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07 crf450r cutting out 1/2 to full throttle HELP PLEASE!

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Bare with me as I have been fighting this problem for over a month now.

 

Bike and mods- 07 crf 450r, all stock execpt for a white brothers full exhaust which has been on the bike for over 2 years.

 

The bike has always run like a top. Rode about a month ago and noticed that 3rd/4th gear 1/2+ throttle keep the throttle steady the bike will just cut out. Fells like a ignition problem, just cuts out then picks back up. After the first day it acted up I checked all the grounds and dielectric greased all of the connectors. Even pulled the carb and cleaned it and tank just to make sure. Next time I go and ride. Same thing so I come back to the pits and change spark plugs(used a old plug, only one I had) same thing. Then while hitting a down hill sectoin I shut the bike down to make a hard corner and it shuts off about 20 ft from the corner. Would not start. Had to push back to the truck(not very fun at all, Thank god for friends). At that point I got the bike to fire back up. It would run for aprox 30 secs then shut off like you hit the kill switch. Replaced the stator and but a new plug in the bike, went and rode this past saturday. Low and behold same thing.

 

Things I have tried. Clean the carb and tank. check and grease grounds and connectors. Replaced the spark plug(with a new one). Replaced the stator(friend had one laying around)

 

I really could use some help.

 

Thanks Ryan

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Sounds like a bad stator/bad coil/wire harness failure

 

Not jetting

Thats what im leaning towards. I looked the harness over yesterday, just visually no ohm meeter. No signs of cuts or bare wires.

 

What are the odds of it being a cdi?

 

Sorry for posting this in the wrong forum. I figured as much.

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No problem, Carbs are the first suspect.

 

 

CDI's are rare for a faliure. A lot of times a new CDI fixes a issue, it is more often the act of unplugging/plugging in and cleaning a contact than a CDi. Howere... some bikes do have a history (but not yours)

 

Harenesses do develo breaks, that in several 'positions' work and in others, a open wire occurs. Ohm check all wires at the steering head, turning the bars and jiggled the harness.

 

I assume when you did the stator, it was with a good one and it included the crank position sensor.

 

Ignition coils too, have a history (like stators) of failing unbder load and/or at rpm. Then when they cool off, seem to work again.

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No problem, Carbs are the first suspect.

 

 

CDI's are rare for a faliure. A lot of times a new CDI fixes a issue, it is more often the act of unplugging/plugging in and cleaning a contact than a CDi. Howere... some bikes do have a history (but not yours)

 

Harenesses do develo breaks, that in several 'positions' work and in others, a open wire occurs. Ohm check all wires at the steering head, turning the bars and jiggled the harness.

 

I assume when you did the stator, it was with a good one and it included the crank position sensor.

 

Ignition coils too, have a history (like stators) of failing unbder load and/or at rpm. Then when they cool off, seem to work again.

Thats good to hear about the cdi's on this year bike.

 

I know all about wiring problems. Thankfully I deal with them on a regular basis at work. The only reason I did not check yesterday is that my volt meter is at work.

 

The stator was used, it did have the crank postition sensor also. But the odds of 2 stators acting the same way is rare.

 

It does seem to be thermal related. I have not read alot about coils giving people trouble.

 

Again thanks for all of the help.

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I'm having a similar problem. High rpm and it cuts off on me.  Only difference is mine starts back up immediately let me know what you find.   Also a 2007 CRF450. 

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Don't you hate when fairy dust makes it's way into your bike!  I think electrical is where I'm at too.  Just for kicks I have heard of a gentle rap on the CDI box has worked with flakey XR650's?  But... just to throw one more idea out at both of you, are you sure you don't have a vent line or air lock developing in your gas tank or carb?  I know this next one is very likely not related too , but did you clean out the pilot jet hole with a bit of fishing line or dental floss with a tiny knot in it.  This hole can be a bit mungy and blowing compressed air up in there may not clear it fully!

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Similar problem...2002 crf450r, completely overhauled..ported polished head, del West Valves,  JE 12.5:1 piston, carb bored out by Dasa Racing to 43.25mm....idles great, up to 1/4 throttle, runs good, then from half to 3/4 throttle sputters, stumbles, and coughs, but continues running...then roll the throttle wide open and she runs excellent, pulls hard all the way to top speed without issues.....any help greatly appreciated....oh, only thing original is electrical...and this issue was present BEFORE the overhaul, but intermittent..........

20170310_131634.jpg

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Throttle position sensor???  Can be checked for smooth operation with an ohm meter.  Its simply a potentiometer that helps cdi to control spark advance.  It should show a smooth resistance curve as you slowly wind open the throttle.   Easy cheap test to rule it out

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Didn't notice how old this post was haha.   Did you fix it, and if so, what was it?  Definitely sounded like an ignition fault...somewhere.  BTw, love the cam chain tension, is that an SAE bolt LOL LOL

Edited by bikedad1
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Yes, I got it pretty much dialed in today...went with 178 main jet and 4th clip position....

Yeah alot of guys are scared of the aftermarket chain tensiiners, but as long as you know what you're doing, theyou work great and never fail....I've had 3 oem tensioner fail....while in glamis...lol

I think it is an SAE bolt :)

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