Poorly 900ss - Help Requested - Cracked Frame And Piston Damage

I don't actually recognise exactly where the crack is (I can see it) on the frame - is it the usual place?

But weld it and brace it IMO.

As for the pistons, I can see they have been blowing oil by - normally caused by worn rings.

But as the scratches are quite evident then I would take a real good look at the bores - because if they are there as well, that's another reason for the blow by because the rings can't seal into the scratches.

If you are spending money, IMO have the new pistons fitted if you can afford them, but not without getting the bores dealt with.

 

The crack is just starting but definitely better to catch now before it grows. There is a lot of force put through the headstock under hard braking, and it's just not worth the risk.
For the pistons, It doesn't look that significant to me. If I was racing it, I would change them for sure, but for normal hard road use or track days, I would be tempted to clean them up and put new rings on.
The scores appear quite shallow and look to me more like poor filtration at some point in its life rather than real scuffing.

 

I agree with the comments aboit the frame, get it welded and buy a frame brace from Steve Bailey in the UK for about 50gbp. Well worth it to prevent future problems. Its a known weakness at the headstock.
As regards the pistons. Piston rings are quite pricey, I can highly recommend the 92mm JE pistons. They drop right in and are high comp. Jetting will be needed and a possible timing adjustment to prevent preignition. Not heard of these other pistons you speak of. JE are about 250gbp. I had my bores replated when I rebuilt my engine as there was a noticeable lip on the Nikasil. As far as I know, Langcourt in England are one of the few places that do it and they are very good. About 200gbp.

 

The bolt and lug threw me.

 

Trying getting the bores skimmed or honed and hope it doesn't go through the plating - they are bad enough to cause oil blow-by.

I would favour replating over scrapping - it depends what the cost is against finding new ones or secondhand ones that you don't know anything about.

 

Which grooves are you feeling with your nails - the horizontal ones or the vertical ones?

Difficult to tell from the pics but if the bores measure both round and in spec then I'd use them unless it's the vertical grooves you are feeling and they are deep.

 

13.5 to 1 that's some serious compression hope you are going to put some equally serious head studs in to keep it all together. :anguished:

 

It it were mine I would give the bores the lightest possible hone to help the rings bed in properly and be sure of a good oil film and good compression.

 

If you can feel the vertical scores with your fingernail, you are wasting your money if you don't deal with them and just fit new rings - false economy IMO.

 

As others have said, although costly I would get them replated. My JE compression is quite high, in fact many recommend taking material off the top of the crowns to lower it. I didnt, it pulls like a train.

 

I have front barrel and piston from 2000 900 SSie spare.

 

Im sure JE do them too, standard pistons that is. Not sure if the later piston rings are the same.

 

You could combine this with a short break in Weston Super Mare, which is always a pleasure.