Valve Clearance Problems

Just got my 1980 XJ 650 Seca Bike not running quite right. slow off throttle, won't rev over 4000 rpm nightmare when warm, stalls, runs ruff,

First stop was to Checked my valve clearance it was coming in at
0.30 / 0.25 mm, on most valves. This cant be right! would expect them to be tight not slack,

Must be doing it wrong! other wise that a lot of shims to buy.

Please advise.

 

Tight is more usual - I would fish one or two out and check their sizes. If they're low values (sub 2.40) then maybe someone has previously cocked up the adjustment. if they're in the 'normal' range 2.6, 2.7 then I'd say you have a problem which will need the head removing for inspection..

 

You are checking them when they are overnight cold, right?

Dave Fox

 

You SHOULD find shim sizes around 265-275. That would indicate that someone has at least changed shims once.....the right way... If you're finding way smaller, someone was messing around and didn't know what they were doing. If you find 275-290, then it probably has never been done and is due.

notice I said "AROUND" not 'exact'. Each bike is different, each valve is different.

Compression numbers may tell us stuff too...........

dave F

 

Had a Bit Of Time Today on the Shim Thing,

must have mucked it up yesterday, So Today!

Cam Lobes 180 degrees from the shim bucket, engine cold

so here we have it

CLEARANCES

EXHAUST
20 35 30 15

INLET
20 20 20 20

SHIM SIZES

EXHAUST
250 1.92? 1.91? 2.12?

INLET
260 270 275 295

3 of the Exhaust Shims have been Ground down so NO Numbers
had to Best Guess with the Instruments to Hand

so i recon i only need 2x 215 and 1x 210

if someone could check my Sums that would be great.


Also found out that Number 1 Spark Plug hole is Stripped,
Blowin' more Air than Johnny Fart Pants. OH! Bother!!

Don't you Just love Motorbikes..!

 

Intake: They are all too loose you will need thicker shims : 265. 275. 280 and 300.

Exhaust: #1 is still OK but on the loose side. According to your measurements, the other ones would need 210, 205, 210.

 

That's still not right...... Shims that thin aren't used yet with engines that are way TIGHT..... We're only getting to the the 255's now after 30 years.

If your valve are way loose, you need thicker shims.... Probably 300's, 305's, and even 310's.

Believe it or not, I have some of those in my pool.... I don't have any 310's but I DO have a couple 315's!!

Now for the ones with the question marks.... No guessing is allowed--- you must measure them exact otherwise you're guessing as to whether or not the valve will be in spec.

 

Thanks guys for the Responses.


hogfiddles
The Question marks denote the fact that they have been ground down,
not in a careful uniform way but with an angle grinder / abrasive wheel, all lumpy Bumpy way, so the size is a kinda average.


quebecois59
Thanks for the double check on the Shim Calculations

This is a 1980 4K0 UK Bike which i thought had 0.20 clearances IN / EX

Had a go with Shim Calculator your right quebecois59 was slightly out
should be:

Ex 2 = 215

Ex 3 = 210

Ex 4 = 205

Thanks again guys, another step forward on my XJ experience

 

Ok, so apparently someone was in there before, and in order to "correct " the clearances they pulled the shims and ground the thinner by hand on an angle grinder.

I was reading the numbers from a different perspective, now I see what you mean.

I highly recommend that after you do your swap you rotate the engine thought several rotations them check the all again. As you do THAT check, you'll be working with more accurate measurements, and EXACT sizes. If anything still needs to be corrected, you are at the right time and place to do it.

Hey, at least this is a "correct-able" issue.

Congrats on jumping right into it

 

Well Rsk_141, I'd say respectfully that I was right and you are wrong, lol!

On #2 EXHAUST, starting from a 192 and swapping for a 215 will give you 23 less clearance, you now have a 35 clearance , so you will end up with 0.12 which will be too tight for and exhaust valve. Redo the same math with a 210 and you'll end up with 0.17, which is correct.

Do the same math for #3 and #4 with the size I recommend and it will give you 0.17 on both.

If my maths are wrong, I will accept the verdict!

 

It is pretty unusual to have too much clearance on these old bikes, I'd say someone messed up with intake valve shims too.

 

Rsk_141, where did you find that specification. I have an XJ550 and thought that for most models the range was:

Exhaust: 0.16~0.20mm
Intake: 0.11~0.15mm

First thing I would do is double check that the cams are properly set by checking cam cap bolts tightened to the proper torque. If everything checks out there, of course replace to the proper shims. But please confirm what your lash range should be for your model, .20 for everything doesn't seem right. For myself, still having shims in the 200 to 220 range to get the right lash seems pretty thin. I would be to scared a shim that thin may pop/slip out at high rpm and cause a catastrophe. I would rather have the reduce the valve stem length instead to gain the clearance and have thicker shims in there. Not quite sure what shim thickness is still considered safe. Especially when the normal shim size from the factory is about 280 for the intakes and 260 for the exhausts. This only a guess on my part. I'm not as familiar with XJ's as of yet as my other bike. Ansd certainly not with the XJ650. Others with better knowledge here will surely correct any wrong information I may specified.

 

I'm going to bet that he found that spec by reading the misprint in the service manual. Use the specs that are printed on the sidecover; they are the correct specs (and the same ones that XJOE550 posted.

 

That IS the reason why all intake valve clearances are at 20, the previous owner used the wrong specs too.

 

+1

Had thought of that possibility. That would do it

Regardless, it is at least a correct-able condition

 

Use the one good exhaust shim to get your exact needed thicknesses on the rest. A PITA, but you'll be sure.

 

This is a Revelation, {Reminds me of the Story of the French Monks.}

So you are telling me that Haynes has it Wrong!

No Reprint, No Supplement?

It Not Just 1 Typo it in there 3 Times Page 41,32,31

and
http://www.motorbikespecs.net/index.dyn ... ake=yamaha

Oh this is a leaf of faith,

Is this some kind of "XJ Hazing!"


.........????

 

No hazing. Haynes aren't famous for accuracy.

There was a Yamaha "service quick reference chart" that came out back in the day, with a mis-print in intake valve clearance specs for the 650R. They simply listed the exhaust specs twice.

That error got picked up and "run with" for years; despite the fact that the correct clearances could be found on the label inside the side cover of the bikes.

The proper intake valve clearance for your bike is .11mm ~.15mm; same as all of the other aircooled XJs of the era.

That's not the only thing Haynes has wrong. They have the jets in the top of the Hitachi carbs mis-labeled too; and a lot of their wiring diagrams are mis-matched with the bikes they're supposed to be for.

 

Don't know about the XJ's, but for my other bike, there are Haynes manuals that have incorrect torque specs for the cam caps (many a stripped cam cap bolt holes). I had read about it in advance and made sure I used the factory service manual for the correct torque. I have both but the factory service manual (on PDF) and the Haynes book. But, when it came time to install my cam chain tensioner body, I got lazy and used the Haynes instead of the service manual. Ended starting to strip the bolt. I stopped and checked and noticed in time. Goes without saying, get a model specific factory service manual.

 

Haynes does misprints?!?!? The EFFIN schematic for the Ford Aerostar van's dizzy shows it rotating THE WRONG WAY!!

Enuff to frost your balls. :x

 

Been Checking Again Today, started by Checking Torque settings on cam Bolts, A-OK! Then Went Through the Shims Again, Got them in the Right Order this Time.

So Check my Maths on This:

EX ] Clearance 20
IN ] Clearance 15


Clearance

EX ] 20 30 35 20

IN ] 20 20 20 20

Shim

EX ] 235 200 210 250

IN ] 295 275 270 260

New Shims

EX ] 235 210 225 250

IN ] 300 280 275 265


Please Check Should have it now thanks to Everyone for there Help

 

Looks good to me

 

You should list your shims always in the same order if you want us to understand something. Yesterday you listed your intake shims like this : 260-270-275-295 and then today 295-275-270-260, exactly the opposite...I hope you know which sequence is the right one.

Also, yout first exhaust shim was a 250 yesterday and now it is a 235...how can that be?

 

fyi, the factory service manual has incorrect listings also. Mostly what I've caught are capacities.

Chris.

 

True, there are errors in the factory manuals; most though are obvious mis-prints or failing to pay attention-type "transposition" errors like listing the 550 MAXIM as also having an 18" rear wheel.

Haynes just flat-out gets stuff wrong. I have their Norton manual and their manual for the Ford 2.0L Zetec equipped Escorts; and both have numerous examples of outright WRONG info.

For XJ-series Yammies, the best practice is the Haynes or Clymer (depending on the bike) plus a factory manual, plus this site.

 

&

I will Answer your Replys with a Small Riddle:

Both are Right it's Plain to See, But in Which Order, Should They Be?

Thought we were Shooting for 20 on the Exhaust not 17 ?

and 12 is still acceptable range of shim.

Ex [ 10.16 - 0.20 ]

IN [ 0.11 - 0.15 ]


Just Sayin'

LOL...!

 

"Also, your first exhaust shim was a 250 yesterday and now it is a 235...how can that be?"

What riddle would answer that question?

 

He's not SHOOTING for 17, just going for the correct shim size that will put him in spec. THAT is what he is recommending. That size puts him as .17 which is in the 'in-spec' range.

ANYWHERE between the numbers is acceptable.

If it's a little close, then that shim will most likely get changed at the next check. If it's more toward the loose side, it'll probably take several checks before it's time to swap that one. I just shimmed a bike where it had NEVER be done before........42k mi on it, still had the 285,290's in it......swapped several, rotated a couple, and there was one that STILL was in spec.

In-spec is in-spec......doesn't matter where, as long as you're in-spec.

You can "aim for .20" all day long, but you're gonna have a nightmare trying to achieve that specific of a number. You'd be trying to micro-size your way through shims that don't exist.

Dave F

 

Thanks again for everyone's input it been most helpful.

Regards

Gary

 

+1.

In the tool making trade, if you wasted unnecessary time getting things nominally perfect instead of within tolerance, you'll get run over, and possibly fired. It takes a LOT longer to get things to a nominally perfect dimension than it does to get it in spec.

Get it in spec and you'll never know the difference.

 

shooters say
aim small, miss small

 

No matter if it hits the bulleyes or misses the barn when you shoot, it still takes the same amount of time.

It don't work that way in metals.

 

Gary,

Love the name.

Gary