question for gurus on cam timing and such

[EXXXCESS]

Is the dot on the cams supposed to line up exactly with the arrow on the caps or is it a little off one way or the other. And if it does than what would happen if it was a tooth off in either direction. Also I never knew this so I want to make sure it is correct does the crank turn 2 times for one rotation of the crank?

[trbig]

You have it backwards... the CRANK rotates two times to the cams' once.

As the timing chain gets stretched, you will notice that it doesn't line up EXACTLY on the arrows. The intake will generally go just a touch past it towards the rear of the motor. One tooth off is equivelent to 22.5 degrees off and you are in REAL danger of valve/piston contact. The valves lose this fight really easily when this happens.


Tod

[EXXXCESS]

So the fact that the dots are both slightly to the front exhaust side could be bad huh
And that's what I ment crank twice one cam

[John]

You should be ok. A chain with some wear (stretch) will allow the cams to be out just a little, but it shouldn't hurt anything so long as the cams/crank are timed properly.

[EXXXCESS]

The dots are both 3/16 to the exhaust side makes me think that the cams are a tooth off?

[Crazcnuk]

Not if both are off the same amount. This would indicate your timing is off down at the timing plate, or the timing indicator has moved.

One tooth is a long ways off the mark, not just a little. It would also be very odd for both cams to be off a tooth, unless it skipped a crank tooth.

To double check, take the sparkplugs out, put something in the #1 spark plug hole (dial indicator works best, but a screwdriver or popsicle stick will work). Turn the motor in the direction of the arrow on the timing plate until you feel the piston is at TDC (it's a 'flat' spot where the piston isn't moving). Also, I am assuming your tensioner is stil in place.

Then look at your timing indicator to see if it is indicating TDC. If not,k then move the indicator until it is then recheck your cams.

[oseaghdha]

Not if both are off the same amount. This would indicate your timing is off down at the timing plate, or the timing indicator has moved.

One tooth is a long ways off the mark, not just a little. It would also be very odd for both cams to be off a tooth, unless it skipped a crank tooth.

To double check, take the sparkplugs out, put something in the #1 spark plug hole (dial indicator works best, but a screwdriver or popsicle stick will work). Turn the motor in the direction of the arrow on the timing plate until you feel the piston is at TDC (it's a 'flat' spot where the piston isn't moving). Also, I am assuming your tensioner is stil in place.

Then look at your timing indicator to see if it is indicating TDC. If not,k then move the indicator until it is then recheck your cams.

To find actual "0 TDC" you should use an indicator. Find approximate TDC and zero the indicator. Then rotate past so the indicator reads some small amount like -.05". Make a temp ref mark on the plate and rotate backwards until it also reads -.05". Make a temp mark there. Actual TDC will be exactly half way in between.

The reason for this is the dwell, or "flat spot", as the rod journal comes over the top. It can amount to several degrees crank rotation.

[trbig]

For the most "Southern ingenuity" way.. take the spark plug out of # 1 (Left side as sitting on bike) put the timing plate on the "T" mark for when the cam dots almost line up, then stick a plastic straw down into the spark plug hole onto the top of the piston. While holding the straw there, rotate the timing plate back and forth just a bit with a 19mm wrench to see where the piston starts going up and down at from it's TDC. Find the middle of this up and down movement and that will be pretty dang close to TDC. See where your dots line up versus your "T" mark.

I'm guessing you have the cams out by one tooth. You never did say if you took out the cams, changed the chain or what. If you tried to move something without the tensioner tight, the crank may have jumped a tooth. You'll have to put it back in time at the cams.


Tod

[oseaghdha]

Wrong!

For the most "Southern ingenuity" way...


If'n it don't involve duct tape nor bailin war*, it ain't Suthron!






* or Sheep.

[EXXXCESS]

I took the head off to take it to the machine shop and when I was done putting it together this is where it ended up I need to rotate the cam gear a tooth and see how it works is there an easier way to rotate the gear

[trbig]

This happens pretty regularly. If you don't keep the chain tight between the crank and the intake cam on installation, you'll usually be off a tooth when you get it together. What happens, is that if it's a bit loose, after you put it together and turn the crank, the crank gear pulls all of the slack out of the chain before it starts pulling the cam gears.

Put the crank back on the "T" mark where your cams almost line up. Then turn the crank close to one full rev, or to where you can remove the two shoulder bolts on the cam sprockets that you can see. Be careful not to drop them down in the motor!! After you removed a bolt from the intake and exhaust, rotate the crank again until it is back on the "T" again. You should be able to remove the other two cam bolts now. You'll also need to take out your cam chain adjuster and the cradle looking chain guide in between the cams.

You'll now need to use a wrench to gently turn the cams to their proper timing mark. Be careful not to get the wrench against the head casing and crack it. After you do that, you take the intake sprocket off the cam shoulder to get some room. Keep an eye on making sure the chain stays tight between the crank and cam on the back of the motor.. and work enough slack in the chain to rotate the sprocket one tooth so the bolt holes line up again. Put a bolt in that one finger tight. Now do the same thing with the exhaust cam. Get it lined up and install a bolt in it also.

Now.. reach around the front of the motor and stick your finger into the adjuster hole and push the bar inside there with your finger to hold tension on the chain. Slowly turn the crank clockwise one turn so you can get the other two bolts in the cams. I always just put them finger tight for now.

Stick your finger back in the hole and hold tension again.. and turn the motor back to the "T" again. Now see if the cams line up. If they're off.. you'll have to start over again.. and that's why I only finger tighten them. If they line up, torque the cam bolts you see. Install the cradle looking guide, hold the adjuster bar again and spin it until you can torque the other cam bolts. Hold the adjuster one more time, spin the motor and DOUBLE check they're still on time. Yes? Rotate the crank to the "C" mark and properly re-install the chain tensioner.

Hope I didn't confuse you...It would be better with pics.. I just don't have any for this. Might be a good writup though for the tech tips.

Tod