CBR250r start-up problems

[Midge]

So heres my predicament...... My bike just doesnt seem to want to start. I try and start her up with full choke and little gas and it turns over and sounds like its about to start but just wont fire up. About a week ago it happened but i had been away on wedding and honey moon stuff for 5 weeks so the poor thing had to sit there for about 5 weeks. When i got home i knew it wouldnt get going straight away so i cleaned out the sparks and put some fresh fuel in and drain the carbs and after a little persisting it kicked over. I have been riding for just over a week every day now and when i go start up today it doesnt want to go. The sparks were only replaced earlier this year so im not sure but i would assume they are ment to last more than 6months? This is my only form of transport so im a little lost as to what to do now. I have had the problem before last year sometime and a change of spark plugs did the trick and it ran fine for a long time, and then after xmas i replaced them this year and again ran fine. Im sure if i replace them again it will run fine but only for a while and im sure i shouldnt need to replace them this often?

Any help appreciated.... Cheers

[CookMySock]

Try different combinations of choke and throttle. Some bikes won't start at all with any throttle on.

Steve

[avgas]

Yep it will either be 1/4-1/3 choke or no choke at all.
I have only needed to use full choke once in my life - and that was at -2 degrees C

[The Pastor]

Not 100% sure on this, but at 100% choke you're blocking nearly all the air out, so it wont start.

Also you don't want to be giving it much gas at all. giving it loads of gas when starting will flood it.

1. Drain the carb. If no fuel comes out the drain hole, here is your problem, check for blocked line / leak
2. let it sit for 10-15mins
3. half choke and hit the starter no gas, repeat a few times, then try a LITTLE throttle on start up.

If it wont start, you have to check on 3 things

Fuel, Spark and Compression

fuel - check if fuel is in the carbs, check for possible water in fuel (it happens often, a little bit of meths fixes this)

spark - remove plug and hold next to frame in the dark and hit the starter to see if any spark. Could be coils, lead or plugs so if you don't get a spark, check the plug with different lead etc. Have a look at the spark plug is it black? is it wet? is it white? it should be a light tan color.

Compression - do a compression test

[quickbuck]

Not 100% sure on this, but at 100% choke you're blocking nearly all the air out, so it wont start.

NO,
You are 100% WRONG on that.
"Chokes" on bikes are actually ENRICRERS.

Full choke actually throws in an extra bit of fuel to increase the fuel/air ratio for starting.
Never actually blocks off any air.
Method for starting all jap bikes post about 1986 is to apply full "choke" and NO Throttle, then hit the start button.

All that happens wehn you twist the throttle is you mess up the fuel/air ratio that the cleaver japanese man determined to be best for starting an engine, and add in your own concoction....

[The Pastor]

NO,
You are 100% WRONG on that.
"Chokes" on bikes are actually ENRICRERS.

Full choke actually throws in an extra bit of fuel to increase the fuel/air ratio for starting.
Never actually blocks off any air.
Method for starting all jap bikes post about 1986 is to apply full "choke" and NO Throttle, then hit the start button.

All that happens wehn you twist the throttle is you mess up the fuel/air ratio that the cleaver japanese man determined to be best for starting an engine, and add in your own concoction....

really? how do they work? would it be a simple hole that by pulling the cable / lever it blocks/unblocks the hole?

[quickbuck]

really? how do they work? would it be a simple hole that by pulling the cable / lever it blocks/unblocks the hole?

Almost as simple as that.
There is a brass plunger (Connected to the cable) that uncovers a metered orifice, more commonly referred to as a Jet.
Multi carbs have a rail doing the same job as the cable on a single carb.

[bogan]

Almost as simple as that.
There is a brass plunger (Connected to the cable) that uncovers a metered orifice, more commonly referred to as a Jet.
Multi carbs have a rail doing the same job as the cable on a single carb.

it used to work by moving a slide across the airflow, which I'm guessing increased the vacuum and drew in more fuel somehow (was in different place and functioned different to throttle obviously), which is how they got called choke I'm guessing

[quickbuck]

it used to work by moving a slide across the airflow, which I'm guessing increased the vacuum and drew in more fuel somehow (was in different place and functioned different to throttle obviously), which is how they got called choke I'm guessing

OR, a ruddy great plate that pivoted in the throttle body......

[bogan]

OR, a ruddy great plate that pivoted in the throttle body......

yup, them too, god i hate carburettors

[quickbuck]

yup, them too, god i hate carburettors

There is still one aircraft type in the RNZAF that has them......

No choke on them though... Just a Manual enriching system!
Yes, turn the throttle three full turns, and then set to 1/4 before hitting the start button!

[Midge]

Cheers guys for the help went through the process and after reading a thread about a ZXR it seems the battery was not putting out enough juice to start up ... so getting a new one of those. It was a bit deceiving thou I would have never thought to check the battery cos there was power seems just not enough.

[eelracing]

Just a thought,but if starting improves everytime you chuck in new plugs maybe you are using the wrong heat grade of plug.

It would not be a problem to ask your Honda dealer what the correct plug should be and then checking.

[quickbuck]

Just a thought,but if starting improves everytime you chuck in new plugs maybe you are using the wrong heat grade of plug.

It would not be a problem to ask your Honda dealer what the correct plug should be and then checking.

Na,
Chucking in new plugs is fixing a symptom.

The thing is If there isn't enough juice in the battery, the Ignition modules won't actually work.
All the current will be going to the Starter to turn the motor over.

So, the plugs will just get wet, due to the fact there is nothing to light up the mixture.

ALSO, if you are one of those that twist the throttle while pressing the start button, then you will also be wetting your plugs......

Believe me, after pulling plugs from all sorts of bikes until I worked out the correct (easiest) way to start bikes got really annoying!!!
Thankfully i was told before I had to pull too many! the VFR400's were are mare!!!