Valve shims

Hey, I was told awhile back that some of the users have shim "banks" and that I could possibly trade my old shims for shims I need now. I finally got into my motor and I need the following: 2-265 and 2-285 I have another motor for parts and was able to get the other shims I needed out of it. I have the following shims to trade: 1-210, 2-275 and 2-290.
Also, the motor I'm working on is a 650J. My maual shows that the intake and exhaust clearances are the same (.16-.20) but the intakes were so out of wack(.090-.102) I rechecked my indetification number in order to insure that my motor was a "J" rather than another motor. Is this common with these bikes? I've owned an worked on other bikes but this is my first XJ.

Harv

 

If this is the first time they were done, they could be all over the place

 

The Council of Elders have met, the Wizards all agree, the specs are wrong in your manual (they also goofed on the location of the jets)

Adjust your intakes to the ".11-.15" spec as seen in all other models.

Ignore the man behind the curtain. . .

 

I dont Know where you are located but if you follow the yellow brick road to member hogfiddles he runs a shim pool

 

Thanks for the info. Finding all four intakes out in the same way and in the same ball park seemed a bit odd. I think Hogfiddles was the person who told me about the shim Pool, I'll get in contact with him.

 

Hi Harv,

PM me, and I'll see what I can do to help. Also, if you're in the USA, let me know in the PM and I'll give you my cell number.

If you happen to be in the middle of NY that would be even better

Dave F

 

I have a couple 260, and 265. I'm open to trades.

 

kontiki, PM sent.

anyone else that can help me out; I need multiples of same size. 265. I have numerous parts available for trades or else cash

 

You do realize chacal has them for about half of what Yamaha gets?

 

OK - - let's assume there are "umpteen" thousands of people who read these incorrect specs, and have their intake valves all shimmed 0.004 thousanths loose. . .

How come we don't hear about people "spitting shims" all the time, and why are we worried about someone being "loose" by a couple thou??

 

Intake valves accidentally being run at exhaust specs won't cause "spit shims" or all of our exhaust shims would keep spitting out. The cams aren't THAT different, the reason for wider clearances on the exhaust valves is because they get considerably warmer than the intake valves.

I'd be more inclined to think that more owners of the bikes "affected" by the erroneous spec went by the sticker in their sidecover (which had the correct spec) than the Haynes manual, or the one factory book that perpetuated the error to begin with.

Worse case scenario is a few XJ650Rs running a bit "soggy" because their intake valves are too loose.

What true percentage of XJ owners ever adjusted their valves anyway?

 

I may get razzed for this, but there is another way. I got a $10. micrometer off Ebay. Used that to shave down the shims I had to the size I needed. (wet sanded them) Just be sure to make a note of the actual size shim for each valve in your motor or the next time someone tries to figure it all out they will go nutts.....

 

Ooooohhh...wait a minute. These shims are surface-hardened (I'm almost positive about that, but I've been wrong before).

 

If so perhaps my valves will not tighen up as quickly? Hmmmm. Ha ha...well will just check the lash from time to time....I think they will be fine.

 

Or not.

Grinding shims is NOT recommended; they are in fact, case-hardened.

While they MIGHT be fine, the damage caused by a spit shim at high RPMs is certainly not worth the false economy of grinding shims.

 

The guys that suggest shaving shims at home aren't doing it to save $7.00, but to finish the job that evening. Wet-sanding by hand, as careful as you are, would be "out of square" by the slightest bit.

A guy who makes high-end $7,000 pocket knives showed me his $3,500 planing machine. It surfaces Titanium stock and folded metal. I don't think he'd trim a shim for me and risk his ruby wheel, but that's the machine that would do it.

FORGIVEN - did you re-radius the lower edge of the shims??

 

Just buy new ones,they don't cost much.....

 

I used 400 grit sandpaper and did it by hand, they should be ok. Will let you all know if I ever have a problem. I do have some extra shims, but for now can't find them. Sorry.

 

Not trying to hijack this topic, but what would be the performance impact of having the intake shims adjusted incorrectly?

From my basic knowledge of physics - and PLEASE correct me if I am wrong on any of this - the minute difference in clearance on the intake would open the valve LESS and DECREASE the duration the valve was open on the cylinder's downstroke, though only slightly.
From this I would deduce that this would result in a smaller volume of fuel/air mix entering the cylinder, but from this point I am not sure what the end result would be.
I suspect a few possibilities would be in order.. less fuel/air means better theoretical fuel economy but perhaps a lower internal pressure upon combustion (in essence less overall power). Could this also result in issues with cold starting or cylinders not firing properly from lack of fuel? And could it also result in an improper amount of vacuum in the carbs?

In a nutshell, what potential 'problems' could such an issue cause in an otherwise well-maintained bike?

 

hmm. kinda sketchy, ahahah but who am i to say that? lol

 

-Poor performance especially compared to a correctly adjusted motor.
-Hard starting, especially once warm.
-Poor fuel economy.
-premature wear of valve seats and valves, especially if too tight.

 

Blue....if the shim is too thick the valve is open too long, or too much. If the shim is too small, the valve doesn't open enough.

As the valve recesses into the head over a period of time, the clearance gets smaller, hence the need for a thinner shim. If a thinner shim is not installed, eventually the clearance gets so small that a feeler guage can't even get in to measure. If the clearance STILL is not corrected, then the shim rides on the cam lobe all the way around and never closes completely. Now you have a loss of compression with all attendant problems.

if a shim is put in that is way too THICK, then the valve opens too soon, or doesn't close all the way, or OPENS TOO FAR and the valve strikes the piston, it bends, and then there's all THOSE attendant problems.

Dave

 

FORGIVEN - did you re-radius the lower edge of the shims??

No I did not, just sanded the top surface. To me the shim is quite small, has a simple job to do and sanding it down will not cause it to break in half IMO. Any slight crown will wear away in time, no big deal. If I turn out to be wrong I will let you all know. Bike ran fine all summer such as it was....cold and wet a lot....so not a lot of riding.

 

You're missing the point: If that shim comes OUT of the bucket, for whatever reason, at say, 6000 rpm it will do an unimaginable amount of damage inside the top end. I wouldn't worry about breaking in half as much as I would a spit shim.

If you turn out to be wrong, it'll explode on you.

I like my bikes too much to chance it for $8 a shim.

 

You are supposed to "surface" the bottom of the shim, if you are inclined to "deck" a shim at all, but please keep us posted if you have an issue.

The cam-side surface (top) is to remain hardened. Or just spend $8.00

 

If you DO resurface the bottom, make sure that you get the size stamped on it in some way that it won't come off or you (or someone) in the future will have no clue what it was.

Please don't push those into the shim pool when you pull them, though.

Dave Fox

 

If you know someone with a machine shop, just surface grind them then lapp 'em just use a micrometer to measure.

 

If someone were to run an XJ with excess clearances (the umpteen thousands of unwashed, unshaven XJ owners) by four thousanths, you would get marginally less duration and lift which would marginally IMPROVE idle quality and even measured compression, as the intake would close earlier in the compression stroke, at the expense of peak Horsepower.

The XJ runs sixty degrees of overlap and is one heck of a hot-rod.
If a 350 Chevy were built to the same level, it would make 625 Horsepower (with mufflers)

 

What's a muffler ?

 

a muffler is a thing that goes on the exhaust pipes that keeps people from considering you a ass

 

When the valve lash is within specs a spit shim is imposible unless it breaks apart, all the shims have the same depth where they cover the top of the valve thus all are locked in with the same tolerances on each valve. Thus changing the total height of a shim will not affect at all the possibility of it being spit out. I am not worried about that at all.
And no I would never put a modified shim into the shim pool. I do have a couple that are original in size, just cant find them now.