KTM 105 pump gas?

If it’s straight from KTM kit with no mods or anything pump should be fine. Just like going from a 125 to 150 won’t require a change in octane.

Do you have ethanol-free 91 in your area? This would be a much better choice, for both bikes if available. Check your owners manual for minimum requirements.

It all comes down to the squish/compression. When you install the 105 kit if you set up the squish similar to the 85 it will run on the same fuel. They jet very similar with the 105 needing slightly leaner jetting in a very predictable manner.

When it comes time to do a top end, it's a little tricky getting parts for the 105. Since it's not sold as a stock model, there is no parts fiche. A few of the parts are different than the 85 and have to be ordered individually.

Good deal. Yeah, they bark. For the power valve, we tried both no-spring/flush and red-spring/flush. The kid likes it with the red spring in better. A little more pull off the corners. Have tried both the FMF big bore pipe/silencer setup and stock. Kid doesn't really seem to think there's much difference, but the FMF sounds pretty cool

When it comes time to do a top end, these are the parts that are different than 85cc:

Right PV gasket 47637908000
Head Inner o-ring 59x2 0770590020
Head Outer o-ring 80x2 0770800021 (Same as 85cc)
Piston Vertex 22991 series, A or B