Rust in the cyinder

[Crazcnuk]

I am trying to get the top end back together on my 80G.

I went to hone the cylinder barrels before I put it on the engine, and noticed I have some rust in 2 of the cylinders. It looks like these two cylinders were open and the bike sat for a long time.

The rust is horizontal as though the water was sitting on the rings.

My question is, other than boring (these are at 74.8mm now) is there any way to clean this out?

The one cleaned up ok, barely a trace left, but the other one has enough that after honing for several minutes, you can still feel it with your finger.

[boyat68]

In my humble opinion, unless there is a significant gouge in the wall, the compression ring should seal the cylinder adequately, and the oil ring should scrape the oil away sufficently where you do not have loss of compression or burning of oil. All cylinders develop some rust sitting for periods of unuse (steel) and the magic of carbon filling the pits and groves renders the cylinders usable. The act of honing (breaking the glaze) will allow the rings to seat properly as long as the cylinder bore is within specs.

[trbig]

If there's anything in the cylinder you can feel with a finger.. that's not good. And 74.8mm?? 71.6 is the wear limit for stock... so not sure what you have there. If the diameter was a 74.5... you only get a tenth on wear limit for stock, so assuming the same for a big bore... you are well past that limit. What is the bore in the other good cylinders?


Tod

[boyat68]

I did not pay attention to your part of the post that said that your cylinder was 74.8 mm which trib pointed out was way over specs of the std engine which is 71.5 + .002 mm and the wear limit is 71.6 mm. If you look at one of TC's post, http://www.xs11.com/forum/showthread...light=BIG+BORE

"Tod spoke right about both of us having the 1179 kits, and allowing room for another increase to 1196 if it were needed. However, I'm quite happy with the smaller bore, having the slightly thicker cylinder wall vs. the 1196 kit, and IF the cylinders get worn out, I can take just about any WORN OUT 1100 set of cylinders, rusty, warped, etc., and install and bore them, 1.5mm would usually be more than enough to clean/clear any defects in a normally worn engine, and still retain the 1179 pistons, and just get new rings from Wiseco!

T.C.

TC's statement about boring 1.5 mm for the 1179 kit indicates that your posted cylinder wear is way beyond the 1179 kit. Make certain that your measurements are correct.

Dan Hodges' post http://www.xs11.com/forum/showthread.php?threadid=16647 indicates that your measurements may be non standard and required a new sleeve , pistons and other mods to get that cylinder to 74.8

[Crazcnuk]

I have RC Engineering big bore pistons. If I calculated correctly somewhere around 1204-1208cc. It's actually the pistons that are 74.8mm.

These are within (or at least were) in spec for the piston size. I was just going to do a light hone before I put it all back together.

This is the problem, I don't want to overdo the hone trying to take that rust out. I have honed this cylinder for a couple of minutes, without an bore guage I don't want to do much more.

I was reading, elsewhere on the net, that this is fairly common, and may only be an issue because I know it's there! If we think about it, ANY bike that has been sitting for more than 5 years likely has some rust on the one cylinder that is open on these engine, yet we put some oil in, roll them over by hand, then hit the starter...

How many have found broken rings later?

[boyat68]

Like you said, "sitting developed rust." I think that what you feel will carbon up and become a less of an issue as the memory fades.

[Crazcnuk]

I hope so, my worry is that it may be enough to damage the rings?

Rings are pretty rigged, but they have thier limits.

[tarzan]

Can you take a fine half round file and file vertically and gently to get the ridge out?
It cant be stronger than the steel so should be fairly easy to remove.You just need to keep the surface as straight as possible.
I think putting rings back in with a raised ring of rust could cause problems.Rings are brittle by design and dont have a lot of flexibility.

[DGXSER]

No expert by far, but just had a "brain fart" and thought I would share. Typically, when a bike has sat forever and may have this rust issue, it is common to put some oil in the cylinder and let it sit against this rust a day or so to "soften" it up and free up the rings. Then the rings just scrape it away during the first runs. If you feel RAISED edges on the cylinder wall, perhaps the same theory will apply. Just put some oil or blaster to it and let it soak to see if it softens it up to where it sill then hone off easily? JAT

[Crazcnuk]

I can't really tell, but I think the rust is actually lower than the cylinder wall.

There is no 'ridge' so to speak, but when I run my finger over it I can feel a change. I thought it was raised, but I tried the file idea and it didn't seem to hit the rust.

A freind of mine thinks it is lower.

What I am going to do is put the piston in the bore, with some oil and slide it past the spot and see if it seems to grab.

[79XS11F]

With the cylinder dry lay a sheet of paper over the area and roll over it with something that is round like a magic marker or piece of dowel. If it's a ridge it will show on the paper. If it's a gully it will not show. If it's a ridge its gotta go, if its a gully you might just burn a little oil.
Rob

[Crazcnuk]

Stupid part is I have 8 more barrels laying around, but no one here will bore one for me....

[Ken Talbot]

Craz - have you tried rubbing it out with one of those pads they sell at Lordco or NAPA for paint work? They make them in various colours depending on the grit of the abrasive, but they also make a white one that has no abrasive. One of these with a bit of high-powered cleaner should get rid of the rust.

[Crazcnuk]

Like Scotchbrite pads?

I read somewhere they recommended those pads and some rust remover chemical...

I've never seen them, but I haveheard of them before.

Another site recommended 000 steel wool?

[Ken Talbot]

That may be the brand name. IIRC, the grey pad would be in the same ballpark as a 0000 steel wool.