My engine is making a knocking noise any Idea's on what all could be wrong?

No I haven't checked the chain. I will do that before I go any further and report back.
Have you heard a knocking noise because the cahin was out out adjustment? Hitting the case some where?

I found the chain roller bolt was not installed through the roller. The roller had walked itself up by the cam spocket. Once that was fixed the knocking noise went away.
Now the chain is too tight and making a whine noise. I'm trying to set tension on timing chain. Service manual says to set it while the engine is running. Where is this set screw located? Can't find it in the manual and where I think it should be (by the gear indicator), just has a phillips head screw.
So one problem down, one to go.

Cam chain Adjustment is a bit different by year.
1985 ATC 70's ( Fig 1) do not have the locking center set screw.

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Pre 85 adjustment screws have a locking center set screw. (Fig 2 )

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The 85 tensioner ( Fig 4 & 4A) assembly works off of a tension spring ,oil pressure, and a check valve

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Notice the holes drilled on the side of the rod (fig 4 & 4a) to allow oil inside the rod.

To release tension, take the bolt out ( #2 in fig 3)
Oil will squirt out and release tension. If it does not, take the bolt at the bottom out ( #1 Fig 3 )and remove the spring and rod ( #3 Fig #3 ) through the bottom.

Inspect for any damage and reinstall , there is no manual adjustment that can be made to the 85.

Oil pressure builds under the tensioner rod ( #3 Fig 3 ) and pushes the rod up against the arm that holds the roller tensioner. The check valve ( Fig 5) keeps the oil presure constant , In other words the oil cannot back flow and let the tension off of the rod without manually removing the screw (#2 Fig 3)


Pre 85 models ( Fig 6 ) are totally different in form an function albeit they both accomplish the same thing.

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Notice that there are 2 springs in pre 85 tensioners (fig 6)

Also notice that there is a flat side on the tensioner rod (fig 7 )




Pre 85 tensioners are adjusted as follows:

Note: If the chain is not making noise there is no reason to adjust it. So we are assuming that you have cam chain noise at this point.



Step 1: With the motor running, loosen the 12mm lock nut that holds the locking center set screw. ( fig 2 ) back the locking center set screw.off ( counter clockwise) which will release the rod ( #3 fig 3 ) and allow the springs (fig 6 ) to push up on the rod

This may eliminate your noise . If so tighten the locking center set screw.down ( clockwise) and then tighten the locking nut , you are through adjusting the cam chain.

If not go to step 2

Step 2: Remove the bottom cover bolt ( #1 fig 3) locate the lower set screw as seen in fig 6 & 8 . With the lock nut and set screw loose as described in step 1, Tighten this lower set screw(fig 8 ) up inside the case ( standard #2 screwdriver) until your noise stops. tighten the locking center set screw.down ( clockwise) and then tighten the locking nut.

Sorry for the vague answer

Incedentaly, The Lifan and most clone motors have adopted the 85 style tensioner

thanks for the reply. I was looking for the adujustment to be on top of the engine, not the bottom. I'll adjust it this weekend and let you know how it goes. Good informaton.