yamaha fzx250 preventive maintenance

**erik** · 16th December 2004, 22:34

Well...
Got myself a compression gauge and measured the compression on each cylinder, just out of curiosity. I did them cold because I didn't want to put everything back together, so I guess they'll be lower than they would be if it was warmed up?
Cylinder
1: 90psi
2: 94psi
3: 82psi
4: 93psi

cylinder #3 is the one with no clearance on one valve, so I'm hoping the low compression is due to that.

Also got the valve shims/pads out. Needed a special valve lifter/bucket removal tool, after heaps of searching I found one, see the pic

(removing the second valve lifter from cylinder 2).

For anyone that's interested, the second pic shows one of the valve lifters and valve pads in my hand from cylinder 1.

The pads all have numbers on them, I've got an FZR400 manual that is similar to the zeal, so I'm basically following what it says in there. There's a chart thing with pad numbers to help figure out what ones I need. I dunno how expensive they are or if I'll be able to exchange the ones I've got in part for other sizes. Hopefully they're a common yamaha part...

Anyone know where to get molybdenum disulphide grease? I couldn't see any at repco the other day. I think all I've got is a lithium based grease and some wheel bearing grease, and the fzr400 manual calls for molybdenum disulphide grease when you're reassembling the valve lifters and pads etc.

**Kwaka-Kid** · 17th December 2004, 17:41

got some here dude, not that its much use to you! can borrow a tube if you want.

**erik** · 19th December 2004, 13:13

Thanks for the offer, Logan.

I just had another look at the FZR400 manual and it says to use molybdenum disulphide (MoS2) grease on the shims and use MoS2 oil on the cam bearing surfaces and buckets. But then in another part it looks like they're pointing to use the oil on the shims too.
So I phoned Repco this time and asked if they had any MoS2 grease or oil, they said they've got a lithium based MoS2 grease but not oil. I'm wondering if maybe it's a stuff up in the manual where it calls for oil, maybe just a bit of grease will be ok? And if lithium based MoS2 grease is ok, then I've already got some of that so should be sweet.

Advice anyone?

I got the new shims yesterday, Ricky at Mt Eden Motorcycles helped me out

. I didn't realise that the numbers on the pads stood for the pad thickness (ie 175 = 1.75mm thick) so he had to help me figure out what new shims I needed from the measured gaps and old pad thicknesses and then gave/sold me some replacement pads from his personal collection and took my old ones. I thought that was bloody nice of him

.

**Milky** · 20th December 2004, 18:24

Originally Posted by erik

So should I try to set the valve clearances that I change to the upper limit in the acceptable range?

Remember the little ditty 'a tappy tappet is a happy tappet'. I always set the clearances to the upper end of the range.

**Milky** · 20th December 2004, 18:36

Originally Posted by erik

I just had another look at the FZR400 manual and it says to use molybdenum disulphide (MoS2) grease on the shims and use MoS2 oil on the cam bearing surfaces and buckets. But then in another part it looks like they're pointing to use the oil on the shims too.
So I phoned Repco this time and asked if they had any MoS2 grease or oil, they said they've got a lithium based MoS2 grease but not oil. I'm wondering if maybe it's a stuff up in the manual where it calls for oil, maybe just a bit of grease will be ok? And if lithium based MoS2 grease is ok, then I've already got some of that so should be sweet.

Advice anyone?

I am not quite sure on the terminology you are using, but I assume the cam bearing surfaces and buckets are where the bearings for the camshaft are located? If that is correct, then the only reason I can see for grease in there is to stop the two surfaces corroding together over time. The whole cam region has oil pumped through it while the engine is running, so the bearings themselves get oil through them.
Talked to my old man, and he thinks that the grease required on the shims(or elsewhere for that matter) is only for the initial startup period after the motor has been reassembled. Should be ok with a light smear of whatever you have.

**erik** · 20th December 2004, 21:39

thanks Milky, I was wondering about the valve clearance, Ricky at Mt eden also said to set it to the upper limit.

Yep, I guess my terminology is a bit muddled, I'm using part what I've read in the FZR manual and part what I've heard used before in other places. Here's a gif of the buckets and shims to clear things up. The cam bearing surfaces was just that, the surfaces the camshafts run on. It's kinda surprising but it seems they just run on the aluminium alloy (I'm assuming) cylinder head and bracket bits that hold them in place. I'd think it would wear out quicker than it does... show's what I know eh

.

Still have to fill the radiator and then I can start it up and balance the carbs...
Fun fun fun

**Milky** · 20th December 2004, 22:10

Originally Posted by erik

It's kinda surprising but it seems they just run on the aluminium alloy (I'm assuming) cylinder head and bracket bits that hold them in place. I'd think it would wear out quicker than it does... show's what I know eh

.

That does suprise me too, but then again, in the BM's crankcase, the conrods run straight off the crankshaft - no ball or roller bearings there at all. I guess with the amount of oil that is being pumped around it doesnt need anything other than plain bearings...

**Kwaka-Kid** · 21st December 2004, 20:21

Crazy!

big end bearing is what id use

as for cams running directly on the heads alloy surface - thats fairly common, the old honda singles all do that, eventually they do wear out by when you either steel sleeve them or roller bearing them.

**erik** · 29th December 2004, 22:42

Update:

The engine is back together and was fired up and seems to be running fine with no leaks (so far...). The carbs didn't need to be rebalanced, they were all about the same so I guess they haven't changed since the last time I balanced them (some time in the first half of the year). I haven't checked the compression yet though, I probably will a bit later, just out of curiosity.
Right now I'm waiting for yamaha to open so one of the yamaha dealers can order me a gasket for between the fuel tap and tank. The tap was leaking, and I found an o-ring to replace the o-ring in the tap, but after bolting the tap back onto the tank, it started leaking from there.

And I'm still waiting for the sprockets. After Frosty's friend Alex recommended I check the wreckers here (with no luck) I thought I'd try Victorian Motorcycle Wreckers in Australia. They said AU$50 for new aftermarket sprockets, I'm still not entirely sure if they mean each or for both, either way it's cheaper than OEM parts.

Yamahamaman · 29th December 2004, 22:51

Good work Erik

**Milky** · 29th December 2004, 23:19

what did you finally decide to do with that cork gasket?

**erik** · 30th December 2004, 07:56

Originally Posted by Milky

what did you finally decide to do with that cork gasket?

The one from my Aunty's floor?

I've decided to test if the gaskets that are still on there leak or not, if they leak, I'll replace them.

**vifferman** · 30th December 2004, 08:24

Originally Posted by erik

I used some silicone gasket stuff when I put the starter motor cover back on after Death fixed it up for me after my bin. It seems to be working ok, it isn't leaking. I'll have to see with the camshaft cover though, as it's not just a thin gasket. I'm kinda hoping I can just put the cover back on and all will be well, or maybe use a bit of silicone in combination with the original gasket.
I dunno if it's a high pressure area, I guess it might be. If I put it back together and it leaks, I'll know I need a new gasket...

Now that you've got it back together, this is probably irrelevant, but be careful when using the silicon tjhat you don't end up with extra little bits squeezed out on the inside of cases, as they can end up coming adrift and blocking oilways.

As for the leaking fuel tap, usually there's a flat metal-to-metal seal between the tap and flange on the tank, so you need to keep things very clean; any grit or whatever wil make it leak.

**erik** · 30th December 2004, 08:58

Originally Posted by vifferman

Now that you've got it back together, this is probably irrelevant, but be careful when using the silicon tjhat you don't end up with extra little bits squeezed out on the inside of cases, as they can end up coming adrift and blocking oilways.

As for the leaking fuel tap, usually there's a flat metal-to-metal seal between the tap and flange on the tank, so you need to keep things very clean; any grit or whatever wil make it leak.

Yep, I was careful not too put too much silicon on the starter motor case, so hopefully it'll be ok.

With my fuel tap, there are just 3 holes in the tank, and the tap has a rubber gasket to seal it to the bottom of the tank (see photo). I tried making one out of silicon, but then after reading a bit more about silicon, it seems it might not be fuel resistant, so I'll wait a week and order a proper seal.