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Dead 03 Crf 450!!!! Why??????

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ok i have a 03 450 my dad bought it new in 04 then sold it to me in 05 well about 4 monthes ago i put a new topend in it and rode it once vavles where kinda tight so i parked it then i took it and had the valves done and it ran great for about 4 rides then the water pump started leaking through the weep hole so i went through it and changed the bearing a seals and changed the oil and took it out today and it didnt leak so that was nice i thought hey my bike is actually running good with no problems so i rode it about an hr shut it down and went back out and rode some more well i was going across a field riding some stand up's when i got to the end and set it down it died so i figured i was out of gas but no i wasent so i went to kick it and it was locked up solid i put it in second and rolled it back and it turned over so i kicked it and it started up then it back fired and died again and was locked up solid!!!!!!! why???????? i change my oil and filter every 2 rides and it never got hot or anything what could of caused this???????? :lol::applause::eek::lol:

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why would it lock up though and then free back up when it's moved back thats usually a sign of main bearing isnt it????

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no it locks up again after about 45 sec of running then if you roll it back in 2nd it will free up but then when you start it it runs for about 45 sec then just locks up

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quit starting it and take it apart sounds like a interference problem. should be pretty obvious. bet it's out of time

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quit starting it and take it apart sounds like a interference problem. should be pretty obvious. bet it's out of time

Yup and everytime you start it you're damaging things further...:applause:

You can't wish it well...

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Its a clearance issue. When you start it up within that 45 seconds things get hot and metal expands then the clearance goes away and the motor seizes. It shuts off cools down and frees up then you can start it again and run it for another 45 seconds....its physics man!

Anyway do you hear any ticking?..like valvs touching the pistion? If it back fires you valves sound like the culprit.......but if not I was gonna say maybe your rings are gapped to tight and expanding to much in the cylinder and seizing the crank until the rings cool. Anyway take it apart and find the problem.

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i only started it once after it seized but thats not the issue n-e way i tore it down tonight and the piston looks fine also so does the cylinder the valves look like they are seated up also they dont look bent the crank does have some side to side play i think more than it should and has the slightest up and down play but it's so minimal you almost cant even tell its there i dont know what the problem is anybody have any suggestions of what to do????

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i only started it once after it seized but thats not the issue n-e way i tore it down tonight and the piston looks fine also so does the cylinder the valves look like they are seated up also they dont look bent the crank does have some side to side play i think more than it should and has the slightest up and down play but it's so minimal you almost cant even tell its there i dont know what the problem is anybody have any suggestions of what to do????

don't you just hate it when it is not obvious :lol: ,----anyway --i know how you feel .

diagnosis is always the hardest part ----i have 4 bikes in the shop now that were doing kinda waht yours is doing -----two blue ---one yellow:banghead: :lol: ---and one red like yours .

i always strain the oil that comes out of both sides and i check that the volum of each is kinda normal -----then i carefully cut apart the oil filter and gather all the metal from the oil and the filter and i try and see if it lots of iron and or aluminum and so forth -------the play in your crank is not good -----and it is an 03 ----so we know the crank is cycled out on borowed time anyway ---

you will more than likley just have to bite the bulit and do the whole motor -----all bearings, crank , seals ----dissaemble the trans ---i always find lots of worn gears and shims and stuff there in the trans --

i know this is not what you wanted to here -----but it generally goes this way -------i wish you the best of luck ,

i always add a new cam chain and i jam the tensioner so it can not move at all ,

even if the guy just had the head done ---i always go back through the head and spin and check the valves ----they bend and you can not tell untill you spin them and really look !! :applause:

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thanks for the opinion either tonight or tommorow im going to pull the flywheel and look at the stator and see if anthing came loose of if there is something binding inside of there and if i dont find anything i guess it will get a new crank and so forth

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Sounds to me like it could be a bad tranny bushing or even a gear, how much Tran’s oil to you put in it after you drain it? I have talked with a few guys that have had tranny issues with there 450’s and when I ask them how much oil they use in the tranny side most of them say “I use 590cc’s or I just use the check level bolt” well this is not what these bikes need, you should be running at least 650cc’s after draining the oil. I have a 2003 CRF450, I bought it new the day it came to my dealer ship I have had it for 4 years now. I only run 650cc of synthetic motorcycle oil in it and I beat the living sh1t out of it and never have I ever had one transmission problem. I took my entire motor apart last year and inspected all the gears and everything looked perfect, the only thing that showed any signs of wear was the counter balancer shaft.

My point is don’t rule out the tranny it could be your problem.

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I'm sorry but i also have a 03 450r; and your running full synthetic in your tranny? I thought that was a no-no. I'm just curious cause at a new track i used the clutch a lot out of corners and it seemed my clutch was fading after the 2nd lap. Then it did it again on the 2nd moto.

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I had a simular situation with a YFZ 450, turned out to be a bad main bearing.

It would lock up only every once in a while, once I had the top end off I had to roll the crank around for a couple of minutes before I could get it to lock up again...my guess is one or more of the bearing became out of round sort of egg

shapped...when the bearing layed flat it was fine but if it got caught end to end that's when it would lock up.

try to determine if it's the crank or trans side and work from there.

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I'm sorry but i also have a 03 450r; and your running full synthetic in your tranny? I thought that was a no-no. I'm just curious cause at a new track i used the clutch a lot out of corners and it seemed my clutch was fading after the 2nd lap. Then it did it again on the 2nd moto.

Just wondering why you would be clutching your 450, to me that's a no-no.

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i run 700cc oil motor oil in my trans side and in my engine side and have never had a problem before it shifts fine through all the grears but you never know and i have always heard that synthetic motor oil is very bad for a clutch but everybody uses something different but i will dig farther into it and see what i find but im still thinking is the main bearing

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believe it or not, im on here with the same exact problem. Im glad to hear that i am not so unique. I have an 02 crf450 that is in what i call lockdown also. I went with new kickstart shaft and pedal. My bike ran great in warm up, then when I rode it wide open from 1 to 4th gear the motor turned off dead silent, no bump or nothing. Now its locked. I have asked a lot of people and have heard everything. The timing issue sounds reasable, we both just did a top end valve job, and now we are having this problem. Please post if u find ur trble, as I will also.

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i have always heard that synthetic motor oil is very bad for a clutch but everybody uses something different but i will dig farther into it and see what i find but im still thinking is the main bearing

Allot of people think this and its totally wrong, I have bin using amzoil motorcycle specific in both my engine and tranny now for 3 years and NEVER had a clutch problem, I just had my clutch out 4 months ago and there is no bluing on the plates nor is there any glazing. YES synthetic “motor” oil will rune you clutch, but only a fool would run none motorcycle specific synthetic “energy conserving” oil in a MX bike.

And no I’m not bashing Mobil synthetic oil, as long as it is not the “energy conserving” stuff. As long as you’re running motorcycle specific synthetic oil in your bike it will simply last longer and perform better, assuming you change often.

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believe it or not, im on here with the same exact problem. Im glad to hear that i am not so unique. I have an 02 crf450 that is in what i call lockdown also. I went with new kickstart shaft and pedal. My bike ran great in warm up, then when I rode it wide open from 1 to 4th gear the motor turned off dead silent, no bump or nothing. Now its locked. I have asked a lot of people and have heard everything. The timing issue sounds reasable, we both just did a top end valve job, and now we are having this problem. Please post if u find ur trble, as I will also.

sorry to hear that you are having the same trouble as me i havent had a chance to go through and check behind the fly wheel or anything b/c i just bought a 01 tl1000r and need to do a little bit of work to it but i am hoping to get to it pretty soon so i'll let you know what i find if i find anything

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I have an '04 CRF450R and I just ran into the same problem. I just did a top end job this spring and it has been running good for a couple months. Last week i took it out and it ran great. No signs of anything wrong and out of nowhere i was in third gear and it locked up c@ck stiff. It seized, but after letting it cool for about 20min it released and started, but has been doing the same thing after it warms up. It WILL run, but not for long. If you found the problem with your bike pleasssssssssssse tell me and hopefully i can fix mine .

Ciao

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