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I just recently bought a 2007 crf250r from a buddy. He had bike completely rebuilt( all bearings, crank, cylinder/piston, new valves, rebuilt carb with stock jets), but I am having trouble getting bike to start. I do know I need a smaller(?) Leak jet, it bogs on quick throttle blip. I have trouble starting when cold or if I've been riding and it sits for 10 or 15 minutes. Ive tried fuel screw, I've been between 1.5 to 2.25 turns. It does help if I cut off gas and lay bike over and let gas out of carb. It will start in 3 or 4 kicks then. If bike is hot it'll usually start 1st kick. Any help would be appreciated. I'm in west Tennessee, not sure about sea level. Temp is 80°\ 90°f20170730_131824.jpg

 

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Yes, valves are in spec. Carb is set to stock. Just seeing if someone could point in right direction of jetting with my description. Thanks

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Try a smaller pilot jet.
Slowly depress kickstarter until you feel some resistance. Bring kickstarter all the way up and give it a good kick. Starts better if it is at beginning of compression stroke.

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Ok thanks. I decided to check valve clearance again. This what I came up with. From what I've read exhaust is ok. And the one intake valve needs to be tighter correct? Or do the exhaust need to be dead on. The mechanic told me .008-.011 is ok on exhaust and .004-.006 is ok on intake. And would the one intake valve being out cause all the starting issues?
20170813_110532.jpg20170813_111155.jpg20170813_111354.jpg

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its lean, you may need a bigger pilot. thatll cause the bog too. but assuming it ran right before, check ur hot-start adjustment, itll never start if its not right. (you need slack in cable)

are you using the choke? when u lay it on it's side ur actually dumping gas into the motor. try this, slow kick it threw a revolution or 2, crack the throttle 2-3 times and then kick it right away. it needs a shot of gas from the accelerator pump.

u should get a flex-jet so you can easily adjust mixture. i wouldnt play with the leak jet untill you get it starting easy, fully warmed up with ur fuel screw set right. if you still have a bog wacking the throttle, you need a larger leak.

couple good vids were posted in the  boyesen quickshot 2 thread. 

if you have any valve clearance at all, it will start. they get tighter as it heats up, tight is not good.

 

dont be like this guy> 

do it it like this guy> 

 

Edited by over rev

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its lean, you may need a bigger pilot. thatll cause the bog too. but assuming it ran right before, check ur hot-start adjustment, itll never start if its not right. (you need slack in cable)
are you using the choke? when u lay it on it's side ur actually dumping gas into the motor. try this, slow kick it threw a revolution or 2, crack the throttle 2-3 times and then kick it right away. it needs a shot of gas from the accelerator pump.
u should get a flex-jet so you can easily adjust mixture. i wouldnt play with the leak jet untill you get it starting easy, fully warmed up with ur fuel screw set right. if you still have a bog wacking the throttle, you need a larger leak.
couple good vids were posted in the  boyesen quickshot 2 thread. 
if you have any valve clearance at all, it will start
 
The bike sat up for about 4 years. My buddy bought it, had a mechanic rebuild everything. Even if I brake to hard and stall out. I'll spend 4 minutes trying to start it. Sometimes I'll get lucky and it'll start in a couple kicks. I've tried hot start, choke, slowly opening throttle and quick blips of throttle. They've all work rarely. But leaning it over dumping gas out and It'll start 3-4 kicks.

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in original post u said it started good hot. 

i hear ya but when u tip it over ur not dumping gas out, ur dumping it in, it may run out the bowl overflow but still. i used to have to tip my cr500 on it's side. 

cold i slow kick it once, wack throttle 4 times and it starts everytime and i have quickshot, took me quite awhile to figure it out when i bought it. hot sometimes i have to wack the throttle too, seems contradictory since most people have trouble hot, hence the hot start ( adds air to lean it) 

 

heres what id maybe try bud. cold engine, hit it with a shot of either or gas into carb. if it starts, ur lean, if it dont start, ur rich. 

 

guys will grid a bit off the decomp lever to aid starting but i wouldnt go to that quite yet. 

 

 

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I find that improper pilot jet and fuel screw setup makes these bikes hard to start. Watch this video and tune your fuel screw. You probably will find that it will like a larger pilot:

 

 

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I went through carb. Everything is still stock except I moved clip down 1 position(3rd), replaced 70 leak jet with a 60 and put new spark plug in. So far it is starting 1st or 2nd kick every time. Haven't had a chance to get out and really ride it, but it seems to be doing good. There is still a bog at quick throttle blip. Not sure if I should go to a 50 leak jet or 175 main?

I went through carb. Everything is still stock except I moved clip down 1 position(3rd), replaced 70 leak jet with a 60 and put new spark plug in. Fuel screw is 2 turns out. So far it is starting 1st or 2nd kick every time. Haven't had a chance to get out and really ride it, but it seems to be doing good. There is still a bog at quick throttle blip. Not sure if I should go to a 50 leak jet or 175 main?

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13 hours ago, scottydeville said:

I went through carb. Everything is still stock except I moved clip down 1 position(3rd), replaced 70 leak jet with a 60 and put new spark plug in. So far it is starting 1st or 2nd kick every time. Haven't had a chance to get out and really ride it, but it seems to be doing good. There is still a bog at quick throttle blip. Not sure if I should go to a 50 leak jet or 175 main?

 

It seems to me that you are making random changes. For ease of starting, it is all pilot jet and fuel screw tuning. Install a pilot jet that nets you 2 turns out on fuel screw.

The bog is 90% leak jet and AP setup. Slap in a 45 leak jet and adjust the AP timing to just miss the slide and a bit of slack per this video:

 

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14 hours ago, scottydeville said:

Thanks I looked for a 45 to begin with, but a 60 is all I could find in the pen section on Rockymountainatv.com

 

 

Before taking the carb apart, try tuning your fuel screw. If 2.5 turns out or more, increase pilot jet size. 

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Before taking the carb apart, try tuning your fuel screw. If 2.5 turns out or more, increase pilot jet size. 


Ok I'll give it a try. Thanks

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