nickCR Posted September 26, 2022 Report Share Posted September 26, 2022 (edited) Hello Forum, My engine sounded like it had a bit of a 'rattle'. Upon opening it up we discovered some scoring on the cylinder walls. My local shop suggested I send the new piston and cylinder to a machine shop so they could remove the scars and match the new piston, so I did and just recently got the bike back together. Everything was going great, she started up on the 3rd kick, compression sounds great, until the coolant started spewing out. The first time it was a tiny hole on the impeller case seal, we removed the case and remounted it and leak was gone, however now I'm getting water coming out of the purge valve on the top of the radiator. I've tried the following: Purged the air by the 8mm bolt on the head. Lifted the bike to 12 o'clock + shook it to try and get any air out By-passed the thermoswitch on the bottom of the radiator by connecting the fan direct near the stem. Fan ran fine with motor on. When the water is getting purged out the top, the top/bottom of the radiator is still very cool/cold but the engine is warm/hot. If I unscrew the radiator screw after the engine is on for a short min there is a hiss for the release of pressure from the system. (no air leaks) My suspicion is that there is air in the system. Is there anyway to know if water is circulating? Will running the motorcycle without the radiator cap for a minute or two help purge bubbles? Thank you in advance, Nick Edited September 26, 2022 by nickCR 2018 -> 2019, added pics. Quote Link to comment Share on other sites More sharing options...
TRS Fan Posted September 26, 2022 Report Share Posted September 26, 2022 Hello Have you bled the air out using the bleed bolt in the top of the cylinder head? Item 4 on diagram attached. I normally part fill and then turn the engine over by hand with the kickstart - not easy unless plug removed. Then top up and bleed at cylinder head. Coolant should be just covering the top of the radiator fins - visible check with a torch if you shine into the fill hole, but I just dip my little finger in to ensure an air gap remains.. If the pump impeller is O.K., it will rotate when you turn the engine over by hand - and can be seen with the impeller cover removed. Assuming no blockages in the coolant path through the hoses and engine, then coolant will circulate. Hope this helps Quote Link to comment Share on other sites More sharing options...
nickCR Posted September 26, 2022 Author Report Share Posted September 26, 2022 4 hours ago, TRS Fan said: Have you bled the air out using the bleed bolt in the top of the cylinder head? Item 4 on diagram attached. I normally part fill and then turn the engine over by hand with the kickstart - not easy unless plug removed. Then top up and bleed at cylinder head. Coolant should be just covering the top of the radiator fins - visible check with a torch if you shine into the fill hole, but I just dip my little finger in to ensure an air gap remains.. If the pump impeller is O.K., it will rotate when you turn the engine over by hand - and can be seen with the impeller cover removed. Assuming no blockages in the coolant path through the hoses and engine, then coolant will circulate. Purged the air via the 8mm bolt yes. I did not kick it over once the coolant was in (nor when it's halfway), except to start it. I'll have to try again. Quote Link to comment Share on other sites More sharing options...
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