XJ 400 - How to replace and adjust command chain?

I have just bougth a 1993 XJ 400, and its engine makes a horrible noise from the head when it runs. I would like to check and replace the command chain as a first step to get it going, but could not find any tutorial on this in the FAQs.
Can anyone help?
This model was exclusive for the Japanese market. Israel, where I live, was the only (other) country that imported these airheads, and ceased to do so in 2000, so parts are as scarce as peace in the middle east...

 

I think you mean the camchain; and I responded to your other thread with detailed adjustment procedures as long as you have the manual adjuster.

 

Yes, "camchain" is more like it. BigFitz, I feel really dumb about this: I am unable to find that "other thread"... I tried hard before opening this new thread, I promise! My profile (apparently) does not allow me to find "all posts by aharon"... Please help - I have not yet gotten the handle of the search feature on this site...

 

Don't feel dumb at all. Actually you posted a question in my valve adjustment how-to; here was what I answered:

"Do you have a 4-cylinder 400?

If so it is very similar to the 550s. Your camchain tensioner is an assembly that sticks out the back of the cylinders, in the center below the carbs.

If it is the manual-type adjuster there is a locknut and bolt on the right side of it. It looks like this-- All you actually see is the body and the adjusting bolt if it's that style, everything else is inside. (Ignore the arrow in the pic, that was for something else.)



Adjustment is as follows: Remove the ignition cover as shown in this thread; and position the pointer to the "C" position on the plate.

Using a 12mm deepwell socket, loosen the locknut on the adjuster bolt. Then using a 10mm socket, loosen a couple of turns but do not remove the adjuster locking bolt. When you loosen the bolt you will probably hear a "click" as the adjuster takes up slack. You may not, no worries. Re-tighten the bolt to 6 newton-meters (51.6 in/lb) then torque the locknut to 9 newton-meters (78 in/lb) and you're done.

If you DON'T have a bolt with a locknut on the side of your adjuster then it is the "semi-automtic" type and I'm not 100% sure on that procedure as all my XJs have the manual tensioners.

The "tool" is Yamaha special tool #90890-01245-00, commonly known as the "Yamaha valve shim tool." It's readily available from almost any aftermarket motorcycle parts supplier like Bike Bandit, you can find them on Amazon http://www.amazon.com/VALVE-SHIM-TOOL-Y ... B000UKIT8U and XJ4Ever (link on the banner in the upper right) carries them as well.

You can also use a piece of #12 insulated electrical (house) wire with a hook on the end, shove it down the plug hole and hook under the edge of the valve to keep it open. I personally do not use or advocate this method."

If your bike is similar (motor-wise) to this Pacific-rim market XJ400, you should be good:



This bike belongs to a forum member in Santiago, Chile; not sure what year it is.

 

Thank you again, BigFitz! Yes, my black beauty's engine is exactly like this. I have great hopes that I will be able to get it running "with a not-so-little help from my new friends"!

 

BigFitz, I took this picture to ask your opinion.
Despite the shitty resolution (I used my Samsung at night with flash), you can notice how much whiter (and cleaner) the middle section of the engine looks. Like new! This is really very suspicious...
When I bought it, the former owner told me that "one cylinder was cracked". However, he made the engine run, and the ugly noise I heard came from the upper part, around or near the camshaft. From your opinion (and before I go any further than first try to adjust the chain tension and revise the chims as per your fantastic tutorial), could it be that he tried to fix the "cylinder problem" (perhaps substituting the whole what-you-call-it, whiter (or "silveryer" hahaha) than the rest on the picture) and gave up for whatever reason?

 

How much cam chain noise is normal?

 

aharon Your picture didn't attach; possibly too big. I would be very suspicious of "one cylinder is cracked" and certainly investigate further. It's very possible that you have an exhaust leak at the head/pipe junction and it's been mis-diagnosed, just from the sound of things. It's often the result of a minor accident or tipover and the assumption gets made that it's a more serious problem.

BillB Let's just say you can hear it. With everything properly adjusted and the motor warmed up, it's quite "busy" up there; when the cam chain gets loose it can result in an audible "slap" against the inside of the cover if you blip the motor.

aharon's 400 and the 550s have a whole different sound component than the bigger bikes though, the primary chain has a sound all of its own to contribute.

 

er... would you please define "pipe" in "head/ pipe junction"?

 

Oh, sorry. Exhaust pipe. Even though they are often hard to see even with the pipes removed, there are soft gaskets in between the head pipes and the cylinder head itself. The collar with the two nuts presses against a flange on the pipe, which compresses a soft composite gasket set into the opening in the head. In the even of a tipover or light crash, the pipe can "pack" the gasket in unevenly and cause a leak. It's not uncommon.

In answer to your other question, now that we can see your photos: The portion of the motor that is brighter silver in your picture is the cylinder unit itself; the grubbier section above that is the cylinder head.

Perhaps the previous owner replaced the cylinders?

You're really going to need a service manual at some point; if you can't locate one for the XJ400 then an XJ550 manual will do you a lot of good. The 550 Seca is the direct descendent of the original XJ400CC 4-cylinder, and the two motors are virtually identical.

 

Thank you BigFitz. Indeed the exhaust (a 4x1) is all scratched, so the girl has been kissing the ground.
I will look for the XJ 550 service manual, because the 400 is non-existant to my knowledge: all my searches came up empty.
On a personal note: I showed your posts and explanations to my son Ariel (he is 24) yesterday, and he started making questions and more questions. I was more than happy to oblige, of course. At some point he said "I am fascinated by engines". I told him that he is welcome to help me rebuild this engine and stuff, my point being: with my best friend as my buddy, this project cannot fail. How I love this guy!

 

That engine looks like the diversion/SecaII 600. I would imagine the manual for the 600 would be correct - apart from obvious size differences.

 

Markie is probably right; as your bike is much newer than the XJ550, a manual for the Diversion/Seca II 600 will probably be even more useful since it would be more current to your bike.

 

now this is embarrassing: I am having a hard time to release the bike's seat!
The XJ 600 manual that I got (thank you - you know who you are! ) tells to use the bike's key - it is different! Mine has no key to release the seat.
There must be a lever somewhere, but I just can't find it...
Can anyone help?
(someday I will remember this and laugh - but I am not laughing now...)

 

Left hand side!

 

Found it! It indeed has a key to open... down, down the fairing. Oh, dang!

 

Hehe, Markie... I am really playing the newbie here!
Thanks, I got it.
I noticed we two have had a couple bikes in common: my first one was also a Suzuki 50cc (green...), and I also had a Honda CB500T, and a Yamaha RD125 (2 cylinders - the only one I have ever bought "zero km").
The list is long and, as I said, this XJ 400 is the 21st - and hopefully the first one I managed to fix myself.
Kind of "Zen and the art of motorcycle screwing, ops, maintenance". He!
Let's keep up the good humor
Aharon

 

Every little happy move must be comemorated! I began purchasing the tools to get my bike going again!
Today I got a set of 9 metric chrom-vanadium hex wrenches ("Allen keys"). Sizes from 1.5 to 10mm. Thanks to XJBike's advice at the FAQ forum, I chose a set with a ball point on the longer arm, for better reach and operation at an angle.
I also ordered a torque wrench with metric sockets from 5 to 25 mm, and a "feeler-gauge" (that is how they called it at the store). They are supposed to be at hand tomorrow.
I am truly excited about being my own mechanic - it is not about the money, it is about the spirit of the thing!

 

Guys, I am having difficulties at stores here trying to explain the type of torque ratchet wrench I need. When I say that I need someone capable of 7 to 9 Nm, they laugh and call it "watch repair tool".
Can you please tell me the specification of the tool I need?
My son is in Israel's air force. He says that the torque wrench he uses there allows him to set the torque desired before applying it to the nut. The air force is rich, I am not, so maybe a more humble model would do?
Boy, it is difficult to deal with israeli businessmen - they act (they fleece you) as if they do not care whether you come back to buy again or not!

 

Tell them you need an INCH-pound torque wrench with a 25-250 inch-pound range (approx 3-30NM's) something like this: http://www.thetoolwarehouse.net/p-2530- ... -3459.aspx

You will also need a "stronger" torque wrench, with a 10-100 foot/pound range, for the larger bolts on the bike. Something like this: http://www.thetoolwarehouse.net/p-2531- ... -3460.aspx

(I just gave you the K-Ds as examples, there are many different brands/price ranges out there and I have no idea what's available to you there.)

 

Thank you, BigFitz. I understand that I will have to buy a separate set "sockets" (you know, those cylinders that are installed in the torque wrench and contact the nuts). Like 8 mm, 10, 12, 13... mm.
My question is, if the wrench is rated in inches, will the metric sockets fit? I mean, japanese bikes are all metric, right? Or it does not matter?
I hope my question makes sense...

 

You don't need special sockets with the torque wrenches. Regular metric sockets work. You just need the drive size to match. 1/4", 3/8" 1/2" 3/4" etc.

You can and probably do have many 3/8" drive metric sockets. I know I do.

 

Right. Both wrenches I posted links to are 3/8" drive (fits the square hole in the bottom of the sockets.) The "drive" size is common to both metric and imperial sockets, and other types of sockets like for spark plugs. You will need an 18mm (3/8" drive) spark plug socket too, by the way (I'm 99.9% sure your bike has 12mm plugs.) You will also need a long (9" or so) "extension" (also 3/8" drive.)

That size, 3/8" drive, is probably the most common size for this type of work.

There are also 1/4" drive tools (the "peg" on the tool is 1/4" square instead of 3/8") which allow smaller sockets for even more precison work.

The bigger sizes, 1/2" drive and 3/4" drive, are generally for automotive use. Most everything you will use on a motorcycle will be 3/8" drive.

You will need a couple of DEEP sockets, though. The most commonly used sockets are rather short, much longer ones are available, known as "deepwell" sockets; you will need at least one (12mm) for the cam chain adjuster locknut. It has to be a deepwell to slide down over the bolt.

If you cannot find an 18mm spark plug socket, you can use an 18mm "deepwell" socket instead. (also 3/8" drive of course.)

Your questions make perfect sense for someone who is unfamiliar with mechanic's tools and the terminology, I am very impressed by the fact that you want to take this on and learn these things and I am happy to help in any way I can. (I'm only a couple years older than you...) A lot of us on this site have been doing mechanical work for years so there is a lot of experience to draw on.

Ask away.

 

Bigfitz, thank you once again. Your (and by that I mean the collective good soul that inhabits this forum) help is priceless.
About taking this mechanic thing on me, I confess that I feel and am proud of finally having kind of "cleaned up my act" in life. I explain. As you can see on my signature, I have had many bikes. The two-stroke ones were pieces of cake to open, scrape out the accumulated carbon on cylinder(s) and close. Four-strokes were scary, they seemed complicated and "unreachable" to me. Also, it was way too easy for me to trade them for another one, money was not a big problem, no family constraints...

In time, I noticed I was changing, staying longer years with the stuff I owned, caring more about them. I could say my wife and kids made of me the man I was supposed to be all along - and I keep kissing and hugging them every time, every day, as many times a day as I can (or they happen to get near me), because this is heaven to me.
Thanks to the internet, the availability of such a treasure of knowledge have finally encouraged me to take the plunge and grab the bull by the... well, horns
Dear friend, I will not apologize for the long post on a personal view, because this is the kind of stuff we would talk about if we were riding together. I know you will agree.
I see I got a deepwell already: a deepwell of friendship, which is priceless!
A friendly hug from the Holy Land!
Aharon

 

Re: XJ 400 - command chain adjusting bolt

The guidelines you gave me regarding the camchain tensioner mentioned a second nut, which locks the main bolt in place. Mine has one single, 12mm bolt with incorporated washer. Perhaps because it is a newer (93) model? Or perhaps it might have come with the cylinder housing, if (as I suspect) it has been transplanted? :roll:
It is tightened so hard I was unable to unscrew it.
What would be the safest way to "wake it up": wd40 (or something similar), or bang it slightly on the head a couple times with a hammer? (that would be the educated cro-magnon approach...)
Attached is an actual picture of the thingy!

 

Urk.

Stop right there; don't loosen it just yet. It's completely different than the one on the 550/650s.

Look in here: http://www.yamahapartshouse.net/pages/p ... parts.aspx This is a link to a USA-market Yamaha parts fiche.

Look up the 1993 or 1994 Seca II XJ600 and look under "camshaft-chain."

Your tensioner unit looks just like that one; it's automatic. Methinks we're barking up the wrong tree.

Look at the other associated parts, the long curved camchain guides, front and rear. We need to be sure all that stuff is installed and in the right place too.

The way to do that is to pull the valve cover (the very top "lid" of the motor) and have a look with a flashlight and mirrors.

Your picture causes me to have another observation: I think your PO (previous owner) replaced the cylinder block assembly; look how clean it is even way back there, and how grubby it still is directly below the cylinders.

It's very possible he didn't get everything reassembled correctly; best course of action now is to pop the valve cover and turn the motor over and have a peek. The problem (if the noise is that bad) should reveal itself. (Do NOT run the motor with the valve cover off, you will drench everything within 50 feet with oil.)

 

I would have to agree with Fitz, Looks like a new or freshly redone cylinder. Inspect all of the chain guides to make sure installed correctly and all of the parts are there.

MN

 

Re: XJ 400 - How to remove cover breathing tube?

5 screws are hex, piece of cake. One however is a kind of breathing plug (there was a black hose in it). How do I remove it, please?

 

well I figured out that the inner part of this "breather" is also a 5mm hex, so I took it out.
Next I was forced to remove the carbs to get the cam cover out. I tried to loosen the retainers of the rubber tubes between the carbs and the manifolds, but one of the crosshead ("philips") screws was, er... screwed, so I took the manifolds out. The carbs "look" like they need some maintenance, so I will ask (research) later how to reassemble (which gasket or joint sealant to use).
I turned the engine gently (counterclockwise), and the only thinkg I noticed was that the front chain tensioner moved up, until it became flush with the rim of the cam case (see picture). Is this normal? Could this be the source of the clanking noise it makes?
next post will show another "suspect".

 

Golly. You're getting beyond my long-distance mechanical skillset here, but let's don't give up.

First off: Turning the engine CCW: viewed from the left side of the bike, in other words the engine turning "forward?" (This is good, by the way, try to limit how much you turn it "backwards.")

If so, the cam chain tensioner/guide shouldn't be moving up or down; that very well could be part or all of the issue.

Your picture isn't big/clear enough to be able to tell what exactly is adrift, can we get a better pic or two?

Take a look at the "camshaft-chain" parts blowup for your bike, and have a look in there with some small mirrors and a flashlight. It does sound to me like something is out of place or has come loose (or a bit got left out) and something is flopping about that shouldn't be.

The guides, front and rear, shouldn't move much as the chain passes over them.

 

Thank you BigFitz for not giving up on me!
This is one of the marvels of modern technology: a doctor can remotely operate a patient in the battle field...
Yes, CCW seeing from the left side. I learned about it reading XJBikes' FAQs.
I removed only the camshaft cover. The only apertures I see for the exam you suggest are the front and rear wells where the cam chain emerges and plunges. I used a flashlight, and all I could see where the tensioners. Please ellaborate a little more about what exam I am to do (using a small mirror - how small?). The way I see it, even a dentist mirror would be too big for that...
Also, I refrained to add a second photo yesterday for fear of looking ridiculous or plain ignorant, but you need the whole picture, I guess. Check the exhaust to cylinder #1: the pipe is compressed, and I guess it's 'light' is reduced to 50%. I know the exhaust port is at the cylinder level (not directly connected to the valves - or is it?), but maybe it could compound the clankinitis (by restricting the outflow of the burnt gasses).

 

Can we get a pic of the whole top of the head showing both sprockets, please;

Plus I want you to turn the valve cover over and have a look in the center gallery. Is there a chain guide of any sort in there? If so, please get a pic of it. If not, please get a pic of the central gallery itself if there is any evidence of the chain contacting the inside of the cover.

I have a couple of ideas but I don't want to send you in the wrong direction;

I already see some things that tell us something you may not have noticed;

and yes, the exhaust valves are in the cylinder head (the part of the motor above the cylinders themselves) and are JUST "upstream" from the exhaust pipes. We do need to discuss the exhaust situation, but let's knock a couple of other items off the list first, since the patient is opened up already.

 

There you go, doctor! If any picture is not what you expected, please let me know. I am keeping the patient sedated (and well tied down). :roll:

 

EXCELLENT. Progress is being made here, as I learn the differences between your motor and mine from 6000 miles away.

I need another picture, please. If you're running out of "upload capacity" you can delete the left-side (timing cover) pic from your earlier post.

I'm saving all of your pertinent pics so we can refer back if necessary, and will be as a matter of fact. Stay tuned.

What I need is this shot, from the left of your bike, but maybe a little closer in. Not so close that we can't see both sprockets and the camshafts in their entirety.





One more bit of info that would help immensely: Please post the "shorty VIN" (vehicle identification number, or serial number) of your bike. It should be cast onto the engine casing in the vicinity of the top right rear, above the clutch housing. For example mine on the 550s are 4U8-xxxxx (the "x"s are numeric.) I really only need those first three digits, the model code.

 

I think my age is showing... My cell camera has autofocus, and it is hard for me to get a clear picture. Hope this will be enough...
Patient's social security number is 4BP003732 (from 1992 according to XJBikes' FAQs on serial numbers... although the title says it is "1993". Scum lying bostards!!! )

 

The picture is fine, exactly what I needed. Model code also a valuable item.

I will have a bunch of observations, questions and more things for you to check in a few hours. I need to "scribble" all over your photos first.

Thanks.

 

"thanks"? Thank YOU, man!

 

Hey no sweat; and by the way, guess what? The USA-market '93 Seca II/600 has "4BP" part numbers scattered all through it. Like the GAS TANK!

The signifigance of that was just discussed here: http://xjbikes.com/Forums/viewtopic/t=28984.html

We're barking up the same tree, or at least two trees right next to each other.

Stay tuned.

 

OK, sorry for the delay. Lets' get started.

This diagram is from the Seca II parts fiche and from what I can tell is nearly identical to your bike. Close enough for our purposes; we will be referring back to "the diagram" throughout hence all the color-coded annotations.




FIRST THING I WANT YOU TO CHECK:

I want to ensure the bolt (#10) holding the lower end of the rear chain guide (#9) is tight. That bolt is indicated by the red arrow:



DO NOT loosen it or try to crank it super tight, just put a wrench on it and give a tug, let's make sure it's not floppy loose.


NEXT THING TO CHECK: We need to ensure that the screw (#7) holding the upper chain guide (#6) into the valve cover, is tight.



Once again, no need to honk on it or anything, just let's be sure it's not loose.


NOW LET'S GET SERIOUS:

I need you to turn the motor over slowly and observe some things.

As you turn the motor over, slowly, "forward" (CCW viewed from left side) I want you to watch the cam lobes (green arrows in photo and diagram) as they push down on each valve bucket (yellow arrows in photo



Each cam lobe should smoothly push its bucket down into the head, and as the cam moves off the bucket, the bucket should come right back up behind the cam lobe, leaving only a tiny (NOT "AIR") gap to the back of the cam lobe. That gap is what we measure when we check valve clearances.

I do want you to check the valve clearances before we put the cover back on the head; the procedure is part of the valve adjustment process covered here: http://xjbikes.com/Forums/viewtopic/t=14827.html But let's get the other checks out of the way first.

MORE OBSERVING: As you're turning, the motor over, use your flashlight and mirror, and check that the camchain is riding ON, not next to, the rear chain guide (#9 in the diagram.) You'll only be able to see the free end (orange arrow) but you should be able to sight down the chain and be sure it's tracking straight. If possible, see if you can see the adjuster plunger (bright green arrow, part of #12) pushing against the guide way down in there. I don't know if you'll be able to see it on your bike.

OBSERVE the front guide (#8 in diagram, blue arrow in pic) as well. Sight down the chain once again, ensure it's riding the guide.

Based on this photo; the front guide appears to be good; the upper mount just sits in there and is trapped in the case by the valve cover so some "bouncing around" is acceptable:



This looks fine. It also appears as though the camchain HAS been replaced as well, it looks brand new.


Fit a wrench to the bolts (#4) holding the sprockets (#3) to the cams (#1 and #2) as they go by and ensure that none are loose. Once again, no honking just be sure nothing's loose.

Turn the motor over a few times, closely watching the cams actuate the valves and the chain sliding along its guides.

If the guides are both in place (allowing for the front one to flop a tad since the cover that holds it tight is off) and the chain rides the guides fine and is nice and tight the whole time then I think we've eliminated the actual camchain as the culprit and need to explore further.

If the chain exhibits any looseness, the we may need to pull item #12 (the adjuster body itself) off the back of the motor and inspect it. But since there's a gasket there we don't want to have to replace and the cylinder block is either new or has just been reworked, let's assume for now that it's OK (unless the chain is loose.)

Check the valve clearances; if between this post and after reading the "how to" I posted the link to, if you have any questions, ask away. Let me know what the results of the valve clearance check are; I believe the specs will be the same as for the other XJs.

Post up the results of all the checking, observing and the valve clearance check.

Once we're happy with the "top end" we'll button it up and then discuss that exhaust system.

If you have ANY questions, refer back to the diagram and ask away.

 

BigFitz, I did what you told me and, but for an anomaly in the clearances, the culprit seems elusive. I mean, all bolts are tight, the chain is riding "on" the front and back tensors, the sprockets are tightly bolted in place and sprocketing as expreckted! :roll:

Here is how the gap clearances came out:

front of bike
0.15 0.15 0.15 0.15 (right side of bike)

0.10 0.10 0.05 0.05

Other than this incongruence (0.10 x 0.05 gaps in the rear camshaft) nothing came up (I never thought I would be cheering to "find a problem" - though it would be easier if the solution were someplace easy to fix...)

Please tell me what my next step should be, and thank you a ton for your help!
Aharon

 

The next step needs to be figuring out your valve clearances.

You got your "chart" right; the cylinders are numbered 1-4 from left to right as you sit on the bike. The valves in the front are the exhaust valves; the ones to the rear are the intake valves.

Are those metric measurements for the clearances (I hope?) If so, they're ALL a bit tight; the two really tight intake valves could be contributing to the noise but I doubt it. However, at the very least, intakes #3 and #4 should really be dealt with before you run the motor too much more; and ALL of the others should get loosened by one size shim SOON.

Here's why, and it's based on an assumption. Specs for the earlier XJ series, from the 400 through the 900 are for intake clearances to be between .11 and .15mm; and exhaust clearances to be .16-.20mm.

The assumption is that your bike calls for the same clearances; I strongly suspect it does. If that is in fact true, then all the valves are slightly tight but intake 3 and intake 4 are critical.

The second thing you need to do is figure out where you're going to be able to find valve shims; are they something you'll need to mail-order from the USA (in which case PM chacal) or can you get them locally?

You don't NEED "the tool" to remove shims, you can use a long piece of #12 insulated wire (house wire) bent to a short "J" on one end, and slipped into the spark plug hole, to slip under the edge of the valve to hold it open and allow extraction of the shim. Others use "zip" ties (nylon wire ties) for this but the house wire is safer (no chance of breaking off/falling into the cylinder.) You will need hemostats or some sort of forceps to extract shims non-magnetically.

Then you follow the procedures in my how-to for valve adjustment.

FOR NOW, until we get the noise figured out, I would say just get the two tight (.05) intake vaves in spec and worry about the other 6 after we get the motor running right. They're JUST tight, so it won't throw off diagnostic efforts.

The first thing you need to do (I said "second" above) is find a Yamaha dealer somewhere in your part of the world who might be able to confirm what the valve clearances for that motor are supposed to be. Remember though, that loose is better than tight; and even if the "spec range" is a tad different than the earlier XJ series, I still suspect those are tight. We might be lucky and they might be on the tight side of within their spec.

What does your Seca II/Diversion book give for valve clearances on those motors? (It should be in the "maintenence" section.)

 

BigFitz, I found this information at www.classicmechanics.com . Mine is 1992 so, do you think this could apply to my valve clearance settings needs?
" WHICH MANUAL?
I have recently purchased an XJ400 import. It was a real bargain and it runs pretty well. There are a few things that I'd like to sort out, but I'm struggling to find any information on the bike. It has been suggested that the XJ550 is very similar – would a manual for this model cover my bike?
Carol Parkinson, Littlehampton, West Sussex.
The early XJ400 produced between 1981 and 1985 was indeed a smaller version of the UK spec XJ550, and much of the service information such as valve clearance settings would be the same. However if your bike is a late model XJ400 it is in fact a member of the Diversion family, and bears a stronger resemblance to the XJ600, a radically different bike to the old 550. Try contacting D&K spares with your frame and engine numbers, they should be able to ensure you get the right manual"
I am in a hurry to go to work, so I cannot search for the XJ550 right now. Your input will tell me if it's worth the trouble. Bye, and thanks!

 

The only thing in here that I can see that applies is the sentence "However if your bike is a late model XJ400 it is in fact a member of the Diversion family, and bears a stronger resemblance to the XJ600..." This serves to strengthen the assumption I've been going on, a "family resemblance" with the Seca II.

You have an XJ600 Seca II/Diversion manual, correct?

What does it list for valve clearances?

 

BigFitz,
After revising our finds with my best friend (my son Ariel), I think the numbers below are truer than those in my previous post:

front of bike
0.15 0.15 0.15 0.15 (right side of bike)

0.12 0.10 0.05 0.05

The first intake valve to the left/ rear was something between 0.10 and 0.15 (all metric, yes!)
Speaking of which, do you know the joke about the US and the metric system? People (outside the US) say that you guys keep using these odd values (inch, ounce, pound, foot, mile) because you have the most atom bombs in the world, and could not care less for "our" complaining about it! In my mind, it makes a lot of sense to take a nice round number like 100 and derive everything from it. But then again, Israel is tiny and we supposedly do not have any atomics!!!
The clearances according to the XJ600 manual are:
admission (intake?) - 0.11 to 0.15
escape (exhaust?) - 0.21 to 0.25
I am far off, aren't I?
I am (hopefully) attaching a drawing from the manual page on the cams (“soupapes”, hahaha!). Notice how they are at a slight angle. When I measured the gaps, I put the excentric at 90 degrees (perpendicular) in relation to the shim face. Is it wrong?

 

The "eccentric" (the cam lobe, it's "pointiest part") should be sticking straight up in regard to the face of the shim, not like the ones in the diagram you posted above. If what you're saying is that they WERE "straight up" (in relation to the face of the shim) when measured, so that you were measuring the clearance off the "heel" of the cam, then yes, you did it correctly.

If the clearances in the book you have apply to your bike as well (and I suspect they do) then yes, they're ALL tight with the exception of the #1 intake (.12 is in spec.)

And yes, admission would=intake, to the rear of the motor (toward the carbs) and escape=exhaust, toward the front (exhaust pipes.)

So the next step is to remove each shim, one at a time, turn it over and "read" it (the size is marked on the back) OR measure the thickness, record all your findings, and then figure out what size shims are going to be required to bring the motor into spec.

With everything so over-tight, it's very possible that this is a large contributor to the initial problem. Or not, unfortunately; however we need to address this first or risk damaging the engine.

Let me know if you have any questions, or need a better explanation of the shim-removal process without the use of "the tool."

 

The XJ600 service manual shows "the tool" in use (picture). What does it really do? Does it pull the shim out as you press the lever down?
This is what it "seems logic" to me - and that where I fail to understand how a #12 insulated electric wire will do the same trick!
You said I should use it "to keep the valve open". "Open" means "pressed", as when the lobe sweeps the shim, right?
But then again, if the darn thing is (supposedly) pressed to be kept open, how in heaven am I going to get the fershlugginer shim out?
When I see the logic, I will know how to do it (or have the "doctor" make a "house call").
Please enlighten me.

 

Aharon: Do you have a manual in English? Also, I found an XJ400s owners manual on the internet but, as it is a Japanese model, the manual is in Japanese to!!!

This should explain how to use the tool.

 

OH wow. Completely different "tool" than the earlier bikes, more like Japanese cars.

Sorry.

THAT tool (and apparently the correct one for your series bike) needs to be positioned so that it just catches the EDGE of the bucket and pushes it down (by virtue of wedging itself between the cam and bucket) enough for you to steal the shim out from "next" to it.

Dexterity.

The "bent piece of wire" trick involves slipping the tip of the "J" I referred to between the edge of the valve itself and the valve seat, preventing the valve from closing as the cam moves away and thus removing the spring pressure from under the bucket, allowing the shim to be plucked out.

THANK YOU MARKIE!!! Stay with us on this, will ya? (You owe me one, remember?)

 

Thank you Markie for stepping to the plate. Poor BigFitz must be going bonkers with my utter ignorance. All I can offer in return is to commit to do my best to bring this Seca back to life - my first-trip-saylor victory will be yours - 80% yours.
I have questions, and I am attaching a couple images to illustrate them.
1- I know "Bucket" is synonimous to "pail". Is it visible in any of the images?
Same with "Valve lifter".

One last remark on the manual page on valves (todaraba, Markie! ): They say to extricate the sim "with a magnet(!)". BigFitz explain why we should use a demagnetized plyer: to avoid have the sucker sucking scrap iron and whatnot, ruining the valve seat and surroundings. I guess my new buddy BF knows better than Yamaha!

 

Aharon - Item 10. bucket and valve lifter are the same thing.
Item 9. Shim (Yamaha call them a pad)
Item 8. Stem oil seal.

Now you have a manual it should be clear. The tool is used to press down onto the top of the valve lifter BUT NOT THE SHIM. You are pressing against the valve spring. This should give enough room to extract the shim. The picture you posted shows a slot (With the dotted circle around it) in the valve lifter which you can carefully insert a small screwdriver to prise the shim upwards and away from the valve lifter.

I have sent you a pm so that you can find a parts catalogue (Sorry, it is for the 600 only) with all the parts descriptions in.