Walk into any authorized Bajaj service center. Ask the parts manager for a "soft copy of the P&A manual for the 135 DTSi." Many will email it to you for free if you buy a few parts from them.
: A 62-page document listing over 500 individual parts organized by component. bajaj discover 135 dtsi spare parts catalogue pdf
Piston kits, DTSI spark plugs, and the 5-speed gearbox components. Walk into any authorized Bajaj service center
“Yeh dekh,” he said, pointing. “The standard Discover uses a 3mm dowel pin to lock the camshaft. But your father’s 135 DTS-i—the early ones—they used a 3.5mm pin. The timing has been off by half a millimeter this whole time. The chain isn’t skipping. The pin is wrong.” DTSI spark plugs