Rear rotor too big

[Noobi06]

When refitting my Yamaha WR450F 2005 Supermoto rear wheel to my GasGas Ec 125 2006, I ran into a little issue. The rear rotors on the yamahas are 240/245mm, which is too big for gasgas which is 220mm.
The mount on the swingarm for the caliper is too low because when I install the wheel, I need to have the caliper sit higher to compensate for the larger rotor, but I cannot have the caliper higher since the mount for the caliper on the swingarm as shown on the picture is too low down.
What would yall suggest me to do? A smaller rotor is not an option since the GasGas Bolt pattern or any other brand does not match with yamahas, and yamahas are 245mm only. I have looked into that a bunch already so that is not an option.
Do note that a little guy like me doesn't have all the means in the world to waste on a thing like this, nor equipment.

 

[blitz11]

Contact SendCutSend.com, and see if you can send the rotor to them to be laser or water-jet cut. (or find a local vendor).

Take your rotor, and see if they an make it smaller with high energy-density cutters. I use sendcutsend.com a lot for my classes - excellent quality and inexpensive. You'd have to contact them to see if they'd cut material you sent to them.

I assume you're in the US - might be bad assumption.

 

[SS109]

Have you looked in to a rear rotor from '90-'96 YZ250? They are 220mm and I think share the same 115mm bolt pattern as your WR450 rear wheel. You can buy cheap ones off of Ebay for under $20 shipped to know for sure before buying a high quality one.

 

[Anders]

Have you looked in to a rear rotor from '90-'96 YZ250? They are 220mm and I think share the same 115mm bolt pattern as your WR450 rear wheel. You can buy cheap ones off of Ebay for under $20 shipped to know for sure before buying a high quality one.

That would of course be a good option.

Failing that, you could try to find a company close to you that does water jet cutting or laser cutting.
It's not very hard to make a drawing of a disk with the Yamaha mounting pattern and 220mm outer diameter. You could use something like the free QCad program to make a DXF drawing to give them. Having a DXF drawing, a cutting company could cut a disk for you for not too much money.

I did exactly this when I installed a KYB Yamaha fork on my 06 EC200. I used the Gasgas wheel, but had to make a bespoke disk, as the Yamaha version of the Kyb fork supported 250mm front disk, not the 260 standard Gasgas size.
My local water jet cutter company has also cut several standard Gasgas sized front and rear disks for me, using my QCad-made DXF drawings.

 

[Noobi06]

Update: RM 125 88-99 has the same bolt pattern as yamaha (134mm) but the old ones had a 220mm rear rotor so I got that sorted out. Now I just need to get these stupid allen bolts off which are all stripped.