Cam tensioner bolt

[XSrunner]

HI GUY'S I have stripped the thread on my cam chain tensioner but i can't get one of the bolts undone the allen key head is now round inside can i give it a wack with a cold chisel or a impact driver or will i crack the alloy? i don't have access to a oxy to heat it up or if i do break the head off the bolt how do i get the old thread out.. any help apreciated thankyou..

[DGXSER]

You could use a dremel or similar tool to cut a slot in the bolt for a crewdriver and use an impact driver to break it free. I would start by hitting it with PB Blaster or the like. Let it soak in that for a while before you try to remove it.

If it snaps off, you could try left handed drill bits to drill it out to the minor diameter of the threads and then peel out the rest.

[Geezer]

Screw fixing it. Replace the whole unit with a Venture XVZ1200 cam chain tensioner. You'll be glad you did...

Geezer

[79XS11F]

If you don't switch it out as suggested your still going to have to remove it to repair it so you might as well remove the unit and work on it on the bench. Before you remove it disconnect the battery so NO accidental operation of the starter can occur while it's not installed.
Rob

[Ivan]

Judging that he said allen head, I am thinking he is talking about the screw that holds it in. If that is stripped, it may be a surprise blessing. STOP, read the tech tips and MAKE SURE you know what you are doing when you pull the tensioner out. You will save bent valves, expense and frustration.

Once you are confident, you might try some valve lapping compound, it will give the wrench some bite. Also, a HIGH QUALITY (Snap-on) socket is the way to go. normal hex keys are so soft they deform, and then cause the screw head to deform, and everything goes bad after that.

Another trick is to get a T35 (I think) torx socket, and pound it in the head so it makes its own splines and that will catch sometimes. It has to be one that is a bit bigger than the hex. A 1/4 in drive bit for a screwdriver works well, and isn't expensive. Then use a ratchet and extension with a 1/4 socket.

[XSokieSPECIAL]

Good advice from all so far but before you remove it completely take the left engine cover off ( ignition cover) and line up the "C" on the timing wheel.

This should keep the cam chain from slipping.

And, like Geezer said, find a venture automatic tensioner to replace that antiquated stock tensioner It'll bolt right on and it's set and forget.

Here's one on an ebay store for sale; http://cgi.ebay.com/85-YAMAHA-xvz120...item5884654ceb

[Larrym]

DANGER! Will Robinson...DANGER!!!

I second Ivan's over sized "torx" suggestion. I also would like to reinforce his "cautions" about removing the CCT and upgrade it to an actual WARNING.

Even if you treat the removal of the CCT as if you were defusing a bomb, doing it very carefully without sudden motion or jarring things, the odds are 50/50 that the cam chain will drop down to the bottom of the crankshaft jumping the sprocket.

The suggested way to prevent this from happening is to remove the valve cover and apply tension to the chain from above AS you remove the CCT. This also allows you to verify that the mechanical timing marks on the camshafts and the crankshaft are correct before you turn the engine by hand or try to start it up.

I Know...I know...Right now you are wishing that it weren't so complicated but then again without those Dual overhead camshafts these bikes would be two-strokes...

[XSokieSPECIAL]

the odds are 50/50 that the cam chain will drop down to the bottom of the crankshaft jumping the sprocket

Larrym,
The chain slipping shouldn't be a problem if you line up the "C" on the timing plate with the pointer as I stated before. I've had mine apart several times for different reasons and I've never had a problem.
Just be careful and DEFINITLY don't turn the crankshaft with the tensioner removed.

Your suggestion is valid and good but IMO unnessesary.

[Larrym]

Risk/Reward

XSokieSPECIAL,

You're right. I mean I'm not saying you're wrong to believe that one can remove the CCT without pulling the valve cover off and all that "etc."

There is not a 100% consensus among the members here about just how to proceed when removing and replacing the CCT. It's split into two camps where you and I both represent the two different options at least for the moment.

The owner has the freedom to choose between the two options depending on his own comfort level when dealing with the risks/rewards.

Thanks for representing the "other" side here. It's important that both options are presented.

[XSokieSPECIAL]

Just saying.

[bikerphil]

Hadn't seen it mentioned, but whenever removing the cam chain tensioner, have the bike on the centerstand so the engine is level left to right. This will prevent the cam chain from falling off to the left of the crank sprocket. It will do this if bike is on the sidestand, and valve damage may result. DAMHIK

[trbig]

When doing an adjustment, I used to remove the tensioner, mash in the plunger and lock it there, then install the tensioner and release it.. then lock it down there after it slapped the chain. I've done it a hundred times (Or more probably) on lots of different motors without a problem.

BUT... I ran into a problem doing this with Bohn Frazer's bike. With the valve cover off and we'd taken the cams out.. I went to do this in the normal order and to put everything back in time.. then the chain adjustment like I always do, and it would jump out of time. I couldn't figure it out.. we must have re-done it half a dozen times. We finally thought we had it.. and it jumped time again and bent valves when we started it. The cam chain was making a loop at the bottom of the crank sprocket. When you applied the tensioner, it would tighten the chain against the crank sprocket.. but there would still be a loop in the bottom of the chain.

So... 99 out of 100 times, there probably won't be a problem. That 1% though, can be a PITA and a little costly. To be sure, you really need to remove the valve cover, and as you remove the tensioner, advance the exhaust cam to take up the slack chain instead of letting the slack drop to the bottom by the crank sprocket. When you re-install the tensioner and it slaps the chain, it will snap the exhaust cam back into place.

This is only a problem if the tensioner is removed, versus just a normal adjustment.


Tod

[mxmikie]

i can mail you a Venture XVZ1200 cam chain tensioner for $37.00

[Ivan]

I got two off ebay for $20 shipped when I thought up the idea.

[DGXSER]

You know, I got mine for like $15 shipped. Just one though. Amazing how the price goes up with interest.