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Discussion Starter · #1 · (Edited)
<--Part 3a

'Continued from part 3a

Nice. Now let's do the install & timing of the intake cam. If the cam chain can be used to measure where the exhaust cam timing mark needed to "point", it can also identify where the intake timing mark should point relative to the cam chain. I already know how many cam chain rivets ("pins") away from the exhaust cam timing mark, the intake pin should be on the chain. We are going to simply count from our starting position of the exhaust cam timing mark pin, and that will identify where we want the intake timing mark to point.


On the exhaust cam chain, start counting from our PIN #1. Count 31 "pins". Place the intake cam on the cam chain with the timing mark (stamped with the capital letter "I") between chain PIN #31 and PIN #32. Now set the cam in place, without slack in the chain between the two cams, above the intake cam seats in the head.

Because the intake cam has cam lobes pointing "downward" toward the buckets, the intake timing mark will appear too high above the engine case until the cam cap bar pushes the cam down into the cam journals properly (and it will open some valves as the cam cap is tightened). When the cam cap is used to seat the intake cam, the intake timing mark "I" will align with the cylinder head. Place the intake cam cap bar on the cam, put the bolts into position but just turn it by hand a turn or two -don't try to push the intake cam down yet with the cam cap bolts.

BEFORE DOING ANYTHING ELSE STOP and do this. When the initial tightening down of the intake cam cap is applied, it will cause the timing chain around the exhaust cam gear to start to "walk" out of the cam gear (trying to slip a tooth).


To prevent that from happening, we are going to proactively "bind" the cam chain to the cam gears so they can't slip, and we use a different method on each cam.

To bind the exhaust cam sprocket to chain, you want to make a small "wedge" using some vacuum line, and run a safety wire or string or I used lawn trimmer line thru the center of the vacuum hose - it's the safety line so leave it long, in case the vacuum line falls into the motor you will be able to easily retrieve it.


"Wedge" the vacuum line cushion down in-between the exhaust cam chain & engine case, and tie the safety line off. It should be hard to get it in place - that's good, it needs to apply some force to the chain, pushing it on to it's cam gear.



That vacuum line is the right size to wedge with enough force to keep the cam chain on the exhaust cam gear.

To bind the cam chain to the intake cam gear, follow the directions in the Yamaha Service Manual, for putting a zip tie around the chain and thru the "hole" in the intake cam chain sprocket (we could not do it that way on the exhaust cam gear because it has no "hole" to zip tie). Here is a blurry picture while I am putting a zip tie thru the intake cam gear hole and will tighten it around the chain, a very easy and effective way to make sure the cam chain is forced against the cam gear, and does not slip.


Once both the cam gears are bound to the chain to prevent a skipped tooth, go ahead with installing the intake cam gear cap following the instructions in the Yamaha Service Manual. ONLY FIRMLY SNUG THE INTAKE CAM CAP BOLTS - you want them secure so things don't move but don't put any serious torque on the cam cap yet.

This intake cam is "up above it's journals" and has a long way to go down as you tighten it (it will be pushing the intake valve buckets to open valves as you tighten), so go slow, tighten the intake cam cap small amounts at a time working from the outside in with a crisscross pattern, to bring that cam and cap down into the seats in a level, even fashion. Seriously, go slow in small increments. If you don't bring the whole cap down in small steps, you could "twist" the cam cap badly.


Now, before applying the proper torque, look at both the cam gears to confirm they are aligned with the cylinder head. Go back to the pictures you took of the cam alignment before they were removed. Check the exhaust cam timing marks with a straightedge. The intake cam timing mark is easy to see, with the big letter "I" next to the timing mark. If it all looks good, refer to the Yamaha Service Manual and torque both the cam cap bars now. If the timing marks are not aligned, you probably already thought something wasn't right and now you can see. Go back if you have to, and do it again, making what ever corrections you think are needed.

Here are some pictures I took just before removing the cams:


Exhaust cam I highlighted the two timing marks in red - straight edge really helps see alignment


and the intake is easy to see that it is aligned, even though my photo is from "slightly above".

Get your eye down at the level of the engine case, and confirm those cams are in time, before going on with reassembly.

Reinstalling the Cam Chain Tensioner and Not Following the Service Manual

When the cam chain tensioner is installed it seems that it can "slap" the chain and knock the cam chain enough to throw a skipped tooth into the chain on one of the cams. But if you put binds on both cam gear/chains, it will not skip a tooth. So we are good to go with re-installing the cam chain tensioner.

Retrieve the cam chain tensioner - it should be where you put it along with that special tool still inserted, keeping the chain tensioner retracted. If the special tool came out, just insert the special tool again and retract the tensioner by turning it counter clockwise until it stops - the fully retracted position.

Follow the Service Manual and lube up the tensioner body with engine oil, and the tensioner arm - it is bathed in pressurized oil when it operates with engine running. Insert the tensioner into the cylinder head (with the special tool still inserted in the tensioner). Use a new tensioner gasket if you have one, and follow the Service Manual - it shows that the gasket is inserted in a certain way. Also the cam chain tensioner has a mark stamped on the body of the tensioner showing which side faces up, when it is inserted.


The cylinder head opening has an oil port visible on the "in" side of the bore, and that's why it has to be installed (along with it's gasket) oriented as described in the Service Manual.


With the special tool still inserted, remount the cam chain tensioner with the two outer mounting bolts, torque to Service Manual specs.

Now we are going to do the initial tightening of the tensioner arm against the cam chain (the last part of the cam chain that still has slack). Follow the manual up to the point where it says to tightened the cam chain until it makes contact. Now do this instead of following the manual.

Turn the special tool clockwise to the point where it makes contact, then snug the cam chain tensioner with some low-to-medium force - don't gorilla it and definitely don't follow the Service Manual (I think it says "turn it an additional half turn" - a great way to over tighten it imo). Just snug the cam chain tensioner up moderately firm against the cam chain guide with the special tool.

Then take your thumb only, and press hard on the cam chain where it shows in the drawing below, between the two cam gears, and then release. You will see the deflection of the chain when your thumb is pressing down.


Now try to tighten the special tool that was already snugged with low-to-medium force. It will probably be easier to turn again for a small distance because you freed up some chain slack, so go ahead and repeat the tightening with the special tool. Snug the cam chain tensioner up with low-to-medium force again.

Then repeat - use your thumb again, and press hard again on chain between cams, then release. You will see the deflection of the chain when your thumb is pressing down, but it will probably be less deflection than that first press. Now try to tighten the special tool again - it will probably be easier to turn again, so go ahead and repeat the tightening with the special tool. Snug the cam chain tensioner up with low-to-medium force again.

Each time you press on the cam chain with your thumb (and you see deflection in the chain), there is more chain slack remaining that you free up, and then remove by tightening the special tool again. But it will probably only need 2 presses & tightening. By the 3rd press, you may see very little or no deflection when pressing down on the cam chain. When that happens you are done "pumping" the cam chain for slack. But always check one last time to see if the special tool has been tightened "snug" against the cam chain guide with low-to-medium force.

If you are more comfortable following the Service Manual, please do. You should always follow the Service Manual.

Remove the special tool, and that lets the cam chain tensioner "snap" into auto-tensioning position. Then put the special tool access cap bolt & (new) washer back on the cam chain tensioner, and save your special tool in the toolbox.

After the cam chain tensioner "snap" into position, you can REMOVE THE BINDS PLACED ON THE CAMS/CHAINS. Cut off the intake cam zip tie and pull out the exhaust cam vacuum line wedge, and don't let any pieces fall into the motor.

Confirming Cam Timing

To get this far, you have already confirmed that the cam timing marks are all aligned properly. But let's confirm it again by rotating the engine and bringing it back to the "Cam Rotation Degrees 360" in our crank chart.


From the "LEFT" side of bike (gear shift side) turn the crankshaft slowly counter clockwise 2 full turns and at the end of the second turn align the rotor flywheel timing marks again. If you feel any unusual contact or resistance while turning, stop and assess the situation (RED timing mark added for clarity).
Glasses Vision care Eye Eyewear Font

Now ensure proper position of the cams by checking the view from the "LEFT" side of bike (gear shift side) cylinder #1 cam lobes "FACE EACH OTHER".


And now check the cam gear timing marks by checking the view from the "RIGHT" side of bike (foot brake side).




If everything looks like the pictures you took before you removed the cams for maintenance, you are done with the CORE VALVE ADJUSTMENT. Now get that naked bike back together and go ride.

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