Replacing the piston rings/top end rebuild

[simon1221]

This may sound like a silly question but i dont know what to do?

What do i need? Is it just the piston rings or will i need other parts such as gasket etc?

Also where can you get piston rings for tzr's from because Wemoto dont sell them.
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DNA50 (sorry) ->> TZR125l >> GPZ500S

[Scotsman37]

Are you taking the piss again because did you not read what it says at the bottom of Wemoto's page in regards if you can't find part your lookin for ?

[Dom_]

You will need:

Coolant
Full top end gasket set.

Basically, drain coolant, remove old top end, fit new one along with gaskets, bolt down, coolant in and away you go. Very easy to do.

[TomC]

Sorry to hi-jack but didnt think it was worthy of its own thread and its on the same topic.
I am replacing the piston in my Derbi Senda, it has two rings, a chrome one and a none chrome one, am I right in thinking the chrome one goes in the lower position? (nearest to the crank)

[Dom_]

Look on the rings themselves, the one with a marking (usually near the gap) goes at the top with the letter facing the top.

My new top end didnt however, but the correct way to fit mine was chrome at the top, bloack at the bottom. The black one was a sort of 'universal' ring so to speak, as in can go in either way. The chrome one will most probably be angled slightly so less compression is lost etc..

[TomC]

There is no clear markings on either of the rings, ive give the shop a quick ring before I rebuild just to make sure I get it right.
Cheers mate.

[Kickstart]

Hi

For the top end rebuild, in addition to the bits Dom_ mentioned you will also need piston circlips (or "oh shit clips", as that is what you say when you try and put them in and they fly across the garage).

Might also be worth fitting a new little end bearing.

To be honest although I would be quite happy using pattern gaskets on a TZR I would be very tempted to stick with an original Yamaha piston and rings.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Frost]

No doubt with some looking around you will find some deals.

For the RGV it was £150 for:

2 Pistons
4 Piston clips (2 per piston)
2 Base Gaskets
2 sets of piston rings

As you only need half of that it should cost around £75 for the lot.
You can do it without touching the head gaskets, but its normally only an extra tenner for the full set so you might aswell.

[Git]

On a side note about rings, if they come unmarked as to where they go study the ring and the piston groove carefully, on the tz top ends I seen before one ring will be totally square as if to say and the other may just be tapered, a close inspection of the ring and piston should give an idea as to where they go.
I guess this depnds on the piston kit so the above may or may not be correct.

[sickpup]

Tapered ring goes on top, square ring on the bottom. The tapered side of the ring should face up so the expanding mixture will force it out against the cylinder.

Some standard size rings have the infinity symbol on them, this type should be fitted with the symbol facing up. oversize rings will have a marking such as 50 or 100, this is the oversize. This type should also be fitted facing up but do check the taper as no doubt some manufacturer will do it different.

[bish777]

Just make sure when you get the barrels rebored, that you order the correct ovversize pistons.

Count yourself lucky its a two stroke, i did a top end rebuild on my FZ750 genesis- 20 valve head shim under bucket 4 stroke! still wake up with cold sweats over that one!

[simon1221]

Cheers, I wasnt sure exactly what I was looking for, so there would not be a lot of point emailing them.

Do I actually need the piston ring clips, or will I be able to use the existing ones that are already there?

So from wemoto I need:

Top End Gasket Set @ 15.23
Small End Bearings @ 5.88

-I just want to get it right before I order it.

How long will I need to run it in afterwards? Do i have to run it in at all?

Thanks
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DNA50 (sorry) ->> TZR125l >> GPZ500S

[Kickstart]

Hi

I presume you are replacing the piston and rings. These will probably come as a kit, maybe with the circlips.

Do not reuse piston circlips. The are subject to quite a lot of stress, and if you should jump out it will wreck the piston and bore.

Yes you do need to run it in. Generally a couple of hundred miles are half the red line max, then build up towards the red line over the next couple of hundred miles.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[simon1221]

So do i just need the 'Top end gasket set' or do i need a 'piston kit'?
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DNA50 (sorry) ->> TZR125l >> GPZ500S

[Git]

You will need both.

[simon1221]

You misunderstood what I asked.

I want to replace the piston rings, as I do not think it has ever been done, and tthe mileage of the bike is at 14k miles.
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DNA50 (sorry) ->> TZR125l >> GPZ500S

[Kickstart]

Hi

The rings are not part of the gasket set. You will need to order the rings as well as the gaskets.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[TomC]

Hi, my new piston rings have no markings on them what so ever, can anyone tell me definately which way round they will go? There is one chrome one black, Dom said further up his was chrome in the top position, is this the same for all?