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Old 07-21-2005, 11:14 AM
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Default how do you press crankshaft halfs together?

Ok, everyone is telling me to have a dealer do it, but i bought the bike (little 80cc) for only $50 and the dealer wants to charge me $120 to change the main bearing + parts. So i want to do it myself. I have a press and a V-block and a dial indicator, so i think that i have the tools to do it, but i dont have the knowledge. Can anyone one point me to a website, or tell me how its done?
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Old 07-21-2005, 11:15 AM
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Default Re: how do you press crankshaft halfs together?

Click Here.
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Old 07-21-2005, 11:30 AM
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Default Re: how do you press crankshaft halfs together?

ok, i still dont get it. What do they mean by the whole shimming thing? See i did it they way that i thought it should be done, but during reasembly the crank binds in the cases, and if i spin it while in the case (case is not all the way together, about 3/4 inch apart) one case moves with the crank, showing that it is not perfectly "true"?
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Old 07-21-2005, 11:35 AM
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Default Re: how do you press crankshaft halfs together?

Sound like your crank is bent....... use your dial quage and do a run-out test. I guess there was a reason the bike was only $50.
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Old 07-21-2005, 11:39 AM
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Default Re: how do you press crankshaft halfs together?

do you think that the crank is bent, or could i just have put the two halfs together wrong?
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Old 07-21-2005, 01:48 PM
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Default Re: how do you press crankshaft halfs together?

Quote:
Originally Posted by soccer2963
do you think that the crank is bent, or could i just have put the two halfs together wrong?
.

You said the case moves with the crank, is it a wobble? The crank should not have any movement other than rotation.
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Old 07-24-2005, 09:46 PM
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Default Re: how do you press crankshaft halfs together?

Your may be better off just buying a complete crank for $160 or having your dealer true the crank for you.

Truing a crank is not a job for the less expereinced. Your's is obviously not correct ("true") right now. It needs to be perfect or it's a grenade. A crank can be close enough to let you assemble the cases and be far enough out to go boom real quick.

As faded's link shows...
Shimming, is to center the crank in the cases while reassembling the cases.

Good luck.

Ian
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Old 07-24-2005, 10:01 PM
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Default Re: how do you press crankshaft halfs together?

i will i could buy a new crank for $160, but no one sells this old of a crank 1985. and the dealer wants $240 for a new crank assembly.
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Old 07-24-2005, 10:34 PM
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Default Re: how do you press crankshaft halfs together?

Whats the bikes make and model?
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Old 07-25-2005, 06:22 AM
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Default Re: how do you press crankshaft halfs together?

You may be best off finding a local mechanic that knows his stuff. Or contact some of the online guru's

I'd recommend this
[Only registered and activated users can see links. ] Very well known and reputable 2 race engine builder.
Contact them and ask what it will cost and lead time to true a crank.

Or ask your dealer what the difference is between an '86 crank and an '85. If nothing, check this out.
[Only registered and activated users can see links. ]

Sometimes the the years listed on parts does not cover all of the applications that it will fit.
From a few minutes of searching it seems that the crank has not changed since the late 80's

Good luck

Ian
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Old 07-25-2005, 10:57 AM
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Default Re: how do you press crankshaft halfs together?

one of the fastest ways to build a truing stand isnt really to built it, but to borrow a lathe that has two "live ends". if you havent had to do some tapping to get it into alignment (where runout on the bearing surface is less than .001" for best results) then it is definitely out of alignment (what some mistakenly refer to as balance, because it wont balance either if out of alignment). A brass hammer is of about 10 oz is suitable for most aligning.

got access to a lathe?
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