Bike not starting! backfire, please help!!

[Guest]

Hi,

I was riding along on my bike yesterday, and it cut out as if there was no fuel. The bike died and would not start again. I tried jump starting it and it just backfired and died out. I have cleaned the carburettor out since then and also checked the spark plug. None of these helped.

All the electrics are working and the electric start will just not catch the engine. The bike is a yamaha sr 125 1992 model.

Please help me!!!

Thanks in advance

[Horseynat30101]

have you checked theres no air going into the carbs? this was a problem on my mums trike, we just tightend the jubilee clips on the air filter and it since stop backfiring.

hope this helps

[Guest]

is the plug cap on tight...

[Guest]

thanks for your replies i've checked the air flow, everythings fine there, air filters not blocked and theres plenty of fuel getting to the carb.

As for the plug cap, i'm not sure what one is!

My friend thinks it may be a problem with the engine timing however i've no idea how to check this or resolve the problem

[Guest]

if it ran ok before and you've not done anything major it won't be the timing...

plug cap, the thing that fits ontop of the spark plug and provides the electrical impulse for the plug to spark. also check plug/plugs, for fouling (haynes do a good guide in the back of a manual) or if its new, did you gap it? or just bung it in and hope for the best..

[Bill_on_a_bike]

You checked it makes a spark atall? I wonder if the coil's died.

Take the plug cap off, take the plug out, put the plug backin the cap, hold the nut of the plug against the fins on the engine (holding it by the rubber cap so you don't get zapped). Then turn it on and hit the starter motor. If all's well there should be a visible spark between the electrodes. If not something's wrong.

Coil is an easy cheap fix so don't worry!

[Guest]

Hi,

yes i have checked the spark plug, and there is a definate good spark so the problem is definately not the electrics. I also replaced the ignition coil a couple of months ago so i'm pretty sure thats fine. Tried starting it again today and still nothing

[Guest]

well if you have spark, and have fuel getting through, i would suggest that you may have a bent valve, happend to me with a GS125es..... basically, no compression, as the valve isn't opening/closing as it should...

might want to have a workshop have a look over it..

[Guest]

just checked the compression now, i dont have a psi meter but i put my thumb over the spark plug hole and there is next to no compression. Does this mean it is a bent valve? and do you know how much it would cost to fix? thanks