R1Z is running

[FZRichard]

I will remove the barrels and look at the piston size and ring gap. Will also measure the width and height of the rings and post them here to see if anyone knows if they are the correct ones or not.

Will also check the joint between the power valves and check the seals and free play on them also.

The exhausts don't look blocked, had a good look at them when I had them off, also removed the end cans and had a look in there.

[FZRichard]

Have the top end apart. Both top and bottom rings have a gap of 0.75mm, book says 0.45mm is the limit.
The piston has a gap of 0.1mm in the bore, so it's at the limit.
There was no free play on the joint between the two power valves. The power valves were surprisingly clean, no carbon build-up.
The measurement of the side movement on the big end was 0.5mm.
For now, I will put a set of rings, new seals for the power valve and put it back together, unless there is something else I should do while I am in there.
I have attached a picture of the measurement of the rings, are these the same as the TZR250?

[FZRichard]

I can get a piston and rings for a 1987-1990 TZR250, 56.4mm bore, All standard size.

TZR Piston 1KT-11631-01-35
       Rings  2MA-11610-00

R1-Z Piston 2YK-11631-04-35
        Rings  3XC-11610-00

Would these TZR parts fit the R1-Z?

[FZRichard]

Looks like the only way I can work it out is to buy a set of pistons and rings.
So, I have now ordered them, hopefully it works out for me.

[FZRichard]

Has anyone had any experience with Forseti piston/ring sets, this is what I have ordered.
I could only find one place in Australia (apart for Yamaha) where I could get pistons, and this is the brand they sell.

[rz500guy]

Never heard of them

[SeaR1ck]

Nope never used them or seen one in person a quick search shows they are Chinese garbage. Walk away.

Get some pistons from a reputable brand.

[James P]

Has anyone had any experience with Forseti piston/ring sets, this is what I have ordered.
I could only find one place in Australia (apart for Yamaha) where I could get pistons, and this is the brand they sell.

I think that Forseti is just one of those companies/brands that sells parts made by others (they buy someone else's part and put it in their own box). The Forseti pistons look exactly like some unbranded ones (in plain white boxes) I acquired in a job lot of parts some years ago. I'm not keen to use these unbranded pistons on account of poor reports from others about similar unbranded (or unknown brand) pistons. Admittedly, some of these questionable pistons seem to come with good rings (Nippon, Riken or Teikoku - identifiable by the N, R or T marked on the top surface of each ring), but I suppose it is possible that the rings may be counterfeit...
I'm not saying Forseti pistons are rubbish - they are just from an unknown/unpublicised source. No doubt the advertising blurb will say things like "from a quality-assured manufacturer", "made from the best quality materials" and so on, but that is just marketing spin and is no guarantee for the end user. Before considering the use of Forseti or other similar generic pistons, I recommend talking to someone (whose opinion you trust) who has used them and can vouch for their satisfactory performance.
While it is true that parts sometimes get a bad report due to incorrect application/installation/use, I think most would rather not risk the expense and inconvenience of another engine rebuild so soon after the previous one!

My first preference would be genuine Yamaha pistons and rings (pistons made by ART, rings by Teikoku I think). If unavailable, my next preference would be cast pistons from long-term known brands like Pro-X or Potenza/Mitaka - I think these pistons were all made by ART too.
Forged pistons are/were made by Wiseco for 1KT-based engines (Part Nos.8158P57, 8158P575, 8158P58, which correspond to 57mm, 57.5mm and 58mm sizes), but I think they have been discontinued now. Having said that, I'm sure you could still order them direct from Wiseco if you buy the minimum quantity or pay the minimum charge to make it worthwhile for Wiseco to make them again. I believe the slightly more modern Wiseco 679M series will work in 1KT-based engines as well. I think Wossner also makes a forged piston for the same applications as the Wiseco 679M.
Beware to double-check sizing with the more modern aftermarket pistons (whether cast or forged) - some/most of them were made to suit 56.0mm standard bores, not the 56.4mm standard bore of the 1KT-based engines. Accordingly, oversizes of these pistons won't match the usual oversizes of 1KT-based engines. This won't be a problem if you order according to actual size, but avoid (for example) ordering a piston described only as 'first oversize'...it may be too small!

I can get a piston and rings for a 1987-1990 TZR250, 56.4mm bore, All standard size.
TZR Piston 1KT-11631-01-35
       Rings  2MA-11610-00
R1-Z Piston 2YK-11631-04-35
        Rings  3XC-11610-00
Would these TZR parts fit the R1-Z?

Either of these sets will fit any 1KT-based engine with standard bore size, but the 1KT-2MA combination uses the early-type rings. Yamaha still lists the 1KT-11631 piston for sale but, if you order one, I'd be inclined to think that the 2YK-11631 piston will actually be supplied. My own experience is that ordering by superseded part number will get you the latest part, not the original.
I vaguely recall that Yamaha changed the design of the rings and the arrangement of ring pegs (or at least the top ring peg) because of several engine failures caused by ring pegs falling out. Hearsay suggested that this occurred only with sustained high-speed use (some said 'abuse'), as there have certainly been plenty of engines which survived many thousands of kilometres with their original (early-type) pistons and rings. However, Yamaha nevertheless decided to change the design so it is unlikely that it would still supply any of the early-type pistons or rings. Of course, it is still possible to find superseded parts on dealers' shelves...

If you do decide to use the Forseti pistons, I'm sure we would all be glad to know how you get on with them!

Regards,
James

[rz500guy]

Agree with others. I know we do not want to spend a lot on a rebuild and want it done as soon as possible but you will be thinking about the engine every time you run it hard. That does not sound enjoyable at all. What about Woessner?

[FZRichard]

I got the Forseti pistons and rings, they arrived today.

I took the barrels, pistons and rings to my mate who is an engine reconditioner. Measured the bore and it was 2.221 inches, so standard. The piston/bore clearance came to 0.0020 inches, and ring gaps are 0.012 inches.

When removed and measured the piston/bore clearance was 0.0040 inches and ring gaps 0.0260 inches, so they were over specifications.

Interesting to see how much of a difference it will make.

[rz500guy]

What are the specs in the manual. Woesner gave me a calculation for ring gap. I put the top one I believe at.013 and bottom at.015. I read somewhere that it reduces ring flutter or some crap. They said most important is loose is better and over will have a minimum impact on compression. Maybe you should ask for donations since you have the test engine. Keep us updated.

[FZRichard]

The specifications in the manual are,

  Piston/Bore Clearance: 0.0019 - 0.0021 inches,
  Both Rings End Gap   : 0.012 - 0.018 inches.

So, I am on the lower limit of both with the new parts.

[rz500guy]

Just an opinion. I would loosen the ring gap a bit. All these measurements were with factory Yamaha parts and materials. If your parts expand more than what is expected you will be in trouble. Woessner told me even 30% over has very little effect on compression. Have seen too many smoker seize because the ring gap was too tight and no where to expand.

[m in sc]

yeah, id open it up to .0020 and be good, thats where mine are on the tzr. (non oem pistons as well). you going to get the squish corrected or has it already been done? that made a big difference on mine.

[FZRichard]

I think I will take the ring end gap to 0.014 inches from the 0.012 inches I have now.

Have heard the term squish but don't really know what it is or how to measure it. I am just going to put it back together. The gaskets I removed, base and head, are the same thickness as the new ones I have to put in.

I don't think this engine has ever been apart before, so the head and barrel heights should all be standard.