Auto-decompressor problem on XR650L

4 replies to this topic
  • sgifford

Posted November 12, 2006 - 01:17 PM


In a previous post I stated that I thought I had an electrical problem from a partial submerging of the bike. After removing the cam shaft I discovered that the new intermittent ticking noise is coming from the auto-decompressor mechanism.

The decompressor cam is loose on the camshaft. It's not actually spinning freely, but it is very loose, and I can see how it will rattle around when the camshaft is spinning.

My Clymer manual says a hydraulic press is needed to remove the camshaft sprocket holder and get at the decompression components. I'm going to try and find another way.

While I'm in the engine, I'll replace the cam chain. It appeared rather stretched (but I don't really know how much tigher a new chain would be). The tensioner appears to be fine, but with problems that people have reported with tensioners, I might replace that while I'm there too.

I"ve included some pics of the camshaft lobes and rocker arm pads. There is some scoring on the camshaft lobes, but I'm going to try and clean it up with oilstone. I'd rather not spend for a new camshaft at present. Plenty of oil seems to be getting to the cylinder head, so I'm suspecting that the scoring happened before I switched to synthetic. I ride hard off-road in very hot Texas heat.


Camshaft lobes


Rocker arm pads


Cylinder head

  • frankstr

Posted November 12, 2006 - 02:23 PM


Dude, That Camshaft is shot...its thru its hard facing....the pitting..
I'd replace the rockers too..Cams and rocker arms are wear mated items..


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  • WY XR650L

Posted November 12, 2006 - 09:02 PM


How many miles do you have on the bike? My 1999 XR650L looked worse than that at 3500 miles. I replaced the cam, four rockers and bearings. 300 miles latter the same thing. It looked like it was getting good oil in the top end. This time I checked the oil pump and the max clearance is .002" and mine was .003". I don't know if this is the problem or not. I see that Honda sells a cam with the decompression stuff and timing gear flange allready assembled. Its about $40.00 more than just the cam. That's the route I am going to try this time. What synthetic oil do you use?

  • BRPXL600R

Posted November 12, 2006 - 09:03 PM


Yup definitely cam and rockers are wasted!

  • sgifford

Posted November 13, 2006 - 04:41 PM


The bike has 13,500 miles on it. Many of those are hard off-road miles, including hot Texas summers. Somewhere around 5,000 I started using Amsoil 20w-50.

I will definitely check the oil pump. I don't want to buy new stuff and fry it.

I've been debating going to a Hot Cam. I like the idea of more mid-range and top-end, but I wouldn't want to sacrifice the low-end torque.


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