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Discussion Starter · #1 ·
Hi,

any one have a sensible solution to this problem, camshaft on 250 EXC 2004 has scuffed up due to the rocker bearing seizing, part number should be 598.36.010.100 but this is not longer available. Given that this bike has a 350 kit fitted will the 450/525 camshaft fit and work, any one know of any new 250 camshafts any where?

Many thanks
 

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Google people that do camshaft re-grinds, they might be able to build it up with weld and grind it back to spec.
 
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Discussion Starter · #3 ·
Google people that do camshaft re-grinds, they might be able to build it up with weld and grind it back to spec.
Many thanks, have gone through a few companies for exactly that, with no joy I'm afraid, some will not touch it because of the roller bearing the camshaft has to hit/roll against, Kent cams don't do any KTM Cam, Hotcams don't have any early upgrade cam kits, have even reached out to the USA!
 

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I'm pretty sure I remember a thread on saying the 250 cam is same as something bigger but not sure what.
590/5521 cams are still available from 450 / 525 motors. Kev might pop in past soon & confirm.
 

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Discussion Starter · #7 ·
Hi,
The problem just got worse - Any one know if you can also use the exhaust rocker arm from a 450/525 EXC/SX 2004 RFS in a 250 EXC/SX 2004, looks like the rocker bearing that hits the cam has given up and taken out the rocker arm, the 250 part number is 598.36.061.044 and is No longer available. Any idea if 590.36.061.144 will work with no issues?
 

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Sadly the 250 rockers are unique to the 250 as the valves are closer together than the larger engines. They've been obsolete for a while.
 

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Discussion Starter · #9 ·
Sadly the 250 rockers are unique to the 250 as the valves are closer together than the larger engines. They've been obsolete for a while.
Appreciate the feedback, any idea where I might get hold of a good 2nd hand one?
 

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Where is Kev when you need him?

Who's got the magic lamp?
 

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Mark, There is good going facebook group for RFS owners riders. Might be worth an ask on there.
Good luck.
 

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As has been said, the 250 rocker arms and most other head parts are unique to the 250. I have often wondered what a 350 would run like with a 400/450/525 head. I suspect the combustion chamber volume is less on the 250 so it will not have a lot of compression with a head off another RFS....
 

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I have often wondered what a 350 would run like with a 400/450/525 head. I suspect the combustion chamber volume is less on the 250 so it will not have a lot of compression with a head off another RFS....
I have seen a head that had been ground and welded to change the combustion chamber shape so that it resembles the 250 head but don't recall if it was a 450 or 250 head in the first place.
For reference a standard 250 head.
Automotive tire Rim Font Automotive wheel system Auto part
 

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Look how cupped that 250 exhaust adjuster is!
 

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Look how cupped that 250 exhaust adjuster is!
Yes, I know and that's what happens when you just rely on the 1/6th turn adjustment method without the occasional feeler gauge check. Only picked it up when refreshing the top end and had a better rocker cover and new rocker kit that went back on.
 

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Yes, I know and that's what happens when you just rely on the 1/6th turn adjustment method without the occasional feeler gauge check. Only picked it up when refreshing the top end and had a better rocker cover and new rocker kit that went back on.
Feeler gauges would give valve clearances which were way too loose due to the cupping
 

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That's what I meant, I do the 1/6th turn then check occasionally with a feeler gauge, if you can't get any feeler gauge in, there's a good bet that you have cupping and that you need to have a better look. The bike with cupped adjusters would hardly run when adjusted with a feeler gauge and was pretty noisy.
 
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