Yamaha ybr 125 running problems

[Steve_ybr]

Hi guys having issues with my ybr custom fuel injected brought it has a none runner got it running yesterday now this problem as occured it when the bike is running it will cut out randomly when the engine is hot or cold it wont rev past 4k revs at all it will just sit there in any throttle position miss firing and back firing and surging till i lay off the throttle then goes back to idle , no smoke or noises from the engine , no fault codes on the dash , i have fully serviced the engine fresh oil , plug (irridium ) and air filter changed the throttle body , spark plug , spark plug cap ,fuel injector , rewired the ignition , cleaned all the pug connectors and sensors , fuel pump is fine primes and pump plenty of fuel , fuel is fresh with half a tank , i have cleaned the coil as it was rusted , only things i can think of now is the ecu/cdi , coil , or stator plate
Video of the problem is below
https://youtu.be/bvpE5EBLpn8

[Rogerborg]

I'd bust out the multimeter and start here:

https://ybr125owner.blogspot.co.uk/2014/08/yamaha-ybr-125-throttle-position-intake.html
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Steve_ybr]

Yeah its looking that way pal , driving me mad to be fair as i no its something simple if the bleeding thing starts and runs

[Rogerborg]

Sadly, that smacks of electrowizardry. There is a Yamaha diagnostics dongle you can buy, but I doubt it'd be cheap.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Steve_ybr]

Thing is i have swapped between 2 throttle bodies which carry on the the cold start sensor , throttle position sensor , i have also swapped the injector only things i have not swapped are the injector cap / sensor , the coil has got sent the wrong one (Ebay) !! , sealed the air box has it had holes drilled into it , swapped the air filter has it was ruined serviced the engine , repositioned the fuel hose , checkee and rechecked the pump sensor , removed cleaned the coil and ht cap , ( bright blue spark jumping around the electrode ) me personally am thinking the ecu maybe at fault i have ordered one

[Steve_ybr]

Update unplugged various  sensors when the bike has been running and the only one that did not cut out the engine and produce a fault code on the dash and made no difference when it was unplugged was the cold start valve / sensor the one just up from the throttle possition sensor , faulty sensor or plug or break in the wiring do you all think ?  

[arry]

[Steve_ybr]

I have today there is none at all , the cdi i have tried a different one off a running bike still no power to that plug to that sensor the sensor it self is fine its the wiring to it so looks like there is a break in the loom somewhere or the wire is earthing need to strip the loom or just replace the loom will also replace the ignition barell at the same time as the wireing is dodgey on that which is probably half the reason why that sensor is getting no power

[arry]

[Mkmechanics]

Sounds stupid but remove all those waterproof caps of your hat lead as they hold small amounts of moisture which can cause miss firing and try dipping the tip of the thermostat in boiling oil for a few minutes. Just try it

[Mkmechanics]

Sounds stupid but remove all those waterproof caps of your hat lead as they hold small amounts of moisture which can cause miss firing and try dipping the tip of the thermostat in boiling oil for a few minutes. Just try it

[Fizzoid]

Indeed, sounds VERY stupid!
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Rogerborg wrote: It'd certainly make it easier to ego-find my own posts on pages, given the number of fags (gay like traps) who insist on putting my name in their .sig