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Crf150r Helpppppp!!!! Pleeeeeease

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07 crf150R big wheel, have had it and my son has raced it for over a year. other than clutches it has been a awesome bike. For reference heres what we have on it: WMI suspension, Outlaw top clamp, Renthal twinwalls, asv levers, step seat, Vortex sprockets, RK chain, Michelin tires, EBC rotors, FMF header and pipe, Boyeson quickshot, MSR Fuel screw, Wire mod, Full Hinson Clutch with stock clutch kit, no motor mods, decal works graffix, hour meter, pro circuit throttle tube and holeshot device, radiator braces and red hoses.

I know it may not be relevant but every bit of info helps.

Recent work: 30 hours ago on meter, new valves, seats recut and top end. Cam recall was done.

We are religous about oils and filter changes

Problem at 1st: The idle or throttle stop screw was binding up and hard to adjust. Also replaced clutch (plates, fibers, springs, oil, coolant) before last race this past weekend. Bike ran fine at race after replacement.

What we did: Note the clutch replacement also above

Rotated the carb sideways, took the idle screw off and tried to lube it. Also took throttle tube and cables off to lube, operation is now snappier than ever (with motor not running ). Rotated carb back, reconnected and adjusted throttle, checked fuel screw setting, tried to set idle.

Part I need HHHEEEELLLPPP with: on the stand running for 2-3 minutes trying to adjust idle. Bike starts right up, will idle but when you turn the throttle it will stall and this has been a problem lately. once warm it runs fine. The major problem is that after only a few minutes of idle / revving the header pipe gets GLOWING RED!!!!! scary hot. we have temp strips on the cylinder head and they read normal temps.

Sorry for all the rambling but please help, what is going on?

Thanks so much!:

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What about the hotstart ... stuck open???? Work the cable to check.

This would create a VERY LEAN condition and stalls??

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Thank you,

I just went and checked. The lever has play and reacts ok. I tugged on the cable and it changed the way it reacted. It seems very possible that when i rotated the carb it put tension on the cable. It always screws up your throttle and then you have to adjust. It's almost like the cables on this bike are too short. It's too late here to crank it up so we'll try tomm. luckily the big race this weekend is cancelled. I'll let you know if it made a diff., we'll check the carb end too. We just replaced the entire hot start assy. recently. would this create the extreme heat in the header pipe if it's sticking?

Thanks again

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The hotstart stuck open will make the big run EXCESSIVELY LEAN = very hot.

It should also be very difficult to start cold if its stuck open.

Hopefully its something that simple. Also you can pull the jets to see if they are clogged.

Good luck either way 👍

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I would all so re-check the valve lash clearance just be sure it with in spec belive it or not this can cuase problem with not want to run rigth cold.

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Its normal for a 4-stroke, i would be worried if it was red past the beginning of the exhaust sheild. You could always turn the fuel srew out 1/4 turn to richen it, but after my 150r is warmed up the pipe will grow if it idles a couple minutes. When you start to ride the air will cool it.

http://www.planetminis.com/f49/glowing-red-crf150r-pipe-87121.html

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I'm pretty certain this was way hotter than normal. Took the carb off and started checking everything. Found on the aftermarket fuel screw the oring came apart and a piece of it was blocking the passage. I'll continue to clean it out and check the hot start, valve clearance, etc. but pretty sure that has something to do with it.

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Hopefully it turns out to be something that easy!

Repairs that don't cost anything are the best kind 👍

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