Piston ring - fzr250 86 2kr

**ducatilover** · 24th February 2014, 22:14

You'll probably find the exhaust side valves are a bit tight.
I would like to know what the compression test results were and how he determined it was rings

**Shak** · 24th February 2014, 22:22

From memory all he said was #3 piston was low (80 I think and 110 for the rest) concluding it to a bad piston ring.

Ok il post up the valve results tomorrow

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**ducatilover** · 24th February 2014, 22:26

It should have a shit load more than that, unless he did the test cold.
If so, fire him, new compression/leak down test and consider checking the emulsion tubes and needles for being worn

**Shak** · 24th February 2014, 22:29

Haha are these things easy to do (im a newbie). So far I have done a full internal clean of the carbs and moved on to the valve clearances atm. I guess if there are youtube videos out there. Il do some research and try it out

And yes I never went back to him lol

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**ducatilover** · 24th February 2014, 22:34

Google is your friend

All easy to do. If you have eyes like me, you will need a magnifying glass to check needles and emulsion tubes correctly.

**Shak** · 24th February 2014, 22:35

Ok after valves il move on to the tests you suggested. Thanks!

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**The Reibz** · 25th February 2014, 08:16

Bro the TDC marks are a real cunt to find. I can't actually remember where they are to be honest but the easiest way to set TDC without them is to take put a long handled screw driver down the spark plug hole for number 1 cylinder and turn the motor over until the screw driver reaches the maximum height. Thats TDC

Alternatively you can line up the marks on the cam if you have the valve cover off

**Paul in NZ** · 25th February 2014, 09:11

Originally Posted by The Reibz

Bro the TDC marks are a real cunt to find. I can't actually remember where they are to be honest but the easiest way to set TDC without them is to take put a long handled screw driver down the spark plug hole for number 1 cylinder and turn the motor over until the screw driver reaches the maximum height. Thats TDC

Alternatively you can line up the marks on the cam if you have the valve cover off

While remembering that the piston will be at the top of the stroke twice in a cycle... TDC is when both valves are closed or close to it...

**Shak** · 26th February 2014, 14:14

Hi guys so these are my findings. Im not sure if I did it correctly but did to best of my knowledge. I used the screw driver method.

So when at peak (screwdriver) the lobes were facing outwards. This according to the markings and book was tdc. I then measured the gap under the lobes. (when facing out)

Then for the second I did the same (screwdriver peak and lobes facing out) and so one.

something interesting about the 3rd piston was that I could with some effort fit the biggest guage as the piston moved lower as I inserted the guage (unlike the others).. ?? Is this normal?

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**Shak** · 26th February 2014, 14:15

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Ami logo side is intake
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**Shak** · 26th February 2014, 14:16

Originally Posted by Shak

Ami logo side is intake

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**ducatilover** · 26th February 2014, 21:37

Originally Posted by Shak

Hi guys so these are my findings. Im not sure if I did it correctly but did to best of my knowledge. I used the screw driver method.

So when at peak (screwdriver) the lobes were facing outwards. This according to the markings and book was tdc. I then measured the gap under the lobes. (when facing out)

Then for the second I did the same (screwdriver peak and lobes facing out) and so one.

something interesting about the 3rd piston was that I could with some effort fit the biggest guage as the piston moved lower as I inserted the guage (unlike the others).. ?? Is this normal?

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Clearance is only to be measured at TDC, otherwise you'd be using a degree wheel or a DTI gauge to find where to set them
And yes, lobes facing outwards is correct, but the screwdriver method is very inaccurate, plus or minus a few degrees can make a significant difference considering the base circle on an FZR cam probably covers near 60degrees between valve completely closed and fuck all valve lift, and with the lobes facing out you are at the extreme end of those areas.

Or something.
I'd use the screwdriver method and look around either side of the engine to find the timing marks, often they're on a trigger wheel

**Shak** · 26th February 2014, 21:42

When the screw driver was at peak I saw the t mark was inline with a notch on the outside case (generator cover) . I used that to line up.

Also to confirm. Every piston (the one iam measuring) has to be at tdc when measured? Piston 3 had me concerned when I was able to move it lower with the feeler guage when measuring

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**ducatilover** · 26th February 2014, 21:48

Originally Posted by Shak

When the screw driver was at peak I saw the t mark was inline with a notch on the outside case (generator cover) . I used that to line up.

Also to confirm. Every piston (the one iam measuring) has to be at tdc when measured? Piston 3 had me concerned when I was able to move it lower with the feeler guage when measuring

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Yep, do each one at TDC.
Or any cam poking outwards, you'll find when #1 is at TDC, you will have the intake closed on either 2 or 3, and exhaust open on the other of the two. But for simplicity, TDC every time as Yamaha tell you to.