case half mating surface cleaning , worried about having removed some aluminium

Hello, bike is a 82 Maxim 750. I first want to say how helpful everyone on this forum has been and that I really appreciate it. I'm pretty new to working on engines and what not so I lack the insight and intuition that those who have done this work many times have gained. Leading into the title of this thread... I have the cases split on my bike and my attempt to clean the case half mating surfaces has gone okay I'd say. I initially tried kitchen scrubber with some acetone which didn't really do anything. Next I wetsanded some 1000 grit then 2000 grit sandpaper with wd40. That got some of the gunk off but there was still a layer left. Then I decided to use a small stainless steel wire brush attachment on a drill. I went over the surface lightly and that seemed to remove most of the rest of it. There still some spots that were there so I used some 2000 grit dry sandpaper and that cleaned those up. Mainly what I started worrying about is possibly having taken enough alumnium off that the mating surfaces won't seal. The surfaces feel smooth and look fine to me but like I said I lack expireience. How hard do you think you would have to go at it to do significant damage?

 

I use plastic scrapers to remove old sealant, well anything softer than aluminium. Hopefully they are not damaged but what you could do it lay a good quality steel rule on it's edge along the surfaces to make sure they are fine. I do not see any visible damage of the faces in the pictures. You should be fine for reassembling them.

 

i mean what are really gonna do about it anyways? to machine it down level would change bearings. welding up and machining down is possible, but for the cost of either of those you just but a used engine for much cheaper.

So i think you just assemble it and we all hope for the best. Dont know until you try unfortunately.

I think you will be fine, or fine enough but im an optimist

 

Thats true, guess I'll find out for good or bad.

 

Yes you cannot add material on once it's removed, go for it they will be fine.

 

I'd be more concerned about sanding in a engine, that can't be a good thing

 

What are you using for a gasket maker?

 

I think what you are seeing is the original imperfections in the original casting. The low spots will have some material remaining, that is what the original gasket filled. I think it looks fantastic. Use a good quality gasket and sealer and you will be fine.

 

Yes, I'm making sure to clean every surface I can with acetone before reassembly.

 

Check the oil nozzles in the main bearings too.

 

I went ahead and checked the surfaces and they are all true to each other. I also figured I could just sit the bottom case ontop the top case to just test fit and this is what I got. I think it looks fine.

 

You are doing a good job on your engine.

 

Thank you, are you talking about the holes in the middle of the bearings?

 

Yes.

 

Here is a photo 900f engine l am assuming the other XJ's are the same.

 

The photograph is from the Haynes manual.

 

Looks the same as mine

 

Yes they should be fine l only mentioned it just in case you wanted to check them prior to your engine assembly.

 

send it

 

sometimes the shift forks are tricky, practice a few times before you put the sealer on

 

Remember and check you can select all gears up and down the gearbox before bolting everything up and get neutral. Selector drum should turn smoothly when moving the selector forks. I get an assistant to hold down the crankcase when checking this.

 

If you use Loctite 515 or 518 on the crankcase mating surfaces any getting inside the case mixes with oil and cannot block oilways. Check your oil spray nozzle for lubricating the starter clutch chain too. It should look like the one in the photograph. As you plastic guide was not broken up nozzle should be ok.

Most important rule of engine assembly it should go together fairly easily. Anything that doesn't means something is not lined up properly.

 

I don't know if y'all can tell in the photos I posted but
In the picture with the exhaust side of the engine, there is a tiny gap between the two case halves. I measured it with feeler guages and it's about .008 inches. I don't think there's a known spec for something like this but what would yalls opinions be? I feel like once the sealant is on and bolts are torqued down it will close it but I'm not for certain.

 

Once the sealant is on and the cases torqued to spec it will probably be fine. Only one way to be sure at this stage. Pity you didn't have some engineers blue to put on the joint faces. Then you could put them together to see if it is on both faces. The only way to find out is to assemble it.

 

Do y'all have any ideas for removing this damn case gasket material? There is still some left like in the pictures and I cannot get this stuff off. I have tried acetone and brakeleen with non scratch dish scouring pads which didn't do anything. I have tried a razor blade which won't remove anything and I don't want to gouge the surface. It seemed like rubbing it really hard with a towel and some acetone sorta worked but it can't remove it all. I'm a bit resistant to hitting it with a stainless steel brush again since it didn't remove that stuff in the first place.

 

I will probably get flamed for this, and bearing in mind i cant touch it to feel it.

That might be clean enough/ as good as your going to get it.

can you feel it with your fingernail?

if a hard scrub with a towel works, maybe rig up a bit of towel on a rotary tool some how? make the work easier? a carbide edged scraper would get it off, but there is some risk there with aluminum and they are expensive.

Some guys user honing stones, knife sharpening wet stones, and lay that flat on the surface and work it. I would suggest you research that more before trying it though and I have never done that myself.

 

that's cleaner than it needs to be
if you go over one case with a magic marker, nice and dark. then put the half's together and wiggle a bit, you'll see where there might be a high spot

 

I replaced a timing chain cover on a car engine after fitting a new head gasket. Timing cover was vertical not horizontal and had one or two sealant marks l couldn't get off. No oil leaks once new sealant was applied and bolts torqued to spec. If you cannot feel high points there shouldn't be a problem. Looks clean enough to me. Try the pen or engineers blue if you want to be certain. The point of sealant arguably is to fill the imperfections between the cases, in mass produced engines. The marks on your cases look like sealant in those imperfections rather than high points. I bet the marks are flush with the surrounding aluminium.

 

Thanks for the responses I can't feel it with my fingernail like vashtsdaytona suggested. I'll probably give it another once over and call it good. I was just thinking about the sealant not curing in certain spots since it cures in the presence of metal ions.

 

What sealant are you going to use?

 

I was thinking loctite 518.

 

That's a good choice.

 

https://www.henkel-adhesives.com/hr/en/product/flexible-sealants/loctite_518.html

 

Is 25ml enough like in that link you sent or should I get the 50ml tube I found on Amazon?

 

I would get the 50 ml one.

 

This is off topic but is it okay to remove the rod bearings to clean underneath? I did on a couple and put them back in the same spot but wondered to myself if I should be doing that. The correct terminology I think is main bearings but I'm not sure. I'm talking about the bearings in the bottom case half.

 

Main bearings are the ones the crankshaft runs on in the two half's of the crankcase. Rod bearings are under the connecting rod caps. If you cleaned those connecting rod bearings you will need new bolts and nuts for them and you need to tighten them to the correct torque.

If you want to clean behind the main bearings make sure you do one half shell at a time remove clean and replace so there is no possibility of them getting mixed up.

 

It was the main bearings I was talking about, and yes I will make sure