve on hold to see how much i got with the bike not using it up.

Who the hell knows...

[F5 Dave]

For a starter try taking the tank off & draining it completely. Then take the connections off the tank & check the filter, it may be clogged on the reserve pipe. There may also be water in the bottom which will only come through on the reserve.

Some meths can help absorb the water so it burns, else it gets trapped in the bottom of the carbs & causes spluttering until it eventually works out if you’re lucky.

[ducatilover]

Check your oil level as well. On my old GSXR400 when I got it back from the mechanic after a service it was going like a cut cat. Couldnt believe how well it was going, turned out the dude hadnt put in enough (possibly any) oil . . .

Needless to say, it wasnt going so well for very long. Cant have been cheap for the poor bastard to fix either . . .

same happened with my gn, it was going like a dead cat not a dead buried cat, so the old man told me to check the oil and it was below empty. just a month after i bought the fucken thing.......