Patches on cylinder walls

When I first got the 83 xj900 the engine was siezed. I carefully got it freed up but when I took apart the engine I found this on the cylinder walls. The patches are smooth to the touch but still concern me. Would I be able to dingle hone the cylinders to get rid of them or should i have a machine shop bore the cylinder? I'm trying to keep the repair as simple as possible. Prefferebly just needing new piston rings. Let me know what you think.

 

Hone then then measure them to see if they are in spec for rings.

 

If I hone them do I need new rings since they have a new crosshatch?

 

if you think your rings are undamaged and good you can reuse them. but why risk it and have to do it over

what was siezed?

partzilla

PISTON RING SET (STD)
15A-11603-00-00

$45.99
$32.11

 

It was one of the pistons in the cylinders. I also have a compression ring stuck on the number 3 piston. So I should probably replace the rings anyway. Is it pretty easy to dingle hone or should I have a machine shop do it?

 

when you hone it you will need to measure the cylinder walls to make sure the diameter is in spec you want to do this before even buying the rings.

price it out at a shop

specs are in manual do you have one?

 

specs

 

You are now in the Twlight zone; between doing a low buck resurrection or a full blown rebuild. Questions are what are your expectations of the bike when you are done; ride and enjoy or fix and flip. IF, IF, there are no scratches on the cylinder walls, you could just hone, do rings and go, that would be the low buck route. If there are scratches, bore it over size. The patches you see; I call that shadowing, is where the pistons were getting real close and personal to the cylinder wall due to moisture and galvanic action between aluminum and iron; I don't think they will hone out with out taking the cylinder out of spec. A "blue berry hone" is not for stock removal, just cylinder wall conditioning, 30 seconds is all that is needed.

 

I am ordering a physical manual soon but I have a pdf one. Compression was good across the board even with a stuck compression ring. Roughly 120-130 with the lowest one being the cylinder with a stuck compression ring. Keep in mind that the bike sat outdoors for 3 years. I'll try to get better pictures of the spots tomorrow and post them.

 

When you hone the cylinder use LOTS of WD40 , I'm sure you already know this but some in the studio audience don't , this saves the hone stones from excessive wear and the same on the cylinder. From the looks that is pretty deep , I would try the hone and see , and by all means replace the rings.

 

I had similar on my Radian motor.. it's water ingress damage - condensation or even rain if the motor was stood without carbs on it. I bought 2-3 more scrap motors for less than 50 quid each trying to find better bores and in the end settled on one which had minimal corrosion on one bore - I posted pics at the time maybe you can even find the thread. I'm cheap so I 'honed' the bores by hand with 300 grit paper I think. Got some new rings (bargain at 100 USD) and buttoned it back up. Compression was slightly down on the 'bad' cylinder but the motor is generally OK. On it's maiden year after the 'rebuild' I went to Isl e of man and put 500 mile on it without any real issues. As JBurch suggests - it depends on your expectations. Hone and rings and it will almost certainly run Ok for most people. As my brother often says of my budget projects ' It's not a race motor is it?'

BTW Rebore, pistons and rings will cost you at least 500 USD probably more - and that's if you can find the oversized parts. Cars are MUCH cheaper for this kind of thing.

 

Does anybody know if any of the other XJ use the same cylinders?

 

You have a 900 there it's the only bike with those cylinders

 

A guy in Ukraine made Seca-II (Diversion) 600 barrels fit the older model, maybe Seca2 900 barrels will fit yours? He did make some slight mods IIRC. See Gaz 8-ball cafe thread,

 

https://www.xjbikes.com/forums/threads/my-xj-eight-ball-cafe-racer.48291/

 

..don't mention it.

 

That is an awesome build. I brought them to a good machine shop I know. They said it mainly looks like stains and nothing too deep. We are going to try to hone it a little bit and get new rings after checking the specs. Thank you for sharing that link. Anybody know if xjforever's oversized piston rings require over sized pistons.

 

Yes, they do!

 

You wouldn't by chance know where to obtain oversized pistons for the xj900rk? I'm just trying to plan out worst case scenario.

 

if you cant get oversized pistons you may be able to resleve the cylinders

 

You could check out having custom pistons made, OR you could study catalogs, match bore, pin diameter and compression height, or find something close.
It's an idea

 

I'm really hoping I won't need oversized pistons haha.

 

No help on those, but as XJ550H points out, in a worst-case scenario you can purchase standard-bore cylinder liners (which we have in stock) to salvage those jugs.

 

I have only honed two bikes so far but that mark in there is not bad. I would have to agree with the shop it is only a stain or blemish in color from sitting for so long. Did the shop measure the inside of the cylinder for you? That would really tell you what you need to do. I would do that and then if you feel you need to have it honed out and get new rings. That will really save the time and money on this project. IMHO

 

I'm gonna have them measure it. And go from there. I was gonna sand blast the outside first and get all the rattle can paint and dirt off so that they can clean everything up at the same time.

 

Unless you can seal those cylinders up I would not do anything to the outside of the engine. You would hate to have to clean all the bits of sand paper, paint and whatever might get in there. I would make sure you engine is in good working condition before you start to do the cosmetic portion of it.

 

Keep in mind that the cylinder jugs are off the engine. I would just need to cover top and bottom, and yics ports. I'm having an experienced blaster do them and he is doing them for cheap. With how rare this bike is I'm planning on putting money into it to get it to my desired results. The engine is currently completely apart.