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Engine Not Cranking, or Stalling when put in Gear...

20076 Views 29 Replies 16 Participants Last post by  sharkbait
[align=center]Sidestand, Clutch and Neutral Switch Wiring[/align]

If the engine won't crank or the engine stalls when put in gear, then this post might help.

The circuit below is a simplifed (and untangled) extract from the CBR250RR wiring diagram. It is much easier to see whats happening and how each of the signals relate to each other when isolated from the rest of the wiring.


To start the bike, the starter relay must have a ground path to work. It can get this if the bike is in neutral. Otherwise, the sidestand must be up and the clutch in to start it when in gear. You can see these two paths on the circuit above.

The CDI needs to see ground on the G/W wire, otherwise it will stop ignition events. That means the side stand must be in the up position. If the engine cuts out when put in gear, its probably the sidestand switch and associated circuit thats faulty.

If the clutch diode fails you can get weird results. Like the neutral light coming on with the side stand down and the clutch in, through to the neutral light not working. If you need to find it for replacement or testing, it's located on the wiring harness behind the air box.


[align=center]Clutch Switch...

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my bike doesnt cut out when the sidestand is left down? because sometimes i ride off without flicking it up, and nothing happens..
That means your side stand switch isn't working.

Hmm where can i find this side stand switch because iv done the same as josh.
If you go and look at your bike you will see the side stand, from there I can only imagine it is quite simple to find the wires and whatnot associated with a switch.
yeah i haven't even bothered to check, ill take a look tomorrow.


I owned CBR400RR NC29, but I guess the sidestand wiring is just the same as CBR250RR MC22.

The problem is, when the engine is hot after a long-distance ride, the neutral light won't coming in although the gear is in N position. Sometimes, it would coming in if I slant the bike a bit to the left (at seating position). I have changed the diode but the problem still persist. I still can start the bike with the clutch in during the problem occurs.

The problem not occurs in short ride (or engine not warm enough). Anyone could help me with the problem ?
The circuit for the J and K models is a little different, but for the L, N and R it looks the same as the CBR250's. Your problem could be the neutral switch itself or the wire between the diode and the switch (including the connector).
Eclipze said:
The circuit for the J and K models is a little different, but for the L, N and R it looks the same as the CBR250's. Your problem could be the neutral switch itself or the wire between the diode and the switch (including the connector).
Thanks for replying mate!

yeah, it seems like an intermittent connection. but, why it occurs after a long-distance ride ? I never had any problem at short-distance.
Give it time... eventually it will fail completely :(
I wish your mad skillz could be applied to all bikes Eclipze :D
I wish I had one of every bike to play with :) In an ideal world I'm filthy rich and have my own bar in the workshop with Gunniess on tap too... but reality is a biatch.

Either way... I have plenty of wiring diagrams for various bikes. Pretty rare to find the wiring diagrams for some of the later model bikes though.
Champion writeup mate :)
Is the clutch diode
Mitsuba RC-2208

if not does anyone have a part number, just curious
checked cmsnl but seems like its wrapped in the wiring harness not a seperate item
It plugs into the harness, but is wrapped over with tape. Should have no problems getting them from a wrecker.
hi, i have a very annoying problem with my cbr250rrl, when the bike is in neutral it rev's normal, however in any instance where the bike is not in neutral there is ignition loss around 7Krpm and complete cut off @9Krpm, this is frustrating becuase i can barely hold 100kph, it also has trouble keeping idle unless i set idle at 3Krpm, ive got next to no experience in auto-electricals


when i rev it above 9Krpm in neutral the sidestand light flickers

any help would be GREATLY appreciated
The sidestand light flickering may actually be your issue. If you are in neutral, it's no problem. But if the sidestand was down and your in gear (clutch out), the engine will cut off. Recommend you inspect the sidestand switch... might be broken or the wires loose.

Idle issues are probably carb/intake issues. Has it been serviced? Carbs clean, balance and air filter clean?
Can i just by pass this system? Has anyone tried doing it. I having hard time to find parts for this that is why I want to by pass it.
Yes, you can bypass the sidestand. You just need to short the green/white wire from the sidestand to ground. But keep in mind, the function it serves is to stop you from doing something accidentally. If you forget, "just once", and take off with your sidestand down, the first slight tilt to the left could send you flying over the handle bars. Would highly recommend to replace/fix the switch and/or wiring... than to spend that time bypassing the safety it provides.
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