Honda Dirt Bikes Forum

my 2001 cr250 has a motor knock it seems to be a top end knock. what should i do i dont want to take it to a dealer and pay the price. dose anyone know what is causing it or any ideas on whats causing it  

if its in the topend a worn topend can do this. i'd take the head off hte cylinder and make sure your piston is ok. ~pat  
PEACE GUYS ITS BEEN A BLAST!!!!! ~patrick

you probably need to run a higher octane gas. What octane gas are you running? You should run at least 93 octane gas.  
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The only reason a four-stroke can beat a two-stroke is because of the double displacement advantage

1996 RM125

ohh damn thats right! rm's right forget mine. what octane are you running? or if it was old gas it cna do this. called preignition. ~pat  
PEACE GUYS ITS BEEN A BLAST!!!!! ~patrick

lol i was in mid post when you posted yours pat  
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The only reason a four-stroke can beat a two-stroke is because of the double displacement advantage

1996 RM125

im using 93 octain and it was brand new gas i mixed it 32:1 i think im going to look at the piston tommarow  

o. careful. you got a manual? ~pat  
PEACE GUYS ITS BEEN A BLAST!!!!! ~patrick

yea pat is prolly right then, and your top end may be worn  
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The only reason a four-stroke can beat a two-stroke is because of the double displacement advantage

1996 RM125

wouldnt have to buy a new cylender would i? just a piston. well i crashed it a few days ago and it had a small knock before and after i crashed it the knock got worse  

you probably wont need a new cylinder, just aa piston, which comes with rings, circlips, adn a wrist pin, and you might want to replace the gaskets  
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The only reason a four-stroke can beat a two-stroke is because of the double displacement advantage

1996 RM125

a crash ehh. hmmm i wouldnt worry about it. my opinion still stands. she probably needs a top end rebuild. hows hte compression feel? ~pat  
PEACE GUYS ITS BEEN A BLAST!!!!! ~patrick

the compression is very good takes alot to kick it over, so i dont see why it would need to be replaced. yea i was riding in my friends field and my back tire hit a smallish rock and it sent me over the handelbars.  

hmm. your top end definitly neds to be looked at. your jetting may be too lean, and thats causing this, its the time of the year when the temperature starts dropping so it will run leaner in colder weather. i'm not going to say you need just a piston because if this has been going on for a while then there is a big probably that you need a new head too. you need to take apart your top end and look for damage to anything. measure the cylinder diameter for spec. and the piston and piston ring end gap. if the cylinder is out of spec then you should get a new one or get it replated. replating is a lot cheaper and its just as good. you should get a top end kit. comes with new bearing and circlips, and new gasket kit. and put a new spark plug in. if its still knocking then you know you have dirt in the carb or your running too lean.  
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Ride 2 strokes, buy 2 strokes, save the 2 stroke.

1998 cr125
2002 cr80