Valve Shims

[sdj1]

Hi Guys,
Finally decided to give the valve gaps a check.
Shit glad i did! How the bloody hell does the thing get tighter though,
got to get looser with wear me thinks.
Place i braught the bike told me they checked them, could be bullshit.

Two thousand miles later and the Inlet valves on number four piston
are really tight as in my .05 feeler gauge wont go in!!!!!!

Any idea as to the best way to buy the shims is Single vs Pack and
were to get them??????

Cheers Steve......

[rockin rexer]

Got mine from my local Kwak dealer, work out what sizes you need, then order them individually! ;)

[motorsiklemad1]

Hi I just measured the gaps, worked out what sizes of shims I needed and my local ex Kawasaki :hail: dealer swapped my old shims for the new sizes i needed. Might be worth going to see your local Kawa dealer, try speakin to the mechanics
GOOD LUCK

[jam]

Your valve clearances will close up and become tight because of valve reccession, the valve hammers shut and sinks into the valve seat, this problem is more apparent with use of unleaded fuels. Leaded fuels were used to provided a cushion as the valves closed the coating of lead on the valve seats and valves absorbed some of the energy as the valves closed. This problem is more common on smaller engines with smaller valves as there is less surface area to spread the impact of closing, and therefore the valve starts to sink into the seat. you can use a lead substitute which can help, but once the valves start to sink then they'll tend to continue sinking. Keep an eye on this as ultimately the valve will sink so far that it fails.

[50pence]

Just a little scaremongering there Jam ;-)

The fact is that valve clearances close up as well as open up, once they are re set then they should be fine for another 7500 miles.

IIRC Kawa quote 15000 miles for the 06 1200R with no mechanical changes to the engine so I reckon they have eventually realised over the life of the engine in the ZRX that 7500 checks are not required. Again IIRC the 7500 came from the ZZR where the higher lift cams and stronger springs create a different environment. I had my 1100 checked first at 8500 and all were fine, my 1990 FZR600 did not require a check until 27000 miles.

[rockin rexer]

Your valve clearances will close up and become tight because of valve reccession, Keep an eye on this as ultimately the valve will sink so far that it fails.

:eek: I assume this happens to all rexes, so at what mileage can I expect the thing to go bang? :cry:

[50pence]

Dont worry, see my post above.

[Pal]

Just a little scaremongering there Jam ;-)

The fact is that valve clearances close up as well as open up, once they are re set then they should be fine for another 7500 miles.

IIRC Kawa quote 15000 miles for the 06 1200R with no mechanical changes to the engine so I reckon they have eventually realised over the life of the engine in the ZRX that 7500 checks are not required. Again IIRC the 7500 came from the ZZR where the higher lift cams and stronger springs create a different environment. I had my 1100 checked first at 8500 and all were fine, my 1990 FZR600 did not require a check until 27000 miles.
Couple of things, in normal use the shims can only get tighter not looser, only if you have a major problem can they get looser ie cam or rocker wear.
The ZZR does have higher lift scams, but I can't see how this effects clearances, the valve opens further thats all, and the double valve springs have the same combined strength as the Rex single springs, they just have a different resonant frequency to stop valve bounce.
I beleve the dropping of the 7500 clearance check to be a mistake on big K's part, when I checked mine all but one were tighter than tolerance.

[Purge]

Checked mine at 7,500miles and all were tight. Put ZZR cams in at that mileage and re-shimed.

Checked again at 15,000 miles before putting the Wiseco 1109 kit in, and all clearances were fine.

I reckon it's essential to check at 7,500 miles to adjust out the initial bedding in. After that, most Rexes don't seem to wear much further, and don't need re-shimming again in their lifetime.

:purge:

[jam]

The problem of valve reccession is more prevelant on 400cc bikes as the surface area is smaller due to the smaller valve size, It only becomes an issue when the clearances start to need doing more frequently than the service interval states. If you think a 400 inlet has a circumfrance of say 45mm with a seat width of 1mm then the valve seat will be 45mm square, if you have a larger valve say a circumfrence of 70mm with a valve seat width of 1.5mm then you have a total surface area of 105mm square. this means that there is a lesser area on the 400 valve to spread the force of closing against, compared to the larger valve. Even with different spring rates the hammering effect of the valve closing will be greater on the smaller valve because of it's reduced area to absorb the energy of closing. Leaded fuels provided a cushioning effect as the valves closed, as the lead was deposited around the valve seat. this is one of the reasons that older cars and bikes need to have a valve seat conversion in order to run on unleaded fuels, as the older materials need the cushioning effect of the lead and without it they suffer from reccession, leading to the valve not sealing and then burning out the seats. I should have said that it's only a problem if the clearances start needing to be adjusted outside the normal service intervals, and one symptom is poor starting when warm as the expansion of metals allow the valve to seal poorly reducing compression and causing poor starting. When cold the clearances are maintained (just) and the bike will start from cold, but get worse at idle as the engine warms up. All valves reccess to some degree hence clearances need adjusting as they close up, hope that clears up any confusion or panic ;)

[sdj1]

Cheers guys,
Was starting to regret asking at first.
I got the bike at 6,500 miles and they told me they did the 7,500
early? Now at about 8,700 getting the head cover off to get powder
coated i decided to check them. Bloody glad i did now!!!!!!!

Seen these HOT SHIMS on the ZRXOA a lot. Any one else used them
or just gone for standard?

Cheers Steve.......

[Salop Dave]

Checked mine at 7,500miles and all were tight. Put ZZR cams in at that mileage and re-shimed.

Checked again at 15,000 miles before putting the Wiseco 1109 kit in, and all clearances were fine.

I reckon it's essential to check at 7,500 miles to adjust out the initial bedding in. After that, most Rexes don't seem to wear much further, and don't need re-shimming again in their lifetime.

:purge:

did mine at 9000km, 6 were too tight. Aswas said bought from Kwak dealer individually. Synching carbs at the same time made a noticeable difference, much smoother through the revs.:bike:

[Lex]

I've never checked the shims on my 1300 Fiesta, car run fine 40k miles.
Surely the valves/shims don't know there any more in a car than in a bike?
I know bike engines usually are revved higher,but over the thousands of miles of use the bikes average RPM is probably not that much higher than that of a car of similar capacity.Maybe us bikers just worry too much....

[Purge]

Just about everyone I have heard about doing the shims on a Rex at 7.5K miles has found the clearances too tight.

If you don't check you risk burning a valve.

Your choice.

:purge:

[mhinagoya]

Cheers guys,
Was starting to regret asking at first.
I got the bike at 6,500 miles and they told me they did the 7,500
early? Now at about 8,700 getting the head cover off to get powder
coated i decided to check them. Bloody glad i did now!!!!!!!

Seen these HOT SHIMS on the ZRXOA a lot. Any one else used them
or just gone for standard?

Cheers Steve.......

Shims from Hot Cams are all I have ever used. I bought two refill kits from them, then went to a store and bought a small box with compartments. I just put my own kit together. As far as I know, one person has found one shim that hadn't been tempered properly, but that is the only case I know of. If there is any difference between "Official Kawasaki" and the shims sold by Hot Cams, I certainly can't find it. My 'kit' cost me less than $100 US dollars.

I don't have a dealer nearby, so running to the shop to swap shims isn't an option for me. If I could do that, I wouldn't have bothered putting a kit together.

Bill.

[nikroc]

Prob a stupid question ..are the shims for the 11/12 rex compatible with any other Kawa shims??

[yox]

er....yes but not all of them, models that is not shims.

[nikroc]

:o: Sorry i should have bin specific..i got a stack of shims for me old gpz1100,b2 n z650's....

[mhinagoya]

Let's do this the easy way.
The shims for the rex are 9.48 mm in diameter. If you have shims that size, they will fit. If they are bigger or smaller, they will not fit.
Shims of this diameter are used on some Hondas and some Suzukis, as well as our beloved REX.

Bill.

[TeZREX]

[QUOTE=mhinagoya;120603]Let's do this the easy way.
The shims for the rex are 9.48 mm in diameter. If you have shims that size, they will fit. If they are bigger or smaller, they will not fit.
Shims of this diameter are used on some Hondas and some Suzukis, as well as our beloved REX.

Bill.[/QUOTE
:agreed: I had a load from my ZZR600 but as my luck would have it they are too small in diameter for my rex! I know new shims arent cheap but a rebuild is more expensive. 7500miles sounds good to me too, I changed my cams at around that mileage and a few were tight. seems ok afterwards.

Tez

[nikroc]

Appreciate the replies chaps...:D:

[esornivram]

i installed the zzr cams in july, then took an 6255 mile trip across country and back, and when i got home i did an recheck, had 4 tight valves,
I for one wont ever increase the valve insection, instead do it more often till your sure, the valves seem to sink into the seat, or when you get valve job, they are now deeper in the seat area, as a result the top of the stem is now closer to the rocker and cam, this is the biggest point that tightens up the clearance.
hot cams supply good shims
i have the kit.
but know i need thinner shims(2.35 to 2.25mm) than what comes in the standard kit.