Here is an update.

I have a 2006 Rubicon that had an upper end engine knock, (see earlier post... http://forums.atvconnection.com/hond...ine-knock.html

When the engine warms up the knock always faded away. I replaced the cam shaft because the auto decompression mechanism was suspicious in being faulty. It worked and all went well.

300 miles later the knock returned. What I discovered is the cam tightener is to its full stoke length and cannot tighten the chain anymore and the chain must be stretched. I solved this with a .50 cent cap nut that I milled to fit over the end of the tightener giving it about 1/4 - 3/8 in further reach - assembled and the engine is quit again.

The chain should be changed but wanted to try this cheap alternative to the major tear down needed to replace the chain - maybe this winter.

Has anyone else had an issue with the cam chain stretching? It's a used machine with 3000 miles on it. Purchased it used so I have no idea what it's been through.

Thanks,
Denguy

 

I have a 2005 Rubicon with about 9700 miles and I also need a new cam chain. It has a knocking noise that does not go away.

I have replaced the chain tightener and it quit for a while but the noise has came back.

I may have to try your trick sometime.

If I do get a new chain installed, would I be basically getting a rebuilt engine? I have talked to two different shops and have got two different answers. The Honda dealer where we bought it from said it would be a engine rebuild and would be over $1000. The second place was a local place and he said you would just replace the chain and not much else. He said the chain comes out the bottom of the engine. He would only charge $400.

 

Angler-

It's hardly a rebuilt engine and can be done with the engine in the ATV. The hardest part is getting the wet clutch off since the timing chain is behind it. No the cam does not simply drop off the bottom of the engine and needs to be removed from the front after pulling the clutch plates. The best illustration of a "McGuyver" fix to purchasing a clutch puller tool you will only use once is this site...

Honda Rubicon Timing Chain Replacement. | 2FarOffRoad.com

This guy used a "pipe dresser" or coupler. I checked it out and they have metric threads and makes sense. It’s that or extend the reach of the cam tightener as I did. Make sure the milled cap nut is firmly fitted to the end of the existing cam tightener before installing. It could come off during instillation and drop into the engine.

You might want to check out the auto decompressor I spoke about in an older post. Which maybe another cause of the same knock?

 

is the knock kinda a tiny sound, at 1/4 throttle like a loose wrist pin? my friends 06 had that, we just ignored it and he sold the quad. my 2001 is still rock solid to this date!

 

it's a knock like a diesel sound - not a ping or "tiny" of any kinda. The cam replacement helped and the cam chain tightener did the rest. Sounds as it should. I have a Rincon as well that had that "tiny" sound to it. adjust the valves and went with high octane gas and it was gone?