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4/28/2016
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CA
I posted awhile back about an engine knock in a 2013 crf250r thot we had the problem sorted out but it turnes out we didnt, after taking the bike apat again everything seems to be fine, and everything in the engine is bran new, valve clearance, piston and rings are good, checked it all, new plug gaped properly, the only thing so far that we noticed might be making the issue is the decomp pin on the camshaft. Does anyone have any related issues or know how we might be able to solve the problem? Maybe adjust the pin or somthing?
Thanks for your help !
Thanks for your help !
I have fixed two Honda engines with the same situation.
Both times the knock was the crank bearing.
THE CONROD SHOULD HAVE ZERO SIDE ROCKING
I thought the rod bearings were okay, until I purchased brand new cranks from Honda and could tell there was zero rocking on the new rod, but the bad rod had so little rocking I was fooled it was good.
The very ends of the crank pin and bearing wears but the middle is okay so there is no up and down play in the bearing, but if you can grab the rod and slightly rock it in a rolling motion side to side it was what caused my knocking noise on a trx450 and also a CRF450.
I pressed one of the cranks apart and sure enough the bearing and pin were worn on one side and under a load it would knock. I was stoked I fixed it because people had said it wasn't the rod that was bad and they thought I was going to get it back together and it would still knock, but of course it was quiet as a mouse.
This was when I could not find anything else wrong in the engine too.
Good luck buddy.
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