Hi all, I got myself an RT1 which was in good condition although was in bits when I got it. Engine has had a rebuild, with receipts, but not run. There was a Powerdynamo kit with it which it fitted as per instructions. 

Got it all running pretty quick, but there’s a rattle/knock coming from the engine at idle. The noise disappears with a bit of a rev, just over idle speed. 

Anything to be concerned about? Sounds a bit like pinging? Piston slap? Early detonation? Happy to hear your collective thoughts! 

Video here;

youtube.com/shorts/hlKbKtIla9Q?si=d4AxFPlw4fN7uIRy

Thanks all 

"Rebuild" is a subjective term.  Some people will throw a set of rings in a worn out engine and call it "rebuilt".  And some shops will "add a little extra clearance" when fitting a new oversize piston.

What do your receipts say was done?

Video does not have any revving to hear how noise "goes away" which might help. 

I tend to shy away from diagnosing from video but I can tell you it's not pinging or detonating at idle.  My guess from what I hear is big end rod bearing is making noise....  but make sure pipe or heat shield or something isn't vibrating. 

Is the tach hooked up? Hope it's something simple like noise from the tach cable. 

Hey Mark, thanks for the reply. The cost on the receipt was £600 ($800) so hopefully more than some rings and a bodged rebore. But you're right, could be anything, I'll try and find the receipt again. The company seems pretty legit though.

I'll grab another vid tomorrow (late here in the UK) and upload it with a bit of a rev.

Big end bearing diagnosis sounds annoying! Triple checked everything that's bolted to the frame or could be loose and rattling around, pretty certain there's nothing that could be. Will keep you posted...

@pahiker that would have been a bonus, but think I've got everything that could rattle, tucked away or bolted up.

Just go ride it & enjoy. Then do another video outside with a bit of light throttle then idle then a good quick rev. I can hear piston noise "I think" but if it's excessive clearance it'll still rattle with a quick blip rev when closing off. If you heard mine rattle you'd be happy with yours. Mind you mine hasn't  been just rebored. Your motor sounds healthy for compression though. If yours has the advancer in the flywheel like my one had they get worn in the arm where it engages in the cam plus the cam arm slot. I guess it's stretching things to imagine that'd make an audible rattle.