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CRF250R - 2004 - Bike not firing HELP please!

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Alright so heres the rundown, I have an 04 CRF250R and today it wouldn't start as well as it should last night, so today I had started it up and noticed it would not fire at all. (Kick and Roll wouldn't work)

First thing i thought it was was the spark plug... however i did a spark test and it worked, but to humor me i threw a new one in there anyways, nothing. It acted the exact same.

So I thought it might have been my jetting, so i set it back to standard jetting from the manual (155 - 4th position on needle) and nothing, acted the exact same. Even cleaned the carb.

So i did all the other little stuff I could think of, clean air filter, oil change, and nothing happened. It was still being stubborn.

It has about the same amount of compression give or take a little at times, so i'm not thinking its anything to do with the piston, however it made me think, my shims? I just had my top end rebuilt roughly 15-20 hours of riding, which i thought they should last longer however I was wrong... possibly. I really didn't want to rip open the head and check the shims with a feeler gauge unless you guys think thats what it is. The carb boot is sealed nicely, gas goes through the carb, i think its just having trouble somewhere in the cylinder area because when I twist the throttle it shoots in gas. Any help would be great and thank you guys so much. You always know how to help a person in need.

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Well first i would take a flashlight and look at the side of the air boot closest to the shock. It is very easy to put the boot on and it looks good from the outside but on the other side there is a gap. If you see this then your new topend has most likely gone. If it is sealed good though, I would check the valve clearences. It sounds like this is the most logical thing that it could be. Checking the valves should be a 15-20 minuite job from start to finish. It is really preety easy. Do these two things and then tell us how it goes.

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Alright guys so it worked beautifully when i re shimmed it, it was a 175 and i threw all the way down to a 155 in there (was just barely over on the low of the limit) .002". It started AWESOME, first kick, nothing wrong, and even ran like a champ. So after 1 hard ride up at the track, (Performing all required maintenence) it wont start unless i bump start it. I could kick it to the moon and back and it wont start, but i can just get it rolling, not even all the fast and bump start it into second. What could be the problem? Still rides like it should, I already tried a spark plug, didn't gap it at first, and went down in small increments on to what it says the correct spacing is in the manual and still nothing. The only bad thing i did to my baby was choke it for a little too long like 2 laps and wondered why it was running like crap and was like duhh, the chode. does this harm the engine or shorten the lifespan of my valves? Also what else could the problem be, im about to rip it down and check the valve clearences right now, but i dont know what else itd be. I probably need to just clean the carb too? Please let me know if you guys have any input on what I should do. Thanks as always!!

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It's the valve clearance. Once you lose clearance they're toast. Let me guess...you shimmed the rt intake?

Who did the head work? If they didn't check and recut the sets then you just threw money away.

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I actaully probably messed it up for myself there then because i did the head work. Im new at this whole thing, so lets see if i truely messed it up.

Had 1.75mm Shims in it, Valves got too tight, couldn't even fit in a .0015".

I went down to 1.55mm shims, and couldn't fit a .0015" but could fit a .002" of .003" maximum. So I left those shims in, and I lined up the arrow and dot, as well as the lines on the camshaft, so it started up first kick and thought I did a great job on it.

Well needless to say, I rode it around maybe 1-2 times at the local orv park just messin around, and 1 track day, now the track day i left the choke on for like 2 laps. not knowing if that matters, but i couldn't kick start it after that, only bump start it. But it runs pretty decent, I dont notice any significant changes in the way it rides so i dont know if its just like sometime i'v overlooked or what. I tried a new spark plug, and that wasn't the problem, so im kinda stuck. I just ripped everything off the bike except the engine. Im about to clean the carb, see if something got jammed in there or a lot of dirt got in (hope not), engine is clean though. I could take pics if that'll help anyone determine what could be wrong. Just let me know what i should take pics of if any. and I'm about to open up the head so let me know i'll check back in 10-15 mins.

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The right valve is tight, wont even fit .0015" and the left one will fit like a 25, any idea what i need to do or what this means? I could i guess put a smaller shim in the right and keep the left like that but is that alright to do? It would need like a 1.35mm shim if thats the case, does that work though? Plus only a couple shops are open monday.

So here is the rundown, Right too tight, left is fine, what do i do?

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How many hours are on your new top end? Because without getting the seats re-cut properly and possibly new guides in your new valve job was basically a big waste of money, and if you have to re-shim that much after that little bitty ride... sorry to be the one to tell you but you're more than likely going to need all new valves and DEFINATELY get your head done (seats cut, etc.) www.mxtime.com and then call him up.

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I had the top end redone by a mechanic at powersport honda, (Washington) the mechanic has tons of experience so i am not to worried, I didn't even know about recutting, i just told him i needed a piston, valves, and a magneto. He rehoned the cylinder and i'm sure he did the necessary work on my valves. I haven't replaced anything in the top end since except for shims. 1.75mm to 1.55mm (which now the right is tight and the left is loose.) So i'd say i have almost 25 hours on my whole new top end, magneto (valves are part of the top end right? but i told him to put those in) It would have been that quick after the first reshimming, so the second time i have to shim it, its that quick, i dont think its right but i might have done something... anyone need pictures of my bike to determine anything, let me know and i'll take them while its apart. I'll check back in a little.

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The right valve is tight, wont even fit .0015" and the left one will fit like a 25, any idea what i need to do or what this means? I could i guess put a smaller shim in the right and keep the left like that but is that alright to do? It would need like a 1.35mm shim if thats the case, does that work though? Plus only a couple shops are open monday.

So here is the rundown, Right too tight, left is fine, what do i do?

I had the same problem, valves kept tightening up on me everytime I rode until there was nowhere to go. So I called Randy Mann about head work and sent the head over there to FastMann Racing. He recut the seats and put new valves in and everything is good now. He said the source of the problem is that the seats werent properly cut out of the factory which in turn messed up the whole deal. I got the head back with the new seats and valves and it runs absolutely perfectly, starts one kick cold, fires right up after you dump it, its great. You should probably look into getting some head work done.

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I had the top end redone by a mechanic at powersport honda, (Washington) the mechanic has tons of experience so i am not to worried, I didn't even know about recutting, i just told him i needed a piston, valves, and a magneto. He rehoned the cylinder and i'm sure he did the necessary work on my valves. I haven't replaced anything in the top end since except for shims. 1.75mm to 1.55mm (which now the right is tight and the left is loose.) So i'd say i have almost 25 hours on my whole new top end, magneto (valves are part of the top end right? but i told him to put those in) It would have been that quick after the first reshimming, so the second time i have to shim it, its that quick, i dont think its right but i might have done something... anyone need pictures of my bike to determine anything, let me know and i'll take them while its apart. I'll check back in a little.

Don't assume that because someone works at a dealership that they know what they're doing! Trust me, alot of them don't! Go to www.mxtime.com. and check out their site. Dave is a super nice guy and has very resonable rates. $68 to cut seats and assemble your head! I'm sending my head to him tomorrow. :applause:

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Are stainless steel valves going to last any bit longer than OEM Valves (Whatever they are made out of) and are Titanium Valves going to destroy my head or are they going to last longer? The only thing I could find out is that the wont bend as easily, they have more heat resistance, and are coated with anti-friction stuff. So will it run smoother and i'll notice a gain? Or would it be a total waste of money? Monday I'll give dave at mxtime a call as well as Randy Mann and FastMann Racing and compare the two. I don't mind spending a little more if its gonna be done right. Thanks for all your guys help. Its nice, I never even knew how to do anything on my bike more than changing the oil and cleaning the air filter until i got a hold of this site!

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Are stainless steel valves going to last any bit longer than OEM Valves (Whatever they are made out of) and are Titanium Valves going to destroy my head or are they going to last longer? The only thing I could find out is that the wont bend as easily, they have more heat resistance, and are coated with anti-friction stuff. So will it run smoother and i'll notice a gain? Or would it be a total waste of money? Monday I'll give dave at mxtime a call as well as Randy Mann and FastMann Racing and compare the two. I don't mind spending a little more if its gonna be done right. Thanks for all your guys help. Its nice, I never even knew how to do anything on my bike more than changing the oil and cleaning the air filter until i got a hold of this site!

Just call Dave! He can hook you up with the stainless valves and everything. The stainless valves will last longer. Dave can answer all your questions.

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Alright thanks fletchman919 (I like your bike by the way!). I'll give him a call tomorrow before work. Stainless steel it is then!

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