Engine Rebuild help needed

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shawnkva

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Finally got my engine back from being bead blasted.

IMG_0141.jpg


IMG_0142.jpg


should i paint it or leave it as is?

I'm working from a pile of parts in bins and baskets, so i need some serious direction. I bought a gasket set and new seals. i also bought a 5th gear overdrive. My question is...where do i start and what else should i replace while i'm in this deep? i will have the cylinder honed and checked and new rings of course.

guide me wise ones!
 
Make sure you read the Yamaha Service Manual for the engine. You will want to use a dial indicator to check for valve guide wear. Valves will have to be lapped of course. Valve spring length checked also. Its all in the Service Manual.
 
Ive been meaning to post about it.....but took mine apart recently and decided since I had it apart to drop in the MikesXS 5th gear overdrive gear upgrade.

.....I looked at the numbers and figured it wouldnt be THAT noticeable.

I was wrong.....its a HUGE difference in rideability. Before it seemed to me there was little difference between 4th and 5th gear. Now 5th gear really drops the cruising RPMs......its a noticeable improvement.

Something you may look into atleast.
 
If you have the budget, send your crank to Hugh and have it rephased. That engine looks great man. What did you have to pay to have that done?
 
i would love to have it rephased, but i'm getting ready to build a house, so this bike restorations budget is too slim. i haven't paid anything....yet. I work with a guy who powder coats and blast as a hobby. i did some CAD work for him and he did these for me. We have not settled up yet. I also have another guy that is painting my tank and side covers. That will cost me dearly, i'm sure. i had to work some serious overtime to get ready to pay for those. One more huge expense is going to be the charging system. My stator and rotor were shot, so i need to replace them with either stock parts or the permanant magnet kit, whichever i can afford.
 
I would start by chasing EVERY thread, & after that washing it all a couple of times in hot water, then blowing it all dry with compressed air, then oiling all metal surfaces to prevent rust.

But hey thats just me.!
 
I would start by making sure there are no beads left in any oil ways, quick way to destroy a new built engine.
 
some good advice here already.

I'd make sure that all the new oil seals are the correct ones for your model by comparing with originals. There are a number of sets being supplied with incorrect seals particularly the output shaft which on my 79 model should be 40-62-9mm not 40-62-11.5mm which I was supplied with recently.:doh:

Check the needle race in the gear selector drum bearing and make sure there is absolutely zero movement in main and big end bearings and liberally lube everything before closing the cases.
 
I've done 2 XS650 engines and a 1966 Honda CA95 engine and have left them all in their natural aluminum state - no paint.

Paint just flakes. I prefer the totally functional look of raw aluminum, even if it does pick up stains or whatever. That and I'm paranoid that I'd never do a proper job painting my motor and after all the time and effort I'd have peeling flaking paint all over the place.
 
Agreed - I am at the point of my engine coming out for a re-build. I am going fo rthe exact same look as shown in your pictures and will be leaving mine bare. The engine has been painted in the past and, I am sure it looked great in the paint booth but now its all flaked, chipped and looks utterly terrible!
 
Don't bother. Clean it out and put fresh assembly lube in it before you put the shift drum back in. It's pressed into the case and is discontinued if I recall.

It hardly rotates - as much as the shift drum does rotating back and forth to change gears.

If it's completely pooched for some reason (like your cases were full of water) then I guess you'd press it out and try to find a match for it or an old one (you'll find them on eBay from time to time).
 
Oh, and it's not clear on the diagram, but it's a closed end 'cup' bearing. You can see the closed end of it from the outside of the engine case. I can only imagine Yamaha made it that way to allow it to be pressed in from the outside of the case vs. having to line it up and press it in from the more awkward inside vantage point.
 
it's not messed up, but the there are some glass beads in there. i can feel them. i dont want to take a chance thinking i got them all out and miss some. i' will look for a new one before i beat this one out.
 
EDIT : Sorry, ignore the below - it's how I get the 2 stroke 490 Yamaha ones out. The xs650 just presses straight out.

I use an internal bearing puller - the same type used to remove clutch spigot bearings from cars flywheels.
I think I have also levered one out with a screwdriver after the needle rollers were removed.
Another alternative would be to drill 2 x holes in the case behind it & drive it out with a suitable sized pin punch + the case would need the holes welded back up.

Personally I would not use any bearing that has been in a set of cases during bead blasting.
 
Last edited:
Tim, I bought the one you posted from ebay. thanks for the link!

hotdog, i really dont want to use it either. i know i will never get it clean. now it will get replaced as soon as my new one get here. i will drive the old one out and then clean the cases a few times to get all of the beads out.
 
I didn't mention this earlier because I didn't want to burst your "resto" bubble but I sure hope that guy didn't bead blast the internal surfaces on any of your motor parts. You DO NOT bead blast internal alloy engine surfaces. The beads imbed themselves into the alloy and you can't just wash them out. However, they will start coming out when you run the motor and it heats up. Needless to say, this reeks havoc inside your engine.

I've bead blasted several top ends but I take the proper precautions and totally block off all openings .....

BlockPlates6.jpg


BlockPlates2.jpg
 
5twins said:
I didn't mention this earlier because I didn't want to burst your "resto" bubble but I sure hope that guy didn't bead blast the internal surfaces on any of your motor parts. You DO NOT bead blast internal alloy engine surfaces. The beads imbed themselves into the alloy and you can't just wash them out. However, they will start coming out when you run the motor and it heats up. Needless to say, this reeks havoc inside your engine.

I've bead blasted several top ends but I take the proper precautions and totally block off all openings .....

BlockPlates6.jpg


BlockPlates2.jpg
Click to expand...

Need to get my engine blasted soon. You should sell those nifty wood plates, I'd buy one from you.
 
They're simple enough to make, just trace your old head gasket on a piece of plywood and have at it with a jigsaw and drill. I plan on making new better ones out of aluminum soon. I'll use them along with a rubber gasket cut from sheet rubber. I already made aluminum ones for some Suzuki heads I'm doing and they worked well .....

SuzHead.jpg
 

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