Valve lash - how do my numbers look?
Posted February 13, 2012 - 08:04 AM
anyway, here's what I got.
#1 - .005" - closest to the kick start lever
#2 - .004" - middle valve
#3 - .003" - closest to the cam sprocket
#4 - .008" - kickstart side
#5 - .008" - cam sprocket side
so, it seems like my #3 valve is just barely out of spec. I didn't have a shim kit so I buttoned it all back up, plan on checking them again in about 20 hours to see if they are moving. Any tips, words of advice, thoughts on what I found?
Also, how hard is it to do the actual shimming of the valves? I have never done that, but have built some v8 engines and have done valve lash using the number of turns method on rocker arm setups....figure the hardest part is re-aligning the cams?
What should I pick up as far as a shim kit goes to do the valve lash? yamaha dealer or is there a universal kit i can get that will have all the shims I will need for this and any future adjustments?
Posted February 13, 2012 - 08:10 AM
Posted February 13, 2012 - 06:11 PM
Posted February 14, 2012 - 06:34 AM
You can buy the shims per shim at the dealership, they might be $4-$8 each, depending on the dealer. You can buy a hotcams shim set off e-bay for about $75, but I think that's overkill for the average guy. I guess it depends on how far you are from the dealer, and how often you will need to be adjusting your valves.
Posted February 14, 2012 - 07:18 AM
The manual pretty much covered it for me, and the maths is real simple:
As valves wear, they stick out of the head more and more, so you need slimmer shims each the time..
I work in metric, with metric gauges, shims etc.. The maths is easy that way.. If you want a 0.15 to 0.20 tolerance and your 0.15 gauge only just fits then you want to go up to a 0.20 by making a gap that is 0.05 bigger. So if there's a 1.60 shim in there, the shim needs to be 0.05 slimmer (to make a gap 0.05 bigger) so the shim 0.05 slimmer than a 1.60 is a 1.55..
Some people like the charts, some people do the maths
Draw a plan of the bike on paper. Put removed buckets on the paper so they can go back the same place they came out of:
Exhaust Buckets O O Want: Got: W-G: Shim: New: Intake O O O Buckets Want: Got: W-G: Shim: New: Fill in.. Want = ..the clearance you want. Go for the upper clearance in the tolerance Got = ..the clearance you measured now Shim = ..with the size of your current shim New = do WANT - GOT and write the RESULT, then do SHIM - RESULT Put in the smallest shim available that is greater than or equal to your NEW value. E.g. if the NEW shim you need is a 169, install a 170 example Want: 0.2 Got: 0.12 W-G: 0.08 Shim: 175 New: 1.75 - 0.08 = 167 167 shims don't exist in the yamaha line-up, so go for the 170
If your RESULT is negative, then you'll have to go up shim sizes rather than down.. Probably means someone shimmed it up wrongly last time
Remember that after calculating the shims you want, you might already have some, in other valves, so meet your wants, then look for a shim swap or purchase to meet the others. Remember to put the buckets back in the same holes they came out of, and don't drop dirt in the top of the engine
Use a magnet on a stick to remove the buckets and shims, much less chance you'll drop them inside the engine
The cam caps have a metal half moon circlip inside, don't drop that in the engine ieither
Follow all the advice from the manual about stuffing rags and hooking the chain to stop it dropping inside the engine
Loosen the spark plug if you dont have an auto decomp engine so you can turn it over easier
Turn the engine over slowly by hand through two full cycles of the flywheel. If it stops suddenly for any reason, don't force it, double check your valve timing
Check your clearances with the new shims after you turned everything over with a wrench a few times
Dont worry, when doing your timing, if the I beam on the flywheel isnt exactly on the mark when the cam cog marks are exactly in line with the head. So long as it's not a whole tooth out. On my YZ, when the Ibeam is aligned the exhaust cam dot is slightly above and the intake cam slightly below the head.. Just take note of how it is now
Put bolts back in the holes they came out of as soon as possible afte rthe part theyre securing is moved away - always handy for any kind of reassembly
Digital camera pictures of the timing are massively handy when putting things back together..
Edited by cjard, February 14, 2012 - 07:20 AM.
Posted February 14, 2012 - 02:32 PM
I'll get back at it on the next service and see just how hard this process is.
I'm a little confused by the statement that I will need slimmer shims, but i suppose I don't really know where the shims are yet until i tear it apart. I thought of it as "lifting" the cams with the shims, but sounds like the shim may be on top of the valve? again, this will be my first go around with valve lash on an engine that uses overhead cams. I'm not that old, but I always have owned v8 pushrod engines for my hot rods so that's what i know!
Posted February 14, 2012 - 04:16 PM
Posted February 15, 2012 - 05:39 PM
Edited by cjard, February 15, 2012 - 05:50 PM.