400 with a 520 Piston/Cylinder

trewent

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#1
Have any KTM 400 owners replaced their piston/cylinder with that from the 520? Or better to just turn the 400 and get the 520? The displacement calcs out to 454 using the stock 400 stroke.
 

Shaw520

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#2
The stock parts are not interchangable, the 520 cylinder has a longer stroke than the 400 crank, so it wont work.
Although, there are a few people on hear punching out there 400's to 450's.
Might want to do a search in this forum and find the thread, from there you will contact the person invloved via IM or e-mail.
 
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#3
The stock parts are interchangeable. You can use a 520 cylinder & piston with a 400 crank!
I just converted my 400 into a 540 ( KTM hard equipment ) but I had to install a 520 crankshaft. If it turns out I don't like that combination, I'm going to try that 454 combination by putting in the 400 crank. Sooo.... stay tuned:)

PS.. the 454 combo should be a revver!!
 
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trewent

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#4
Old Stroker,

Please let me know how it works!

What do figure the P/C & misc parts would run?

Thanks!

Trewent
 

Shaw520

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#5
Stroker. With a 520 crank installed, you bsically have a 520, but with the 400 crank (64mm stroke) in a 520 cylinder that has a stroke of (72mm),....... Sounds like some major machining going on!!??:eek:
 
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#6
Shaw520
All the cylinders, 400, 520, & 540, are the same in physical demensions. The bore is the only difference. No machining is necessary. You can run any combination of bore & stroke you want.
 
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#7
trewent

To convert your 400 into a 540 will cost you about $1800.
$1250 for the 540 kit
$350 for a 520 cranshaft
$110 for a 520 camshaft
$90 for gaskets & misc.
 

Shaw520

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#8
Stroker, forgive me asking these 'stupid' questions but; installing a 520 piston/cylinder on a 400 crank, with the 400 stroke being 8mm shorter, wouldnt that reduce compression too much? :think
 
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#9
Shaw520
The 8mm shorter stroke has nothing to do with the compression. The piston still comes to the top of the cylinder.
 

BCR-Bob

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#10
Old Stroker, I assume then that you have to put in a diff length rod then right?

The reason I ask is that KTM has different part numbers for the 400 and 520 rods.
 
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BCR-Bob

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#11
Never mind Old Stroker, I figured it out. Must have had my head somewhere else than my shoulders.

The 454 combo sounds very interesting.
 
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#12
BCR-Bob
I wouldn't replace the rod because I want the stroke of the 400.( they are different length rods ) But after thinking about it:think I would have to have a piston made. I checked the pin location on the 400 ( vs ) 520/540 and the 400 is 4mm lower ( measuring from the top of the piston to the center of the pin )
 

BCR-Bob

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#14
I was wondering about the pin locations but just figured that if they made two diff length rods that they would leave the pin locations the same between the two pistons. Would have made the whole thing a lot easier huh?
 

Shaw520

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#15
Cylinder length being the same, w/different stroke, the pin location would have to be different to achieve proper compression.