hi, im having trouble getting my cbr 125 r started, it turns over but wont run, ive changed spark plug as that was on its way out, i put a bit of fuel in the spark plug socket and it managed to start up but as soon as i went to give it any sort of rev's it died it did this a few times and now just wont start, im wondering if ive got a problem with the fuel not getting through. any ideas please as this is doing my head in now because i just wana get out on it

 

if ive got a problem with the fuel not getting through.
Yup !
Check your fuel tap/ fuel hoses, and if you're bike has a vacuum hose from the carb to the petcock, maybe a problem there.
Start with those.............

 

thanks, i cant find a fuel tap on it anywhere so dont think it has one, i don t really know a lot about bikes so bare with me, what does the petcock look like, and do you think the problem is in the pipe between carb and petcock? someone said to me about cleaning the carb out, would this help

 

hey mate,

not sure if your setup is similar to my 250 but heres what id check.

1. take the tank off and check fuel runs out when you turn the tap on, if theres a vaccum hose (will be around 5mm diameter and probably have a funny bend at the end) sometimes you need to give it a little suck to start it flowing.if not there maybe a blockage somewhere in the tank

2. check the fuel pump is running once you turn the engine over... put your hand on it and feel for it pumping, if its not check it pluggeds in properly, if it is it may be dead.

3.look for four little screws at the base of the carbie probably on the back (seat side) 2 will face out to the left to be un-done and 2 out to the right. by un-screwing these it will drain the carbie. if you've found the right ones then fuel should drain out,if it doesn't then you have a blockage or kink in the line between pump and carbie.

4.if fuel is getting to the carb pull your spark plugs and test for spark by leaving it plugged into the ignition lead and touching the other end against the frame or engine and turn the engine over to check for spark. if theres nothing then your coil packs probably dead. if there is clean the plugs and put them back in.


im no mechanic but this may find the issue, smaller capacity cbr's hate being left sitting for a period of time so can be a bugger to start. see how ya go

chris

 

thanks for the advice, i have checked all of these things and they all seem ok apart from maybe the spark, i could just about see a spark but it is hardly anything ive changed spark plug so do u think it could be the coil then

 

I'll throw my two cents in the ring, here:

Sounds like you're getting fuel to the carb since you said you can drain it OK. I would absolutely test for spark, next. You said you changed the plug as it was "on its way out." What made you think that? Usually when a coil pack (the thing that sends electricity through the plug wire) is going, it won't be completely dead, but will produce a very weak spark, or won't spark on every crank. Is this what was happening? Check the new one. If you see this, or no spark, I'd change your coil pack.

While you're in there, have you cleaned the carburetor lately? Not a bad time to do it, and there's a chance it might be the problem.

 

yeah i changed the spark plug for a new one to see whether it was that and im getting like what you said a very weak spark so should i go and change the coil pack then, i checked the carb as i was going through what could be wrong and it looked pretty clean

 

Yep, coil pack is the next step. The carb you have to disassemble and inspect internally, they just get gunk inside of them from the general course of what they do. The jet tends to clog when that happens, and thus you don't get fuel into your cylinder. I was suspecting that as well, considering your bike runs if you throw gas right in the cylinder. In fact, I'd clean that jet out first.

 

yeah i think i will have a good look at the carb then, but i did try again yesterday putting a bit of fuel down the cylinder and it didnt go this time i think that the spark is too small to do anything so im ordering a coil now, thanks

 

looks like im a bit late but mc19 and mc22 both have very weak spark as it is.. i would say its fine, any spark will be enough to make it fire. i dont know when the last time you rode it or had it running was but the only times ive had an issue is when a cam was broken, the ignition leads were on in the wrong order or when i had a "new" engine and valve clearances were way out.