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· Registered
2 Posts
Discussion Starter · #1 ·
Hi, I have a fourtrax trx350d 89 model. I've had it for about 8 years.
It's always had a rattle/tap/knock,
Always sounded high up, I've done the tappets and had the cam out, didn't make any difference. Chain seems tight.
So I've joined up to see if you guys can help me get to the bottom of it.




· Registered
124 Posts
There are some very knowledgeable people on here, but I am sure they need more detail.
Does the sound change with RPM changes?
Have you run the oil through a coffee filter to see if there are metal bits?
Makes the sound all the time (forward, reverse, startup, warm, etc)?
Did you notice galling anywhere when you had the valve cover off? Have you run a scope in the jug?
Have you compared it with another 350D to see if it makes a similar sound?

Good Luck!

· Premium Member
5,960 Posts
Is it faint ticking, a tapping, a slapping or a loud knocking? Ticking might be valve adjustments set too loosely. If it sounds like a slapping noise it might be the cam chain is worn out and the chain tensioner is running out of slack adjustment range. If it is tapping it could have a broken piston skirt or severely worn rocker arms. If it is knocking it can be a number of things: A leaking exhaust gasket at the head, upper connecting rod at the wrist pin, lower connecting rod at the crank pin, etc. You might be able to isolate the noise using a mechanics stethoscope, or press the plastic handle of a long screwdriver against your ear while touching the various areas of interests on the head, cylinder & cases.

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