Crankshaft assembly jig

Bruce372
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Bruce372 2/26/2015 8:47pm
2/26/2015 8:47pm
cool stuff guys!!!

hey southwick, are you the guy that posted on facebook regarding machining rm250 cases so the cylinder clamps correctly???
southwick_mx 2/27/2015 6:44am
2/27/2015 6:44am
Bruce372 wrote:
cool stuff guys!!!

hey southwick, are you the guy that posted on facebook regarding machining rm250 cases so the cylinder clamps correctly???
Hi,

I don't know if I made comments on FB about it, but I sure just had my -05 RM250 cases blueprinted... They were off by "too much", like 0.04mm main bearing bore/cylinder mounting surface.

Engine is now finished and found a new home. Just some small stuff left till first start up of that one.



jsmx97
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jsmx97 3/17/2015 3:15pm
3/17/2015 3:15pm
DPR250R wrote:
Oh... so this... [img]http://www.chrome-addiction.com/prodimages/k-l-supply_3801-0152.jpg[/img]
Oh... so this...

slipdog wrote:
FYI for anyone reading this thread, I got one of these dirt cheap from a shop going out of business. It was unused, still in the...
FYI for anyone reading this thread, I got one of these dirt cheap from a shop going out of business. It was unused, still in the box so I figured it was a decent deal. Immediately, like I've since read on several forums, i noticed that the inserts seemed loose in the fixture as well as the inserts seemed to have a loose fit on the crankshafts as well.

So far not one crank has come out better than .004", what a POS, I can eyeball a crank with a straigh edge at .004" so why would I need a $1k jig for that???

Should have bought one from KRG...
Try it with spacers set to the measured width of the crankshaft. I've only done a few, but gotten them within .001"-.0025" first wack . It definitely isn't as precise as I hoped. I haven't done a 450 yet, I have a 12' KX450F test crank to try... I guess that will be the true test.
slipdog
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slipdog 3/17/2015 4:17pm
3/17/2015 4:17pm
jsmx97 wrote:
Try it with spacers set to the measured width of the crankshaft. I've only done a few, but gotten them within .001"-.0025" first wack . It...
Try it with spacers set to the measured width of the crankshaft. I've only done a few, but gotten them within .001"-.0025" first wack . It definitely isn't as precise as I hoped. I haven't done a 450 yet, I have a 12' KX450F test crank to try... I guess that will be the true test.
Thanks for your input, I assume you are meaning to make spacers/stoppers to place in the jig that will stop the top plate at exactly the crank width spec(e.g.'14 KX 450=64.3mm)?

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jsmx97
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jsmx97 3/18/2015 7:37am
3/18/2015 7:37am
jsmx97 wrote:
Try it with spacers set to the measured width of the crankshaft. I've only done a few, but gotten them within .001"-.0025" first wack . It...
Try it with spacers set to the measured width of the crankshaft. I've only done a few, but gotten them within .001"-.0025" first wack . It definitely isn't as precise as I hoped. I haven't done a 450 yet, I have a 12' KX450F test crank to try... I guess that will be the true test.
slipdog wrote:
Thanks for your input, I assume you are meaning to make spacers/stoppers to place in the jig that will stop the top plate at exactly the...
Thanks for your input, I assume you are meaning to make spacers/stoppers to place in the jig that will stop the top plate at exactly the crank width spec(e.g.'14 KX 450=64.3mm)?
Exactly. Obviously that doesn't eliminate issues with the collars not fitting as tight as they should, but it did help for me.
jsmx97
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jsmx97 3/18/2015 8:42am
3/18/2015 8:42am
Just pressed a cr85 crank together (obviously one of the easier ones). Initial assembly .00075" on drive side, .00175" on rotor side. Small amount of clamping opposite crank pin brought both sides under .001". Still need to do a big 4-stroke. I oil the adapters as well as the crankshaft axles before installing in Jig.
krgperformance
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krgperformance 3/18/2015 8:48am
3/18/2015 8:48am
What fixture are you using ??
jsmx97
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jsmx97 3/18/2015 8:50am
3/18/2015 8:50am
krgperformance wrote:
What fixture are you using ??
K&L. I would rather have had yours, but at the time you didn't have any and I got this one for a good deal.
southwick_mx 3/18/2015 1:03pm
3/18/2015 1:03pm
I'll chime in with a report on my crank jig adventures while the subject is up here again:

I've only pressed one crank so far, and as I wrote I was a bit disappointed at finding a 1,5/100mm runout measured between centers. Now I've measured the same crank with one end mounted to an absolute ZERO in the chuck of a very high precision lathe and I was shocked to find the result measured on the other main bearing surface..:

0,001mm runout.


Now, I am pleased! And I'll never use the center holes for measuring again, if the crank is not brand new and unmolested.

/Lasse
Slosh 112
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Slosh 112 3/18/2015 4:05pm
3/18/2015 4:05pm
This looks like a piece of crap after seeing the two jigs Southwick_mx & KRG made
FastMX.lt 1/4/2021 9:25am
1/4/2021 9:25am
I see this is old thread, but maybe someone is intrested in crank assembly jig. It will come with 4 pins, but i haven't machined crank centering spacers.

Holes CNC machined in one op, so they are spot on.
280€ including shipping in EU.
tadas@fastmx.lt



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