Interchangable parts?

[CR480R]

I mean that its already pressed together and the crank wheels are out of true in several directions... After messing with it for over an hour and it is still .006" out... Its hard to imagine, but the crank pin can press in crooked.. I used some v-blocks clamped to the crank while pressing, but its not even close to accurate enough for this kinda work... Its not even worth trying without the proper fixture...

[ihampson]

Can you buy fixtures or do you have to make one? i have never seen one before. Must be frustrating as you are only of by a fraction but that small amount can  be significant at high revs.
precision engineering - easy with the right tools, a guessing game without!
what i`d give to have my own work shop!!!!!

[CR480R]

Actually I may just re-press it... Last night a guy I know here in town offered to let me borrow his pressing fixture, He used to race motocross and run a small engine repair business... I hope it works, he said it works good and they usually press very close to true.... I noticed that my new crank pin fits tighter into one crank wheel than the other. The press I was using had a pressure guage and one half took 12tons to press and the other less than 8tons... So if I get this thing trued I am definately having my buddy weld the pin..

[stewart]

i would not weld the pin,, the pin is diffrent than the counter wieght matirel and its a single throw,,, crank springs the hollow rod  pin smaller about .005 thousanths in diameter to hold it in place ... takes the right fixture to get perfect ,,,,,,,,,,,,,,,,,,,,,,,,,,,, check run out thread cr 480,,,

[CR480R]

Thanks for the input stewart That is basically how I have been checking mine(I got the idea from your thread), my main problem is the pin wasnt pressed straight so I was of out of clock on the wheels and also crooked on the pin... Thanks for the heads up on the welded pin, it makes sense that a single throw crank wouldnt need it anyways... I am going to start over using a pressing fixture, hopefully It gets me close enough that I can get it true...

[don46]

Yeah pressing the crank myself with out a proper fixture has turned into a mess... its almost within specs, but I am having trouble getting the wheels to move with any sort of control.... If I dont get it dialed in soon I may end up just buying a new one

How are you trying to move the wheels? A nice heavy brass hammer works well, you have to get a bit viscious at times.

[BDI]

When I true a crank I use a copper hammer because it is less likely to dent the crank weights then a brass hammer. I hold the crank in one hand and hit the weight that is out of clock with the hammer and then set it back in the V-blocks and check it. It is very hard for a pin to be pressed in crooked from my experience.

[don46]

When I true a crank I use a copper hammer because it is less likely to dent the crank weights then a brass hammer. I hold the crank in one hand and hit the weight that is out of clock with the hammer and then set it back in the V-blocks and check it. It is very hard for a pin to be pressed in crooked from my experience.

I would agree, if the pin were to be crooked you would notice damage either to the counter weight or the pin, and the pin is soooo hard don't think it would happen.

[CR480R]

How are you trying to move the wheels? A nice heavy brass hammer works well, you have to get a bit viscious at times.

my wheels were .030 out of clock initially and It doesnt seem to like to move that much...It was easy to get a couple thousandths out of it, but the more it moves the harder it gets to move... Maybe my hammer wasnt heavy enough? I was getting some pretty good whacks with it though... I was afraid I was gonna knock the crank out of the soft-jaws in my vice

I would agree, if the pin were to be crooked you would notice damage either to the counter weight or the pin, and the pin is soooo hard don't think it would happen.

I should probably get a new crank then. There may be somethin wrong with one of my crank wheels. I had .002 runout directly over the pin when I first checked the wheels after pressing.. and the pin pressed much easier into one side..  8ton vs. 12ton..

[don46]

I should probably get a new crank then. There may be somethin wrong with one of my crank wheels. I had .003 runout directly over the pin when I first checked the wheels after pressing.. and the pin pressed much easier in one side 8ton vs. 12ton..

Not sure what your measuring over the pin, do you have a dial indicator on the crank wheel? It would not suprise me that they would be off .003. I think Stewart was chucking them up and truing them, but the measurements you need to be concerned with are on the bearing surfaces, I have a set of ways with precision bearings that I use, but them I've used V blocks and Lathe centers as well.

Thinking about it, the crank wheels do have a center on the inside, so they could be chucked up and trued to the rotating points, that would probably help make the motor run smoother than just truing the crank.

Stewart, are you truing the crank wheels in a lathe?

[CR480R]

Not sure what your measuring over the pin, do you have a dial indicator on the crank wheel? It would not suprise me that they would be off .003. I think Stewart was chucking them up and truing them, but the measurements you need to be concerned with are on the bearing surfaces, I have a set of ways with precision bearings that I use, but them I've used V blocks and Lathe centers as well.

Yeah i am using a dial indicator to measure.. With the dial indicator on the o.d. of the crank wheels one at a time there is very little runout.. maybe a .0005... so I know the pin is not in right... If it were simply out of clock 90degrees from the pin I would already have it trued... this crank is messed up.. I am gonna take it apart and try again...

Stewart, are you truing the crank wheels in a lathe?

I bet it takes some kind of grinder to remove the hard material that the cranks are made from

[BDI]

If you don't mind hearing my two cents I would not take it back apart you can spread the crank by wedging something between the counter weights or you can go the other way by putting the counter weights in your vice with the soft jaws and giving it a squeeze.

[CR480R]

If you don't mind hearing my two cents I would not take it back apart you can spread the crank by wedging something between the counter weights or you can go the other way by putting the counter weights in your vice with the soft jaws and giving it a squeeze.

I dont mind at all... I will give that a try first... thanks for the suggestion

[ihampson]

Any luck with that crank cr480? I`m having some trouble splitting the crank cases on my kx. it seems to be stuck on the crank on the ignition side. I`m using a puller and have looked all around and cant find any bolts clips etc that would stop them coming apart.

Could the bearing be siezed on the crank and in the case? It doesnt apper to have been taken apart for a while.

Is there a hidden away clip somewhere or do i just keep tightening the puller?
dont wanna strip the threads or damage anything by going too tight. I have made another post "splitting cases?" that goes into more detail.

Any of you guys got any advise?

[CR480R]

Any luck with that crank cr480? I`m having some trouble splitting the crank cases on my kx. it seems to be stuck on the crank on the ignition side. I`m using a puller and have looked all around and cant find any bolts clips etc that would stop them coming apart.

I havent had a chance to work on the crank again... its at my buddies shop and he's been away... As for the splitting the case mine have always came right apart with gentle taps with a rubber mallet.. Are you sure you have all the bolts out?