Removing shims with a magnet?

The dude in this video uses a magnet tool to pull out the shim.



I think I heard here a while back that this is bad idea? Thoughts

 

It is not a bad idea. It is the factory recommended method. Magnetizing steel requires a lot more than a few moments of contact with a magnet. The concern is that the shim may get magnatized and have metal stick to it, causing premature cam lobe wear. That concern, while logical, is pure bunk.

 

doing that may magnitize the shims and therefor attract and collect metal particels which could ruin your cams

 

K-moe is correct. It's in the factory service manual. There's already a magnet down in the oil pan to catch anything anyway

 

Among the many things that I have to do is to periodicaly remagnatize the student magnets in my science kit at work. They are made of a steel that is similar to the steel our shims are made of. Remagnatizing one steel bar magnet takes around 10 minutes of rubbing the steel bar against a neodymium magnet in a specific pattern. Even after all that, the steel bar magnets lose their magnetic field in a few weeks if not stored properly. You won't be magnetizing a shim by plucking it out with a magnet.

 

when I work on cars and bikes I have a magnetic tray to put all the small parts in. would it be fair to say I should not put the shims in that when I pull them out?

 

I have seen tutorials on the tube that say you should de magnetize your screwdriver before using it to "prise" out the shim to prevent the shim from becoming magnetized. If K-moe's scientific experience is correct, then having a screwdriver magnetize the shim is pretty much impossible, right?

 

he is not saying its impossible just improbable to "charge" a disc easily enough to be concerned.

there are many conflicting opinions about things, oil, recently ss screws being used with aluminium ,now magnetizim . better safe then sorry comes to mind quickley

 

That I would not do. The shims will get very slightly (and temporarily) magnetized if they sit for a while, but more importantly any metal shavings that have found ther way to the pan will have been magnetized. The risk would be in the shim getting a bit of metal from the shop stuck to it and that being introduced into the engine. This may not be a risk in your shop, but it is in mine since I do a fair amount of fabrication. That is the same reason why demagnetizing a screwdriver is recommended; it may have bits of metal on it that could be introduced into the engine. I just keep my shim popping screwdriver in a drawer and don't use it for anything else.

 

ok so next dumb question - Once i remove the head-cover do I need to replace the gasket and the 1/2 moon grommets before putting it back together while i wait to order shims or can I just put it back and wait for the shims before replacing the gasket and the grommets?

 

you can just put in on to cover the motor . without the new gaskets to keep the flying objects out. I assume it is not being rode.

 

If the gasket still works, just go and ride. Unless you removed the shims and didnt put the back!

 

Alright so that was easier than expected. Here's my readings - can I get a sanity check on my numbers?

XJ650 Maxim '81

Intake Spec - 0.11-0.15mm
Exhaust Spec - 0.16-0.20mm

Piston --- gauge-that-fits -gauge-that-doesn't-fit --- Shim Number --- New Shim?
#1 IN ---- 0.063 --------- 0.076 ---------------------- 290 ---------------- 230?
#2 IN ---- 0.102 ---------- 0.127 ---------------------- 285 ---------------- 270?
#3 IN ---- 0.102 ---------- 0.127 ---------------------- 300 ---------------- 285?
#4 IN ---- 0.102 ---------- 0.127 ---------------------- 290 ---------------- 275?

#1 EX ---- 0.152 ---------- 0.178 ----------------------- 270 ---------------- 250?
#2 EX ---- 0.178 ---------- 0.203 ----------------------- N/A ---------------- IN-SPEC
#3 EX ---- 0.127 ---------- 0.152 ----------------------- 270 ---------------- 240?
#4 EX ---- 0.127 ---------- 0.152 ----------------------- 275 ---------------- 245?

What do you think - guess theres some wiggle room here and there, just went with what I thought from what I've read but I sure would appreciate some experienced advice.

 

Ribo, here's what you need:

1 in 285
2 in 280
3 in 295
4 in 285
1 ex 265
2 ex - in spec
3 ex 265
4 ex 270

Move the 285 from 2 in, over into 4 in. Move the 270 from 3ex to 4ex. Then total up the rest that you still have to get.

 

There is no wiggle room. In spec is in spec and out is out.

Remember to round your measurements to the second decimal place since you are using SAE feeler gauges.

#1 intake 0.06 needs a 285
#2 intake 0.10 needs a 280
#3 intake 0.10 needs a 295
#4 intake 0.10 needs a 285

#1 exhaust 0.15 needs a 265
#2 exhaust 0.18 in spec
#3 exhaust 0.13 needs a 265
#4 exhaust 0.13 needs a 270

{Edit} Hogfiddles types faster

 

Bam!

 

What chart did you look at to get your shim changes Ribo?
The shim numbers are the actual measurement in mm. A 265 measures 2.65 mm.

 

I kind of think he wasn't using a chart...........

 

Oh there's a chart? lol - This is perhaps where i goofed...

Thanks guys - I now see the chart and it makes more sense and much easier - the chart was on the next page of the book and my dumb ass didn't turn the page.

 

I'm going to bump #1 intake to a 280 cos I measured it again after taking the shim out and in and wasn't able to get the 0.06 all the way in.

I so believe I can reuse these right - so I can move them around. By my reckoning I just need to order:

280
295
285
265
265

 

You can reuse them.... That's why I told you what ones you could move....

 

I would not bump to a 280. Unless you rotated the engine several times after reinstalling that shim it probably was not fully seated. Trust your first measurement.

 

there is a chart. At the end of this how to.

http://xjbikes.com/forums/threads/airhead-valve-adjustment-with-pics.14827/

Also now is a good time to clean up that valve cover. Unless you already have or care to.

http://xjbikes.com/forums/threads/valve-cover-refurb-step-by-step-with-pics.22125/

Personally I wouldn't use a magnet no need to. A pair of hemostats worked great for me. But if it works for you then great!!

 

I'd rotate a few times and re measure. If you go to the thinner shim you will be on the loose side of spec, maybe too loose. If you go with the first size mentioned, you'll be in spec ... On the tighter side of in spec but in spec is in spec. Pretty good bet that one will be out of spec at the next change, so you'll swap it then instead.

I have no problem using a magnet ..... It says so right in the manual, so I'm not afraid to use one.

 

Dave, sorry I missed that part in your post where ya told me which ones to re-use. I kinda figured that out and I got it sorted now but thanks for the help all of you. Feel like I really learnt something today, and not only to just to keep reading the manual else you look like a duffus.

I'll check that #1 shim again tmw and see. Sounds like it's best to go 285 so unless it's gotten worse I'll do that. I found a local place with 29mm shims so should be able to get them tmw.

I didn't need a magnet in the end I found it pretty easy to pull them out with a pair of needle-nose and small screwdriver. Only real gotcha I ran into for a few minutes was rotating the cam follower so the little gap was on the right side after engaging the tool.

I will be cleaning up the value-cover and have a new gasket and 1/2 moons. All said and done I think it's safe to say the PO lied when they said they'd done this before I bought it. Some of those were pretty badly out of spec.

Cheers again
R./

 

PO's are the only ones.... I've seen enough things that were " done at the dealer/repair shop" that weren't done. They never expect that you'll actually go into the engine and find out----

 

if you reuse and move them around re measure as well

 

So.... things were going well here until I came to fit the new shims and I'm having a hell of a time getting them to seat in the cam follower. They won't. is it possible I was given the wrong size. There appears to be a very slight difference between my original ones and these - like maybe a mm bigger. It's hard to say but the original ones seat fine when I move them around - I tried 2 of the new ones and no bueno.

 

According to somebody in another shim thread (Chacal maybe?), Yamaha shims have a beveled edge. Could this be the issue preventing fitment?

 

Thought it was Suzuki shims that had beveled edge? the original shims don't and they snap right in.

 

Maybe I'm remembering wrong. Gimme a minit to search...

 

Yeah, you're right. He was talking Suzuki shims. Sorry. I is dmub.

 

no worries, thanks for trying to help. Tonight went form great to bad and then got worse. My new tires are sweet and I got the wheels on no problem but the front brake is locked shut on the wheel now. I tried to put the pinch bolt back on and it won't engage in the nut, I snapped the rear pinch bolt off inside where it goes in the rear and then spent 2 hours trying to get these damn shims to fit and they won't. I'm now drinking rum.

 

You should do a write up on how rum helped the build... is it more effective than beer?

 

I have seen 29.5 mm shims listed but are not the ones you need for Yamaha.
Suzuki uses 29.5 mm shims

 

I just ping'd Chacal with my list - should have done that first but thought it would be quicker to get them locally - which it was, just not the right one

 

shims, did you measure them with your H F caliper? do the old shims go back in? you might have a little nick in the bucket.
the front brake, maybe you didn't tighten axle in the right order or the speedo drive is out of place.
the pinch bolt sometimes bends because it's been tightened too far, then as you turn the bolt, it snaps. turn the nut, hold the bolt

 

I didn't measure with my H F caliper because my dog ate it. Need to get another. I tried the shims on 3 different valves with the same issue. Now I have ordered from Len so I know they'll be good.

Speedo looks fine to me. I'm going to try and pull the axle and see if I can get the pinch bolt to engage without fully tightening it before putting the axle back in.

 

All done. I got the shims from Len and ordered replacement pinch bolts at the same time. Looks like the original one was a lot shorter that it should have been, perhaps not "original" Mr PO??? Anyway it's all sorted. Thanks for everyone's help. It's a pretty awesome feeling knowing that the shims are good now and man she's purring like a belly rubbed kitten now

 

I removed my cams, cam followers, shims, valves, collets and springs. I placed them in 4 bags for cleaning and reassembly after ring job. think i made a mistake with the shims....I didn't mark exhaust or intake...was that a huge error or not really? guessing i'll have to regauge the shims after reinstall of cam anyways? Please respond.

 

It’s a mistake to not label them, BUT it’s just a time-costing mistake, in your case.... just stick the shims back in. Then you’ll have to measure/do the shim clearance adjustment procedure. I’m more concerned with the buckets...... ideally they go back into the same bores they came from. Since you kept things in at least cylinder-specific bags, I’d recommend that you pay close attention to them when you re-install. For each cylinder they should feel very smooth and slippery in the bore but with zero ‘slop’ and zero binding. They should feel this way through up and down motion AND rotational. If one of them doesn’t feel perfect, then swap them and try again. Make sure the bore are meticulously clean And the buckets, too. Also make sure they are well oiled.

 

would have been easier to know what went where.
if you kept the shims seperated by cylinder you have a 50/50 chance of replacing them correctly.
not a big deal unless you have a Maxim X.
if all your shims are in the same bag
I would recomend getting the plastic shim place holders from chacal install them
take your thinnest shim install it measure clearance and install the correct shim(if you have it)

if your shims are all close in size you could just install them and measure clearances.
then see what you have and get the ones you need after you swap what shims you can.
and get the remaining cylinders as close to spec as possible
those plastic shims come in handy.

 

1. I’m assuming he’s working on his 650 maxim
2. Since he said he put everything into 4 bags, I’m assuming 1 bag for each cylinder. That’s why I thing he’s ok to just carefully feel the buckets. The shims.... it’s either gonna be one shim if the other. Either way, once they’re in and the crank is spun a bit, ( and cools all the way back down if the bike fires up), a check/adjustment will take care of things.

 

Yes 4 bags one for each cylinder contains; valves, springs, buckets, shims, seats and collets. This is my first rebuild...ever so not my first mistake and not my last i'm sure. had to get 2 snapped intake boot studs extracted and the mechanic recommended lapping the valves which again in another new process for me. Guessing lapping would thro off shim sizes anyhow.

so valve adjusting takes place AFTER rebuild and firing the engine?

i'll watch the buckets durring install to insure smooth operation. i was impressed on how smooth they turned with your fingers and fell out of the heads. Most of the shims were the same way, rotated very smooth (2 did not and had to be pried out with tiny screwdriver. valve guide seals were like a dentist extracting teeth with a plyers...next remove and pistons, gudgeons pin and rings...then soda blast piston heads.

top half rebuild is interesting to say the least. i've been ordering gaskets and stuff from Len, rings and a few other things are next.

 

If you’re lapping the valves, yes that would throw things anyway. In this case, I’d recommend putting all things in, then measure clearances and make. adjustments to get in spec. Then close everything up, dial it in.Then ride it for a week or so. Pull the valve cover off and recheck on a day that the bike has not been fired up, so it’s stone cold..... remeasure all clearances, adjust any still needing to get back in spec. Re-sync your carbs as needed. NOW you should be good for another 5k til next clearance check

 

I lapped mine during my rebuild and I did this exact thing (probably Dave's advice to me back then too) and it worked out perfect. In spec during assembly, rode it for a few hundred miles and rechecked. Had a few out of spec and replaced those.

 

I've been hearing for years it's a bad idea, and even did it myself a few times, but have never come across any evidence of the downside.

 

I’ve done it for years.... the manual says to use one— I’m not concerned with it

 

Great video on shimming.

Hogfiddles says: 'If you’re lapping the valves, yes that would throw things anyway'. I don't understand? Are you simply saying put the shims back, ride awhile THEN do the shimming procedure?

Also; checkout this image from underside of the valve cover. the chain is dangerously close to the cover......is this normal? perhaps the chain was extremely loose. (see attached image)

 

A lot of semi-educated people have passed along a lot of bad advice over the decades. Magnetizing steel is not as easy as just touching a magnet to it.