what would you do?? *pics added*

[I-K]

Pulled it apart because it's gotten a bit clattery, vibey and juddery at low revs since coming back from the Island.

Only things wrong with it that I could find were two missing intake port vacuum-bleed blanking screws... and a camchain tensioner which didn't... spring back from the head on its own with the retaining bolts undone-indicating the spring hasn't advanced it enough.

sounds like what happened to my cam chain tensioner. had it and the chain replaced at about 74K and its been fine ever since.

The tensioner had come out with only about a qurter of its travel used up. I think I'll first give it a go just with the tensioner advanced a bit further. If that fixes it, I'll splurge on a new tensioner.

Which reminds me... when I take cams out of an engine, I dab whiteout markings on the camchain to ensure I keep the correct number of links between the intake and exhaust camwheels and between the exhaust camwheel and the gear on the end of the crank.

In principle, you could use the same method when changing camchains to get the cam timing correct; dab markings on the camchain before removing it, count links between the markings, and replicate the markings on the new chain before installation.

Why, however, do you never hear anything about equivalent methods either when speaking to mechs or when reading mech books; how do the pros do it?

[I-K]

yep--- telling the bloody wrecker to stuff his '99 engine where the sun don't shine.....

You could; I reckon it would be more brutal to tell him to stick it where the ignition coils don't fit.

the next motor i found is $2500 (locally) for an '00....

Yowzah! For that sort of money, that better be to buy the motor outright, not to exchange it. $1500 should be just about top dollar for an exchange motor for a five-year-old 600.

Gunna give the engineering ppl a go at "fixing" the busted case!!!! come on MONDAY!!!!

I'd be really curious to hear their thoughts on why that little rib failed, actually.

Have we heard what actually locates the input shaft laterally?

[Gosling1]

Why, however, do you never hear anything about equivalent methods either when speaking to mechs or when reading mech books; how do the pros do it?

Usually there are markings on both inlet and exhaust cams, which indicate where the cams should be located when installed correctly. Most cam chains I have serviced require a 'count' of either links and/or pins, from 1 marking point on the exhaust cam, to another point on the inlet cam, which ensures that the inlet cam is correctly positioned in regard to the exhaust cam. This info is *generally* found in workshop manuals. If not, use the white-out method as described by I-K.

If you don't have any markings, the only real fail-safe way to install a new cam-chain is to split the old cam-chain in the middle of the top run, attach one end of the new chain to one end of the old, and s-l-o-w-l-y rotate the crank, keeping tension on the chain from both ends, and pull the new cam chain through. Then join the camchain together normally, and the job's done. You need to be patient and careful . ( Take the plugs out... )

Input shaft of any gearbox is located with the use of either locating dowels or large C-clips. Sometimes they also have shims ( of varying thickness) to control end-float of the shaft, and output shafts can also use shims ( basically you get a choice of 3 or 4 shims/(washers), you use 1, depending upon the amount of end-float measured.......)

I am pretty amazed at the location of the C-ring in Yankee's motor, that is stuff-all crankcase material to hold in a C-ring

cheers

[Maty10]

OT I know, but are cam chains usually sold endless or with a joining link?

[Strika]

OT I know, but are cam chains usually sold endless or with a joining link?

I have only ever seen replacement ones with joining links. they are a peen link. Not to say they don't come endless! You coming for a cruise up Reefton and the Black spurs tommorrow Maty?????

[I-K]

Why, however, do you never hear anything about equivalent methods either when speaking to mechs or when reading mech books; how do the pros do it?

Usually there are markings on both inlet and exhaust cams, which indicate where the cams should be located when installed correctly. Most cam chains I have serviced require a 'count' of either links and/or pins, from 1 marking point on the exhaust cam, to another point on the inlet cam, which ensures that the inlet cam is correctly positioned in regard to the exhaust cam.

Nod-nod. However, that's not what I'm iffy about. The main reason I use the whiteout dabs on the camchain is so as not to put the cams back in having hooked them back onto the camchain a link or two too close to or too far from the *crank*.

Ya dig now?

It's not just the phasing of the crank and cams which comes into it; it's also the number of links between the crank and the cams on the drive (and, hence, the return, as well) runs of the camchain.

Hook the exhaust cam onto the camchain so there are fewer links in the camchain run between the camshaft and the crank than before and, if you hook the inlet cam on in the correct position relative to the exhaust cam, the return run on the camchain will be too long, causing it to flap around uncontrollably when the engine is run, and the shortened run of the chain on the drive side will put undue pressure on that side's chain guide.

The tricky part is that you won't notice this when you do the post-reassembly hand-crank of the engine with the cam cover off. The engine's no harder to hand-crank than it should be and the cam markings and crank position markings line up. The first clue you get that something is wrong is when you fire up the engine and it starts sounding like World War III due to the extra links on the return run on the camchain taking it beyond the CCT's ability to take up the slack, which allows the chain to slap around like a bastard.

It's what happened to me after I had a poke around in the top end of my ZXR250 back in early 2002. Scared the piss out of me.

On the flipside, this won't be the case if you reinstall the exhaust cam so there's a longer chain run between it and the crank; when you first turn the crank by hand, you take up the slack in the chain, so the cams don't move together with the crank, and you know you've done something wrong.

Either way, though, I can't see how the cams can go back in in anything other than the *exact* same position relative to the camchain as they came out. Consequently, I can't see how any work involving the removal of cams can proceed without the use of something to mark the camchain so you *know* where to put the cams back in, yet I seem to be the only person I know of who does this.

I am pretty amazed at the location of the C-ring in Yankee's motor, that is stuff-all crankcase material to hold in a C-ring

To me, that says that that retaining ring/clip/thing is not supposed to come under any lateral loading and that the input shaft is laterally located somewhere else.

[Yankee]

Quote:
I am pretty amazed at the location of the C-ring in Yankee's motor, that is stuff-all crankcase material to hold in a C-ring


To me, that says that that retaining ring/clip/thing is not supposed to come under any lateral loading and that the input shaft is laterally located somewhere else.

you gotta be right, otherwise they were designing a bomb.... would it be the "dowel" system on the other end? my mechanic and I were also thinking that if a machinist couldn't make it like "new", possibly it could be fitted with another dowel/hole on the clutch side as well (on the thick spacer) to hold it all together......
wait, nope....
the lateral force must be located on that stupid sliver of case (partially) because everything wants to slide away from the actual dowel (pin and hole)......
MAN, I have no clue!
thank you for the advice on the costings for an exchange motor versus straight out I-K, I also had no clue about that. and also thank you for the pics of the G-J not fitting coil plugs... that thing looked nothing like my motor!! I'll use those pics to show some dim-wits that it ain't gunna work!!

as the sands through the hour glass flow, so to.......

[Gosling1]

Either way, though, I can't see how the cams can go back in in anything other than the *exact* same position relative to the camchain as they came out. Consequently, I can't see how any work involving the removal of cams can proceed without the use of something to mark the camchain so you *know* where to put the cams back in, yet I seem to be the only person I know of who does this.

Now I understand what I forgot to mention was that you should always ensure that your crank is at TDC ( Top Dead Centre) on *generally* cylinders 1 & 4, before removing the cams. The when you replace the cams ( either using the factory mark, or a dab of white-out) to locate the exhaust cam correctly, you will ensure that the exhaust cam is positioned correctly.......you do need to ensure that there is no 'slack' in the cam-chain run from the exhaust cam to the crank, make sure all the slack is in the rear run, so the CCT does its job correctly......and we all lived happily ever after

Yankee - I am pretty sure that the input shaft is located laterally by that 'sliver' of crankcase area which looks way too small imho, but there you go. Good luck mate, I hope you can get it sorted without too much costy

cheers
Dave

[HemiDuty]

But when making sure that no. 1 is at TDC you have to make sure it is on the firing/compression stroke right, not the exhaust stroke?

[Jonno]

Marty, I reckon that piece broke off when your final drive chain was too tight, the rest just gave way in time with a clutch up wheelie or 3 and then some general riding when it happened just to confuse you about when it may have really started Sorry, it is the only thing to explain it and makes sense really as it is a one off type thing IMO.

I just hope you get it fixed soon mate, missing ya on rides

[Gosling1]

But when making sure that no. 1 is at TDC you have to make sure it is on the firing/compression stroke right, not the exhaust stroke?

Yes, dead right. *Most* 4-stroke motors should have some type of marking on the backing plate and/or ignition advance unit that show TDC 1-4, and a Full advance position. Make sure you set it to TDC, not full advance ( otherwise it could get confusing when re-installing the cams).

If you are doing this for the first time, take some photos of everything in the stock position - it will help later on ( another one of Life's Hard lessons......)

cheers
Dave

[I-K]

But when making sure that no. 1 is at TDC you have to make sure it is on the firing/compression stroke right, not the exhaust stroke?

Not really necessary... sparkplugs either fire near TDC on both the compression and exhaust stroke, or they take their cue from the camshaft.

[Gosling1]

But when making sure that no. 1 is at TDC you have to make sure it is on the firing/compression stroke right, not the exhaust stroke?

Not really necessary... sparkplugs either fire near TDC on both the compression and exhaust stroke, or they take their cue from the camshaft.

Hang on a minute.......... If you do not set it at TDC on the compression stroke, your cam lobes will be 180deg out !!! mate if you set up your cams incorrectly you will end up with valves bashing into pistons

Yes, you may have a 'wasted' spark ignition system, that also sparks on the exhaust stroke, this means jack as far as correct cam timing is concerned.

Use the stock timing marks, refer to your Factory manual, and when in doubt, take it to the Shop.........

cheers
Dave

[I-K]

But when making sure that no. 1 is at TDC you have to make sure it is on the firing/compression stroke right, not the exhaust stroke?

Not really necessary... sparkplugs either fire near TDC on both the compression and exhaust stroke, or they take their cue from the camshaft.

WRONG !! If you do not set it at TDC on the compression stroke, your cam lobes will be 180deg out !!!

But does having the cams (not, I repeat, not the crank) out by a full 180 degrees make any *theoretical* difference? As far as the cams are concerned, the crank "looks" the same every 180 degrees of *their* rotation, doesn't it?.

With #1 and #4 at TDC, the engine could either be at #1 compression, #4 exhaust, or the other way around, and the cams will be in phase with the crank whether they go in with either the #1 or #4 lobes pointing outwards, no? In principle?

Having the *crank* out by 180 degrees (cyls #2 and #3 at TDC), is a different matter, of course... did that one time when I confused the factory white daubs on camwheels with the ones I put on prior to taking the cams out.

[Gosling1]

But does having the cams (not, I repeat, not the crank) out by a full 180 degrees make any *theoretical* difference? As far as the cams are concerned, the crank "looks" the same every 180 degrees of *their* rotation, doesn't it?

With #1 and #4 at TDC, the engine could either be at #1 compression, #4 exhaust, or the other way around, and the cams will be in phase with the crank whether they go in with either the #1 or #4 lobes pointing outwards, no? In principle?

Having the *crank* out by 180 degrees (cyls #2 and #3 at TDC), is a different matter, of course... did that one time when I confused the factory white daubs on camwheels with the ones I put on prior to taking the cams out.

Remember, the cams spin at half engine speed. The crank might "look" the same every 180deg, but the ignition timing is only set for 1 point in the cycle on the "power" stroke, not for 2 points on the cycle ( ie not for the "exhaust" stroke as well.) - even though it might have a wasted spark on the exhaust stroke ( and many do). Whats crucial here is the firing order of the motor, if you set up the cams incorrectly, then the sequence of valve opening/closing and ignition timing will be incorrect.

This is why you have to turn the crank through 2 full rotations ( ie 720deg) in order to re-check your cam timing, to make sure it is correct. You cannot check it with 1 full rotation only.

If you want to try installing cams 180deg out of phase, let me know, I want to come around and watch you start the engine Trust me, I have installed *heaps* of cams, you don't want them installed 180deg out....

cheers
Dave