TBI vs TPI vs Carb! Back to back ride on my 2023 KTM 300XC with Throttle Body Injection (TBI) vs my 2021 KTM 300XCW Erzberg with Transfer Port Injection (TPI) vs a 2017 KTM 300XC with Keihin carburetor. Even on this short woods loop the differences between TBI and TPI and Carb stand out.
2021 KTM 300 Erzberg: Lap time 1:36
The 300 TPI engine on my 2021 KTM 300 Erzberg has smooth linear power that has run perfectly for me from 11F to 95F temperatures. I like oil injection for the gas and go simplicity. The TPI 300 engine has very smooth roll on torque - which some riders complain is too smooth and lacks the stronger more torquey response of a well jetted carburetor. The PDS chassis feels smaller and has quicker steering than the newer linkage chassis on the '23 300XC.
2017 KTM 300XC: Lap Time 1:38
Easy to feel the stronger initial throttle response of the Keihin carb 300XC, especially after jumping off the 300XCW TPI. That meaty low end bark of a well jetted Keihin carb is what some riders feel TPI lacks. The carburetor is such a simple device and this 2017 300XC still runs strong.
2023 KTM 300XC: Lap time 1:33.6
The '23 300XC TBI engine is powerful! The low to mid partial throttle roll on torque on the '23 300XC TBI engine feels stronger than the 300XCW TPI engine with a more classic carb like meaty power feel. The 300XC TBI engine feels even stronger than the 300XC carb engine down low. There is also a noticeable difference between Map 1 and Map 2 on the '23 300XC TBI engine. Map 1 is a little smoother response while Map 2 is beast mode with stronger throttle response and is very good for moto tracks. The chassis on the '23 300XC feels firmer and bigger (better ergos for taller riders...I am 6' 2" 190 lbs).
All three of these 300 2-strokes are great engines with broad linear power though the character of each stands out when ridden back to back. The 300 TPI is so silky smooth it feels a little less powerful overall with a smoother roll on power feel. Perhaps better for the off road woods riders. The 300 TBI feels like it makes 3~4 more peak HP and has more meaty and stronger low to mid throttle torque feel and Map 2 is very responsive. Perhaps better for more open style off road and moto riding but I have ridden it on tight slow technical trails and it ran fine. Finally this Keihin carburetor equipped 300XC has strong initial throttle response and runs strong. The all new TBI matches that "carb" feeling with a little more power and refinement and no need for jetting. TBI fuel injection just might be good enough to get a few riders to give up their carburetors and jetting. All are very good engines. Nice to have choices!
