Cam installation questions

[brian4wd]

Working on a POS '89 FJ1200 - that really should be parted out but the owner is attached to the bike for some reason.  A few of the exhaust valves were down to .003" clearance.....

I'm struggling with the intake cam installation/timing - I've read the posts about rotating the crank but I haven't tried that yet.  Can anybody tell me the number of chain pins that shoud be between the marks - I should have counted before dissassembly but I didn't.....

Also, on the tensioner is it supposed to be installed with the ratchet teeth facing up or down?  There seems to be discrepancy between the Clymers manual and what actually fits.

Brian

[oldktmdude]

G'day Brian, sorry I can't help with pin-count but I know for a fact, the Clymer manual is wrong about the cam-chain adjuster position. The ratchet teeth face down. The adjuster will only fit one way. The manual has a few other mistakes in it as well, which have already been mentioned on this site.  Make sure you get your timing marks aligned correctly. Sometimes this can take a few attempts due to chain stretch and slackness in chain tension.     Pete.

[SkyFive]

I believe the most important information I have came from Randy. Don't turn the engine backwards after timing the cams. Set your crank with #1 top dead center, set your cams on the timing marks, allow for some backward movement of the intake cam after the slack is taken out of the chain and then rotate the engine by hand 720° and recheck. Use the dimples on cams for timing, get both of them in the windows and your done, it don't matter how many links are between the cams. If you turn the engine backwards even the slightest amount and you will be off a "1/2 link" every time.

Now my tip of the day, tighten your ignition trigger before you time the camshafts. Why? because if you tighten it afterwards you will turn the engine backwards.

Edit; There is a very informative disscussion somewhere here that explains eveything in great detail, I read it several times before I "figgered out" how to do this delicate operation. The most important thing is Don't turn the engine backwards!

[SlowOldGuy]

I believe the most important information I have came from Randy. Don't turn the engine backwards after timing the cams.  If you turn the engine backwards even the slightest amount and you will be off a "1/2 link" every time.

Is this only when installing the cams?  Or are you saying don't "ever" turn the engine backwards?  Because that would make valve adjustments very difficult.

DavidR.

[andyb]

If you rotate the motor backwards while setting cam locations, the slack ends up on the wrong side of the motor--in a running condition, you just retarded both cams and wasted your time.  Retard them enough and you'll have broken bits.

Once it's assembled, timed right, and tightened down, spin it however you please. 


It's not difficult to time stock cams in, even with adjustable sprockets.  Find TDC with a positive stop, put the tensioner in, spin it forwards twice, then align the dots through the cam caps, job done.

[brian4wd]

So I got the cams timed where the dots line up in the holes when the #1 TDC mark is ~.090 past the trigger - figured I was a victim of the 1/2 tooth problem and attempted to move the cams- that was a disaster...... Time to start over.

So now, I align the cams and go to rotate the engine 720 deg to verify the timing and the chain snaps/pops/rides up on the exhaust cam gear.  WTF is going on?

Brian

[andyb]

New cam chain?  Sitting on the tensioner blades properly? 

[wakdady]

is there a write-up on valve adjustment or/and replacing all the timing components?

[fj1250]

Why'd you pull the cams to adjust the valves to begin with?

You'll find FJ's run better with the intake cam advanced one tooth.

Yes it'll give up some top speed, but the torque gain is well worth it at everywhere except the Bonneville salt flats.

Yes i've done many motors this way. Factory cam timing is aroound 112 degrees. Advancing the cam takes it down to 102-014 degrees.
The engine will run cooler, stronger and easier to tune!

MC