valve clearances too tight?

[mr blackstock]

Hello, I have an '85 FJ1100 that I am preparing to get legalised and on the road, it runs well, etc. But before I get the carbs synched, I checked out the clearances, with some odd results.  The bike is about 5000kms from an engine rebuild, rebore, new cams, etc. by a motorcycle mechanic.  My maual states valve clearances should be: exhaust between .16 to .20mm, and intake beteen .11 to .15mm
my measurements are in mm:
EXHAUST     INTAKE
.17              .10
.17              .07
.15              .10
.15              .10
.17              .15
.17              .08
.20              .10

I have not removed any shims yet, and I am assuming that all clearances were checked when the bike was reassembled, is there a reason why a mechanic would leave such tight clearances on intake?  Should I replace the intake shims to allow more clearance?

cheers, Gareth

[Dan Filetti]

Gareth,

They tighten up over time with this style valve.  5000KM seems a bit too quickly, to me, maybe it's because of the freshen-up?  Others will have a more precise input.   You want to set the clearances to the loose side.  So it seems to me that you have one intake, and one exhaust clearance measurement that is perfect.  The rest need a tweak -although I'm not sure I'd actually worry about any of the exhaust clearances.   

Do you have (have you made) the special, hold-down tool (technical jargon) to do this work?

Good luck,

Dan

[mr blackstock]

Thanks for the help,
I do not have the tool, it is available from various internet sites for around $70USD, but I am inclined to attempt to make a copy, failing that I will have to trailer it into a mechanic, hopefully it would not cost too much as I am only considering changing the intake shims.

This person on ebay seems to have a variety of shims for a good price...

http://cgi.ebay.ca/Honda-CBX-Yamaha-FJ1100-FJ1200-Valve-Shim-Size-2-90-/160490219590?pt=Motorcycles_Parts_Accessories&hash=item255df66846

cheers..

[Arnie]

Gareth,

How come you only have 7 valves each of intake and exhaust?  Where's the other one?

If I'm reading your post correctly, the engine was rebuilt 5,000 kms ago.  Is this right?
If the valve seats were ground and the valves lapped to fit then, it may just be that  they are settling themselves in.  The valve clearances do tend to get tighter over time.  I would replace all the shims on the valves that are too tight.  You will need to remove the shims before you'll know what shims are there and therefore what you'll need to replace them with.

While the price you show from that ebay site seem fair, you won't know what you need until you've removed the shims and see what's in there.  Then you may find that you can swap some of your existing shims and reduce the total number of shims you'll have to exchange.  Many dealers will swap shims with you for free or a nominal price.  Make sure you measure the shims and don't just believe the number stamped upon them - that is frequently wrong.

Cheers,
Arnie

[racerrad8]

Thanks for the help,
I do not have the tool, it is available from various internet sites for around $70USD, but I am inclined to attempt to make a copy, failing that I will have to trailer it into a mechanic, hopefully it would not cost too much as I am only considering changing the intake shims.

This person on ebay seems to have a variety of shims for a good price...

cheers..

Look here for a better price on both of those items; www.RPMRacingCa.com

But, Like Arnie says, you won't know what shims you need until you take the old ones out.

Randy - RPM

[Dan Filetti]

Many dealers will swap shims with you for free or a nominal price.  Make sure you measure the shims and don't just believe the number stamped upon them - that is frequently wrong.

Cheers,
Arnie

Look here for a better price on both of those items [valve shims and tool]; www.RPMRacingCa.com

But, Like Arnie says, you won't know what shims you need until you take the old ones out.

Randy - RPM

So, I've read these two statements from each of you a number of times, and I've always meant to ask.  Randy: do you measure these shims before you send them to ensure accuracy, and if so, have you found innacuracies?  Or is Arnie just being cautious?

Dan

[mz_rider]

My home-made valve tool. Like others I try to keep the gaps at the top of the range. This means they are less likely to need adjusting next time. It's unlikely you'll need to buy shims for all the valves you adjust since you'll be able to swap them about.

http://www.fjowners.com/index.php?topic=1784.msg14197#msg14197

Stuart

[racerrad8]

So, I've read these two statements from each of you a number of times, and I've always meant to ask.  Randy: do you measure these shims before you send them to ensure accuracy, and if so, have you found innacuracies?  Or is Arnie just being cautious?

Dan

I do not measure new ones as they are clearly marked on what they are. The only ones I measure are the difficult to read ones that someone installed with the numbers up and the cam wore off the numbers.

I was only documenting he will need to remove the shims to determine what is installed and then be able to order what is needed to get him back into tolerance.

Randy - RPM

[Dan Filetti]

I was only documenting he will need to remove the shims to determine what is installed and then be able to order what is needed to get him back into tolerance.

Randy - RPM

I think you missed the point of my question.  I was asking whether the shims actually did measure differently than what was printed on them, or if perhaps Arnie was being cautious when he says to measure them. 

HIS point seems to be that despite what's printed on them, they are sometimes actually a different actual measurement. This seems odd to me.   How would someone order specific new ones with any accuracy then?

Not a big deal, just curious.

Dan

[Harvy]

So, I've read these two statements from each of you a number of times, and I've always meant to ask.  Randy: do you measure these shims before you send them to ensure accuracy, and if so, have you found innacuracies?  Or is Arnie just being cautious?

Dan

I do not measure new ones as they are clearly marked on what they are. The only ones I measure are the difficult to read ones that someone installed with the numbers up and the cam wore off the numbers.

I was only documenting he will need to remove the shims to determine what is installed and then be able to order what is needed to get him back into tolerance.

Randy - RPM

Dan, my take on this is if the numbers are worn off because someone installed then upside down, then it would mean that shims do wear down over time. So if using second hand shims, measure them, cos they may in fact be thinner than the number on the shim suggests.

Harvy

[FJmonkey]

So, I've read these two statements from each of you a number of times, and I've always meant to ask.  Randy: do you measure these shims before you send them to ensure accuracy, and if so, have you found innacuracies?  Or is Arnie just being cautious?

Dan

I do not measure new ones as they are clearly marked on what they are. The only ones I measure are the difficult to read ones that someone installed with the numbers up and the cam wore off the numbers.

I was only documenting he will need to remove the shims to determine what is installed and then be able to order what is needed to get him back into tolerance.

Randy - RPM

Dan, my take on this is if the numbers are worn off because someone installed then upside down, then it would mean that shims do wear down over time. So if using second hand shims, measure them, cos they may in fact be thinner than the number on the shim suggests.

Harvy

+1 on that, measure each shim, they wear with use, know what goes in and know what goes out. you will have spot on clearances when you know the shim sizes.

[racerrad8]

I think you missed the point of my question.  I was asking whether the shims actually did measure differently than what was printed on them, or if perhaps Arnie was being cautious when he says to measure them. 

HIS point seems to be that despite what's printed on them, they are sometimes actually a different actual measurement. This seems odd to me.   How would someone order specific new ones with any accuracy then?

Not a big deal, just curious.

Dan

Dan,

I cannot answer your question, but I will measure some of my new ones and report back if you would like. I have probably sold well over 5000 shims new & used since I started all of this and no one has ever told me a shim was not as marked or returned a single one for any reason. In fact, I just got an order in today that included 200 shims. I was told yesterday from my supplier they have increased production of shims because the other shim companies such as Hot Cams and cam grinders such as Web Cams has stopped some of their production and are buying from the same place I have been getting them for 15+ years.

I will say that maybe 1% of the ones I measure are not what is etched into the surface, but I have honestly never checked a new shim to compare it to the number on the face. But you are talking about a 260 shim measuring 259.x; not really a difference that will create any issue. That is why there is not a single number associated with the adjustment, but a target range they should be in.

I have always removed them from the bag, installed them and let them rip since there is no way to recheck the clearance after replacing the shim without running the engine for several miles and getting it up to full operating temperature.

The numbers are worn off from the cam when installed upside down as they are somehow etched into the top surface of the hardened face if the shim. I would say the number is gone because they are "polished" off and not worn off. If you see a shim that has worn through the hardened surface there is pitting in the metal. Usually when I see that the cam lube shows signs of wear as well.

The one thing I do know for sure is that when they are worn through the hardened surface, the wear is not even across the face of the shim and the center is thinner that the shoulder of the shim, so measuring with a caliper type instrument will not tell you if it is thinner than marked.

I must admit that I probably have over 1000 used shims at my disposal, and again I only measure those that do not have numbers clearly visible.

I would recommend if you are not used to handling the shim(s) that it might not be a bad idea as, through my hands, there have been hundreds that have passed that he been "thinned" or "ground" on a grinder, surface grinder, or something to make the shim thinner. As long as the side that was ground is placed in the bucket there is no much chance of cam wear, but when they are put in ground side up, valve clearance is no longer a problem as the cam lobe will be gone.

I cannot answer to why Arnie states his position and I will let him explain his take on this.

Randy - RPM

[Dan Filetti]

Thanks for the generous response, Randy.  It makes sense to me that used ones *may* be slightly thinner, and an ounce of prevention and all that.  No need to measure new ones on my behalf, unless you are curious yourself.

Good to know,

Thanks again.

Dan

[Arnie]

Hello folks, sorry for being missing for a day or two ....

My point about measuring each shim really is about used shims.  I have run across shims that either have no readable numbers, OR have numbers but are wrong because someone decided to file or stone them so they didn't have to go get a new shim.  I haven't run across a shim that is worn from use to be off.  (if no oil and obvious blueing, then all bets are off)  And, I do tend to be cautious about these.

Cheers,
Arnie

Thanks for the generous response, Randy.  It makes sense to me that used ones *may* be slightly thinner, and an ounce of prevention and all that.  No need to measure new ones on my behalf, unless you are curious yourself.

[andyb]

Or, depending on who the PO was, there's always a chance that they found it easier to resurface their shims so the numbers aren't right anymore.  Ditto for jets, used jets I always question because some people think drilling them is the correct way to adjust things.