Quinten Posted October 25, 2023 Share Posted October 25, 2023 So I noticed my bike was burning oil and i thought the valve seals were worn. It's a single cylinder 4 stroke mini bike Honda st50 (dax). And the engine was pretty worn on the inside. Cylinder was chipped by the previous owner, the valves were completely burnt. So i just simply rebuilt the engine with a new Cylinder set. I did everything right. Set the valves to 0.05mm and 0.08mm. The timing is correct. The piston rights arent worn. Did an engine flush before the rebuild so it would be completely clean. Cleaned the carburator. And now when I turned it on for the first time. It runs, pretty good actually, but it won't idle unless I gave gass for like 15 minutes straight. And I saw oil coming from the Exhaust manifold. It's also burning oil but everything is okay, from piston rings, to valve seals, and so on. I do not know what could be the cause. Does anyone know what i could do? Quote Link to comment Share on other sites More sharing options...
RideWithStyles Posted October 26, 2023 Share Posted October 26, 2023 From what ive found both IN and EX are 0.05mm. could be two issues, are the rings correctly installed? Including the rings correct Orientation? did you disturb the carb Settings? reset the carb. Quote Link to comment Share on other sites More sharing options...
Quinten Posted October 28, 2023 Author Share Posted October 28, 2023 On 26/10/2023 at 09:37, RideWithStyles said: From what ive found both IN and EX are 0.05mm. could be two issues, are the rings correctly installed? Including the rings correct Orientation? did you disturb the carb Settings? reset the carb. Thanks for the reply. My user manual. Says the Intake valve should be 0.05mm and the exhaust valve should be somewhere between 0.05 and 0.10mm. checked it multiple times and it's correct. I only cleaned the carb, i didn't change anything about it. I've managed to make the bike rideable. It runs like a charm, but still struggling with the idling issue. It ONLY runs when the bike is only warmed up. Not 5 minutes warm, but a full 15 minutes warm. I fixed my air leaking issue with new carb gaskets. Nothing seems to help. Even when i put the idling screw insanely high, the engine just dies. Could it be an oil issue? Because my oil is at the max. So maybe when the engine is warmed up, the oil is thinner and the engine is having less trouble pushing it around? Just a theory ofcourse. Quote Link to comment Share on other sites More sharing options...
V650 Posted October 28, 2023 Share Posted October 28, 2023 (edited) Oil through the exhaust could possibly be damaged head gasket / incorrectly torqued ( If it has one ) allowing oil in to the combustion chamber if you are convinced the piston rings / valves are good Have you done a compression test ? Edited October 28, 2023 by V650 Quote Link to comment Share on other sites More sharing options...
Quinten Posted November 4, 2023 Author Share Posted November 4, 2023 On 28/10/2023 at 19:51, V650 said: Oil through the exhaust could possibly be damaged head gasket / incorrectly torqued ( If it has one ) allowing oil in to the combustion chamber if you are convinced the piston rings / valves are good Have you done a compression test ? I haven't done a compression test yet. I replaced the head gasket, but it was okay. So there was no need for a replacement. O-rings were okay too. I'll do a compression test. Quote Link to comment Share on other sites More sharing options...
Guest Posted January 23 Share Posted January 23 mho piston rings Quote Link to comment Share on other sites More sharing options...
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