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Cam Chain Tensioner Troubles

November 7, 2011

I found more debris in the oil filter and more shavings in the oil so figured I better get a look inside and check it out. I tried to pull the cam case cover to get a peek, but it was not possible with the motor in the frame, so I figured it was best to take it out and get a really good look. When I drained the oil I found chunks of black debris in the oil plug.

 

Engine Out

 

I managed to pull the motor off the bike in a matter of three hours and was able, barely, to lift it up onto the bench alone. That's a heavy little sucker.

 

I pulled the cam cover off and took a look inside; it looked as good as new. Nope no problems in there.

 

Cams and Rockers All Look Good

 

On a whim, I pulled the cam chain tensioner unit off the back of the cylinders. Ah Ha! There is supposed to be a black plastic wheel on the shiny hub of what's left of the cam tensioner roller in the back and middle of the cylinders, between and below the intake boots. Now, I also know what the black chunks were that I found in the oil drain plug.

 

The Cam Chain Tensioner Sans Rear Wheel

 

At least it is good to know what the problem is. But the tensioner assembly pin is nested between the cylinder case and the top crankcase half. I would have to go deeper to get the tensioner out, including pulling the head and cylinder case.

 

So, off came the cam case, and then head and cylinders, and all was revealed—no rear tensioner wheel at all and a front wheel reduced to less than half its proper diameter. Both would need to be replaced.

But where was the cam guide? It belonged along the front wall of the cylinder case going from bottom to top, where it hooked by means of pins into the case. I took a look deep inside the engine case below where it should have been and there were the twisted remains of the guide, missing its pin and with the top pin and the ear to which it was supposed to be attached torn off. Carefully, I reached in with a pair of needle-nosed pliers and pulled the bits and pieces out. There was a bit of metal stuck in the wall of the chain passage which I grabbed with the pliers, and of course, promptly dropped into the engine case.

 

The Pair On Right is what the Tensioner and Guide Should Look Like.

 

What was Left of my Tensioner and Guide

 

 

There has to be a lot more stuff laying in the bottom of the case. I am going to pull the right side cover and clutch so I can take out the oil pump, and hopefully there will be enough access to the inside of the engine case that I can get all the debris out and hopefully I won't have to pull the engine top case off, also. That will be tomorrow. Fingers crossed.

 

I found all the tensioner and guide parts I need NOS (new old stock) at Western Hills Honda in Cincinatti, a trusted source for many of the parts for this old bike. The prices, too, were barely more than the original prices. About $49 plus shipping bought the guide, its pin, and new front roller. On ebay I found a new redesigned rear roller, made of better material and with roller bearings, which the original lacked. That ran me $58 including shipping from Poland. So, for little more than $100 I will be able to get this motor back in shape. All the parts will take a while to get to me here in Florida, so while I am waiting I will have time to do a really good cleaning of the engine's interior, hopefully being able to do that without pulling the case apart, but if that is necessary I will have the time to do it.

 

I was surprised the cam chain tension and guide could have gotten that bad that quickly without more warning. I had recently replaced the head gasket to cure an oil leak and had seen the tensioner, which at that time appeared to be in decent shape. But now, looking back at it, I did notice silver shavings in the oil last time I changed it. I figured it was stuff I had not cleaned off the head and cam case well enough before assembly the last time I had done the gaskets. Apparently, though, the shavings were from the rear roller's metal hub, which must be soft aluminum, luckily, because I can find no sign of wear on the cam chain that had been constantly running against it.

 

They say what doesn't kill you makes you stronger; and I guess what doesn't completely kill your motor makes you a better mechanic. We'll see. Now, the wait for parts begins.

 

Cheers,

 

Road Dog

"Ride Your Own Ride."

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October 26, 2018

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