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Discussion Starter · #1 ·
So I’m a beginner and not familiar with all the jargon and technical terms, so bear with me please.

1. Just got the valve cover thingy off, checked clearances for cyl 1 (out of spec), and as I went to rotate for cyl 2 I lost track of how far I’d rotated, and without thinking i rotated the flywheel (?) backwards (clockwise) again quite a bit.. did I do any sort of damage here or is it fine to crank (?) both ways?

2. When I’m done and closing it all up do I have to position the cylinders in any sort of way, or do I just leave it as is (which is probably on cyl 3). Mind you I won’t be adjusting them myself, but I’m curious.

Thanks. Without this forum there’s no chance I’d have come this far on my own, so keep sharing, so beginners like me can learn too.
 

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2016 xsr 900
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it is unlikely that you broke anything, especially if you did not hear any bad sounds, or use excessive force. The reason you are only supposed to turn the engine one direction is that there are Guides & a cam chain tensioner that are 'designed' for the chain to have all its slack on one side, and for the chain to move one direction. When you spin the motor backwards you have a mechanical advantage that is being used to force the slack out of the side of the chain where it was designed to be, which in theory could cause something to break. I've never personally heard of or seen this happen, but in the future it is best to just keep going 'forwards' until you get back to the proper place.
 

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Discussion Starter · #5 ·
you need to buy a service manual if your going to play with things like this, yes the motor needs to have cyl 1 at tdc when you reinstall the cams.
Thanks. I have the service manual on PDF. So if I just keep rotating the flywheel I'll cycle through the cylinders and end up back at cyl 1?
 

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you need to buy a service manual if your going to play with things like this, yes the motor needs to have cyl 1 at tdc when you reinstall the cams.
Thanks. I have the service manual on PDF. So if I just keep rotating the flywheel I'll cycle through the cylinders and end up back at cyl 1?
Yes if you keep rotating you'll come all the way back to #1 TDC. I added some emphasis to vcyclenut's post - if you haven't removed the cams (you said you were not going to attempt the adjustment), then it doesn't matter where the engine is when you put the covers back on. If you removed the cams so that you could actually change out the shims and adjust the valve clearance then it is important to have things aligned as specified in the manual during re-assembly.

Did you remove the circled parts?
164904
 

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Discussion Starter · #9 ·
Okay, so I've checked all valves now.

Just to clarify:

is there no other way to tell that you are TDC on cyl 2/3 other than to rotate xxx degrees and looking at the camshaft lobes' "symmetry"? Cyl 2/3 don't have a a mark on the generator rotor? Couldn't find one at least, if they do have one I'll have to go back and try it again.

Yamaha MT-09 2016 / 43.500 KM ≈ 27.000 miles. Bike has full Akrapovic titan/racing exhaust.

Clearances:

Intake: (spec is 0.11 - 0.20 mm)


Cylinder #1 - 0.13 / 0.13
Cylinder #2 - 0.11 / 0.10
Cylinder #3 0.11 / 0.11

Exhaust: (spec is 0.24 - 0.30 mm)

Cylinder #1 - 0.22 / 0.22
Cylinder #2 - 0.18 / 0.18
Cylinder #3 - 0.22 / 0.22


I'm thinking I must've done something wrong, cause I thought for sure they were going to be tight as hell?
 

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it is an old 'hack' but you can stick a little wooden dowel (like a pencil size) into the spark plug hole and when it stops moving 'up' your at TDC. Just be careful if you choose to do this because you don't want to drop anything into the cylinder, tie a string to the end in case it gets away from you so you can recover it. Looking at the lobe's on the Cam as described is sufficient, because it doesn't really change the gap if you're off of TDC by a few degrees either way.

All of your measurements are 'tight' which is to be expected. A lot of people think that the gap will 'increase' over time, but it doesn't. What actually happens is the valve sits 'tighter' into the head over time and so the gap decreases, leading to tight clearances as you've found. It doesn't really matter if you're going to pay someone else to adjust them, they'll measure them again so they know what shim thicknesses they need to put in. What you found is that you do actually need a valve adjustment done.
 

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Discussion Starter · #11 ·
All of your measurements are 'tight' which is to be expected. A lot of people think that the gap will 'increase' over time, but it doesn't. What actually happens is the valve sits 'tighter' into the head over time and so the gap decreases, leading to tight clearances as you've found. It doesn't really matter if you're going to pay someone else to adjust them, they'll measure them again so they know what shim thicknesses they need to put in. What you found is that you do actually need a valve adjustment done.
Gotcha! Thanks for all this info, next time around it's gonna be a breeze. Would it be too risky driving the bike like this (re-assembled obv) for a couple thousand more KM's or am I running a serious risk of burning valves?

There really aren't that many mechanics or Yamaha dealerships where I live, and the few ones nearby already have the next few weeks booked. Obviously I won't drive it if it's gonna cost me, but might as well enquire.
 

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I don't feel qualified to answer that question. Your exhaust valves are already 'too tight', which by the book means that something bad 'might' happen.
 

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I've been follow this thread as I'm going to be doing this job in the off-season. What's the best way to order shims?
 

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you need to buy a service manual if your going to play with things like this, yes the motor needs to have cyl 1 at tdc when you reinstall the cams.
#1 @ 125 degrees BEFORE TDC on the compression stroke, if you set the crank at #1 TDC, valves are going to hit pistons. READ the manual.
 

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I've been follow this thread as I'm going to be doing this job in the off-season. What's the best way to order shims?
I bought a hotcams kit but I needed a few more duplicates of some of the shims, so I just called a local shop and got some from them for like $6 a piece.
 

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I took my old shims to a local dealership and they swapped them out for me for free. If yours isn't as cool they may "sell" you just the ones you need. You can likely shuffle yours around and get say half of them in spec and only buy a few others... I just hated the idea of buying an entire kit for something i should only have to adjust once.

back to the questions though. Doesn't matter where the crank is for re-installing the valve cover. But as vcycle said; there is a very specific procedure for removing/reinstalling the cams. You mentioned not adjusting yourself and only checking. But with what all you've done I don't feel that removing the cams and replacing shims is very much more effort personally.
 
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