Pinned FZR250, ZEAL, FZX250 Valve Clearances howto

OK guys
This is a simple step by step howto for doing the valve clearances.

Tools I assume you have already: Good quality set sockets, with a screwdriver handle for 1/4" drive sockets as this gives more feel than with a ratchet bar. You'll likely also need a 3/8" drive -> 1/4" socket adapter for the 8mm bolts on the cam retainer shells.

Good quality set of allen keys or socket equivalents.

Tools you'll need past what you may already have in your possession:
Decent quality set of feeler gauges - cheap ones I had were approximately 0.02-0.03mm too thick over the 0.1mm range.

Good quality torque wrench which goes down as low as 7.2 ft/lb - You can get them even at Bunnings 3/8" drive Kinchrome ~$80. I consider this compulsory.

Some molybdenum disulphide grease - I've already got some LMM CV joint grease on hand.

I removed the engine, to clean it and the surrounding frame areas.
I'm going to assume you're up to already having removed the rocker cover and the stator cover.

TDC = Top dead centre
BDC - bottom dead centre
Both these terms are usually used in relation to cylinder one - TDC used alone is usually a reference to Cylinder one firing.

Note: the firing sequence is #1 -> #2 -> #4 -> #3
Cylinders are 1-4 left to right , sitting on the bike

First step is to measure the actual clearances.

I marked the stator with a thick black sharpie to make it easy to see the 0 and 180 degree points.



I also marked the inside of the stator with the cylinders which are at top dead centre for each 180 degree rotation on the inside.

You can make out the rotation direction arrow and the TDC - zero marking on the stator and the small zero extrusion on the case.

Set the crank to TDC - I had removed the plugs and did all of the rotation by hand so I would feel any resistance later when I'd re-assembled everything.

Check the two dots on the cam retainers/shells against the two small holes in the ends of the cams. If you don't see the dots then you are at TDC - cylinder #4 firing.
I'll add a close-up photo of this later as I forgot to take it.


Note: I've made two versions of the table to keep notes on the clearances depending on which orientation you're working and if the engine is still in the bike.
Valve-Clearance-Reverse.pdf is for working with the engine facing you i.e working from the exhaust side
Valve-Clearance.pdf is for working from the intake side.


Next check your clearances for cylinder #1, work from the lower clearance up.
Intake valves cylinder #1:
0.1mm straight single feeler gauge ->
0.05mm + 0.08mm ->
0.1mm + 0.05mm ->
0.1mm + 0.08mm ->
0.2mm - upper limit

If you're below minimum, hopefully not, work backwards till you can get a reading.

Exhaust valves cylinder #1:
0.2mm straight single feeler gauge ->
0.15mm + 0.08mm ->
0.15mm + 0.1mm ->
0.2mm + 0.08mm ->
0.2mm + 0.1mm - upper limit

Now the reason I combined smaller feeler gauges where possible is because the those two will bend easier down into the space past the rocker cover gasket edge on the head.

Note the clearance ranges lower limit reading<X<upper limit reading for intake and exhaust on cylinder #1.

Rotate the stator 180 degrees so that Cylinder #2 is firing.

Take measurements and note your readings.

Rotate the stator 180 degrees so that Cylinder #4 is firing. This is TDC - ZERO marking on the stator.

Take measurements and note your readings.

Rotate the Stator a final 180 degrees so that Cylinder #3 is firing.

Take measurements and note your readings.

This is @kiffsta better valve clearance - shim thickness recording sheet
https://www.2fiftycc.com/index.php?resources/valve-clearance-sheet.232/

 

The next step is to simply remove the cams to get access to the buckets and shims above the valves.

Before removing the cam retainer bolts the engine should go back to TDC #1 cylinder firing with the alignment marks on cams and retainer ends visible and aligned

Please note that I haven't removed the cam chain tensioner at this stage - that comes later. The chain tension also keeps the cams down because there is one pair of valves on each cam partially depressed which makes the cam want to rise out of the lower retainers.

Start by loosening the retainer cap bolts a quarter turn at a time - there isn't a loosening sequence that I could locate.

Then go through and give them a half turn each and finally a full turn.

Once loosened fully - I left the bolts in position

Now if you remove the cam chain retainer and bolts separately there will be one vacant bolt hole so there will be no confusion as to which retainer goes where.


There's also small black ticks and crosses, for valve clearances that were in the middle of the range - ticks and for valves that were in the low end of the range - crosses.

Fortunately mine were all within spec, with 4 intake valves though they were between 0.1mm and 0.13mm so they got the largest clearance increase.

The retainers have an arrow pointing towards the right of the engine - as viewed sitting on the bike.
I also marked them with IN and EX and placed them in position on the bench with the cams once removed.

You may have to wiggle them to get them up off of of the dowels - patience and subtlety are key here, if they start to come off crooked tap the high side back down.

Please note also that the each cam has an I marked on the intake cam and and E cast on the exhaust cam, between some lobes so there should be no confusion as to what goes where come time to re-assemble.

 

OK so now to removing the cams
It's time to release/remove the cam chain tensioner on the intake side of the cylinders.

12mm socket, undo and there's two concentric springs so once fully loosened the bolt will want to escape. Mine also has a copper sealing washer.

Once that's done, remove the cam chain tensioner



https://www.2fiftycc.com/index.php?threads/fzr250-cam-chain-tensioner.3336/

 

My gasket tore when I removed it so I made another out of 0.4mm gasket paper. - That's for later.

To ease the tension on the chain rotate the stator backwards a little - then you can remove the exhaust side chain tensioner which goes down into the engine.



Also remove the retainer dowels in the centre of the engine - these pics are at the re-assembly stage - thus the moly grease but you get the idea. Some will come up with the retainers and some will remain in the cylinder head.



The above shot is with the intake cam removed, so I advanced the timing on the stator a small amount to give some free chain travel so I could lift it.

Do the same for the exhaust cam, retard the stator timing slightly to give the cam some freedom to rotate up and out of the lower shells.

I placed a compression tester extension in place below the chain to keep it from falling into the crank cavity.

Pic of chain prevented from falling down into the engine.

 

OK next step is to remove each bucket and shim to record the thickness of the shim. I did these one at a time, i.e removed one, then replaced it before proceeding to the next one. Each bucket should go back to it's original position as it will have mated with bore in the cylinder head, so just pulling them all at once isn't sensible unless you have the space to lay them all out carefully in order for re-assembly.

I used a magnetic pickup tool to do it and the shims came out attached to the underside of the buckets.



At this stage you may need some vernier calipers of a 0-25mm micrometer. If the shim thickness etching was placed face down onto the top of the valve it may be worn and illegible. I had two that were illegible or at least difficult to be certain of till I had used the micrometer on them.

Now when it comes time to calculate the required clearance changes just use the worksheet in a vertical flowing downwards direction.
Presumably you're going to need to keep the same clearance or increase it.
Any increase in clearance is going to require a thinner shim. So for the four intake valves which were at the bottom end of range:
0.1mm < clearance < 0.13mm I deducted 0.07mm from the shim value. E.G 182 became 175 yielding the 0.07mm clearance increase I required.

www.precisionshims.com.au is the place to get them - I ordered one day and had them the next morning with the postal delivery.

Their thicknesses ranges go 00 - 02 - 04 - 05 - 06 - 08 - 00
You want 7.5mm diameter ones - the smallest ones they offer.

You can use the next closest i.e up or down 0.01mm -> 0.02mm as it's the thickness of a piece of cigarette paper

For all of my exhaust cams I increased by between 0.02mm > 0.04mm to put them into the upper range and the intakes by between 0.04mm . 0.07mm.

I noted on the worksheet, which ones I had from thinnest to thickest, and which ones I needed then simple process of elimination to see what I needed to order.

When it came time to change the shims, do them one at a time and start with one that is going to be re-used elsewhere and replaced with a new one.
That way you only ever have two buckets and shims out at any one time.
Be methodical, that's all it needs and check your notes.

When I'd replaced each shim I put the smear of moly grease over the valve top, placed the shim, replaced the bucket and put the smear of moly grease on top.

 

EDIT
I'll make specific mention of the fact that the cam retainers are both marked I for intake and E for exhaust as are the cams.
They are also marked with numbers (right besides the I or E letter).

It is very faint and easy to miss unless you get the light across it just right to be able to see/read it.

One the cam retainer caps I have here, the light stamping is located right beside the left hand rubber oil gallery plug.

The arrows point from left to right and the numbers 1 an 2 are from left to right as you would be seated upon the bike.

They need to go back into the same locations, if you get them in incorrect position, they may tighten down, however it's likely that the came will bind an not turn (that will be your first clue) - worst scenario is that the cam retainer cap cracks/breaks as you're tightening it down.

Once they're all done, for re-assembly it's the reverse.

I placed a smear of moly grease on both tips of each lower and upper retainer shell edges. This engine hasn't been run for literally years and is bone dry.



Turn the stator slightly backwards - counter-clockwise and re-insert the exhaust cam with the alignment hole pointing upwards.

It won't sit flush down into the cylinder head as there's two lobes pointing slightly downwards onto their respective buckets

Then advance the timing slightly and reinsert the intake cam, check the orientation -> alignment mark.

Now that this stage I had my exhaust cam out by one tooth, difficult to tell for sure before reassembling fully - however no big deal.

Put the locating dowels back into their respective holes and proceed to re-install the upper retainer shells and upper chain guide

Work end to end on each pair of bolts and use a screwdriver socket drive, keeping an eye on the retainers going down straight. I took up the slack then added 1/4 turn for each bolt before proceeding to the next one



One side will go down first because of the depressed buckets, just take your time and it'll all go back together very nicely.

Once they're back down, retard the timing slightly and re-insert the exhaust side chain guide then return it the stator to zero - TDC.

Now you can just discern the exhaust cam 1 tooth out in this shot, so I had to remove the chain guides and rotate it 1 tooth forward - I hadn't tightened the bolts down at this stage any more then hand tight with the screwdriver socket handle.



Process: remove upper chain guide -> rotate stator counter clockwise to give the exhaust cam some slack, remove the exhaust chain guide and lift the chain and move it one tooth on the exhaust cam - DONE!

reverse the process. Exhaust side chain guide - upper chain guide - stator back to Zero - TDC #1 firing.

The last steps are tighten the retainer bolts in two to three stages to the final torque which is 7.2 ft/lb.
Then re-install the cam chain tensioner, depress the small ratchet and shorten it. Put the allen bolts back into place then re-install the springs and retaining bolt and washer.

Then you can rotate the engine a few times with your hand to check for no binding resistance and back to TDC #1 firing and verify the cam alignments marks.

Final step is to verfiy the clearances

Combined feeler gauge fingers




All in all it took me much longer to write this than it actually takes to the do the job - it's that easy.
Be methodical, double check measurements and notes and save drinking beer till after you're done and it'll all go well.

I have some photos still to take and add to the first segments of this, but all told you should be able to get by just fine without them

peace out and happy measuring

Glenn

 

There's the dot on the top of the LHS - cylinder 1 when you're facing the front

 

You can also wind the stator backwards just a bit to get the necessary chain slack to get the cam in the correct position and into position, then put the stator back to the TDC mark and check the cam TDC position

 

Wondering if it's dropped below the crankshaft end and doubled up a link

 

You need to check it, that part is really, really easy, feeler gauges and follow this howto - once you've done it the first time, you will then have a record of the shims in your bike.

Then next time, when you check, if you need to adjust [change shims], you will already know what's installed and what to order

 

You don't need to remove the engine to do that, to check them you need a good quality set of feeler gauges, you need to remove the cam cover gasket and the stator cover to turn the engine, which means lover fairing and fuel tank

Once you've got the cam cover off and can turn the engine, the rest takes 10 minutes, then another 5 to double check

Trust me you got this