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RMX Fork swap

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I have an 89 RMX250 and want to update it with some newer forks. I figure the cheapest way to go about it would to find a triple clamp set that would fit the frame first then pick up some forks for whatever year the clamps go with. So I was wondering if there was anywhere I could look up steering stem lengths and diameters? Does anyone know of a website or anything that could provide this info? Or has anyone ever updated the forks on a 89 RMX?

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What don't you like about the stock forks? They are fine, so long as sprung correctly. My son had a pair on his '90 RMX and I put a set on a DR350 project bike.

 

If you insist then any RM125/250 forks will work so long as you use the clamps; they pretty much bolt right up.

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I know where there's a complete front end off of a 2000 RM250 (forks, triples, wheel, axle, brakes & master cylinder) going for a pretty reasonable price and it should bolt right in, pm me if your interested.

 

Beyond that, look up the bearing sizes from the donor, that'll tell you if the stem will fit your frame and if that fits the rest will bolt on.  But you might need the front wheel and caliper as axle diameter and brake disks did change over the years.

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I rescued this bike from a friends back yard the forks where ruined and full of rust. I figured if I was going to replace them I might as well update them if possible. Plus I am not a big fan of fork guards they don't seem to cover the tubes very much. Checking the bearing size seems like a good way to go about it thank you I will look into that and see what I find.

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So far what I found from researching the bearings is they have been the same from 89-07 so in theory I should be able to throw any set of forks from any year on my bike.

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So far what I found from researching the bearings is they have been the same from 89-07 so in theory I should be able to throw any set of forks from any year on my bike.

will any set of stock rm forks fit with the stock triples? or are you gonna use the triples from another bike?

Edited by Ryino

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So far what I found from researching the bearings is they have been the same from 89-07 so in theory I should be able to throw any set of forks from any year on my bike.

 

I believe that you are correct.  Just know that the front axle diameter (like the rear) did get bigger over the years so you may have to get a different front wheel because an older wheel hub may not be able to accept a bearing that has the correct ID.  Case in point, in 2000 the rear axle grew to 22mm from 20mm.  To do that the rear wheel bearing OD also had to grow to accept that bearing, and because of that a rear wheel from a '99 or older RM250 will not fit a 2000 or newer RM250 because no one makes a bearing that will fit (I once spent a week looking....).

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will any set of stock rm forks fit with the stock triples? or are you gonna use the triples from another bike?

 

He can't, he will need to get the correct triples for the forks that he's going to use.  So any triples (from what he's read) from '89 on will bolt on to his frame, but those triples need to be off of the same approximate year based on who was supplying Suzuki forks and that generation of forks.  Like the '99 and 2000 RM250 both used the same Showa forks, so he could use triples off of a 2000 and forks off of a '99.  He would also need the axle and front wheel off of either model.

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Bad news I did more research today using chaparrals website and comparing part numbers for the steering stem bearings, here is what I learned. If you have an RM, Suzuki used the same bearing, a 30x52x16, from 93-06, in 01, 07 and 08 they used the same bearing for the bottom but a different one for the top. From 89 to 92 they used a 28x54x16 bearing. If you have a RMX like me from 89-96 they used that same 28x54x16 bearing then in 97 and 98 switched to the 30x52x16.So this limits me to RMX forks from 89-96 or an RM 89-92. To answer a previous question I plan on buying a set of triple clamps matching whatever year forks I find because the fork tube diameters do change over the years. I will have to do some more research comparing the front axel part numbers to try to avoid having to buy a front wheel too. Which made me think the front brake caliper may not match the mounting bolts on the forks I find.

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Bad news I did more research today using chaparrals website and comparing part numbers for the steering stem bearings, here is what I learned. If you have an RM, Suzuki used the same bearing, a 30x52x16, from 93-06, in 01, 07 and 08 they used the same bearing for the bottom but a different one for the top. From 89 to 92 they used a 28x54x16 bearing. If you have a RMX like me from 89-96 they used that same 28x54x16 bearing then in 97 and 98 switched to the 30x52x16.So this limits me to RMX forks from 89-96 or an RM 89-92. To answer a previous question I plan on buying a set of triple clamps matching whatever year forks I find because the fork tube diameters do change over the years. I will have to do some more research comparing the front axel part numbers to try to avoid having to buy a front wheel too. Which made me think the front brake caliper may not match the mounting bolts on the forks I find.

 

Your still good on the top bearing.  The ID is 16mm, so you would have to use the RMX top bearing no matter what, but all of the stems will fit through the ID (16mm).  So you could still pick any set of RM250 forks for your bike.

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I'm still trying to find something on the internet that explains it but I am pretty sure the 28x54x16 is Inside Diameter x Outside Diameter x Width. I might actually just take my existing steering stem out and measure it. 28mm =1.102 in and 16mm=.630 in from what I remember last time I took it apart it looked closer to a 1 in diameter. But still I'm not 100% I am reading that bearing dimension correct you could be right.

Edited by XRBEATER02

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The bearings are probably the easiest part of the conversion.  All Balls has fork conversion bearings     http://www.allballsracing.com/index.php/forkconversion

 

 

 

 

The setup that zig06 has would probably be your best bet....whatever forks you put on there, you'll more than likely need a different axle, front wheel, brake caliper. Plus the '00 RM250 forks are valved and sprung a lot better than the original RMX forks.

 

 

I put a 97-98 RM250 front end on my '90 RMX....

Edited by moto2000

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The bearings are probably the easiest part of the conversion.  All Balls has fork conversion bearings     http://www.allballsracing.com/index.php/forkconversion

 

 

 

 

The setup that zig06 has would probably be your best bet....whatever forks you put on there, you'll more than likely need a different axle, front wheel, brake caliper. Plus the '00 RM250 forks are valved and sprung a lot better than the original RMX forks.

 

 

I put a 97-98 RM250 front end on my '90 RMX....

So you had to get conversion bearings to put the 00' forks on your bike?

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I just used the bearings that came with the clamps (and the RMX races I believe), but All Balls is an option if what you have doesn't work.

 

I used the All Balls kit to mount a RM front end a 84 CR250 for example......

 

Picture312_zps70acc826.jpg

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If you end up using a 1996-1998 RM125/250 front end get a hold of me; I have and Applied top clamp for oversized bars in the original box. I also have spacers to use it with 1996-1998 RMX forks - they had the same offset.

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The bearings are probably the easiest part of the conversion.  All Balls has fork conversion bearings     http://www.allballsracing.com/index.php/forkconversion

 

 

 

 

The setup that zig06 has would probably be your best bet....whatever forks you put on there, you'll more than likely need a different axle, front wheel, brake caliper. Plus the '00 RM250 forks are valved and sprung a lot better than the original RMX forks.

 

 

I put a 97-98 RM250 front end on my '90 RMX....

The all balls website mentions putting a different year set of forks on your bike could affect the rake and trail of my bike therefore alet the handling of my bike. I would like to see what years will be the closest to the current setup on my RMX. Does anyone know where I can find the specs for rake and trail on the different model years.

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