132 replies to this topic

[ChrisG]

Thanks to Facebook keep changing the way they host photos the bloody links keep breaking, photos should work on this link if they don't show up in the post below
https://www.facebook...=3&l=4d458f092a
 
 
 
Someone (Studley?) asked me to post up some notes on doing valve clearances when I got round to checking them. This is on a Mk1 but once the tanks off I’d expect most of it to be the same for a Mk2. Where I say left/right or front/back I mean from the point of view of you sat on the bike. I started with the bike on a paddock stand, as I find it easier if it’s vertical rather than leaning on the sidestand.

First off, get the faring off (you could probably leave the nose cone on but removing it gives more space at the sides to get the radiator off), then fuel tank. For the tank close the tap, remove the 2 bolts from the tap, then take off the bottom pipe off the tap, be aware this will dribble some fuel out so have a rag handy.

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One bolt at the back of the tank, and a bolt in to the frame on either side, and the tank will lift up enough to allow you disconnect the breather on the back left, and feed the fuel tap up clear of the frame, before lifting the tank off.
Airbox off next, with a screw at the front, 2 clamps on the rubbers, and the crank case breather seen here between the rubbers. As you lift it up you’ll find another breather on the left hand side

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With the bash plate off (2 bolts underneath and the long pin) you can undo the coolant drain bolt, you’ll need to take the radiator cap off before anything comes out though.

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Next it’s the radiator. I find it easiest to disconnect the right hand pipe at the bottom where it attaches to the water pump, and to take the left hand pipe off the radiator. Disconnect the power from the fan (black connector somewhere under where the airbox was) and don’t forget the overflow pipe just below the radiator cap. With a bit of newspaper to protect the front mudguard I find I can undo the 4 bolts that hold the radiator frame to the bike and just about wiggle it free, less hassle than taking the radiator off the frame

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There are 3 electrical connections on the top of the thermostat; a 2 pin connector, a push fit for the sender, and screw and spade that I guess is probably an earth. With them all disconnected remove the hose from the pipe that sticks out of the valve cover, then there’s just 1 bolt holding the thermostat to the frame.

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The silvery bit sticking up is the sender, I seem to remember a Mk2a owner enquiring about that.

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After removing the spark plug leads it’s just 4 bolts (6 on a Mk2 I believe) and the breather pipe (it’s not attached the other end but disconnecting it makes getting the cover off easier) and the rocker cover can be lifted off, leaving the coolant pipe in place.

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The rocker cover seal can be reused a few times, but as it’s rubberish I guess it will degrade with time, so probably worth replacing if it’s not been done before. I put this one on a couple of years ago and it’s been off a couple of times since and still looks ok. Same applies to the airbox rubbers, mine are only a couple of years old, the original ones had gone very hard and it was a nightmare getting the airbox back on.

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There are 2 covers on the generator casing on the left of the engine. Removing them will reveal a big nut and the edge of the rotor disk.

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Using a socket to turn it anti clockwise you’ll find an “H” mark, then an “I” mark on the rotor. Doesn’t matter exactly for checking the clearances, but you should turn it to the I mark with the cam lobes facing away from other other on the left hand cylinder. The engine is now in the correct position to measure the clearances. Gently shove the feeler gauge between the cam lobe and the bucket, and keep changing the thickness of the gauge to work out the clearance. Measure from between the cams, ie poke it backwards like this for the inlet, and do the exhaust by poking it forward from behind the cam. Once you've done the left cylinder turn the engine 360 degrees to get the lobes on the other cylinder facing away from each other and repeat the process on that side

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I now ruin the whole left/right side thing by marking it up as I look at it to record the clearances.
In my case (ie in the first instance, a 0.18 will fit in, but a 0.19 won't)
CODE
In 0.18-0.19 | 0.17-0.18 | 0.17-0.18 | 0.18-0.19 | 0.17-0.18 | 0.19-0.20

Ex      0.29-0.30  |    0.27-0.28    |    0.31-0.32    |    0.30-0.31


As the inlet valves (6 of them so no danger of mixing up inlet and exhaust) are supposed to be 0.15-0.2 and the exhaust 0.25-0.3 this shows that 2 of my exhaust valves are slightly out.

This took me about an hour and half including stopping to take the photos, but changing the shims will take a little longer as I'll need to remove the cam chain tensioner before taking the cam shaft off.

If you do ever change the shims make sure you record what you've put in there. I already know I've got a 160 and a 155 in the two that are out, so swapping the 155 for the 160 and putting in a new 165 will take those two valves to 0.26-0.27 and 0.25-0.26.



Question for the experts, is it worth changing the 0.30-0.31 exhaust valve or should I leave it as is and just change the 0.31-0.32?


Part 2, changing a shim, added further down.

Edited by ChrisG, 28 August 2014 - 06:31 pm.

[TDMick]

Thanx Chris.
is it worth dropping the forks out to make more room, as I have a centre stand an could arrange for a tie down at the back?
Mick

[ChrisG]

Not really, there's plenty of room for getting at the valve cover with them in place, only thing that it would make easier is getting the radiator out, though just removing the wheel and mudguard would be as far as you need to go, and even that is more effort than seperating the radiator from the cage.

Forgot to add shims are 9.48mm, same as the WR450. There's a bloke on e-bay sells them for about £2.60 each delivered.

[ChrisG]

Dapleb has a small collection of shims but reckons due to too many 900 riders most are now quite large sizes. When I did it before I visited my local Yamaha main dealer and the bloke in thier maintenance department sold me a few for next to nothing, the ones he didn't have I got from a bloke on e-bay that sells them quite cheaply as the only other local place I could find them wanted £4.50 each to exhange them. There's a link to his e-bay shop in my "winter maintenance" blog on here.

[dapleb]

The tank/airbox off soley for thermostat removal? I extended the thermo wiring so it can be removed from below.

Lettuce snow what shim sizes you need Shoto and oil ave a look. As Chris says the 900 bhoyos have pilaged my small shim sizes but might be able to help. Even if its only one or two it'll save ya a few squiddles.

[ChrisG]

Yeay, I remembered you saying about extending the wiring as I was dismantling it. Makes sense but then again I'd still need the faring off and it's not that long a job to get the tank and airbox off. Also planning to wrap the HT leads while I'm in there so that whould be a little easier without the airbox too.

[Studley Ramrod]

Nice one Chris ! I can't remember asking you that question although I've asked you just about every other

Was it the Exhaust valves that had virtually closed up, only if it was I'd be tempted to leave the 2 borderline gaps if it was, but I'm def no expert

I can also see the importance of logging the shim sizes. I can only assume mine are the standard size and I'd have to physically check them before ordering new shims. Handy info matey !

I have actually checked mine but I didn't record the gaps as I'm not doing the work just yet. And i can vouch for yer comments about removing the forks as not really necessary.

The biggest benefit would be a one-piece fairing !! ....dream on eh !

Edited by Studley Ramrod, 27 May 2009 - 12:08 pm.

[TonyDevil]

moved to KB

[ChrisG]

On to part 2, changing a shim.

There’s a table in the Haynes, to work out what sizes you want to change, but it’s pretty simple. I had a valve with a measured gap of 0.31-0.32, its supposed to be between 0.25 and 0.30. The shim I had in there was a 160 (ie 1.60mm thick), they come in increments of 0.05mm for replacements, though the original ones will be in smaller increments. To close that gap slightly I need a thicker shim, so 165 will take the gap down to 0.26-0.27.

Note that you will need a torque wrench to reassemble this. The head is quite soft and if you over torque any bolts you could cause some expensive damage.

First thing to note is the timing marks. With the rotor on the “I” mark and the cam lobes on the left cylinder facing away from each other (cams rotate at half the speed of the engine, this is for a Mk1, the relevant position on a Mk2 might be different), take a look at the timing marks on the cam sprockets. There should be an “I” on the inlet (rear) and an “E” on the exhaust. Below the letter will be a line, these lines should line up with each other and the edge of the head. I didn’t manage to get a particularly good photo though.



The cam chain tensioner (arrowed) is hidden behind an engine mounting bracket on the Mk1. It’s easiest to take bracket off before trying to remove the tensioner.



Remove the central bolt from the tensioner to get the springs out (it’s one spring inside another so make sure you don’t loose the inner one), then the other 2 bolts to remove the tensioner.



You should replace the cam gasket, though if you’re a bodger you might consider using some form of instant gasket goo. The copper washer on the central bolt should be either replaced or annealed. I always tend to anneal and reuse copper washers (they’re also used on banjo bolts for the brakes and oil feeds). Heat the washer up with a blowtorch until it glows cherry red then either leave to cool or dunk it water to cool quickly (cooling speed doesn't matter for copper). This is to soften the copper, if you try and reuse it without annealing it will be to hard and won’t make a good seal.

Remove the metal guard over the top of the cam chain, and the coolant pipe sticking up out of the head. You’ll usually find loads of crud around the coolant pipe so try and give it a wipe without sending bits of crud down in to the engine. The o-ring on the coolant pipe is supposed to be replaced but if it’s in good condition it should be fine. I replaced mine last time I had it open so left it alone this time. A quick pull on the chain between the cam sprockets should free the rear guide that’s currently holding a bit of tension on the chain, and you can then undo the bolts holding the cam shaft brackets in place.



The brackets each have 2 hollow metal locating dowels, they might stay in the bracket, they might stay in the head, keep an eye out for them and don’t drop them in the engine. If you’re taking both cams off hook a bit of wire round the cam chain to stop it falling down the tunnel.

Use a pair of long nosed pliers to lift the bucket off, the old shim will probably be stuck inside the bucket by the oil.



Place the new shim carefully in the little hollow that’s left on top of the valve stem



You can now put the cam shaft back on (remember the lobes on the left cylinder face away from each other) and torque it up correctly (10Nm), though I leave the guard that goes over the chain off until I’ve got the timing set. The front side of the chain will be tight, but the rear will be loose because the tensioner’s not in. Using screwdrivers or allen keys as levers though the holes in the middle of the cam shaft rotate the shafts towards each other to get the timing marks aligned and the front side of the chain is tight. You’ll find you can easily turn the cam the other way a bit and skip the chain on a tooth if it’s not quite right. Once it’s in place put the tensioner back in, then the tensioner spring, and check the timing again. Now hand crank the engine a couple of rotations and check the timing and the valve clearances again to make sure you’ve not made a cock up. Don’t forget to put the chain guard back on and torque the bolts up properly.

Assembly is the revere of the disassembly. Remember to torque things up correctly and if you make sure you put everything you take off in a pot you’ll know you’ve not missed anything when you put it back together.

Valve cover bolts – 10Nm
Cam shaft bracket bolts – 10Nm
Engine mounting bracket to frame – 30Nm
Engine mounting bracket to engine – 60Nm
Cam chain tensioner – can’t get my torque wrench in there so I just got for tight, not bastard tight.

Edited by ChrisG, 04 June 2012 - 04:48 pm.

[aytcat1]

Nice write up Chris,when it came to taking the shims out i used a telescopic magnet which can be got from M&P or some tool shop at open markets.
Found these were really strong and stick my tools together,so used that placed on top of shim bucket and when i pulled on it the shim would be underneath.I didnt want the risk of having the shim drop into the engine.

[Galilee]

Very good writeup. I did my camchain and valves recently, and you forgot the bit about bandaging bloody knuckles. And the bit about stepping back and having a beer before you decide to hit the bike with a very large hammer.

Shims can also be obtained from motorcross clubs or shops, as many 400cc 4-stroke bikes use them. Most motorcross mechanics around here has the hotcams kits. I think several of the larger Yamaha outboards also use them, so a marina might also be a good idea to try.

If you get used ones, measure them. If the cup over it didn't have an exact fit in the previous installation, it can be worn.

Tip: Crank is easier to turn if the plugs are out.
Tip 2: When fiddling around with small bolts and shims, put the plugs back in. In fact, put a rag in each plug hole and the water connection too. These are helpful when oiling up everything before assembly.

Edited by Galilee, 21 June 2009 - 09:12 am.

[emperador]

Perhaps, stupi off topic cuestion:

If I release one of the engine mounting bracket to make it easier to access de carb sync screw, do I have to hold the engine?
Motor vibration could brake the other engine mounting screws? Or it´s no problem?

It´s a pain in the ass reaching mixture and sync screw with out disassembling tank, filter, etc.

[ronoc88]

Lads I need some help.

With the help of this helpful write up I have measured the valve clearences, I found that all the inlet clearences were tight so removed and ground them to sufficent size.

I have replaced them in the cups but am now stumped. What marks do I follow to set the timing? I marked did mark the cams before removing them but im now not confident my marks line up.

Can anybody give me some direction?

Thanks

Conor

[JollyGiant]

Lads I need some help.

With the help of this helpful write up I have measured the valve clearences, I found that all the inlet clearences were tight so removed and ground them to sufficent size.

I hope you have your tongue in cheek here??

[TDMick]

Lads I need some help.

With the help of this helpful write up I have measured the valve clearences, I found that all the inlet clearences were tight so removed and ground them to sufficent size.

I have replaced them in the cups but am now stumped. What marks do I follow to set the timing? I marked did mark the cams before removing them but im now not confident my marks line up.

Can anybody give me some direction?

Thanks

Conor

Conor exactly what did you grind?

The shims are case hardened I'd guess and would need to be case hardened again once ground, to be any use.





I think.

Just noticed jolly still awake

[dapleb]

Eeeks. Set up as you marked when you took apart. Show us a picture of what ya have.

Grinding shims/valves not such a great plan!

[Studley Ramrod]

Lads I need some help.

With the help of this helpful write up I have measured the valve clearences, I found that all the inlet clearences were tight so removed and ground them to sufficent size.

I have replaced them in the cups but am now stumped. What marks do I follow to set the timing? I marked did mark the cams before removing them but im now not confident my marks line up.

Can anybody give me some direction?

Thanks

Conor

I'll give it a go, hehe...

Engine timing set to TDC

Camshafts postitioned with cam lobes at No. 1 cylinder facing away from each other. (No. 1 cyl is the one on the left as you sit on the bike.)

Camshaft Sprocket markings 'I' and 'E' lined up with top of cylinder head.

A Haynes manual has it all in there. It might take a few attempts to get it lined up properly as it's a fiddly job.

[ChrisG]

Make sure you're on the I mark not the H mark on the rotor behind the inspection cover on the left hand side of the engine.

Never managed to get a decent photo if it but the I and E marks on the cam sprockets are just about visable here. As Studley said the cam lobes should be facing away from each other on the left hand cylinder.

Edited by ChrisG, 14 April 2010 - 05:22 pm.

[dapleb]

http://www.carpe-tdm...o...40&hl=valve