I can't put pistons in the cylinders.

[MrOT1]

Hi guys,

first of i'm not english native speaker so a lot of technical mechanics-related word are unknown to me - please forgive me if anything sounds weird.

I have a big problem with my FJ 1200 that I'm fixing

I am in the phase of reassembling the engine, more precisely the insertion of the pistons in the cylinder block - rather the sliding of the cylinder block on the pistons.

And oil or no oil, nothing to do with it, it won't fit. I manage to retract the sealing ring of the two middle pistons, and then nothing.

There is also something that bothers me, it's the distribution chain guide, which tends to block the lowering of the cylinder block; but even once shifted, it blocks after a while.

Someone would have any idea ?

I even thought about removing (again) the pistons from the connecting rod, inserting them in the cylinder bloc with a piston ring compressor tool, and then put it. But it seems a real pain in the ass to do tbh.

Thank you !

[MrOT1]

up mates !

[RPM - Robert]

No oil. We carefully use a small screwdriver/our fingers and compress the rings as the barrels slide down. It takes time especially if you aren't doing them regularly.

[MrOT1]

Why no oil ?

Honestly i've spend 3hours the other day, with 0 impression of progresse, i must be doing something wrong

[RPM - Robert]

Why no oil?

Because you do not need it. If you want to use an oil you need to use something with zero friction modifiers and something that will burn away as soon as you fire the engine up. You want the rings to seat during break in. The cylinders should have been wiped clean with something like an ATF with no friction modifiers. It is more than slick enough to install the rings and pistons.

Installing them can be frustrating, like I said it takes time and patience especially if you don't do them all the time. Getting the cams back in and in time correctly can be equally infuriating to some. Something else for you to look forward to.

[MrOT1]

Would a piston ring compressor help?

[RPM - Robert]

No, at least not for me. Like a said in my first reply, I use my fingers and a small screwdriver with care.

[Pat Conlon]

The folks at Ross pistons want *all the oil* off the cylinder walls. They specify the cylinder walls to be washed with hot water and soap before installing their pistons and rings.

[red]

MrOT1,

Welcome to the forum!  We will help you, when we can.

Are you trying to put the pistons into the cylinders, all at the same time?
It is helpful if you rotate the crank to put two pistons up high, and install those two pistons.  Then rotate the crank a little more, to bring up the last two pistons and install them.
One ring compressor tool may not help much, but two ring compressors at a time can be a big help.  I have made "ring compressors" from the thin hard steel sheets which I cut from smooth food cans, or anything like that.  Wrap the piston with the steel, and compress the rings using a screw-type hose clamp.  If you do not have large hose clamps, you can join them together, end-to-end, to make a clamp large enough to encircle a piston.  It will take patience, but you can win if you persist.

Your "ring compressors" do not need to overlap, around the piston.  You should have a centimeter gap between the steel ends, when wrapped around the piston.  The ends of the rings must be well covered by the steel, as it wraps the piston.

[RPM - Robert]

Why no oil?

The cylinders should have been wiped clean with something like an ATF...

We've gotten a couple email/PM questions about this statement.

Just to clarify, we wipe our cylinders down with ATF with lint free paper towels, immediately after washing in hot soap and water to prevent rust. Then another wipe down of ATF when time to install the cylinder.

We do not use motor oil(s).

[MrOT1]

Ok thanks

I did not know ATF !

I'll try again... and again...

[RPM - Robert]

Red also made a good point. If you are trying to do all four at once it is almost impossible. You need to do two at a time.

[fj1289]

Have the cylinders been bored or had the sleeves replaced?

If there is no chamfer cut in the bottom of the cylinder liners (or it has been bored away) it will be MUCH more difficult to get the piston rings started.

[indyblue]

The chamfer on my cylinders was intact.  I did them two at a time as noted above.  My biggest problem was trying to keep the rings stay clocked the right way while fiddling them into the cyls.

It was kinda like picking a lock.  Work each ring in until they're all in.

[Old Rider]

There are many ways to install the pistons i like to first oil  the rings and bores and use a ringcompressor and put a circlip in one side of the pistons.The side that face to center of engine
then lay the engine on the side (it is also possible to do it when engine is in the bike) Then connect them with the rods and install the circlips on the other side after that.
A tip is to use a strong sewingtread or a thin fishingline like fireline tied to the wristpincirclip to avoid the clip to fall into engine or outer space. Tie the tread so it sits at about 5  on clock where the grove in piston that is made  for removing the circlip with a screwdriver or similar later if it needs to be remowed  .Also cover the holes with something
to avoid things falling into engincase.

There are many ways to install the pistons i like to first oil  the rings and bores and use a ringcompressor and put a circlip in one side of the pistons.The side that face to center of engine
then lay the engine on the side (it is also possible to do it when engine is in the bike) Then connect them with the rods and install the circlips on the other side after that.
A tip is to use a strong sewingtread or a thin fishingline like fireline tied to the wristpincirclip to avoid the clip to fall into engine or outer space. Tie the tread so it sits at about 5  on clock where the grove in piston that is made  for removing the circlip with a screwdriver or similar later if it needs to be remowed  .Also cover the holes with something
to avoid things falling into engincase.

Here is a very good article about pistons and rings :https://www.ms-motorservice.com.tr/fileadmin/media/MAM/PDF_Assets/Piston-Rings-for-Combustion-Engines_53094.pdf