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Harleydavidson

may the lord help my mechanic soul

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learned i gotta split the cases on my kx250 to replace crank seals was wonderin best way to get them to split got another kx250 engine that threw a rod in 2020 still in the junk pile cause the cases would not split broke 2 pullers on it took it to a shop and then they couldn't was told kx250s are hard to split and technique to get em apart also doing crank bearings while i'm in there i know put the case in the oven and bearing in the feezer to get then in, but what about out, just beat them?

 

 

 

 

EDIT: just noticed should've put this in motorcycles but technically is a quad since the frame

Edited by Harleydavidson

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I use a case serperation tool like this one. Screws into the holes in the case halves and pushes against the end of the crank.

 

Screenshot_20221027-204555_Amazon Shopping.jpg

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1 hour ago, SlammedRanger said:

I use a case serperation tool like this one. Screws into the holes in the case halves and pushes against the end of the crank.

 

Screenshot_20221027-204555_Amazon Shopping.jpg

I’ll try again that’s one I broke

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22 minutes ago, Harleydavidson said:

I’ll try again that’s one I broke

You can add alittle heat to the casting around the bearings. But dont go crazy. The cast should expand at a way faster rate than the hardened material the bearings are made of. I would put some pressure on it with the seperator and heat it gently. It will probably start popping and moving little by little.

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On most cases there are hollow steel dowels at the very rear and possibly front, Heat that area with some pressure on the seperator tool and with right side down crack the counter shaft with a plastic dead blow hammer.   

They all come apart just did a KX250 last week new main bearings and seals and rebuilt the crankshaft with new rod, pin, bearing and spacers!     Good Luck !

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Well after the catastrophe the cylinder was now some idiot put JB WELD on the cases

 

 

 

update: it’s only in one little spot so not as bad

Edited by Harleydavidson

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Victory folks I got it apart now I just gotta get the parts ordered 

9D9A9528-30AA-4C4C-8CCB-9CBAB2231CA2.jpeg

Edited by Harleydavidson
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parts came in today got the right side seal and bearing in gotta go pick my left case up from the shop had to get the stator off to get the bearing out and the screws were stuck pretty good in  a few days she should be running

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Should go on with no problem. Sometimes the seal is a bit tight a little lube and a tap or two should do it.

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Got that stuff back on now the left bearing gets really tight if I put the case back together if I leave probably 4mm of space it’s fine but tighten it the crank barely moves

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4mm is a lot of gap, did you replace/get the correct bearings? If it was 1mm or less I would just say a bearing wasn't completely seated and usually a couple taps on the crankshaft (protecting it of course) will get everything in place and moving freely. That much gap I would double check stuff.

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Is the crankshaft centered in the case ?   I take a feeler gauge to both sides and center them.  I do have a press.  Though as to deep said are You sure the main bearings were completely seated ?

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Been a hot minute since an update but I figured out why it got tight the right bearing wasn’t seated all the way got it fixed now just gotta wait in parts

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Looks like You have some gouges and worn nikasil on the exhaust port and some aluminum stuck to the nikasil on the intake side. Does not look pretty.  What does the piston look like ?

Muriatic acid removes aluminum from nikasil plating.

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1 hour ago, oldmxrider said:

What did You end up doing with it?

Bought a new cylinder for $150 haven’t had time to put the engine back in but I got it together 

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