I own an 06 Scorpa SY 250 which has had very little use. When riding in the woods today It cut out and would not start again. When it tried to run it would not rev and would backfire then stop. I had been riding in a very shallow stream during the ride out.

When i got home, I took off the petrol tank and removed the air filter to check it. The bike started first kick and ticked over fine. Maybe someone could help with the following.

1) Would I be right in thinking that it was an electrical problem caused by water if so what can i do stop it happening again.

2) I also noticed that my coolant level dropped. Is this normal after a few hours of riding or could the head gasket have gone?

thanks.

Make sure you hadn't pinched either the fuel line from the tank to the carb or the fuel cap breather tube when last fitting the tank as either will restrict the fuel flow to the float bowl and produce similar symptoms to those you describe. I know of a couple of instances where this has happened on a SY so it is a possibility.

change your gearbox oil that should tell you if the head gasket has gone

The engine oil will tell you if the waterpump seal has gone but not the headgasket, its a two stroke remember. did the electric fan work ok ?

coolant can drop if you over fill them as you are supposed to leave a slight gap between coolant and the top of the rad to allow for expansion.

try a new plug cap andf check that the wiring hasnt been hitting the cylinder

change that too I am stupid! did think just as I posted it but ah well

Thanks for your advice... another thing, would the bike start and tick over ok if the head gasket had gone? Thought that any water would make it run like a bag of nails...

It's only a thought but I stalled mine a a very cold stream last year and couldn't get it to go.

I pushed it out of the section and kicked and kicked until I was close to having a heart attack.

My mate then came by and offered a fresh leg. He felt the cyclinder head and said it needed some choke as it was cold.

I told him not to be so stupid as I'd been kicking it for ages and there must have been plenty of fuel in the cylinder.

He ignored me and put the choke on and the damn thing started first kick.

I think the cold water had simply cooled the bike right back down.

hqd a yam enduro bike that would stop dead if it rained never mind went near water turned out the insulation on the HT lead had broken down ( although it looked fine) and a new lead sorted it

my advice would be though that if its running OK now LEAVE IT ALONE dont touch it until it does it again then do one check at a time until you crack it,

good point

the HT lead on the Scorpa gets nipped between the barrel and the petrol tank, if its got hot previously this may have damaged the insulation. Check this and re route it anyway while your on, turn the coil the other way so that the HT lead comes out from the top, you will need to extend the single black lead from the CDI.

Thanks for your help and advice. The bike seems to start fine and run ok now. I will check the route of the HT lead in future. Matter of interest.... will the engine get hot enough of tick over to cause the fan to switch on. Also is there a way to test it as I am still concerned about where I lost the some of the cooling fluid as there is no visable leak.

Mark.

you can test fan by simply shorting out the two wires at the bottom of the radiator with the motor runing. it will get hot under tick over but it will take a long time for the fan to kick in.

also i doute you will have done the head gasket unless you really cooked the motor,remember its a yamaha motor and not as fickel as some other brands you see on here.if water was leaking from there i cant see how it could get into the combustion chamber as as pressure from the cylinder would usally push things out not suck them in. head gasket is about

you can test fan by simply shorting out the two wires at the bottom of the radiator with the motor runing. it will get hot under tick over but it will take a long time for the fan to kick in.

also i doute you will have done the head gasket unless you really cooked the motor,remember its a yamaha motor and not as fickel as some other brands you see on here.if water was leaking from there i cant see how it could get into the combustion chamber as as pressure from the cylinder would usally push things out not suck them in. head gasket is about

I am still concerned about where I lost the some of the cooling fluid as there is no visable leak.

Mark.

It could of just been an air lock in the system which cleared so the coolant level then dropped

connecting the terminals tests the fan motor works but doesnt test the thermstat which is a weakness. Take the bike up a fast track gently, dont cane the motor in case the stat has failed but 5 mins of moderate speed should get the fan going. if its starts pinking badly or spitting out coolant and the fan isnt working stop the bike, let it cool down and replace the stat when you get home.