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2012 wr450 won't accelerate when hot

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Looking for input, or if anyone has had the same issue.

Bike has no issues since new.

First ride this year after about 2 hours riding the bike on technical trails it started to bog, and would not accelerate.

Would idle and start no problem. Give it gas and would die, but idle.

I got onto the road and idled along the road. After 15-20  minutes the bike started to run perfect again. So back into tight stuff and it would act up again.

Runs perfect down the road, but when it heats up bogs

New gas, spark plug, took a multi meter to everything and all are in spec

Took the stator out and looks fine. Anyone had a similar issue and solved this problem

Thanks

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My WR does the same thing when it gets hot, only a minor annoyance on longer rides but the bike will never actually die it just doesn't have as much throttle response.

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8 hours ago, Darc McKeown said:

Looking for input

Give it gas and would die, but idle.

I got onto the road and idled along the road. After 15-20  minutes the bike started to run perfect again. So back into tight stuff and it would act up again, took a multi meter to everything and all are in spec

Thanks

Sounds like fuel issue to me, how many hrs are on the bike? Fuel filter? I'd verify fuel pressure and look into the basic stuff. Fuel, Spark, Air, Compression are decent places to begin troubleshooting a drivability issue such as you have described. What do you infer by the statement of taking a multi meter to everything and finding it to be in spec?

 

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A multimeter or a multitester, also known as a VOM (Volt-Ohm-Milliammeter)

Tested the coil, plug cap, fuel pump, stator, 

New battery, battery holds charge and is not being drained

All where to spec as per the service manual

200 hours, compression good, valves in spec

Checked wiring, could not locate any problems

Only acts up when hot - not overheating

Cools down and runs perfect

On the road you can drive it for 100 miles hard and doesn't act up

Not that I drive on the road,,,

Something heats up, and kills the engine under load

 

 

 

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I'd be looking at the coolant temp sensor, an engine typically runs cool on roadway and heats up under load (Single-track). Check the temps between both conditions and see if anything is awry there. From what I understand the fuel injection system is simple(Nearly closed loop) in those bikes and an indicated hot temp from then sensor might create a lean fuel condition?

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Pull the fuel pump, and clean or replace the fuel filter.

While you are in there do a bench test of the pump using water, for 5+ minutes.  You can use a psi meter, or just watch the pump's stream for a drop in pressure after it gets hot.

I think you will find the pump is failing, from trying to work through a dirty filter for so long.

That, or the inector nozzle is really contaminated....

The filters are supposed to be cleaned or replaced every 30 hours !

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Thanks for the input

I just ordered a fuel pump rebuild kit, and will test the coolant sensor

Will post back if either of these solves the issue

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Problem solved thanks to Krannie

Pulled the pump and did a  bench test. Motor would run but not pump.

Pulled off fuel filter and pump worked perfect.

So,, fuel filter was clogged.

Installed new filter and runs perfect..

Thanks again

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9 hours ago, Darc McKeown said:

Problem solved thanks to Krannie

Pulled the pump and did a  bench test. Motor would run but not pump.

Pulled off fuel filter and pump worked perfect.

So,, fuel filter was clogged.

Installed new filter and runs perfect..

Thanks again

Do yourself a favor and not ride too far from the truck/garage your next time out, as the pump often gets damaged/fatiqued from trying to pull through that bad filter.

It may only work well for 5 min or so, then drop pressure....

You will know it's ok if the pump still works well after 15 min or so of hard load on the motor, getting it hot ....

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FYI

The kit I ordered did include a new fuel pump and filter. Ordered from Caltric in California.  Under $50 delivered

Installed both.  If you have it apart just change both. I have been out several times on long rides and bike runs and starts like new

As others had suggested look at the fuel pump and filter when bike is not running properly. Cheap fix

Thanks 

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