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· Registered
256 Posts
Discussion Starter · #1 ·
The most common thread posted on the old forum was "my bike wont start!"
Maybe this could be stickied so that people can do the simple checks first.

Do not respond to this thread with anything other than facts.:mad:
I know this thread is awesome so pm me rather than post here.:blush:
Do not post your starting problem here, try the suggestions then make a new thread with as much clear info as possible.

I am not a mechanic but i have some knoweledge of bikes.
This thread is for facts only, anything I have missed please add.
Anyting I have gotten wrong let me know and I will edit it.

The simple stuff.
Its a big red button on the right hand handlebar, make sure its on.

Is your fuel tap off? on? reserve? Try it on reserve if you are low on petrol.

Is the petrol old? if it is drain out the tank and refill with fresh petrol.

Sidestand switch? is your bike in nuetral, if it is in gear it will not start with the side stand down.

FUSES! Check all fuses!


Can you push start it? Put bike in 1st gear with ignition on and run with it(or even better if you get a mate to push you) jump on and release clutch.
Give a little bit of throttle and make sure your on a clear road.

Check all earth connections on frame/engine etc.

If none of the above apply read on.

The basics for an engine to to go are fuel, spark and air.
One is always missing completley, lacking or getting/giving too much.
If you can determine which one is the problem then that makes things easier, if you cant it is a process of illimination.


Is your spark weak?
If your bike is turning over but not starting your spark plugs may be not getting enough power or could be in need of replacement.
Buy a multi metre, they are cheap and will last a lifetime.
Your battery should be putting out about 12.5 volts when the bike is not on.
Charge it for a while and try and start it again if its lower than this.
If your battery keeps dying replace it, if you get the bike running and your battery keeps dying change the regulator rectifier.
Check this golden nuget from eclipze if you think if you think you are having batt/reg rec problems... http://cbr250.com/forum/thread-282.html

To check if you are getting a spark take out a plug attached to the plug cap and touch the metal off the frame.
Hit the starter and check if you can see a blue spark.
WARNING!!! only hold the rubber plug cap and not the metal as you will fry yourself.

If you have the plugs out you may aswell replace them!
If your a cheap ass you may rub them down with sand paper or a wire brush. (or if you know they are relitivley new.)

If your bike is running on less than all four cylinders throw water on the header pipes and see which one doesnt steam off.

If you have replaced the spark plugs and you are still not getting spark replace the HT leads and or plug caps.

If that does not work Check the coils, replace the coils or get a friends coils to test and rule them in or out.


Are you getting fuel?
Is your fuel tap blocked? take off the fuel line from the tank and turn fuel on, if its not dripping out your tap is cloged up.

Are your fuel lines connected properly?

Is your fuel pump working? check with a mulitmeter if its getting power.

Clean your carbs! Clean your carbs! Clean your carbs!
CBRs carbs can get clogged up for many reasons restricting fuel.
Take the carbs apart one by one and use carb cleaner found in any auto shop.
You tube has some good carb cleaning vids.
Check there is no holes or tears in the diaframs (Black rubber nipple things), this can hinder running.
Make sure you clean the jets and put everything back exactly as you found it.
Count the amout of turns in on all idle screws etc.
Inspect the float heights.
Only use petrol resistant silicone to seal back up the carbs, I recomend a product called "indian gasket" go easy with it and its messy!

Thanks to K916 for this "how to clean your carbs write up" http://cbr250.com/forum/thread-231.html

If you suspect you have flooded your bike, leave it for an hour and try again with no throttle!
If that doesnt work drain the carbs and try again.
If its still not working you may have hydrolocked your pistons, take a plug out and hit the starter for a second.
Put the plug back in and try again.

LASTLY make sure your carbs are on perfectly and tight!

If all that fails burn your bike:rolleyes: thats a joke.


Is your air filter durty as hell? change if for a new one.
Make sure your airbox is on perfectly and tight.

Check fuses.
Check battery connections.
Check relays.
Check for corrosion on the starter motor wires/connections.
Check starter button in switch gear for corrosion/connections.

Oh and Info from Studricho,
The main rule to starting a cbr (or any bike for that matter) is don't turn on the ignition until your ready to start the bike.

I've seen so many people turn the ignition on, then fiddle with gloves, then jacket, sit on bike, then forgot to put back pack on, then can't do up helmet with gloves on and then perform a 47 point safety check and decide to hit the starter button with kill switch on for at least 10 attempts.


Battery has dropped in voltage and not enough to crank the engine quick enough, spark plugs fouled and no start.

This is the simple stuff covered.
Hope this helps a few people.
Good luck.:)

· Registered
60 Posts
To help with troubleshooting, get yourself a copy of the manual and parts fiche.

· Registered
90 Posts
Another thing you might want to add is to check the compression, and if it is low in one or more cylinders (like it was in mine) check valve clearances BEFORE pulling the head off. i thought it was my rings that were gone but evidently my valves have just become tight and need the shims replaced resulting in low compression and backfiring through the carby because the inlet valve wasn't closing.
Also maybe add some deets about standard compression values you should get (mine was round 140psi for the good cylinders if i remember correctly, but don't know if thats the standard)
maybe also stick up the points to spark plug order for those rebuilding their bikes?


· Registered
1,502 Posts
figured this is a good thread to ask this in...
went to start the bike (mc22) this morning and it didn't fire straight away, so i pulled the choke on, had another crack...sometimes it would start, others it wouldn't...even when it did start it would idle low and then cut out.
got the bike started and running with no choke just before, but it didn't rev well (as in it was bogging down big time, but would eventually come good and rev like it should...while low in the revs it didn't sound normal either, very low and 'grumbly').
what would be the most likely cause of this?
there is no battery issues as the battery is new and checked the charge level on it just now and all is good.
i was going to check the plugs but i'm going out so don't have the time right now.
i'm also assuming maybe a carby clean and balance is needed??

edit: when i had the bike running it stalled out by itself after about a minute.
there is fuel in the tank and it is fresh.
almost seems like its overfuelling itself??

· Registered
256 Posts
Discussion Starter · #8 ·
mat_p said:
figured this is a good thread to ask this in...
Ah for fuck sake! So the big red writing doesn't apply to you?
Make your own thread like the instructions say!

On regaurds to your problem, fuel starvation I suspect.
Try raising the idle revs, and let your bike warm up before you try to rev it.
If you reply to this thread You will get negative reps! From everyone!

K916, please lock this up again to save us from colourblind Aussies!

· Registered
38 Posts
Two things I have found:

Bike difficult to start can also be because of not riding it enough, or only doing short rides: result fouled plugs, battery in poor condition. Then, even though the engine can still turn over (sometimes giving the false impression that the battery is ok), the spark can be weak because the CBR250 ECU needs a decent voltage to get a good spark. (The voltage drops while the starter is cranking over) Starting is made worse if the plugs are fouled. I find if I leave the bike idling for too long just before turning it off, it will be a little difficult to start next time. Same for leaving it sitting for more than a week. But ride it properly (i.e. decent revs as well as not just doing short 5min trips) the battery and the plugs will be in good shape for starting next time. (The CBR250 batteries are only small, so you really need to look after them)

Of course there are more elements to why this practice may seem to work, but basically, it works! (my own bike was not ridden for 2 months. Would not start at all. Cranked for ages but would not start (well almost started, but that was clutch starting it.). But charge battery, once going, take for a decent ride and next time it started first go! (My fuel was still ok btw)

Probably obvious to most of you, but just in case... turn your headlights off before you attempt to start, it will start easier!

The Dwarf: Thanks for starting the thread!

Cheers all.

· Banned
1 Posts
What do you think of Google Plus?

What do you think of Google+?
I'm liking it. I think Google got it right this time. Circles are great. I believe it encourages networking.
When they implement apps and social games I hope they make sure it does not pollute my stream.
Also, I think "sparks" is useless.
My pamietnik internetowy: Callan angielski

· Registered
82 Posts
Got my bike a few months ago, but had to get it serviced and a few minor things done to it. Got it back, over a week ago, and has been running foine. Though, i've come across one problem, something to do with the battery..I think. The day I got it back, I went for a ride, and all was good, went to a mates, and only dropped by for around 10-15 minutes. Went to start the bike, and nada. Only got one clicking sound. Only one. Jump started it, and the battery was around 12.5, which I read is normal. All was good for around a week, until an hour ago. Stalled the bike on a hill, and same thing happened, got one click again.

Was pretty annoyed, as it was raining, walked to my friends, and got the battery jump starter kit, but could not find an allen key, or any screw drivers, so I ended up calling nrma, on hold for 15 minutes, and I got ahold of them, I was going back to my bike, and giving them my details, so they can come around around and help me, I got to my bike, and just thought I'll see if it works......and it started up fine.

I'll go and see my mechanic tomorrow, and see whats going on.. now I'm back to being paranoid, that my bike won't start, so I don't like going somewhere, and turning it off, and walking up to it, thinking, is it going to start...

Starter relay/solanoid - no big deal. happens with moisture, like a dry solder. I have had this problem with a car before. Just change the starter relay and you should be sweet...... a mechanic will arse rape u, try a 10$ relay first.

erm... think a relay is like $20, but if u dont know what you are doing get a mechanic because it will work out cheaper for $400 :D[hr]
the square box connected to your battery the size of a 20C piece.... replace that...
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