Hey everyone, just purchased a 79 suzuki gs 450. bike runs fine for 20-30 minutes and then slowly shifting gears becomes challenging (gets stuck in first gear). then when coming to a stop, the idle gets lower and lower eventually leading to the bike shutting down.
bike has new clutch cable, carbs cleaned, and new spark plugs.
I see this is by now a very old topic. Here goes anyway…Seems like you have a friction source in the engine that gets more pronounced as the engine heats up. Before you have a complete engine seizure, it might be best to pull the engine and disassemble the gear box. From there you might be able to identify possible hot spots by the likely off color metal. Possible culprits: crankshaft main bearing, gear box shafts bearing or bushing, cam bearing… Another possibility is a piston that slowly overheats, causing it to interfere with its cylinder wall. In any case, disassembly will reveal all and be a good education at the same time. 🙂 Start with a good service manual and go slow. Pete