560 SMR in My 04 525EXC

I've got 7000 miles on my 04 525EXC and I blew a head gasket. While contemplating the motor build I came across a 560 SMR motor and bought it. Now I'll ask the question, This should bolt in right? To my understanding the RFS motors all had the same mounting bolt patern. Besides the charging system and starter is there anything I need to worry about? The cylinder is shorter so I'm wondering if I need longer/different radiator hoses. I did purchase a 41mm carb to help with fuel delivery.

The next question is what to do with the 525 motor? Trophy cart? Motorized bar stool? Put it in my ACT 200X?

It should bolt right it. Cylinder/rod is shorter yes, but not much. Radiator hoses probably fit, but exhaust will be a bit pinned and you might have to relocate the mid-pipe mount.

About the 525, sell it to me! :excuseme:

Unfortunately unless the 560 smr motor has been taken apart and the crank issues fixed you have a grenade with the pin pulled.

In 50 hours on the street and much less on the track in smr usage with smr tires there was a 100% failure of the clutch side main bearing.

Crank needs to be trued,converted to factory ntn tmb ball bearings on both sides instead of only on the ignition side then the rod pin needs to be lightly welded to slow the failure rate to almost zero

Most exc owners won't like the close ratio, short rod engine setup with a 1 pound lighter crank.

Buzzy, revvy, top end cam, low torque all horsepower setup for a smr track.

I change the non available If worn short rod to a long exc rod and either space up the cylinder with a spacer plate or substitute my own 100mm taller cylinder

With the longer rod(same as your exc) the piston stays longer at tdc and the increased rod angularity(how far way from the center of the crank the rod is half way down) more torque is generated

Runable and a straight bolt in if it has been upgraded.

Or take your chances.

I have a complete one of those in stock all ready to assemble all serviced.

Wrong parts sort of to scrounge

Unless crank done then will work fine

The close ratio is 77% in total gear ratio spread

Your exc is 99%

Second through 5th on your exc is roughly the gear box on your smr.

Contact me if you need more info.


The close ratio and top end power I can handle. I had Hotcam in the bike earlier and had a blast with it. One of my ideas is to keep the 525 motor stock for the summer mountain riding and have the 560 motor for the winter desert riding.

I wasn't aware of the crank issue. This is a concern seeing that we do a lot of long distance desert rides.

I wasn't aware of the crank issue. This is a concern seeing that we do a lot of long distance desert rides.
525 has the same problem, it's just not as common because smr is run harder, has better traction, makes more power, likes to rev higher and has a shorter rod. To cope with track conditions SMR has ball bearing on one side as caflashbob said which is not as durable, but can take the spreading better or something.

It's difficult to say what happens if you go flat out on the desert, but I would keep a very close look at the crank axial clearance.

OK, I have read about the crank/bearing upgrades and was planning on this with 525 motor. The place were this may become an issue is Glamis. The big dunes are 3rd and 4th wide open and it's surprising how much traction you get with a paddle in the sand. I don't ride on the street very much. The plate is mostly for trail hopping or cruising around town in the Sierras. I won't dare get out on a SoCal freeway.

I think I’ll run it this season and plan for the crank upgrade next summer. This will also give me a chance to see how I like the transmission. The low 1st and 2nd are nice in the tight stuff and I think I’m going to miss them. The close 5th and 6th sounds fun.

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