running problem - as if running out of petrol

[Nick8529]

Hi,

I have been having a bit of problem with my bike. It has been running with really low revs an is really jerky as if it is running out of petrol but there is plenty petrol in. The engine sounds really rough and is shaking alot. I had to have the throttle open quite far and every so often it will suddenly go back to normal and because i had the throttle open far it would suddenly shoot off. Then the revs would drop back down again and would die if i didnt keep the revs up.

I have got no idea what is wrong. at first i thought it could be out of oil but there is loads of oil. When this happened it was raining quite heavily so i thought that might have something to do with it but it is dry now and it still has the problem.

Thats all my ideas so if anyone could tell me what the problem could be and if i can fix it fairly simply as i dont have much knowledge about bikes that would be great!

[starks]

im having a similar problem at the mo pal, dont know wat it is yet sorry but when i find out i'll be able to give you a heads up to what it could possibly be

[monkimagic]

sounds like a trapped vaccum hose, have you had the tank off or poked about under there lately.

or a fuel feed problem

or

[Scoobs]

....or water in the fuel.

[Nick8529]

I had a look under when the problem started but not for a while before the probelm.

Anything i can do if there is water in the fuel? or am i going to have to run it till its dry and refill it?

[maviczap]

Make surec that the drain hole under the filler cap is clear so that if it is raining hard water isn't getting into the tank via this blocked drain. Think it's a problem on some curvy's.

Make sure its not the front spark plug getting wet either, as mine was a bit like this before in the wet. Cured with a fenda extender & a bit of silcon grease round the front plug cap. WD40 on the spark plug & make sure the drain on the front cyclinder is clear as well, otherwise the water can't get out

And you could check to make sure that all the vacum & petrol pipes haven't perished and letting a tiny amount of air in somewhere. I had a car do this to me once

Do the spark plug first, as this is a common problem on Sv's in the wet for some, but not all

[Nick8529]

If it was the spark plug would it not work fine when it was dry?

[yorkie_chris]

Wet front plug I reckon.

Water takes a while to dissipate.

[maviczap]

Not if the drain hole is blocked and the spark plug is still damp. Mine took ages to get back to normal, even though I'd sprayed loads of WD on the plug cap & spark plug

[maviczap]

Wet front plug I reckon.

Water takes a while to dissipate.

Thanks YC +1

[yorkie_chris]

You can shoot some WD40 up the drain hole with the straw. Works a treat, who'd have thought it was a water-dispersant :-P

[Nick8529]

Ok i will give that a go tomorow

I will keep you updated on if it works or not

Thanks for your help.

[maviczap]

If it is the front s/plug, then make sure you get a fenda extenda for your model, otherwise you're going to have this happen regularly in the wet.

Plus its flippin scary & dangerous if the front keeps cutting in and out, as I found out the only time it happened to me

[vardypeeps]

Wet front plug I reckon.

Water takes a while to dissipate.

+1 :smt023

[boot]

You can shoot some WD40 up the drain hole with the straw. Works a treat, who'd have thought it was a water-dispersant :-P

That's because 9/10 people don't actually know what WD40 stands for.

+1 for wet plug, I had what sounds like the same issue (http://forums.sv650.org/showthread.php?t=140539) not so long ago. It takes a while to 'burn' it off.

Start bike and keep revs up for... a good while, and all should be swell after a bit.

[MrMoonface]

Had the same thing happen to me this weekend. Scary! When you've taken the plug out and dried it off try putting a bit of vaseline around the top of the plug cap to stop the water getting back in. Works a treat whilst the fender extender is on the way!!

[yorkie_chris]

Yup you can slather some grease around the cap to seal it.

[Owenski]

Cheers boot :) saved me posting the same link.

+1 to what most have said.

[punyXpress]

Hesitating :
a ) Choke not fully opening - either plungers & cables need greasing OR Operator Error
b ) Carb icing - even relatively mild mornings can have this if moisture levels are right for it.

[Nick8529]

the problem seemed to sort its self out so i think the spark plug had ebough time to dry. but i sprayed some silicone spray around it when i had the lead back on to protect it but it seems to have started the problem again. I am going to take it apart this weekend and give it a proper clean and a dry. Hopefully that will sort it out.

[Taipan]

My SV deffo displayed carb icing symptoms this morning.