CR250 99/2000 model engine differences

[nmilne]

Just wondering whether the 99 and 2000 model CR250's had the same motor dimenionally ie. could you drop a y2k motor into a 99 frame or vise versa?

I just want to work out whether the 2 frames have the same basic motor mounting points, swingarm pivot location in relation to crank location and engine width etc.

Thanks! :)

 

[Pete Payne]

Yes they do interchange . It is a drop in and bolt up . No cutting or welding required .

 

[mx547]

Yes they do interchange . It is a drop in and bolt up . No cutting or welding required .

are you sure? 2000 was the first of the second generation frames.

 

[James]

93-2001 drop in interchangeable. Maybe 92 also, but not sure.

2002 was when they changed the engine cases.

 

[nmilne]

Beautiful! Thanks guys ... there will be some cutting and welding involved, but I know that what I want to wedge into this frame will fit into the later 00/01 frame, so by rights it should be about the same amount of work :)

 

[James]

What exactly are you building?

 

[nmilne]

I'm planning on dropping a drz400 motor into it.

Now before you all screw up your faces ;) it's going to be quite a worked drz, bored and stroked to 470 - the donor motor is in need of a gearbox rebuild and is already bored to 435 and running hotcams. Add an offset crankpin, CRF450 FCR and possibly RHC cams as well as their valves and we should be cooking on gas. I'm specifically after the 97-99 frame due to its extra rigidity (bad for mx, but good for sm!) and because the separate cradle tubes should make exhaust routing easier, and hopefully mean I don't need to weld and reprofile the exhaust port.

The idea here is that I'm going to build my ultimate street motard - good power from a reliable motor (the 475 drz that burned has on TT dynos about 56hp which is roughly what i'm aiming for with the aid of some further cam work) and light weight from the CR frame. Yes, I could buy a CRF and tard that, but it wouldn't be near as reliable as the drz motor even in heightened tune simply down to the fact that it isnt a competition motor and hence hasn't been lightened to buggery (I know this from lugging the darn thing out the frame the other night).

Actually, while I'm in the question asking mood :) Has anyone torn or cut apart a CR frame and know whether the main beams are just simple hollow extrusions that are welded sealed with the castings on either end? I'm planning on using the main spars as oil tanks (with an equaliser) and need to work out whether I need to cut them open and potentially re-weld their end points to make them liquid tight...

 

[dirt bike dave]

93-2001 drop in interchangeable. Maybe 92 also, but not sure.

2002 was when they changed the engine cases.

I knew the cylinders were interchangeable on 1993-2001. Never heard that about the cases as well.

Are you 100% sure? That range covers quite a few different frames.

 

[James]

Interesting.

BBR built one of those and they still have pictures on their site. I would love a DRZ-400/XR400 engine in a CR frame.

Some of the Thumpertalk guys are running coolant/fuel in the front downtube and spars on their CRF frame. The CR frame is bound to be comparable.

You may have more room in CRF frame for the engine.

 

[James]

I knew the cylinders were interchangeable on 1993-2001. Never heard that about the cases as well.

Are you 100% sure? That range covers quite a few different frames.

I am probably as sure about the cases as you are about the cylinders...I'll go 99% just because I haven't actually switched every one of those around myself.

I have read numerous threads about swapping those years, looked at many bikes in person, and viewed countless pictures online and in parts diagrams. From all that I have gathered, the engines are identical regarding external dimensions. Pipes, carbs, CDIs, porting and other things were different from year to year so a 93 engine may not work perfectly with an 01 pipe and CDI and I doubt you'll get a 93 pipe and silencer to easily mount on to an 01 frame...but the engine itself should go right in.

 

[Pete Payne]

92 -01 will all interchange . No problem .

 

[Pete Payne]

nmilne,
Drop me a PM or e-mail me at hdr81@verizon.net
I have quite a few old 97 - 99 frame parts lying around.

 

[nmilne]

Thanks for the replies guys ... the BBR conversion was the basis for my question, just in terms of knowing the bike fits reasonably into a 00/01 style frame (http://www.bbrmotorsports.com/Bikes/Bike 37/CR-DR400.jpg) so at least I know the basics in terms of case width and swingarm pivot to crank length are OK. As you can see with the BBR version in that picture they've done some cutting to remove at least the left hand cradle half and it appears they have moved the Y junction for the cradle lower down to clear the exhaust. I'm hoping here that the separate twin cradle design on the 97-99 will give me more room for less drastic options, even if it means having the exhaust port re-profiled to give me a more centralised and downward exit angle.

Thanks for the offer for parts as well pete - unfortunately I'm on the other side of the world :( Which really sucks since I just found a cr frame on the bay place for $100!