[stipa]

Has anyone here had any exposure to the CMW "blueprinted" crankshaft assembly?  Or especially the ALPHA big end bearing and pin?  Doing some crankshaft teardown/reconditioning and thinking I might just go with a whole new enchilada. 
It sounds like a really nice assembly, a little more refined than stock. 
Been trying to keep this low-ball and close to stock, but, uh....it's gonna start getting away from me now I think. 

Steve

[clamp]

Theres always something to spend your money on. I would think stock is good enough for a 18HP engine.

[cyrusb]

Did your crankpin break too? If you have access to a decent lathe you can just replace the broken part and "blueprint" it yourself. As Clamp says, that crank is good enough for the horsepower, it just has to run true to survive.

[stipa]

Did your crankpin break too? If you have access to a decent lathe you can just replace the broken part and "blueprint" it yourself. As Clamp says, that crank is good enough for the horsepower, it just has to run true to survive.

I have a decent lathe, (South Bend 9" ),  and access to good turning stock, but it would take me all day to set up to cut the threads, if I could at all.  I don't know what steel that part is;  I have some old Cooper-Bessemer exhaust valves (1.3" dia.), that would work I'm sure, (pin dia. is 1.263), but I think the new OEM part is no more than 50 bucks anyway. 
Also, the right (timing) side wheel suffered small cracks (a couple chunks fell out), the entire periphery of the pin boss.  That'll either be a overbore with an insert, or reweld and rebore.  Ugh. 
I would really like to learn how to balance a crankshaft though. 

[cyrusb]

Ah, there is a misunderstanding, I refer to buying the parts and using the lathe for alignment. Normally a truing stand (adjustable dead centers) would be used for this but a decent lathe will work also. This is not covered in any of the RE manuals that i have seen,but if you get a hold of some Harley bottom end info it would suffice. It's pretty straight foreward, the assembly should run true on all axes,while rotating between centers. This is usually done by slowly tightening the crankpin nuts while indicating the runout of the assembly,until the nuts are at the recomended torque. Dont be afraid to hit it!!(see harley info it's amazingly brutal)

[stipa]

Ahh, unagi!!  Yeah, my misunderstanding;  wasn't thinking too clearly anyway at 5 in the morning. Arthritis woke me up around 1 and I was waiting for the Ibuprofin to kick in.
I will definitely start looking at the Harley stuff.  I wonder what the torque on that 500 crankpin is anyway?  All of the manuals are pretty vague on that. 
When I broke them free, I would estimate they were no more than 120 ft/lbs. though.  Came pretty easy with a socket and a 15" breaker bar. 

Thanks for the heads up.

Steve

[SRL790]

I rebuilt my own using the roller bearing kit.  Not sure if thats the ALPHA or not.

Didn't have a lathe at the time so just screwed two sturdy brackets to my work bench, hung it between a couple of centers with screw threads for adjustment (cut a taper on the end of a couple of stainless steel concrete anchors) and proceded to whack it with a hide mallet while checking with a dial indicator.  Didn't take that long and ended up way truer than before I took it apart.

[clamp]

Yup --you hit it with a big lump of wood,--great fun.

   Has anyone thought of cutting the crank pin to an eccentric shape. Only a few thou say .005 this would increase compression ration a proper way by increasing swept volume.  Instead of just slicing a bit off the head which increase C ratio but decreases by the same amount cylinder volume.

   Increasing the throw of the crank pin by 005 would mean the piston goes down 005 further and up 005 further.      Would make a difference!!!

[stipa]

Ah, there is a misunderstanding, I refer to buying the parts and using the lathe for alignment. Normally a truing stand (adjustable dead centers) would be used for this but a decent lathe will work also. This is not covered in any of the RE manuals that i have seen,but if you get a hold of some Harley bottom end info it would suffice. It's pretty straight foreward, the assembly should run true on all axes,while rotating between centers. This is usually done by slowly tightening the crankpin nuts while indicating the runout of the assembly,until the nuts are at the recomended torque. Dont be afraid to hit it!!(see harley info it's amazingly brutal)

I would think then I should be able to counterbore the crankpin hole (right side wheel), to clear the cracks away, then re-weld with something modest, (7018?),  rebore to a couple thous. of original, then ream?  Yahoo, farm engineering!!
I don't think CMW would give me much for an exchange on the flywheel anyway;  the cost to send it out for the repair would probably justify the scrap bucket?
I think I could do this if I heated the entire piece to a couple hundred degrees, then a quick pass with the rod. 
Does anyone know if the flywheels are some exotic un-obtanium, or just a cast steel?

Thanks, Steve

[clamp]

That could easily be done here in Malaysia and Thailand they are masters at this stuff, engines never die here.

       I think that what 'they' would do would be to machine out the cracks and push in a bush, then ream. Welding is not good.  Welding is capable of distorting some amazingly thick peices.

[cyrusb]

Cracked flywheel? UGH, I don't know, that might not be worth fixing. And the cracks being(of course ) right at the pin bore is pretty scary. I guess if there were no other parts available it would be worth a try. The bright side is your cases survived. Right?

[Eric911]

Hey now, I like the idea of offset grinding the new crankpin some. That would give more comperssion and a few more cc's also, by increasing the stroke. I wonder how far one could go and how much weight would have to be removed from the pin side of the assembly to compensate for the mass of rod and piston being further "out" on the wheels. I too have access to a lathe and I can see alot of steel shavings in my future... I shouldn't be allowed to read ideas like this.

[cyrusb]

You know this might have been mentioned  previously but  I think it's good advice for everybody to check their crank runout at their next service. Peek in the quill bolt hole and kick the bike over(spark plug out) and look for runout. Do the same on the primary side at the alternator. If visually detectable runout is there, it's only a matter of time before something breaks. Remember, really bad runout can shear off the quill bolt oil tube, so thats the magnitude of runout we are talking about. Catching it early is key to keeping this an inconvenience instead of  a total disaster.  Since there is virtually no data on this issue, I can tell you that my crank runs with no visual runout, and probably one or two mils if I could get an indicator in there. Now I'll wait and see...

[clamp]

 Run out so bad that it could be seen would be horrendous misalignment!!


   A couple of mills? ----------    A couple of thou !!!!

[cyrusb]

same thing