Crankshaft split overhaul assembly

gggGary

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Crank rebuilding. I am looking for how to's, what has and hasn't worked.

Welding cranks, pros and cons.

Bearings availability, quality.

Measuring, jigs, alignment, presses, other methods for splitting, assembly.

I am thinking the cheesy 12 ton HF press I have won't be up to the job and there isn't much room between the beams. The big press will allow the flywheels to fit between the beams.
Maybe tooling to use a bottle jack with the wedges like mrriggs uses?

So what have you done, thought about, heard?
It would be wonderful if Hugh chipped in his two cents on this.
I have one crank with a bent rod that is good for experimenting.
Tried separating the flywheels of the bent rod by driving a pair of cold chisels between the flywheels that just dug grooves in the chisels, flywheels didn't budge.

It seems when pushed hard the crank likes to spread. What joint usually moves?
Ideas or measurements while the crank is still in the engine?

Thought this might become the crankshaft tech thread if the info flows in.

related thread finding keywords
connecting rod big end roller bearing ball bearing taper tig journal caged alignment hoos punkskaller 650 central rephase torque tons sprocket timing bottom end
 
When a friend and I did mine we used a 50 ton press. The new 270 center pin was tight! Welded the rod pins, but not the main center pin.

Used MikeXS bearings and the performance rod/bearings setup.(more rollers) Got the crank to about 1.5 th runout. Very pleased.

I like this method by mrriggs;

http://www.thechopperunderground.com/forum/index.php?showtopic=50055&page=2

Gary, My son drives the bike, I just built it. At times he drives like he stole it.

(replied here to help try and keep this post of yours clean)
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Over at the XS650garageusa there is a good tutorial on rebuilding a crank. This one is for a rephrase but the rebuild is the same just don't do the rephrase part.
It's in the modified engine section. I think mashermoto authored the thread.
Your 12 ton my do it but the spring of alight press will effect the reassembly. A heavier press with less spring will be more predictable when assembling.
As you press things together the press expands and when the parts move, some times more sometimes less. A light press as you pump the lever to press the parts the frame stretches. You keep pumping and when the part moves it moves in a large jump as the frame comes back to the way it was. This big jump in movement is hard to control. Lets say you have the flywheels with in .015 of spec. Your light press might jump .025 because of the frame stretch. A heavy press with a stronger frame won't flex at all or very little. You might get a movement with each handle pump. Each handle pump may give you a .001 in movement. It will be easier to set the clearance.
The distance between the frame rails won't matter. You use a section of steel pipe large enough to slide the crank through. Cut a slot part of the way down the side for rod clearance. A flat piece of steel about 1/2 thick bigger than the pipe with a slot cut for rod clearance.
Deep well sockets make good push pins. They come in many sizes and you can find one just the right size to match pins.
Set the pipe on the frame rails Slide the crank in the pipe with the rod hanging out the slot. Slip the notched plate in the crank so it supports the flywheel. Press out the pin.
This is basically now they come apart. Reverse to assemble.
I have done it on two cranks. One to stock specs, a second for a rephrase. The hard part was truing the crank. You need a set of vee blocks or use the lower case.
Set the crank in the vee blocks or case, use dial indicators to check runout. If not in spec mark the flywheels where you plan to hit them. Lift out, set on floor. Use a LEAD head hammer. Maybe a dead blow will work, NO steel hammers, they will dent the flywheels. Whack it few times in the way you think will move the flywheels to correct the runout. return to the vee blocks. check runout, repeat as needed to get the crank true. The crank isn't really heavy till you lift off the floor back to the vee blocks 20 to 30 times.
The second or third time you get better at determining just where and how hard to hit the flywheels to get them to move the amount you want.
Will I ever do it again, probably not. It was a good experience to learn the process but I learned to respect crank builders a lot more than I did. Hugh will get my business now.
I think if you want to, go for it. It will help you to better understand your engine.
Leo
 
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I don't recall the numbers exactly but the rephrase I got to .0001 on one side about .0006 on the other. My regular crank I got about .0008 0n one end and .0006 on the other. The max is .0012 inch
Mine was a 75 crank, the rephrase was on a 79 crank. I think the 79 crank was better to start with than my 75 crank. It was closer to true before the rebuild than the 75 was.
I'm pleased with the results. The closer you get the runout the smoother the engine will be.
In my 70-74 Yamaha factory book it explains how to tear a crank down and rebuild it.
Over at the Garage I posted to the crank rebuild thread to bring it up to the top of the list. Under Engine, modified engines.
They also have a lot of the factory books for download. Under General Discussion, General board, thread Factory Combined Service Manual 70-74. This has the factory crank rebuild procedure. Page 58 in my book starts talking about the crank, Page 60 starts the tear down and rebuild.
Leo
 
Leo any issues with cranks walking apart for you? Do you run em hard? I am starting to think this is fairly common if the motors are used hard. Thanks for the book ref, I'll go look in the early book. toss in the garage link?
 
Walking crank, not so far as I can tell. I didn't weld it. I don't baby it but I don't pretend to be in a race all the time as some do.
I'm not computer literate enough to know how to do links.
http://xs650temp.proboards.com should get you to the Garage.
Once there scroll down to Engines, click on the modified engines in yellow, scroll down to find the Building a 277 re-phased crankshaft.
It starts with a few false starts but gets into the crank rebuild after a bit. To do a 360 crank just don't recut the notch for the re-phase. You'll understand that as you read the thread.
Leo
 
I found this guide from Alpha Bearings very helpful.

http://homepage.ntlworld.com/david.gibbison/v-tec/Files/Alphacrankreconditioning.pdf

I assembled a jig and it works well.

As others have said trueing the crank is time consuming.

With regard to welding the crank I have a rephased motor that has done 8000 pretty hard km. It is not welded, on the advice of a local tuner and racer. His opinion was don't weld the crank if the pins in the wheels are too loose get oversized pins made, once you weld the crank its game over when that one needs rebuilding.

However in the US where XS engines are so numerous you are almost tripping over them it might not be such a concern.
 
gggGary, glad you started this thread, a place to put all the crankshaft overhaul info.

I've done some jap single cylinder and Harley v-twin cranks, but never twins. Been collecting tooling and info for this, so I'll share.

These threads have some excellent info and pics from our top-tier members:

http://www.xs650.com/forum/showthread.php?t=12390
http://www.xs650.com/forum/showthread.php?t=21710
http://www.xs650.com/forum/showthread.php?t=23581

And Hugh's writeup:

http://www.bikermetric.com/techtips/

Several years ago I acquired a Cummins 20 ton press. The hand pump and press cylinder are separated, the press cylinder can slide across to a desired position, and there's a large pressure guage mounted atop the press cylinder. Made a 'tonnage' readout ring for the guage. If anybody has one of these presses, and wants a 'tons' ring for the guage, let me know and I'll attach a suitable printable pic to this post.

A caution about these cheap press arbor plates. They're castings, poor surfaces, and will break. Several folks have been seriously injured using these.

This outfit offers a pair of stout arbor plates:
http://www.undercoverfab.com/fabrication-tools/146-ucf-arbor-press-plates.html

The attached pics show these plates, plus some cheaper cast units, and bearing puller plates.
 

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I grabbed two of the most random nuts and bolts just to see what I was up against and lucky for me it split right open. One thing I did learn that might be useful is when pressing out the rod pins, block up the opposing side. without the spacer I think it binds making it extremely hard to remove. I used a 12 ton press from HF and it came fairly easy.

IMG_0675_zps96aca2e5.jpg
 
I have done over the years many dirt bike cranks and done a few HD stroker cranks but never did a twin. I have done some race cranks that went into a GS1100 and had somewhat good luck and do Hayabusa cranks now. The only thing that I can add to this is the balance of the crank and if you have no way to tell if its TRUE the vibration at high RPM's are going to cause you a problem. Most 650 don't rev high and I get the rephrase to take out some vibration but unless you have the proper tools I would just send it to someone like HUGH. I get it that you want to try this in your garage and say I did it but have you ever seen what damage there is when a crank lets loose and comes threw the cases.
If I was going to do this I would spend the money to take it to a GOOD speed shop and have it balanced. Again never did one so I can't say for sure it will walk apart or vibrate your teeth out of your head but I have done enough to know it has to be 98% perfect or you will feel it. I will add this also two years ago I put a small turbo on one of these motors to see what it could take and the whistle noise that came from the crank at 11 pounds of boost was scary. I have run 21 pounds of boost on a KZ1000 and never heard that. Put that same crank in another build still running today. So my point is that crank may have come out of balance at high tork and not on stock.
Twomany
Keep me informed on what you do find because I would like to do another turbo motor. I think it would look cool with a 5" frame stretch with turbo inside frame.
Good luck guys.......Leo good info as always.............Gary keep the post coming great info
Be good but be SAFE!!!:thumbsup:
 
I've accumulated all the parts and pieces to split cranks but haven't "got r done" yet.
50 ton press, a chunk O big ass well pipe, press plates etc.
 
Again my concern would be the correct balance after it was put back together. 6 ton press is still enough to put the pin in wrong. As much as I read and not a lot on the XS 650 crank aren't the newer pins lighter. Good person to pic his brain would be Hugh he does them like a Ford assembly line if you ever seen pictures of his shop. There has to be a proper way or jig???? to do it right every time. Like I said before I have done cranks but most of the motors I build spin faster than 12,000 rpm and they have to be knife cut and balanced to get max performance. Some cranks I have used only lasted a dozen runs at $3000.00 a crank that sucks others I get a full season with close to 100 runs. The cranks I do we want them to spin free easy and cut threw the oil with less resistance and be lighter. I would think that would be a goal on a XS 650 crank. Motors that spin easy run better in my experience. Maybe they are easy to split.... throw in the new pin and be done but I don't think so and I could be wrong.
ANYBODY! do one and have worst luck with vibration? I have done a lot of damage with a 1 ton press so 6 tons or more I may press the crank threw to china.LOL
 
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