Fuel Choice for Smallbore TBI KTM's

Smuffers

I have a 2025 KTM 150sx and love the bike. Just threw a Pro Circuit Shorty on the bike and was impressed with the results. I still want a little more out of this thing and am looking at race gas (currently running Sunoco 94). Seems most folks around here are running C12 VP. Does anyone have experience with running race gas in these TBI KTM's? Did it require a remap, did you notice a difference in performance, was it worth it?

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Tomok
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Tomok 10/21/2025 4:26am
10/21/2025 4:26am

I've always read that these bikes like high octane. I've run 50/50 93 pump/C12 for about 102 octane since day one and it runs great.

Smuffers 10/21/2025 5:31am
10/21/2025 5:31am
Tomok wrote:

I've always read that these bikes like high octane. I've run 50/50 93 pump/C12 for about 102 octane since day one and it runs great.

Were you running that on stock compression?

Tomok
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Tomok 10/21/2025 10:19am
10/21/2025 10:19am
Smuffers wrote:

Were you running that on stock compression?

Yes but now running the TSP head with their ERM power kit and it runs even better!

wrc777
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wrc777 10/22/2025 6:49am
10/22/2025 6:49am

For small bores ktm says 98 research (RON) octane which is equivalent to 93.5 in the US. 94 octane pump fuel is a little hard to come by. In CA I think they mostly have 91 octane which meets the ktm requirement for the 250/300. 

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sandman768
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sandman768 10/22/2025 8:34am
10/22/2025 8:34am

Running straight c12 on a stock engine will likely hurt performance…You need to find a shop/ engine builder with a setup for your bike… head squish/ ECU tuning will determine fuel requirements…then a rear sprocket can fine tune for your locale…

Travis610 10/22/2025 2:34pm
10/22/2025 2:34pm
wrc777 wrote:
For small bores ktm says 98 research (RON) octane which is equivalent to 93.5 in the US. 94 octane pump fuel is a little hard to...

For small bores ktm says 98 research (RON) octane which is equivalent to 93.5 in the US. 94 octane pump fuel is a little hard to come by. In CA I think they mostly have 91 octane which meets the ktm requirement for the 250/300. 

Just picked up a '23 TC125 (I'm in Canada) and we have 93 at the local shell and 94 is available at a different station 1/2hr away. I have always ran a bit of maxima hi-test additive, found it worked many years ago with a CR125 I had that would detonate on pump gas but not with the additive

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