Complete workshop re[air service manual with electrical wiring diagrams for Suzuki GSX-R400 1984-1987. It's the same service manual used by dealers that guaranteed to be fully functional and intact without any missing page.

This Suzuki GSX-R400 1984-1987 service & repair manual (including maintenance, overhaul, disassembling & assembling, adjustment, tune-up, operation, inspecting, diagnostic & troubleshooting…) is divided into different sections. Each section covers a specific component or system with detailed illustrations. A table of contents is placed at the beginning of each section. Pages are easily found by category, and each page is expandable for great detail. The printer-ready PDF documents work like a charm on all kinds of devices.

Suzuki GSX-R400 GSX-R400 (GK71B, GK71F) 1984-1987 Service Manual.pdf; 246 pages

EXCERPT:
SPARK PLUGS
Clean and Adjust Every 6 000 km
Replace Every 12 000 km
The plug gap is adjusted to 0.6- 0.7 mm. The gap is correctly adjusted by using a thickness gauge (special tool). When carbon is deposited on the spark plug, remove the carbon with a spark plug cleaning machine or carefully using tool with a pointed end. If the electrodes are extremely worn, replace the plug. Also replace the plug if it has a broken insulator, damaged thread etc.
NGK C8HA or NIPPON DENSO U24ES-U as listed in the table should be used as the standard plug.
However, the heat range of the plug should be selected to meet the requirements of speed, actual load, fuel, etc. If the plugs need to replaced, it is recommended that the standard plugs listed in the table be selected. Remove the plugs and inspect the insulators. Proper heat range would be indicated if all insulators were light brown in color. If they are blackened by carbon, they should be replaced by a hot type NGK C7HA or NIPPON DENSO U22FS-U.
…