Metal Tapping Sound from Engine

[jbfla]

Originally Posted by Eco Mouse

Might be a good excuse to get an inspection camera.

http://www.harborfreight.com/high-re...der-60695.html

I have one, but it's at my shop in North Carolina. I was hoping to ride the RX3 there next month.

jb

[Juanro]

Perhaps a loose or broken cam chain tensioner? And the sound is the chain randomly slapping around? That's an easy check/fix

[jbfla]

Originally Posted by Juanro

Perhaps a loose or broken cam chain tensioner? And the sound is the chain randomly slapping around? That's an easy check/fix

I was thinking likewise.

I can't find anything in the service manual that even mentions the cam chain tensioner.

Do you know if it is an automatically adjusted tensioner, or if it has to be adjusted manually?

Awaiting a response from CSC as to what to do next.

jb

[Eco Mouse]

Oh great, is this the RX3's Doohickey? I'm all too familiar with that on 2 different KLRs.

[Juanro]

It's "automatic" (spring + ratchet), is that right there where you're sound probing

[Juanro]

Take a look at this picture from the AKT (colombian) bike

[Tiger12XC]

Originally Posted by jbfla

I have one, but it's at my shop in North Carolina. I was hoping to ride the RX3 there next month.

jb

My Orange RX3 has a noisy top end also. My wifes White RX3 sounds like a sewing machine it makes me wonder if my riding style is contributing to the noisy valve train or its just the nature of the engines (I wring this baby out merging onto Texas freeways). Chain noise and clutch basket sound noisy on my Orange RX3 also. The White RX3 purrs like a kitten and they both have the same mileage give or take a few miles. I hope you get it figured out JB spring is here!

[SpudRider]

Originally Posted by Juanro

Perhaps a loose or broken cam chain tensioner? And the sound is the chain randomly slapping around? That's an easy check/fix

Originally Posted by Juanro

It's "automatic" (spring + ratchet), is that right there where you're sound probing

Indeed, the NC250 engine has an automatic, cam chain tensioner (ACCT). Here are instructions for inspecting the ACCT, from the following thread.

http://www.chinariders.net/showthread.php?t=15545

First remove the center bolt to release the spring pressure.
Remove the spring and O-ring.
Remove the two screws at the base of the ACCT.



Caution:
After removing the ACCT, return the plunger to its initial position by pressing on the locking cam, and pushing the plunger to the base of the tensioner.

[SpudRider]

Here are instructions for installing the ACCT, from the following thread.

http://www.chinariders.net/showthread.php?t=15546

Replace the Automatic Cam Chain Tensioner (ACCT)

Install the ACCT with the two screws at the base.
Install the spring and O-ring.
Install the center bolt to set the spring pressure.

[Tiger12XC]

That is the area where the chain tensioner is and in the video it did sound random like chain slapping it would be worth a shot at checking it out.

[jbfla]

Originally Posted by Juanro

Take a look at this picture from the AKT (colombian) bike

Thanks for the photo, Juanro, Spud, and Tiger.

I removed the tensioner, and the spring, and the piston click mechanism seem to be working properly.

When I reinstalled the spring, I could hear (with the stethoscope) the piston clicking into place.



jb

[SpudRider]

Originally Posted by jbfla

Thanks for the photo, Juanro, Spud, and Tiger.

I removed the tensioner, and the spring, and the piston click mechanism seem to be working properly.

When I reinstalled the spring, I could hear (with the stethoscope) the piston clicking into place.

jb

Did you retract the plunger, and lock it with the cam lock before you re-installed the ACCT?

[Jay In Milpitas]

Originally Posted by jbfla

I was thinking likewise.

I can't find anything in the service manual that even mentions the cam chain tensioner.

Do you know if it is an automatically adjusted tensioner, or if it has to be adjusted manually?

Awaiting a response from CSC as to what to do next.

jb

One quick (and easy) thing you can do is to remove one of the cam window plugs and the crankshaft plug, then with your hex wrench, rotate the engine forward until you see one of the cam marks, then rotate the crank backwards ( it will be harder) and note how much or little the crank moves before the cam does. Repeat a few times until you are certain the chain is either tight or loose. If loose, then likely the tensioner or one of the shoes is needing attention.

Alternatively, you may be able to removed the tensioner assembly (carefully avoiding damaging the gasket) and check that it's parts are working as they should.
Note: just before posting this I see Spud has also chimed in.
Edit: I see you got here also, JB.

[jbfla]

Originally Posted by SpudRider

Indeed, the NC250 engine has an automatic, cam chain tensioner (ACCT). Here are instructions for inspecting the ACCT, from the following thread.

Originally Posted by SpudRider

Did you retract the plunger, and lock it with the cam lock before you re-installed the ACCT?

Thanks, Spud.

Followed the directions.

However, I hope I didn't sign up for an engine disassembly when I purchased the RX3.

jb

[CSaddict]

Sent the video to friend that ran the service department at the local Yamaha/Suzuki/Can Am dealer and he said it sounds like a wrist pin or crank bearing issue.

Edit. listened again and now thinks rod bearing.