FE290 Knock When Hot Only on Startup

[Romrok]

This one puzzles me folk,



Today marks the day that I found another cart with the same issue.



Both carts had been in long term storage (2+ years) without being put to sleep.



Both are 98 DS Villagers.



After cleaning carbs and draining tanks and replacing filters and the lot, the carts spring to life. I took it for a shakedown cruise and find that after driving for say 15min, stopping the cart and then pushing the pedal to drive away, you get a deep knocking, only until the engine starts speeding up under its own power past the starter-generator speed. After that, quiet as you can expect from a gaser. Leave it to cool for 15 mins and it is perfectly normal on startup again.



On the first cart, I replaced the clutch with a good unit to check, its still knocks.



Checked carb, fuel flow, valves for correct adjustment when steaming hot and not sticking.



yucked the engine out and split it, no gunge or anything, checked big end and those bits, couldn't find anything a miss, but hey its cold then.



Anyone seen this before? I must be missing something simple.



Rom