wossner woes!

I've run into a couple of problems with Wossner - not even recent I have to say but right from the start.

One I cleared up today and another that is still on going - it's a nightmare!

In the 400, 501, and 470 there are two choices of piston ring. It could be true of the 550 and 650 but I've never come across it.

the 400
Husaberg have used wossner very little for OEM stuff but they DID use them for their 400 with the 92mm piston.

the factory insist on three ring and then when Wossner made the very same piston as aftermarket they went to two rings, a different oil ring at that and a different width to the oil ring.

If you fit the three piece oil ring that is 2.0mm wide in the 3mm groove and don't notice it you'll smoke like hell! the difference in price between OEM and aftermarket is 100% so the temptation is to buy AM and hope....

470
we're only talking aftermarket here and this one is a little clearer to me, i hold a 470 piston that needs the rings off a 520KTM with their 2mm oil groove and oil ring. yet the book shows that if you ask for a ring set, you'll get 2.5mm 'XSY100' rings. what you need are rings called 'ADS1000'. this I sorted today after the dealer i use denied it, then wossner denied it and then only after I shouted at them and quoted the ring code off the front of the box did they back to wossner and they agreed that 'oh! a long time ago we made them with 2mm oil rings'!

the 501
Wossner actually supplied the factory with under size rings. the factory insisted on 2.5mm ring grooves, Wossner said 'we only make 2.0mm' and so they literally made the piston with undersize rings. you then have to source the right rings but I believe you need to fit the Mahle/Asso rings which you can order through the dealer by selecting another year.

I'm a bit vague on this one but if the bike produces plumes of smoke then this will be the problem.

we also have a problem of light smoking
I have a paraplegic customer who brought a 501 to me and it lightly smokes, it never ran before it came and I never stripped it but there it is.

I also have this problem with one I did rebuild and I also had this trouble of the 2mm ring in the 2.5mm groove three years ago and stripped the engine twice after the initial rebuild before I twigged the problem! I told you all of that problem here and I think it was a case of 2mm rings in a 2.5mm groove and I had to either go to another manufacturer and put their rings on a wossner or I stuck half an oil ring down the outside simply to take up the slack...

I will try and look deeper into the 400 and the 501 when I get a chance but I'm suspecting that from the middle tail about the 470 rings that the 501 story isn't complete.....

regards

Taffy

Did you already contacted wossner about this?

They do reply on email (in contrary to most other manufacturers) and will try to solve your problem.

I've never had any problems with wossner and i am using their pistons in all my bikes.

ElSnorro said:

Did you already contacted wossner about this?

They do reply on email (in contrary to most other manufacturers) and will try to solve your problem.

I've never had any problems with wossner and i am using their pistons in all my bikes.

Click to expand...

I appreciate what you're saying Thijs but I'm talking about 2-3 pistons per week sometimes and this is all the models and all the pistons all in one thread!

I spoke with them and they explained the that factory wanted one ring width and they do another. I've said this. OK?

I'm trying to inform people that when they hit a problem that they are informed of the situation and won't be 'fobbed off' with ******** like I nearly was yesterday. I thought it was what this place was about but maybe I'm wrong? :roll: :roll: :roll:

regards

Taffy

just making sure a few more faces get to read this....

regards

Taffy

the 501 UPDATE
OK the factory used Wossner and I would think that Mahle/Elko were the other suppliers.

I'm not sure what you'll see on an Elko but there's two types of Wossner. that supplied to the factory and those that Wossner choose to sell in the aftermarket. a Wossner piston has a casting stamp on the underside and they use dots to code the piston on top.

all sizes vary due to heat so plus or minus up to 0.1mm.
Wossner aftermarket
beleived to be coded "21101 - 21" above and the casting number is "W8537" underneath.
compression ring groove width is 1.1mm while the ring width is 0.9mm.
the oil ring groove is 2.6mm while the 3 piece ring width is 2.3mm which is quite loose
the oil ring is a two-piece unit with a one piece spring in the back.

Wossner OEM
coded "151008" and casting "W4103"
compression ring groove width is 1.3mm while the ring width is 1.1mm
the oil ring groove and ring I don't have but I believe that it was 2.75mm width

because we don't know the years of each piston we can't quote part numbers to get out of the jam?

however, part # 580 30 631 000 will get you an oil ring that is 2-piece, not wossner, but has a width of 3mm and will get you out of the jam. the groove needs to be 0.5mm deeper as well so now you've got to take 0.5 off the top edge and 0.5 out the depth as well. probably an Elko/Mahle ring.

Wossner's
ring set for the aftermarkets is coded "950XSY". but it is the OEM Wossner that is a struggle.....

regards

Taffy

Taffy.
Do I understand correctly that its the ordering of rings for an OEM wossener that is the issue? and that aftermarket wossener KITS are ok?
Sorry in advance for my stupids.

yes that's pretty much it.

regards

Taffy

Hi. What should be piston ring and oil ring clearance?
Oil ring clearance was 0.2mm and piston ring was 0.3mm, when we but new wössner piston in the engine 50km ago. And then the engine blow up, and started to smoke.

I quess piston rings clearance was too small?

you don't mention either the CC or size of bore?

it seems to be too small but I didn't think the manufacturers made that small of a gap?

regards

Tafdfy

Bike is fs650e (engine is from fs650c).
Piston I put in was wossner piston, it is size B. Piston and cylinder are still ok. Oil ring have taken some heat and lost its compression strength. Compression ring looks normal. These piston rings came with piston, so we put those in.
Now we ordered new wossner piston rings, this time maybe more gap?

the gap on the oil rings is unlikely to be a problem. the oil ring ends would never 'butt up to each other'. the compression ring would though.

Taffy

I found old topic "http://husaberg.org/mechanical/9180-wossner-warning.html" where was something about wossner pistons and those oil rings. You had the same problem? Did yo find any solution?
I think, that next time I assemble the engine, im going to put both piston rigs gap at 0.4mm for the safety.

not really the same problem?

we have trouble with Wossners now in getting a true face off them. the skirts aren't machined in parallel to the crown for instance.

Taffy