CR 500 rod replacement

[mas2de]

Got an 89 CR 500, the rod is getting kinda slappy in there. I was wondering if I can press the crank back together or if it is like professional, high precision, or just be careful. I've heard of some just pressing it and hitting it with a hammer (doesn't sound quite right to me) but I am wondering if it Has to go to the pros. I have a 55 ton press, and I was planning on actually using our big milling machine because it isn't sloppy. [Just like setting the crank vertical and pressing the other end into the arbor by cranking the table up. Or something like that]
Any help is appreciated.
Thank you
Mike

 

[julien_d]

We pressed my buddies KTM 300 crank back together with a 30 ton press. I do not recommend it. Tolerance for the crank halves is like .002" or something. Best to pay the $50 labor to the shop and have it pressed correctly, by someone with plenty of experience rebuilding crank shafts.

 

[whenfoxforks-ruled]

If you have the capabilities, and the tools? Most shops scribe a line(opposite from the low spot of the big end bearing), press it apart, press it back together, with the proper thrust washer clearance(should be in the manual), check the run out between centers, and knock it within spec,-+.002". The flywheels move on that pressed pin unbelievably easy? I send mine to Eric, he uses a special jig, it omits the .002 alignment? Personally, the next one I have done, I want it spot welded to prevent future movement out of spec. I believe it moves, backfire or some other jolt, can knock it/twist it out of spec, even not being careful putting the drive gear and rotor back on. Shorter rod life and vibration from being out of the .002 spec, I want .00000000! And the 500 has to be the worst for vibrations? A 1 ton press could probably do the job, as long as its not sloppy, its not a tight press fit.

 

[jsantapau]

some Hondas have a tin casing around the crank halves that you can't use the dial indicator and brass hammer style of aligning but I don't believe that applies to the 500.
If you have V blocks or a set of live centers, a couple of dial indicators,a brass hammer,bearing separator,feeler cauges,calipers and a press I say go for it. If you don't have 2 dial indicators it ain't worth it to buy them just for doing your own cranks. Cheap harbor frieght type indicators are useless.

as for truing them it is kind of a brain teaser trying to figure out which way you have to knock the crank to get it lined up right. You have 4 things to measure, outside dimension of the crank bells (so the crank fits in the cases and is supported by the main bearings in the right place),connecting rod thrust clearance(so oil can flow to the bearing without excessive slop). Those two are dependent upon each other and if you measured the outside before you started and press to those dimensions the thrust dimension will usually fall into place, if it doesn't you have to find the best compromise between the two.

Then there is what I would call phased where the centerline of the crank halves are in the correct degree of rotation with the centerline of the rod pin. If the crank is supported by live centers on the outsides and you have the dial indicators on the main bearing surface the dial indicators will sweep in the same direction at different times.
Then there is a V'ed wobble when the Phase may be correct but the crank halves are not parrallel to each other having an imaginary v instead of a straight line thru the centeline of the crank halves. This will show up on the dial indicators as the sweeps imitating each other.
Those two must be kept as close to perfect as possible, with .001" being the standard maximum, I have built my own cranks as far out as .004" but you can just tell the bike isn't as clean and tight feeling and you will be going thru pistons and bearings quicker.I have seen brand new cranks come from the manufacture at .008 being knocked around in the lousy packaging so double check even if you send it out.


what I do is to press the pin into one 1/2 crank home, assemble thrust washers,bearings and rod and other crank half, start pressing the assembly together using a square to get you close, when you have the second half pressed on only about a 1/2" or so take it out of the press and get it as close to phased a possible by knocking it with a brass hammer(easier to spin the crank half around the rod pin if it is only half way in compared to all the way pressed). do the final presssing to outside dimensions,double check thrust clearance of the rod, check and adjust phase and wobble, triple check thrust clearance and O.D. If you have to make any adjustments go back to the previous step.

 

[mas2de]

Thank you guys. This should help alot. We may just send it out for the $90 for the pressing and another $90 for the Hot Rod. With my dad's stupidvision :) we could probably do it right but he doesn't need that bother.
Mike