Date: 28-03-24  Time: 21:07 pm

Author Topic: Cylinder head removed  (Read 1884 times)

Rich74

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Cylinder head removed
« on: 26 December 2018, 08:57:13 pm »
I have removed the cylinder head and when doing so the cylinder below, which I always call a barrell cylinder, has moved.
If anybody has done a cylinder head job before, have you removed both cylinders and replaced both gaskets?

Fazerider

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Re: Cylinder head removed
« Reply #1 on: 27 December 2018, 12:17:11 pm »
So long as the gasket is intact and clean I’d be inclined to leave it in position.
Taking the barrels off can mean a lot of fiddling about to persuade the pistons back.

red98

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Re: Cylinder head removed
« Reply #2 on: 27 December 2018, 12:48:07 pm »
 :agree ?.....yep agree with FAZERIDER , you'll get the barrels off easy, getting them on is a lot harder , compressing the rings and guiding them into the barrel on a single cylinder is easy , different story with an inline four and all four barrels in one block   :wall


you'll have to renew the head gasket as that seals the power In and keeps oil and coolant separated , i think once you torque down the head the base gasket will re -seal , no compression at the bottom just oil pressure  ...
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Bretty

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Re: Cylinder head removed
« Reply #3 on: 27 December 2018, 04:38:13 pm »
Getting the pistons back in is quite easy as the fzs600 has a slight taper/lead on the edge of each cylinder, so you can guide the piston rings in with your fingers, you'll just need a grown up (extra set of hands) to help you guide the head and/or prevent the crank from turning so you can do the pistons two at a time.

If re-using the gaskets i would be tempted to run a small bead of auto gasket over them... But then I wouldn't reuse them. If you've gone to tge trouble of pulling the engine out to do major service work, I'd stretch to the extra £60-80 for the gaskets.
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daviee

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Re: Cylinder head removed
« Reply #4 on: 27 December 2018, 04:46:03 pm »
if the barrels have moved opening up the gasket then replace the gasket , think about it this way if you dont you might get away with it may be , but if it leaks then you have to strip the engine back out and replace both gaskets again  as  reusing a head gasket could cause leaks and then you have to take it out again and replace both agaain see where im going with it do it right do it once

Rich74

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Re: Cylinder head removed
« Reply #5 on: 27 December 2018, 07:44:41 pm »
Cheers for your replies. I will get a new bottom gasket, as I bought a new head gasket before doing the job. I will try the finger method on the rings of getting the pistons back in the cylinder, if that doesn't work, I will buy a couple of piston ring compressors.
Just one last question. In the PDF service manual, it is showing 4 o'rings that fit on the bottom of the barrels but on the Yamaha parts online list, they don't show any o'rings.
I will have a look at the weekend and take the cylinder off and have a look.
If I do buy a couple of piston ring compressors and anybody on here would like to borrow them, you will be more than welcome, as it's not the everyday tool you would use.

daviee

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Re: Cylinder head removed
« Reply #6 on: 27 December 2018, 07:54:58 pm »
if you can get someone to help you it makes it alot easier to fit the barrels to the the pistons as for the o rings at the bottom of the barrels they should be fine as is

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Rich74

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Re: Cylinder head removed
« Reply #8 on: 29 December 2018, 09:50:04 pm »
I have checked and no o'rings. The picture in a pdf manual is wrong of showing o'rings, so waiting for the bottom gasket to arrive.
I have checked the head and cylinder and both are within 0.05 of warpage. Just out of interest what have people on here used as a flat edge with wet and dry to skim the heads or have you taken them to a machine shop to get skimmed?..
The exhaust valves have very slight leaks, so will use my stick to lapp them in. The inlets are fine, but as I have the head off, I will change the seals and give them a clean and lapp them in.
I will update with any problems and tips I come across.

daviee

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Re: Cylinder head removed
« Reply #9 on: 30 December 2018, 02:15:40 pm »
only way to skim a head properly it getting it machined if its within tolerance  i wouldnt bother if you have to lap thee valves you will probably need to re shim it aswell

Rich74

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Re: Cylinder head removed
« Reply #10 on: 12 January 2019, 07:29:28 pm »
Started to put the cylinder on the pistons after buying two piston ring compressors and what a ball ache they were. In the end I put 2 and 3 cylinder with my fingers, but then the problem came with trying 1 and 4 cylinder. I thought I had them in the cylinder and when I went to push the cylinder down the bottom ring on cylinder 1 popped out and bent.
So I have bought a secondhand set of pistons with rings from a low milage bike to try again. This time I will get my neighbour to give me a hand. The piston has a little edge mark on the groove from where the ring came out and bent, so it may well be ok to use but I will take it off and put one of the pistons I am buying in it's place. The only thing, will I have to buy a new clip for the pin when putting the piston back on or can I use the old one?

tommyardin

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Re: Cylinder head removed
« Reply #11 on: 13 January 2019, 09:49:54 am »
Sounds a bit like one disaster after another.  :'(
Not sure about putting a piston from one engine into another, if the original piston is only lightly marked where the ring popped out ( I am guessing the scratch is from the bottom ring down towards the base or skirt of the piston) I would polish it with a very, very fine bit of wet and dry to remove the scratch and polish it with Solvo polish, as long as the ring groove is not compromised. The bottom rings are not usually compression rings but oil control rings, or oiler rings, so will not impact on engine compression. Gently pop on the oiler ring from one of the pistons you have bought and use that, saves removing the Gudgeon Pin from the original piston and the hassle of replacing the gudgeon pim circlips.
The skirt or land of the piston having a scratch or mark with not effect the performance of the engine as it is the rings that are in mechanical contact with the bore not the alloy piston itself.
If the scratch is really deep, wide and long then replace the piston as it could compromise the strength of the piston at high revs causing the piston to break up or fail in some way.


If you do decide to remove the piston, stuff the crankcase mouth with rags before you start, because a gudgeon pin circlip falling into the crankcase mouth will cause a whole new set of problems.
« Last Edit: 13 January 2019, 09:57:29 am by tommyardin »

red98

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Re: Cylinder head removed
« Reply #12 on: 13 January 2019, 10:54:58 am »
Mmmmmmmmm....well I did warn you :( ......not an easy job but good to do a proper job in replacing the base gasket  :thumbup ....well , youve had a bit of back luck which happens to us all at times , a few pictures of the scratch would be good , also , whats the bores like ? Again a picture would be good , as for using second hand pistons, yes fine but check size first , very unusual for anyone going to the trouble of re-boring these bikes, great bikes but most would replace the engine if any serious problems and probably cheaper .....re using pistons rings is something i wouldnt do, rings wear and bed into the cylinder , swapping from one used engine to another could result in poor compression and a smoky engine caused by oil getting past the rings and burning in the combustion chamber..........not sure of the cost of rings but thats the way i would go.....good luck   :)
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tommyardin

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Re: Cylinder head removed
« Reply #13 on: 13 January 2019, 03:13:46 pm »
Red is right, If I were doing what you are, I would certainly replace all the rings with a NEW set.
If the rings and the bores wear at approximately the same rate then you will have halved the wear by replacing the rings.
Don't forget to take it easy for a few miles while the new rings bed in, should you decide go that way.