[tpheloz]

Hi just picked up a 2012 crf450r fixer up bike for 2500 a couple weeks ago. I got told it only needed shims but after I was paranoid and pulled the motor out, I found out that its more than just shims. So, I've done the valve clearances, timings good, rebuild fuel pump, good compression, cleaned throttle body and injectors, tested for spark by spraying engine starter in and kicking it, all good. BUT, the bike wont start up. I noticed some form of rust/corrosion/buildup ontop of one of the intake valves, could the valves be seized? I get nothing but a sort of hissing sound when I kick it, no firing up rumble or anything, but if I crack the throttle a little bit just as I kick it, it backfires once or twice. I'm stumped and I can't take it to a shop. Anyone got any ideas????

[JimDirt]

Welcome to the site !!

What exactly was it that made you paranoid that you wanted to pull the motor ?? , if it was just valve adjustment , that , along with removing the head and cylinder can all be done with the engine in the frame , you can even pull/replace the timing chain with the engine in the frame , so not sure the reasoning for the removal unless you were planning on a complete engine teardown/disassembly , like splitting the cases replacing the crank kind of teardown .......

The backfiring could be timing , you said the timing is good , but are you sure you are not 180 out ?? , how did you verify the timing was on ??? , were all 3 timing marks aligned ??? (clutch side large round plug , ignition side small round plug , cam marks level with head while lobes on cam facing 2 O-clock to the rear of engine) ........ How did you kick the engine over to start it , did you give it a Harley kick ?? , or a 2 stroke kick ?? , if you do not kick the 450's like you are mad at it , they don't like to start ........ Did you try pulling the choke on the Throttle Body (EFI do have chokes it is the white round flower shaped knob right by the engine mount on the shifter side , you turn it to adjust idle , or pull it to work as a choke) , to see if it made any difference ?? .... Also , you generally do not open the throttle on a EFI engine when starting ...

Is the gas FRESH ??? , if the gas is more than 2 months old , you need to pour it in your car or lawn mower , these bikes do not like old gas .... I would think if the valve was seized the engine would lock up and not turn over rather than hiss , usually a hiss is compression releasing , so it may be possible the valve is hanging open and not completely closing ..... have you done a Compression Test ?? , or a Leak Down Test ??? , either of those would explain a lot

Try this .... pull the tank and spark plug , pour about a teaspoon of gas directly down the plug hole , put the plug back in , put the tank back on and try to start it , if it starts then dies soon afterwards , I would suspect the fuel filter is clogged or the pump is not working , but the gas directly in the cylinder will verify if this is a fuel related issue or not ....

Are you getting any blink codes on the Map switch ?

[tpheloz]

Welcome to the site !!

What exactly was it that made you paranoid that you wanted to pull the motor ?? , if it was just valve adjustment , that , along with removing the head and cylinder can all be done with the engine in the frame , you can even pull/replace the timing chain with the engine in the frame , so not sure the reasoning for the removal unless you were planning on a complete engine teardown/disassembly , like splitting the cases replacing the crank kind of teardown .......

The backfiring could be timing , you said the timing is good , but are you sure you are not 180 out ?? , how did you verify the timing was on ??? , were all 3 timing marks aligned ??? (clutch side large round plug , ignition side small round plug , cam marks level with head while lobes on cam facing 2 O-clock to the rear of engine) ........ How did you kick the engine over to start it , did you give it a Harley kick ?? , or a 2 stroke kick ?? , if you do not kick the 450's like you are mad at it , they don't like to start ........ Did you try pulling the choke on the Throttle Body (EFI do have chokes it is the white round flower shaped knob right by the engine mount on the shifter side , you turn it to adjust idle , or pull it to work as a choke) , to see if it made any difference ?? .... Also , you generally do not open the throttle on a EFI engine when starting ...

Is the gas FRESH ??? , if the gas is more than 2 months old , you need to pour it in your car or lawn mower , these bikes do not like old gas .... I would think if the valve was seized the engine would lock up and not turn over rather than hiss , usually a hiss is compression releasing , so it may be possible the valve is hanging open and not completely closing ..... have you done a Compression Test ?? , or a Leak Down Test ??? , either of those would explain a lot

Try this .... pull the tank and spark plug , pour about a teaspoon of gas directly down the plug hole , put the plug back in , put the tank back on and try to start it , if it starts then dies soon afterwards , I would suspect the fuel filter is clogged or the pump is not working , but the gas directly in the cylinder will verify if this is a fuel related issue or not ....

Are you getting any blink codes on the Map switch ?

Cheers mate,
I was paranoid just coz the bloke i bought it off was a big dodge so I just wanted to take a look over it. Gonna be checking timing. I checked 2 and I had marked it with a sharpie on the camshaft so I wouldve thought that'd be right
Yeah I've tried the choke thing and it doesn't make any difference, and I know you dont open the throttle just hoped it might do something, which it does (spit fire out the intake)
Fuels all good, completely emptied the tank and refilled with new fuel from the servo.
I can't do a comp test or fuel psi test etc because I dont have the gear, only got basics socket kits and ., not even power tools
I cleaned the fuel filter as best I could when I took it all apart so I think thats ok. I tested the flow by taking the fuel line off the tank and leaving the power on and kicking it over. Flow is pretty weak, so I guess it could be blocked a bit?
Also gotta find a mate with a spark plug socket because spark plugs right down on the top of the head.
I don't know about blink codes on the switch, I haven't checked it or know what theyd be. First EFI bike, and I hate electrical systems on bikes. This ones my upgrade from a 02 crf250 where it was basically all mechanical apart from kill switch and spark plug.

[Back2-2]

It is not a "choke" it is a Fuel Enrichment.

[tpheloz]

It is not a "choke" it is a Fuel Enrichment.

Like I said, first fuel injected bike. I don't know . about it yet.

[Back2-2]

Just trying to keep ya from sounding like a hillbilly.

[Aussiecrf230]

Neil, Don't you mean a reverse hot start device.LOL.
You know, a cold start device

[JimDirt]

Fuel Enrichment ...... You mean a Choke ???

[Back2-2]

No. two different things. You do NOT choke a EFI anything....