WR 400 -98 engine noise


4 replies to this topic
  • Magnus78

Posted May 28, 2011 - 11:14 AM

#1

Hi.

My engine have a rattle noise from the left side of the engine but its only there when i rev the engine not on idle. I have checked the cam chain and to me its tight but how do i know if its to lose or tight ?
I can make it tighter if i whant but the tensioner spring should add the right tightnes right ?

The bike always starts on first kick.
It takes no oil.
Dont smoke.

Runs just great i think :smirk:
Good idle and realy strong from bottom to higher revs.

I did think mabe the piston is slaping but if it did do that it should run wery bad to right ? Take oil and hard to start. Or do i need to check the piston ?

Sry for my bad english but i rly need to know what i should do.

  • grayracer513

Posted May 28, 2011 - 11:39 AM

#2

Piston slap does not mean the engine will necessarily run badly.

Does the engine rattle as it is speeding up when you rev it, and stop rattling when it's coasting back to idle after you close the throttle?

Or does it sound OK until you close the throttle and then it rattles?

Or, does it just rattle all the time while it's going faster than an idle?

Is the noise louder or quieter if you make the engine work hard, like in high gear?

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  • Magnus78

Posted May 28, 2011 - 11:59 AM

#3

grayracer513: Does the engine rattle as it is speeding up when you rev it, and stop rattling when it's coasting back to idle after you close the throttle?

Yes as sone i begin to rise the rpm it begin to rattling. But think its there on idle to but not so loud.

grayracer513: Is the noise louder or quieter if you make the engine work hard, like in high gear?

I think its alot quieter when its under load. If i cruise it on low rpm i can hear it when i have my helmet on. If i rev the engine slowly on the stand with no gear it sound rly bad i think. But on rly high rpm´s the engine sound rly good :smirk:

  • grayracer513

Posted May 28, 2011 - 12:12 PM

#4

Open the right side of the engine and check the nut that holds the drive gear on the crank. Also check the key that locates the balancer gear on the crankshaft. These are known to loosen and rattle.

If that doesn't do it, you may have a problem with the crank, the rod, or the piston.

  • Magnus78

Posted May 28, 2011 - 12:21 PM

#5

Ok i will do that and get back to you :smirk:

Btw if i take of the valve cover and put my finger on the chain betvine the cams and push it should it be any play at all there or should it be tight ? Dont trust my tensioner at all becose i know that someone did open it up before to check the spring. I know that i can make it tighter if i need to but i rly need to know how tight it should be. If you should install a manual tensioner its the same thing. How do i know whats to hard or to lose on a cam chain ?

Thx for your help.

Edited by Magnus78, May 28, 2011 - 12:44 PM.






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