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I have to replace the cases on my 98 rmx 250 (stupid crank bearing) was wondering what years will fit. I see on ebay some say down to 94 and some say 95 any help is appreciated.

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Have you stripped your engine down yet?

 

There are several different crank types for the RMX, and you need to know exactly what type you have as the main bearings are specific to the crank and cases.

This means that not all RMX casings are interchangeable.

First step is find out exactly what you have before buying different cases that may not be compatible with your crank.

IIRC the flywheel side main bearing stays the same size through all the years, but the primary drive side varies from small to large, back to small again.

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Are both your main bearings the same dimensions or are they different sizes?

 

Does the crank have aluminium "stuffers" on each halve either side of the conrod?

Edited by rmxdan

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I believe that all of the US model RMX's used the same crank cases.  We only had one RMX-250 model.

 

Post a picture of the damage, it's been a long time since I've seen a destroyed case due to a main bearing failure.

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Zig, I double checked and there are various differences between the models over the years. As we know the RMX did get upside down forks and latterly switched to the Showa conventional type so some things definitely change.

 

Engine wise, if the OP's 98 model crank has a nut rather than a bolt holding on the primary drive gear that would suggest there was no change over the years from the original K model, but I suspect the RMX engine did have changes over the production run, and components such as the powervalve parts also change.

So OP needs to check this carefully.

 

The pics in the following links are actually very detailed and not just generic images. You can see the various differences in crank designs quite clearly. The main bearings #13 and #14 are dimensionally different. Some years used the same bearing both sides, others did not.

 

K crank

http://www.ronniesmailorder.com/oemparts/a/suz/50d38d78f8700229982f26b7/crankshaft-model-k

 

L,M,N crank

http://www.ronniesmailorder.com/oemparts/a/suz/50d38d78f8700229982f26b8/crankshaft-model-l-m-n

 

P,R crank

http://www.ronniesmailorder.com/oemparts/a/suz/50d38d78f8700229982f26b9/crankshaft-model-p-r

 

S,T crank

http://www.ronniesmailorder.com/oemparts/a/suz/50d38d79f8700229982f26ba/crankshaft-model-s-t

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Zig, I double checked and there are various differences between the models over the years. As we know the RMX did get upside down forks and latterly switched to the Showa conventional type so some things definitely change.

 

Engine wise, if the OP's 98 model crank has a nut rather than a bolt holding on the primary drive gear that would suggest there was no change over the years from the original K model, but I suspect the RMX engine did have changes over the production run, and components such as the powervalve parts also change.

So OP needs to check this carefully.

 

The pics in the following links are actually very detailed and not just generic images. You can see the various differences in crank designs quite clearly. The main bearings #13 and #14 are dimensionally different. Some years used the same bearing both sides, others did not.

 

K crank

http://www.ronniesmailorder.com/oemparts/a/suz/50d38d78f8700229982f26b7/crankshaft-model-k

 

L,M,N crank

http://www.ronniesmailorder.com/oemparts/a/suz/50d38d78f8700229982f26b8/crankshaft-model-l-m-n

 

P,R crank

http://www.ronniesmailorder.com/oemparts/a/suz/50d38d78f8700229982f26b9/crankshaft-model-p-r

 

S,T crank

http://www.ronniesmailorder.com/oemparts/a/suz/50d38d79f8700229982f26ba/crankshaft-model-s-t

 

Hey Dan, you are correct in that the US models changed over that period (like the forks), but the parts are backwards compatible.  Like if you had a complete '97 front end (triples included) it would bolt onto our first year RMX ('89).  Same deal with the engine parts, even though the part numbers changed slightly it mostly showed that it was updated but will still work with the older models.

 

Can't find a crank listing but Wiesco only has one standard piston for the entire RMX250 line ('89 thru '99) which actually covers models sold beyond it being discontinued in the US.  This shows that bore and stroke never changed for us, although the early cylinders had a smaller exhaust port (changed around '92).  Same for the powervalves all being the same (although the early models did have a travel limiter).  I can say that pipes changed over the years too.  That just means that if you bought a '97 cylinder for your '89 RMX then you'd also need a '92 or newer pipe and silencer.  Which is actually a pretty cool thing about RMX's, you can mix and match parts to build it into what you want ~ or just bring back and old steed because parts are easy to get (just not very cheap ~ aka "power valves").

 

So to the OP, I still believe that any US market RMX case ('89 thru '97) can replace your damaged ones.

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Hey Dan, you are correct in that the US models changed over that period (like the forks), but the parts are backwards compatible.  Like if you had a complete '97 front end (triples included) it would bolt onto our first year RMX ('89).  Same deal with the engine parts, even though the part numbers changed slightly it mostly showed that it was updated but will still work with the older models.

 

Can't find a crank listing but Wiesco only has one standard piston for the entire RMX250 line ('89 thru '99) which actually covers models sold beyond it being discontinued in the US.  This shows that bore and stroke never changed for us, although the early cylinders had a smaller exhaust port (changed around '92).  Same for the powervalves all being the same (although the early models did have a travel limiter).  I can say that pipes changed over the years too.  That just means that if you bought a '97 cylinder for your '89 RMX then you'd also need a '92 or newer pipe and silencer.  Which is actually a pretty cool thing about RMX's, you can mix and match parts to build it into what you want ~ or just bring back and old steed because parts are easy to get (just not very cheap ~ aka "power valves").

 

So to the OP, I still believe that any US market RMX case ('89 thru '97) can replace your damaged ones.

 

It's correct that some specific parts will fit all models. But not all parts fit all models.

You can't fit all RMX cranks in all the RMX cases. Check out the dimensions of the main bearings in the links. The primary drive side on certain models differs in ID, OD, and width, and therefore they will not fit in certain cases.

 

I've picked up both L,M,N and P,R type engines for spares for my own S,T model bike. I can see the differences first hand. Hence why I 100% know the pics of the cranks in the links provided are a very true representation of what is actually fitted to the engines.

 

If the OP's crank has aluminium stuffers held on by 5mm allen headed bolts it comes from an engine that uses the same size main bearings on both sides. Therefore he needs casings that take the 68mm OD bearing on the primary drive side. A 68mm OD bearing will not fit in a case designed to take a 62mm OD bearing, and that issue is still present if a 62mm OD bearing is fitted to a case designed for a 68mm OD bearing.

 

Which raises the question, is that possibly the reason the OP thinks he needs new cases...or has the bottom end been swapped for an RM type at some point.

Edited by rmxdan

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I'm at work right now but I'll post pics and specs when I get home the for all the info

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Unless I'm missing something ~ with a little bit of de-burring and cleaning, add a new seal and crank bearing and I would have no problem using that case.

 

Racing vintage bikes (early 70's stuff) will give you a new perspective on what is and is not useable.

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Can't see in the pics but there are 2 cracks in it

Edited by Howard218

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Both sides are the same dimensions 66 od and 28 id

 

 

***63 od on the bearing not 66

 

?...Neither of those OD measurements seem to be accurate. Do you mean 68mm?

 

And as I suspected, your late model RMX has a crank with the aluminium stuffers and bolt to hold on the primary drive gear, which uses the same size main bearings on either side.

You therefore need to ensure you source compatible replacement cases if you want to retain your crank.

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