Wossner 3XV R/RS Piston Kits Coming Soon - Pre Order Yours Now

[jcsnook]

Forgive me, Jim. But to add weight to the pistons based on some unsubstantiated internet forum posts seems somewhat foolish . The boys at Wossner know what they are talking about, and matching the dimensions of the stock pistons seems entirely sensible as they are not prone to any inherent crown problems at all.
Surely it's better to listen to the engineering experts over an unsubstantiated internet forum post-referring to an experience with an entirely different motor - of unknown set-up etc.?

I think the pistons should be as per the stock Yamaha ones - i.e. do not increase the dome thickness.

Murry,

The best I could measure...I believe the stock piston has a 6mm dome thinkness, but remember it's a cast piston.  The new Wossner's will be forged pistons, and be made of much stronger 4032 high silicone aluminum material.

You're not comparing apples to apples here - ie: cast to cast, so matching the original dome thickness does not seem so critical.

And as Warwick points out, the failures that Lozza was experiencing, were on a completely different motor...a Aprillia GP race motor, most likely running race fuel, with higher compression and tuned to the edge.

I asked John to review the forum thread and have a look at the failed piston and let me know what he thinks.  His responses pasted below.  Feel free to contact him should you have any offsite questions:

Jim,

I took a look at the image and find that it is not due to the dome being too thin that caused the failure, it was due to an improper tune up/timing condition.  That piston was not only forced to suffer an early death it kept running after the initial damage, the dome thickness had nothing to do with it.  Now if the top land (distance from the top ring to the dome above the ring) was taller it would have taken more time for the damage to occur.

John
_____________________________________________________

When asked about the brown spot on the dome:

Jim,

It looks like nothing more than carbon buildup or burnt residue from the fuel and oil mixture..

John
_____________________________________________________________________

His contact info:

John Noonan

Sales Manager
Wössner Pistons USA
714-369-8879
john@wossnerpistons.com

WWW.WossnerPistons.com

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[muz_j]

I spoke at length with both Alex and John about the dome thickness, and they didn't feel it was necessary to make the change, as these will be forged pistons, which will be significantly stronger than the OEM cast pistons.  They tell me that they make a turbo Hyabusa piston with the same 5.3mm dome thickness and have never had an issue with them.  Then they said "However...the customer is always right, and they would be happy to make whatever changes I wanted to these pistons"...so as to not loose face here and have everybody happy with there pistons, I told them to thicken the dome to 6mm 

Hi Jim,

Your last post in this thread is not clear to me.
Earlier in this thread you have been discussing the dome thickness of the pistons, based on comments regarding a Wossner piston in an Aprilia motor.
Your quote above and other comments in this thread suggest that the stock piston dome thickness is 5.3mm. Your comment above states that you have requested the piston domes to be thickened to 6mm.

My point is as per Warwick's comments - and given your comments above regarding comparing apples with apples and the forged pistons being stronger than cast ones, can you please confirm what dome thickness the Wossner 3XV pistons are being made with?

I see no logic at all based on your earlier comments and your most recent post for increasing the thickness of the piston domes to 6mm from 5.3mm and your post from Wossner confirms this - i.e. that there is no need to make this change.

I would like a set of forged pistons that match the original Yamaha Specifications.



>>> Can you please clearly state what dome thickness the pistons will have ? <<<



Thanks and I appreciate your efforts to get these pistons.

[jcsnook]

Sorry for any confusion, I'll try to clarify...

• The stock (cast) piston, to the best of my ability to measure it, appears to have a dome thickness of 6mm
• The sketch provided by Wossner of the NEW (forged) pistons they are making for us, proposes a dome thickness of 5.3mm
• In a post from Lozza (EEKNOWS) it was suggested that the dome of the NEW Wossner (forged) pistons be thickened up to 6mm, to ward off a "possible" problem similar to the problem he has been having in a Aprilla RS125 GP race bike running Wossner pistons.

Other buyers chimed in (understandably) saying that they were up for any improvements that could be made to these pistons.  That's what started all this...

You are correct in that Wossner does not feel it is necessary to make the dome 6mm...as I said, it was suggested by others that I ask Wossner about it, which I did, and posted their reply.  I'm stuck in the middle here, trying to do right by everyone and get us all a top shelf piston option that will suit our needs.  If their was a known concern with a 2 stroke Wossner piston, I wanted to make sure it was addressed before they make us these, and I distributed them to everyone.

Just to clarify, you won't be getting a piston that will match "exactly" the original Yamaha cast piston specifications, you will be getting a forged piston made to the specifications in the diagram provided by Wossner and previously posted.  Bear in mind that (as stated) a forged piston is much stroger than a cast piston, so there can be some subtle differences in the two designs, ie: dome thickness.  Wossner also added more material in the area of where the ring alignment pins are located on the piston.  However Murry, the outer diameter of the piston, the location of the rings and the ring alignment pins, location of the piston pin, piston height, etc, etc...will all be exactly the same as your OEM Yamaha piston.  It will be a plug and play installation so to speak.  It will not require any modifications to your barrels, heads, etc.

Hope that helps clarify things.

[muz_j]

Sorry for any confusion, I'll try to clarify...

• The stock (cast) piston, to the best of my ability to measure it, appears to have a dome thickness of 6mm
• The sketch provided by Wossner of the NEW (forged) pistons they are making for us, proposes a dome thickness of 5.3mm
• In a post from Lozza (EEKNOWS) it was suggested that the dome of the NEW Wossner (forged) pistons be thickened up to 6mm, to ward off a "possible" problem similar to the problem he has been having in a Aprilla RS125 GP race bike running Wossner pistons.

Other buyers chimed in (understandably) saying that they were up for any improvements that could be made to these pistons.  That's what started all this...

You are correct in that Wossner does not feel it is necessary to make the dome 6mm...as I said, it was suggested by others that I ask Wossner about it, which I did, and posted their reply.  I'm stuck in the middle here, trying to do right by everyone and get us all a top shelf piston option that will suit our needs.  If their was a known concern with a 2 stroke Wossner piston, I wanted to make sure it was addressed before they make us these, and I distributed them to everyone.

Just to clarify, you won't be getting a piston that will match "exactly" the original Yamaha cast piston specifications, you will be getting a forged piston made to the specifications in the diagram provided by Wossner and previously posted.  Bear in mind that (as stated) a forged piston is much stroger than a cast piston, so there can be some subtle differences in the two designs, ie: dome thickness.  Wossner also added more material in the area of where the ring alignment pins are located on the piston.  However Murry, the outer diameter of the piston, the location of the rings and the ring alignment pins, location of the piston pin, piston height, etc, etc...will all be exactly the same as your OEM Yamaha piston.  It will be a plug and play installation so to speak.  It will not require any modifications to your barrels, heads, etc.

Hope that helps clarify things.

Hey Jim,

Okay - thanks - that's clear to me now.
On that basis, I'd happily accept either thickness.

6mm would match the Yamaha originals and might make the piston stronger.
5.3mm would likely be fine too and the pistons might weigh a little bit less.

I am inclined to say that whatever Wossner are doing NOW should be left as is, rather than changing the order. If that's 6mm, then fine. If they are ready to make them at 5.3mm and the change will bump the cost up - then I think leave it at 5.3mm.

...those are my thoughts really.
Cheers,
Murray
- (with an "A" in it )

[jt3xv]

is it too late to order a pair of these pistons? how much deposit is needed?

[jcsnook]

No, I don't think it's not to late.  Wossner is currently on hold awaiting the go ahead from me.  They have my credit card info for the deposit, and a (preliminary) piston kit count of 22, however I'm sure I can ask them to add a couple more to the order when I give them the green light to go.

I've asked that a deposit of $150USD be provided to insure you a pair of piston kits.  If your interested, please PM me and I'll give you my email/paypal account info.  It's the quickest and most cost efficent way to do it. 

[Cru Jones]

Not to stir shit up, but I'd much rather have Vertex make some pistons than Wossner (Vertex are cast like OEM). In the GP world many people have had issues with Wossners (in the Honda RS125 usually), but that's running much tighter tolerances and that's running a leaded setup usually. Hopefully, these work out for you guys as that sounds like a great deal.

[Wullie3XV9]

For what it's worth, I'd go with Wossner's original spec., i.e., dome thickness of 5.3 mm. The ( vast ? ) majority of us will be fitting these to relatively low powered road bikes so I wouldn't think there'd be any issues with them once fitted.
Once again, many thanks for all your hard work & perseverance with this, Jim.   

[Kingy38]

low powered Wullie? i'll be racing on these Wossners once i get hold of them....

[jcsnook]

I've had several conversations with John at WossnerUSA, as did Lozza.   While I agree with Wullie and Warwick that the dome probably does not need to be made thicker, I saw no real harm in it, nor did John indicate any negatives, other than the known few grams of extra weight in material.  Chances are these pistons will still be lighter than the stock units, even with the 6mm dome.  I know there are a few guys here, like Ian (Kingy38) or Paul, that could be putting these into track use, so why not play it safe...I don't want or need any unhappy piston owners   John said there should not be any additional engineering fees, so no harm there.

So it made sense to give him a thumbs up on the thicker 6mm dome.  I'll still need to give him that "officially" in an email, along with the total number of pistons wanted, and and on doing that once I get a deposit from jt3XV (Jon)...which should be on the 25th.

For what it's worth, I'd go with Wossner's original spec., i.e., dome thickness of 5.3 mm. The ( vast ? ) majority of us will be fitting these to relatively low powered road bikes so I wouldn't think there'd be any issues with them once fitted.
Once again, many thanks for all your hard work & perseverance with this, Jim.   

Your most welcome Wullie...thank you for the kudo's.  We need options to keep these fine machines on the road and track!  

[Wullie3XV9]

I've had several conversations with John at WossnerUSA, as did Lozza.   While I agree with Wullie and Warwick that the dome probably does not need to be made thicker, I saw no real harm in it, nor did John indicate any negatives, other than the known few grams of extra weight in material.  Chances are these pistons will still be lighter than the stock units, even with the 6mm dome.  I know there are a few guys here, like Ian (Kingy38) or Paul, that could be putting these into track use, so why not play it safe...I don't want or need any unhappy piston owners   John said there should not be any additional engineering fees, so no harm there.

So it made sense to give him a thumbs up on the thicker 6mm dome. I'll still need to give him that "officially" in an email, along with the total number of pistons wanted, and and on doing that once I get a deposit from jt3XV (Jon)...which should be on the 25th.

For what it's worth, I'd go with Wossner's original spec., i.e., dome thickness of 5.3 mm. The ( vast ? ) majority of us will be fitting these to relatively low powered road bikes so I wouldn't think there'd be any issues with them once fitted.
Once again, many thanks for all your hard work & perseverance with this, Jim.   

Your most welcome Wullie...thank you for the kudo's. We need options to keep these fine machines on the road and track!

OK, Jim, 6mm dome thickness it is then.    I should have said my only worry is that the Wossners end up heavier than OEM pistons causing primary balance / vibration issues.  ( Conversely, lighter pistons will cause excessive vibration too, which would also reduce crank component life!  )

[jt3xv]

hi all you will have my deposit on the 25th ,when i get paid thanks jon

[jcsnook]

OK, Jim, 6mm dome thickness it is then.    I should have said my only worry is that the Wossners end up heavier than OEM pistons causing primary balance / vibration issues.  ( Conversely, lighter pistons will cause excessive vibration too, which would also reduce crank component life!  )

Wouldn't there only be an issue if one piston was heavier than the other on the same crankshaft...ie: you mix and match different weight pistons?  Is that what you were referring to?  I see the concern with that...I'll weigh them when I get them and compare the weight to a stock piston.  If they are not the same...I suppose they will have to be replaced in pairs, which is what most would be doing anyway I would think?

The sketch provided did not reflect a weight that I saw.

[jt3xv]

deposit sent ,thanks jon

[jt3xv]

any news ?