Topic: Replacing Cam Chain Tensioner?

[chadheins]

How big of an undertaking is this operation? I've been looking on ebay for a working one and prices are good. Mine is stripped and I don't feel so safe riding it. I suppose it is still always applying tension, but I'd rather be able to lock it in to that tension.
Thanks,
-Chad

[Patrick]

What bike?

[fuzzybutt]

the the 750's the motor has to come out and the head and cylinders have to come off.

[Steve F]

the the 750's the motor has to come out and the head and cylinders have to come off.

If you're refering to the 750, the spring part of the tensioner is held on to the back side of the motor, just below the carbs with three bolts and is easy to replace or fix, any other engine, I'm not familiar with.  If you have to replace the part that contacts the chain, then yes, you have to pull the top-end of the engine to get to it (again for the 750 engine).

[chadheins]

Oops that was dumb of me, it's a '76 CB550K

[bryanj]

Head and cylinder need to come off

[chadheins]

I just need to replace the tensioner closest to the carbs, the bow type one. From looking at schematics it seems like with the head off it would be doable. Yes, no?

[gregimotis]

I just need to replace the tensioner closest to the carbs, the bow type one. From looking at schematics it seems like with the head off it would be doable. Yes, no?

If you're willing to pull the head, the cylinder isn't much more effort (on a 750)

And then you could drive yourself into the madhouse thinking of all the other things you should do while in there: honing the cylinders, replacing the cam chain, fixing the head gasket leak, replacing the internal tensioner parts, valve lap, etc etc.

[WFO]

I just need to replace the tensioner closest to the carbs, the bow type one. From looking at schematics it seems like with the head off it would be doable. Yes, no?

If you're willing to pull the head, the cylinder isn't much more effort (on a 750)

And then you could drive yourself into the madhouse thinking of all the other things you should do while in there: honing the cylinders, replacing the cam chain, fixing the head gasket leak, replacing the internal tensioner parts, valve lap, etc etc.

Well now that you told him 

[Drewery]

I don't think the tensioner did a lot on those 70 Honda engines anyway. I mean, they sort of work, like you need one in there, sort of, and that's the reason those engines always had such a loud cam chain chatter. Personaly, I wouldn't bother until you have to take the engine apart because of something else catastrophic either next week or in 200,000 miles.

[bryanj]

No, the cylinder needs to be lifted and once you have loosened the nuts on the head it disturbs the base gasket and O rings anyway so they need replacing

[gregimotis]

I don't think the tensioner did a lot on those 70 Honda engines anyway ... and that's the reason those engines always had such a loud cam chain chatter.

Mine doesn't.  Maybe you aren't adjusting it right?

[bryanj]

I agree, if adjusted right you only get a clatter if the chain is toast

[ieism]

I can relate to  what Drewery is saying. On my first 550 I thought the cam was so loud (compared to other bikes) that the guide or chain must have been completely gone. I bought a new one to replace, only to find out it didn't make much difference. You have to be patient adjusting it.
If the bolt to the guide is stripped, I would get a new one for sure. It will wear out the camchain faster, and a broken chain is a big problem.

Taking the head off and replacing it is only a few hours work. You only need to lift the cylinder block a bit to get the guide out. So theoretically you don't have to get the cylinders out of the barrels (that saves a lot of work trying to get them back in), but you'll have to see if you still trust the gasket when you lift the block.
I lifted mine, and the gasket looked really new. So I left it and it never leaked.

You also need a torque wrench to put the head back on.   

[Drewery]

I find that if one torques the bolts back to spec they sometimes strip the aluminum. They just dont go back together like when the robots do it the first time. Is it unreasonable to dial back on the torque spec to avoid this? (just a little maybe) I realize it might leak a little oil but still.... Anybody have a suggestion?

[BobbyR]

I find that if one torques the bolts back to spec they sometimes strip the aluminum. They just dont go back together like when the robots do it the first time. Is it unreasonable to dial back on the torque spec to avoid this? (just a little maybe) I realize it might leak a little oil but still.... Anybody have a suggestion?

When you torque a bolt you stretch the bolt which wants to spring back to it;s original length. Old bolts that have been torqued may not stretch as they originally did. If you use a lubricant you can cut back 20% on the torque value. If you want more peace of mind you can use a mild(blue) loctitie as a lubricant which will harden and make the bolt more vibration resistant.

[bryanj]

They aint bolts they are studs with nuts and NO it aint alright to reduce the torque value

[754]

A base gasket installed with a thin smear of silicone on each side would likely allow it to lift and be re-used.. but if you glued it you are h :oped

[Gregorymoto]

Hay Chad M3 racing has a real nice up grade for like 60 might be less.
Its worth it.