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just rebuilt bike now i hear rattling and it dies

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05 crf 250r just put new in valves and new piston.Rode for about 5 hours and at the end it just died. Then i was ables to start it and heard a rattling sound kind of like a ratting chain it sounded like. I took of the head cover and the cam chain seems tight and the valve clearance were good. what could this be? the oil was still the same level. it was hardto kick through sometimes and sometimes it wasnt. it almost seems as though sometimes it was scraping whent i tried to kick it like maybe it was the rings. Can anyone give me some input of what you think before i go into it and have to buty new gaskets? it will still start but makes that noise and then shut off after a minute or so

also it actually wasnt me riding this one.I was riding my 06 and my friend that was supposed to be buying the 05 rode the 05 for the first time he is the one that put 5 hours on it and he said before we went riding he was going to buy it for sure so i said it was his. But i told him im still keeping at my house until he gives me the cash.Anyway i asking if you guys thing he should pay for the damage or me. im going to do the work for him tho. So what do you guys think. hes uses to 2 stroke and he kept killing it because he wasnt in the right gear in the trails and stuff like that. we rode in the trails and it over heated to i nhad to keep stopping for him because he was going so slow. so i think thats why it over heated i dont know. but who should pay for the problem?

Edited by specialkcrf

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Did you look at the decompression pin spring? Also, pull the oil filter and see if it has any metal in it. Hopefully the spring is broke.

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i just checked that and its good it doesnt seem very strong but neither did the one on my 06

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amd just checked oil filter and there were metal shavings lots of them they look like copper but i did change the oil when i did the rebuild but not the filter i no it was stupid

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oh yeah, thats the crank. time to split the cases and replace it or rebuild it.

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Your bottom end is gone or going. that is shavings from the crank bearings. do not try and start your bike anymore it will only do further damage.

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so the bearing will make the bike die? this sucks man i just put in new valves and a new piston . what all am i going to have to replace? should i make him replace this stuff?are those shavings only from the crank bearings?

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nice! yep lost the crank, at least it didnt come apart on you and cause even more damage.. time to invest in a crank, main bearings/seal, and prob oil pump while your at it

hopefully none of the metal got between ur piston and cyl.. your going to have to split the case to find out everything you need

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How many total hours on that motor?

I doubt your friend did anything to cause that riding in too high a gear on trails....

You know how boats are holes in the water that you throw money into? Well that's what motocross R bikes are on land...

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nice! yep lost the crank, at least it didnt come apart on you and cause even more damage.. time to invest in a crank, main bearings/seal, and prob oil pump while your at it

hopefully none of the metal got between ur piston and cyl.. your going to have to split the case to find out everything you need

just curious why an oil pump.Because im in there?

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How many total hours on that motor?

I doubt your friend did anything to cause that riding in too high a gear on trails....

You know how boats are holes in the water that you throw money into? Well that's what motocross R bikes are on land...

not sure how many hours bought it for 1500 from some1 i didnt know and it didnt run put in new piston and in valves and started first kick

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do i just need the connecting rod or the complete crank shaft assembly are there kits that have eve thing i need any advice on brands and where to buy them?

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sometimes when metal is in the oil the oil pump rotor clearances can be outta spec..

you can choose between a new assembly or if the crank isnt damaged beyond repair you can send it in and get it rebuilt and trued, i find that most guys like stock cranks the most, Charlie has tried a few different cranks so he may be the better choice to answer this question.. a used crank thats rebuilt trues better then a new crank because of all the heat cycles..

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I used the stock crank assembly and the pro-x bearing and rod with a lot of success. I did have one fail prematurly and the guy that did the work wouldn't stand behind it after I sent him a ton of work. I prefer that method, but my second choice it the Wiseco assembly. I've used the Hot Rod assembly a few times with pretty decent results, but they were in bikes that weren't ridden very hard at all. My kid and a few of his friends are a real test to these different manufactures. I just installed a Hot Rod in my kids bike a few months back. It has roughly 20 hours on it right now, so time will tell. Be smart about this rebuild and replace any of the bearings that don't feel smooth and do replace the main bearings and seals regardless. The brass you see in the filter is the thrust washers that ride on both sides of the connecting rod the keep the lower bearing in place. It's really important to get that out of the engine and you'll find it in places you wouldn't believe. Do check the oil pump. The bad part is the metal that's roaming around the engine when the crank fails usually grooves the case where the pump rides. I might have a fix for those groves, but I don't know for sure until the crank I put in is goes bad. I tried something different that may have actually worked to restore the oil pressure.

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my book says i can slit the cases with a rubber mallet so i woulnt have to buy a case splitter.is that going to work. and do i have to buy a crank puller in my book its also just showing i can just pull the crank out and just put it back in it didnt show any special tools for that. And there wasnt a spec to torque the crank case bolts either. it just said tighten them securely? shouldnt there be a spec tohave them torqued down?

Edited by specialkcrf

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my book says i can slit the cases with a rubber mallet so i woulnt have to buy a case splitter.is that going to work. and do i have to buy a crank puller in my book its also just showing i can just pull the crank out and just put it back in it didnt show any special tools for that. And there wasnt a spec to torque the crank case bolts either. it just said tighten them securely? shouldnt there be a spec tohave them torqued down?

I just rebuilt my sons 08 bottom end less than two hours ago on the bike. You don't need a case splitter or crank puller. A few taps with a rubber mallet around the the case does the trick and the crank will pull right out. Keep an eye on all the washers. Be careful tightening the case bolts, I was unfortunate enough to snap one off, not fun...had to get a welder to tig weld it to build it up and tack another bolt to back it out. Get them snug and a 1/4 turn should suffice. If you feel better torquing them down I am sure 5 to 7 ft lbs would be all you need. Are you going to re-use the current top end gaskets?

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I just rebuilt my sons 08 bottom end less than two hours ago on the bike. You don't need a case splitter or crank puller. A few taps with a rubber mallet around the the case does the trick and the crank will pull right out. Keep an eye on all the washers. Be careful tightening the case bolts, I was unfortunate enough to snap one off, not fun...had to get a welder to tig weld it to build it up and tack another bolt to back it out. Get them snug and a 1/4 turn should suffice. If you feel better torquing them down I am sure 5 to 7 ft lbs would be all you need. Are you going to re-use the current top end gaskets?

well if i could reuse them but im not sure if thtas a good idea.the gaskets do only have like 5 hours on them. thanks for all the info.

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