South West Bikers | Motorcycle Forum

hi there i have a zxr 400 thats started being abit of a problem,,,i can goto it when its cold and start it us straight away but when the engine's been started or its warm and i stop it,if i try starting it up again straight after theres no joy,,it turns over but wont start unless i leave it for a while,now ive been told a number of things but ive been talking to a guy that knows quite abit about bikes and hes said it must be the CDI could this be the problem with the symptoms ive got,as i dont really wana start playing a guessing game with the bike,,,,,i dont think its the valve clearences as the bikes only done 1500 miles and sounds sweet when its running,,,many thanks stu

could be one of a few things but i am sure jam will be along soon and tell exactly whats going on.

have you checked plugs for colour ?
might be coils
cdi is also on the cards


whats does it run like when its going and you are riding it ?

runs perfect till i stop it and try start it again

How hot is it getting? does the choke make any difference? you say the clearances were done 1500 miles ago, but have you checked them? the 400s suffer with valve recession and clearances can close in under 100 miles when they start going, as the valve face starts to deform and the valves sink into the seats, eventually they pull through, I've taken them out of a 400 and they were sharp enough to slice paper on the edges where the margin had failed. Another thing to look at is the vent on the filler cap as if it is blocked it will struggle to pump fuel against a vacum in the tank. What colour are the plugs? Run a compression test when the bike is cold and then again when hot and note whether there is a significant drop when hot which could indicate valve clearances, if the compression is down when hot put a couple of squirts of oil down the bores and repeat the comp test and see if the compression increases, if it doesn't then look at clearances. I had a similar issue with a ZRX400 would start when cold but when warm only 2 would fire and run, because the clearnces were so tight the expansion when hot was holding the valve open and losing compression, once the revs were up it would run on all 4 due to the compression raise with the piston speed increasing with rpm.

the valves werent done 1500 miles ago,i meant the bike in a whole has only done 1500 miles as has the engine,so i cant really see there being any issues with the valve clearences,,it takes a while to get upto half temp as it should and once running theres no problem with fueling or idle it goes like a rocket and sounds sweet as a nut,not rattles or tapping ,obviously when temp is right and i try a little choke the bike cuts out as it should do,it will bump off but wont start electricily,but will bump off and run perfect again,hope this helps?

Where on earth have you managed to find a ZXR4 thats only done 1500 miles

It sounds in that case like a new battery is called for, it has enough to spin it over, but not enough to fire it, and if it bumps straight away when warm it's likely the battery is at fault. Will it start easily when warm if you jump another battery on it?

thats something i havent tried,but it will keep turning it over untill it back fires

it turns over and over but just wont fire into life when its warm,its not like the battery is dead,

The battery doesn't have to be dead it can have enough life to spin the motor but not enough left over the fire the thing.

right ill attach another battery to mine tomorrow and see what the outcome is,i'll let you know

just banged the jump leads on the car battery and i cant beleve it....after all my wondering what it could be its something as silly as that,,,,,so i THANKYOU from the bottom of my heartless heart your a star lol