98 Steel subframe 04 EC crossover?

[RobD]

HI,
I've got (bits of) an 04 EC250 that I'm building up for trail riding, when I start the build proper over the next few weeks I'll start a thread but ahead of that I've got a question about subframes.

My 04 frame came with a subframe but it was in very poor shape with broken brackets and a clean break on one of the upper legs just behind where it bolts to the main frame. After reading on this forum about the crossover with older KX subframes I had planned on sourcing one but then remembered the pile of bits from a 98 EC250 I had in storage. I've dug out the subframe for that and it's steel and in good straight condition. The only issue is that the seat from the 04 doesn't sit nicely in the top rails if the brackets on the seat base are lined up with the holes. The gap is about 1/2 an inch. with the holes lined up the cross bar is in the correct place. If I bend the upper rails upwards to match the profile of the seat base then it'll be out of line where it bolts up to the frame. Currently the frame mounts line up spot on.

Would the KX subframe be a better fit?

Cheers,

Rob

 

[stainlesscycle]

have you checked airbox fit? i had an issue fitting a 99 steel subframe onto a 00. also iirc fender fit needs some grinding to work.

 

[RobD]

Hi,

I haven't checked the airbox fit as I've got a 98 airbox and one for the 04.

From an initial look the airbox on the 98 seems like it would be more water resistant. The carb bellows look to come out in exactly the same place.

I'm using an 07 engine but I don't think that affects the airbox?

 

[desertgasser300]

Does your 07' engine line up in the frame? I was going to transfer my 97' motor into my
07' frame at one time but the mounts had changed over the years. Only because that CB motor is smooth and virtually zero vibration.

 

[RobD]

The lower engine mount is slightly different, the 07 cases are 10mm narrower at that point and so the bolt for the 04 frame (which is 10mm longer than the 07 part) has to be used with 10mm spacer or some washers to take up the space. The mountings on my 98 and 04 frame look to be the same. The hole in the engine casing for the pivot bolt is larger in the 07 motor so a piece of tube with the correct internal and external diameters is needed to take up the play.

Because you are going the other way round (early engine late frame) you'd have to bore out the pivot hole in the engine cases and move the lower engine mount on the frame 10mm out on the gearchange side.

 

[cbutler]

I have a steal sub farm on my 03 MC 250 and had to do zero mods. It bolted right up with no issues.

 

[RobD]

Hi,
Is is a GG or KX steel subframe you have?
Cheers,
Rob

 

[cbutler]

It is a gasgas one I think it is off a 99 EC250.

 

[RobD]

Hi,
fixed up the subframe onto the frame with it all bolted up it's fitting nearer now. The rear of the seat has to be pushed down about 10mm for it to bolt up but there's plenty of flex in the base at that point to take up the difference. Will try it with the clarke tank when I pick it up at the weekend as that may lift the front of the seat anyway.

Thanks for help. Moving on to the front end now so will post in the suspension board.
Cheers,
Rob