Valves nice and bent, just the way I like them... :mad:

[MPittma100]

Bent Valves

Unfortunately, this has happened to too many bikes, too many times! It is one of the worst things that we can do to these engines concerning time and expense. It is way too easy to not realize where the valves are in relation to the pistons. Surprisingly and sadly, we find out really fast when they are out of sync. And then it is too late.

The correct engine valve timing procedure on any engine cannot not be taken lightly. It is quite complicated, but not impossible for any of us to add the ACCT or adjust valves.

If you do either without a service manual in front of you, you have just made your first mistake. If you have a manual and you are still unsure how to proceed, please ask someone who knows FIRST!

Do yourself a favor when adjusting valves - buy the special tool and DO NOT REMOVE THE CAMSHAFTS.

I apologize in advance for being so LOUD.

MP

[D0wn5h1ft]

Unfortunately, this has happened to too many bikes, too many times! It is one of the worst things that we can do to these engines concerning time and expense. It is way too easy to not realize where the valves are in relation to the pistons. Surprisingly and sadly, we find out really fast when they are out of sync. And then it is too late.

The correct engine valve timing procedure on any engine cannot not be taken lightly. It is quite complicated, but not impossible for any of us to add the ACCT or adjust valves.

If you do either without a service manual in front of you, you have just made your first mistake. If you have a manual and you are still unsure how to proceed, please ask someone who knows FIRST!

Do yourself a favor when adjusting valves - buy the special tool and DO NOT REMOVE THE CAMSHAFTS.

I apologize in advance for being so LOUD.

MP

That's the thing. I've done this twice already. Once for a head gasket change and once again for not cleaning the surfaces well enough for the first head gasket change.

I knew I'd catch a lot of flak for this but even following the manual leaves important considerations and basic checks to do before turning over the engine. For instance, installing the guide BEFORE the CCT...not after like it says in the book. Not blaming this on the author rather than myself but I guess I should have used more common sense. I got a little cocky after having done this already two times.

[skids]

Damn I am getting old, but I *THINK* I remember the intake valves being a larger diameter than the exhaust valves and from your pictures, the intakes are not closing - the exhaust valves look OK to me.

[TopCatGr58]

Hey Gabe,

I posted this last year so you may not have seen it, I did the Carriage Bolt adjuster mod instead of the ACCT. My cam chain is a little loose, and so this thread shows the technique I used to pull the slack up on the CCT side when pulling the old cct off and then how to then release the tension after putting the new CCT or ACCT on so that the chain doesn't drop down around the crank and skip teeth!

http://www.xs11.com/forum/showthread...tension&page=3

T.C.

[BA80]

Damn I am getting old, but I *THINK* I remember the intake valves being a larger diameter than the exhaust valves

They are skids, but on the 78-79 engines they are smaller than the later engines. Theoretically the larger intake is to make up for the milder cam grind on the 80,81,and XJ. It worked too.

[D0wn5h1ft]

They are skids, but on the 78-79 engines they are smaller than the later engines. Theoretically the larger intake is to make up for the milder cam grind on the 80,81,and XJ. It worked too.

Yep, I'm dumb. It's my intakes that bent, I just checked it.

[IanDMacDonald]

Anybody wanna chip-in and explain why two dummies had only the intake valves bend and not the exhaust?

[BA80]

Uhhhhhh..........the intake cam was out of time.

[BA80]

Also Ian, the exhaust valves are smaller so they are less likely to hit the piston.

[IanDMacDonald]

Makes sense Greg, thanks.

[jjz28]

Are those valves the original ones? I was just wondering If they had that stamp on them back in 79. Makes no difference at all was just wondering. I have never touched my cct and am scared to death to do it. My bike has a little over 16k on it and I have only put about 3k on it myself but I don't think it needs it yet, I cant hear anything anyway. The PO may have adjusted it before.

[TADracer]

To kind of answer Downshift's original question, there should not be any excessive slack between the sprockets.

I got into this when I installed slotted sprockets years ago but with them I use a manual CCT (not an automatic). To degree in your cams means you need to valve cover off anyway so it is a simple operation to tighten the CCT enough so that there is about 1/4" up/down movement in the chain between the sprockets. This mimics the chain slack with the factory tensioner. All slack should be on the back side of the chain as the motor rotates and that is taken up by the tensioner. So if you want to check out your setup, pull the cover, take out the bridge and try the chain.

One other thing to check, if you take the chain off of the sprockets for any reason, make sure it is back correctly on the crank teeth. If the chain is off of the crank teeth, it still can feel like it is on when you rotate the motor because the teeth are pulling the edge of the chain along between themselves and the block. But it will slip shortly resulting in bent valves.

[mharrington]

This scares me. this winter I want to pull my head to de coke, lap the valve seats and new valve seals. Very skeery

[D0wn5h1ft]

So I have a question about this then. My heads get in tomorrow and I'm worried about losing my nerve.

Everyone has mentioned slack between the exhaust and intake sprocket when putting the cam chain back on the sprockets during reassembly. The question I have is that if there is slack between the two then won't it pull the intake cam out of time when I turn the crank from "T" to "C" when I go to reinstall the CCT?? The reason I ask is because if there is good tension then the intake cam will rotate a few degree to take up the slack between the exhaust and intake before the exhaust start spinning too. Will this cause the exhaust to "lag" behind where it should be?

[IanDMacDonald]

Gabe- Once again, you're over-thinking everything. Are u spliiting your chain or leaving it in-tact? Any questions during the process, STOP, walk walk, breathe, and either post your question on the forum, or call me.