KTM 250 - 300 - 380 Repair Manual - Introduction - General

Oct 28, 2026

Repair manual provides maintenance and repair instructions for KTM motorcycle engines in the 250/300/380 range, covering general procedures such as bleeding the cooling system and carburetor adjustment. It includes guidance on step-by-step coolant filling to remove air, prerequisites for safe carburetor changes, rule-of-thumb mixture adjustment for altitude and temperature, and safety warnings on using specified gasoline and two-stroke oil. It also outlines basic concepts like defining mixture problems and notes component wear replacement intervals.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages59

Reading Time2 h 29 min

AccessFree to download

Introduction

1.0 General

1.1 Bleeding the cooling system

1.2 Carburetor adjustment

1.3 Definitions

1.3.1 Idling range

1.3.2 Opening up

1.3.3 Part-throttle range

1.3.4 Full throttle range

REPARATURANLEITUNG REPAIR MANUAL MANUALE DI RIPARAZIONEMANUEL DE RÉPARATION MANUAL DE REPARACIÓN MOTOR ENGINE MOTORE MOTEUR MOTOR 250 / 300 / 380 ‘98 7. 97 ART. NR. 3.205.20 | 1 General | 1 | | --- | --- | | 2 Removing engine / Refitting engine | 2 | | 3 Dismantling engine | 3 | | 4 Servicing on individual components | 4 | | 5 Engine assembly | 5 | | 6 Electrical | 6 | | 7 Trouble shooting | 7 | | 8 Technical data / maintenance schedule | 8 | | 9 Wiring diagrams
(see at the end of this repair manual) | 9 | INTRODUCTION THIS REPAIR MANUAL OFFERS EXTENSIV REPAIR-INSTRUCTIONS AND IS AN UP-TO-DATE VERSION THAT DESCRIBES THE LATEST MODELS OF THE SERIES. HOWEVER, THE RIGHT TO MODIFICATIONS IN THE INTEREST OF TECHNICAL IMPROVEMENT IS RESERVED WITHOUT UPDATING THE CURRENT ISSUE OF THIS MANUAL. A DESCIRIPTION OF GENERAL WORKING MODES COMMON IN WORK SHOPS HAS NOT BEEN INCLUDED. SAFETY RULES COMMON IN THE WORK SHOP HAVE ALSO NOT BEEN LISTED. WE TAKE IT FOR GRANTED THAT THE REPAIRS ARE MADE BY QUALIFIED PROFESIONALLY TRAINED MECHANICS. READ THROUGH THE REPAIR MANUAL BEFORE BEGINNING WITH THE REPAIR WORK. | 􀀂 WARNING 􀀂 | | --- | | STRICT COMPLIANCE WITH THESE INSTRUCTIONS IS ESSENTIAL TO AVOID DANGER TO LIFE AND LIMB. | | ! CAUTION ! | NON-COMPLIANCE WITH THESE INSTRUCTIONS CAN LEAD TO DAMAGE OF MOTORCYCLE COMPONENTS OR RENDER MOTORCY CLES UNFIT FOR TRAFFIC. „NOTE” POINTS OUT USEFUL TIPS. USE ONLY ORIGINAL KTM SPARE PARTS WHEN REPLACING PARTS. THE KTM HIGH PERFORMANCE ENGINE IS ONLY ABLE TO MEET USER EXPECTATIONS IF THE MAINTENANCE WORK IS PERFORMED REGULARLY AND PROFESSIONALLY. FOR TECHNICAL DATA SEE LAST SECTION OF THIS MANUAL. UP-TO-DATE INFORMATION IS PUBLISHED IN OUR UPDATED SPARE PARTS CATALOGUES. KTM AUSTRIA’S CERTIFICATE OF ACHIEVEMENT FOR ITS QUALITY SYSTEM ISO 9001 IS THE BEGINNING OF AN ON- GOING TOTAL REENGINEERED QUALITY PLAN FOR A BRIGHTER TOMORROW. KTM SPORTMOTORCYCLE AKTIENGESELLSCHAFT 5230 MATTIGHOFEN, AUSTRIA ALL DESIGN AND ASSEMBLY MODIFICATION RIGHTS RESERVED. 1.0 General Chap. Component / Component unit Page 1.1 Bleeding the cooling system .............................................1-2 1.2 Carburetor adjustment ................................................1-2 1.3 Definitions .........................................................1-3 1.3.1 Idling range ........................................................1-3 1.3.2 Opening up ........................................................ 1-3 1.3.3 Part-throttle range ....................................................1-3 1.3.4 Full throttle range ....................................................1-3 1.4 Checking the float level ................................................1-3 1.5 Checking the setting ofthe TVC system ....................................1-4 1.6 Special tools ........................................................1-5 1 1 1 1.1 Bleeding the cooling system If the coolant has been drained, the cooling system must be bled as follows after refilling. – Make sure that the drain screw 1 is fastened. – Pour approx. 0.5 litres coolant into the system. – Remove the screw 2 on the right radiator and tilt the motorcycle to the right approx. 30 degree angle. – Now pour coolant into the system until it escapes from the right radiator free of bubbles and replace the screw 2 immediately so that no more air may reachthe right radiator. – Return the motorcycle to its original position and top up the left radiator until the coolant can be seen approx. 10 mm above the radiator fins. – Check the coolant level again after a short ride. 1.2 Carburetor adjustment Basic information on the original carburetor setting The original carburetor setting was adapted for an altitude of approx. 500 meters (1600 ft.) above sea level, and the ambient temperature ofapprox. 20° C (68° F), mainly for off-road use and central European premium-grade fuel (ROZ 95 MOZ). Mixing ratio 2-strok

FAQs

What is the correct procedure to bleed the cooling system after draining and refilling?

Fasten the drain screw, add coolant to the system, open the right radiator screw and tilt the motorcycle to bleed air until coolant flows without bubbles, then tighten immediately. Return to level and top up the left radiator until coolant is about 10 mm above the fins, then recheck after a short ride.

How should carburetor adjustment be approached when changing settings?

Start from the original carburetor setting and ensure a clean air filter, airtight exhaust, and an intact carburetor. Use adjustments of the main jet, idling jet, and jet needle; other changes are not expected to strongly affect performance.

What safety and fuel/oil requirements are emphasized for this engine?

Use premium-grade gasoline mixed with high-grade two-stroke engine oil of known brands. Avoid insufficient or low-grade oil to prevent piston erosion, and proceed cautiously with leaner adjustments by reducing jet size in steps of one number to prevent overheating and piston seizure.

Oct 28, 2026

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