super tight valves? am i retarded?

Hi, I have been a "viewer" of this forum for some time, just now registered to ask some questions. This forum has been of great help to me while working on my 1981 maxim xj650. Here is a question that i hope you guys can help with:

I am trying to spec my valves but it seems i cannot get the feeler gauge between to rocker and valve no matter how i position the rocker. I assume the pointed part of the rocker needs to point directly away from the valve to check clearance, am i right? I have a metric feeler gauge but not one of the gauge will go through, not even the .006, not even close! am i doing something wrong or are these valves damn tight? This bike has 22,000 miles on it and i doubt the valves were ever adjusted. The bike runs now after a good carb cleaning but the idle speed seems to change on its own, it will idle at 1000 for awhile the surge to 1600 or so and back down to 1000 after awhile, it just wont settle.

If these valves are extremely tight, what shims should it go with, all the valves are not allowing me to insert the feeler gauge.

Im out of ideas, please insert your knowledge below:

 

The correct term for what you are calling a "Rocker" is camshaft lobe. Yes the lobe has to be 180 deg from the valve shim and bucket. You should be using metric feeler gauges and at .006" you are way to tight.

MN

 

have a look at this and go from there, just in case you havent seen it,
http://www.xjbikes.com/Forums/viewtopic/t=14827.html

good luck.

 

Camshaft lobe is what I meant to say. And I have looked at the valve adjust topic on here, it is very informative, but I got stuck at the clearance part.

So, can valves actually be this tight, if so, now what?

 

You'll have to get a manual and follow the instructions on replacing the shims. Would be best to get some used shims for checking purposes.
I would get the tool to remove the shims. Some here use a zip tie and stick it in the valve you are working on. I like the tool to do the job but to each his own.

MN

 

You are on the compression stroke, right?

 

Yeah, here's what you do, since they seem to be super tight. Just pull all the shims(one at a time! You have to have the shims in place when that lobe hits the bucket.) Record the numbers so you know what size they are. Then look at the shim chart and move down two sizes. Then, you should at least be able to get a reading to know what size to put in there. But I never heard of valves that tight, myself. Mine were only one shim out of spec when I did mine, if I recall.

 

Doesn't make any difference as long as the lobe is pointed 180 deg away from the shim and bucket.

MN

 

Oh, they can be that tight, all right. I would pull them and read and record them. Then swap them out for a couple of sizes down as suggested and use that clearance to work with. You'll probably be able to swap some of them around; see what's in there.

 

I'll take out the shims and go a couple sizes down to get a good reading. Thanks.

 

If you don't want to buy an extra set of shims for measuring, could you just get ONE that is two sizes smaller than your smallest shim? So pull an measure them all like what was said above, and order one that is two sizes smaller. With one extra, you can play musical shims and get good readings on all of them, then order only the right sizes. You might even get lucky and be able to switch a few without ordering new ones.

Take good notes on the positions and measurements. And what ever you do, just incase you missed it above, DO NOT rotate the cam lobe without a shim in place (why you need to have at least one extra).

 

+1 Manbot. Be sure not to rotate cams on buckets without shims you will cause damage to your cams and buckets. Only remove one at a time , make a diagram as to which valve has what size shim and go from there.

 

If your valves are like mine then one of your shims will be 2, 3, or maybe 4 sizes smaller than your largest one-like 290 is your largest and you have a 270 as well. You could follow the above advice and swap the smaller into the larger ones to get a reading-at least as much as possible until you can't swap anymore. That should get you most of the way there or indicate to you how much smaller you may need to go.

It is also possible you won't have any number printed when you extract your shims because they've been rubbed off. I had one that was like that. In that case you could measure with some digital calipers to get the 'true' size of the shim and go from there.

The valve bucket holding tool is a little tricky to use-the key is to have it centered (precisely) and keep it from lifting or moving while you tighten the allen screw-that way it stays just on the bucket and lets the shim pop free, and don't let the tip of tool get coated in oil or it will slip off easier. Also in my case the rubbed off shim was VERY unwilling to pop loose. Based on how easy the other's were I take it as an anomaly but it was a BITC#! So the second time I went in I made some tools to help me go faster and be less stressed.

Check these out made from a computer chip puller



+1 to what MN says here is a link for a chart I made to keep track, made it for my 550 but yours is the same.

https://docs.google.com/file/d/0BxLr6l1 ... 2YjJk/edit

EDIT: fixed the link above should work now.

 

Just as a side note. There is a shim tool out there that does not work quite right. Someone who knows which one it is should chime in here and refresh our memory as to which tool to avoid buying.

MN

 

I just picked mine up from XJ4Ever, but I remember someone saying they had bought one from another online supplier and it was bunk-something about it being made for a slightly different setup or maybe it was poorly engineered-don't remember who it was though.

 

From my observation you want the one that dosent have a nipple in it. The nipple is designed to go in the gap in the bucket but this blocks your pry point on the shim. Im going to order the flat one that rests on the bucket flat leaving the notch open. I could b wrong about this. But it seems like common sense to me.

 

Nope.....the nipple (tip) of the shim bucket retaining tool rests on the edge of the bucket, and the notch in the bucket should be rotated 180-degrees (exactly opposite-facing) from where the tip of the tool contacts the bucket..........so for example, tip-of-tool on the bucket at 6-o'clock, notch in bucket should be facing 12-o'clock. The notch is where you use a very thin screwdriver blade (or equivalent) to pry/pop the shim loose from the bucket.

Look at the last 2 images on this thread posted by BigFitz and you'll see the proper method of usage:

http://xjbikes.com/Forums/viewtopic/t=29209.html

 

For a spare shim to use so that you can do preliminary measurements, contact me..... I run one of the shim pools, and have a couple shims that are good only for that exact purpose. You can then get your measurements and we can set you up with most, if not all, of the shims you'll need. PM me with the little 'pm' button at the bottom of this reply.

You can also order all brand new stuff from Len Chacal, our local parts supplier/expert extrordinaire.

As far as the question of 'can they really be that tight'......they sure can, and I've seen ones that are so tight that the bucket is riding on the cam for the full revolution, leading to low compression reading in one cyl. Once the correct shim was in, everything was good. It's just a hassle at that point, cuz you have to do what you're gonna have to do.....put a smaller and smaller shim in until you CAN get a clearance measurement, and THEN do the math to get the Correct clearance again.


The notch in the bucket is there so that you can rotate the bucket so that you can get to pop the shim out. Do NOT line up the shim tool with the notch.

I use the tool, but on the last one that I did, I used the ziptie method and I think I'm probably going to do it that way from now on. Once I got the feel for it, I had the whole bike measured and swapped in about 10 minutes.


Welcome aboard!

Dave Fox,
Registrar- XJ900RK(USA-Delivered) Seca Database
Operator - Central NY XJ Shim Pool
Host - Central NY Carb Clinic #6, June 2013 (date tbd)

 

You guys are awesome, some very good advice that I probably wouldn't have thought about till I had messed up something. Goes to show how experienced shared can make a job so much easier. You guys should be proud of your forum and the knowledge therein. I'm going to remove the shims one by one, record the number and location then reinstall. I'll post my shim sizes them pm the member above to maybe swap some shims around. I'll be glad to trade my existing shims for others I can use.

 

That's basically how the shim pool works.

Yes, we are proud of our forums and we work hard to keep a high quality thing going here.

Make sure you do the math once you get clearances that will work, then I'd recommend that if this is the first time you've done a shim/clearance check.....post the numbers here, and we'll either confirm or correct what you need.

Then we'll check what's available in the pools.

Make sure that you keep the numbers in the correct colums:

Exhaust 1 2 3 4
Intake 1 2 3 4

Dave Fox