'99 Yam S115 TLRX 2-stroke temp alarm on idle

Just came into ownership of this motor ('99 Yam S115 TLRX). It had been hung in a garage for 3-4yrs and had average to low hours. Runs great on the stand with ears. Pisser going strong. About 5min into idling, alarm goes off. The right cylinder head feels hotter than the left but i don't know the temp. I replaced the water pump and housing and bought 2 new thermostats. Fired her up with the ears and 5min in, alarm with right cylinder heads hotter than the left. There was mild/moderate crystal crap around the thermostats, but nothing looked obstructed unless there are some really small holes that need to stay open.

I don't know much about this motor yet so I'm stumped on the next step. I feel confident (naively!) that circulation through at least the right head is poor. Can someone explain how water is regulated in these 2 strokes?

Thanks in advance!

Re: '99 Yam S115 TLRX temp alarm on idle

Re: '99 Yam S115 TLRX temp alarm on idle

The starboard head is the last to get water in the grand circulation of things. Which means, water isn't making it up to the top of the head where the sensor is. Probably due to the poppet valve not sealing and holding pressure in the block.

Re: '99 Yam S115 TLRX temp alarm on idle

Re: '99 Yam S115 TLRX temp alarm on idle

Thanks! This makes good sense and helped me search on the forum to find more info. Much appreciated!

Re: '99 Yam S115 TLRX temp alarm on idle

Re: '99 Yam S115 TLRX temp alarm on idle

Pulled the poppet and it had some crud but looked functional. Inside the hole looked perfectly clean. I cleaned the poppet/spring/grommet and replaced. Will test tomorrow if the problem is solved.

Question: What should I see at idle if I take the thermostat/cover off? If I'm understanding the water flow correctly, water should come out. The water pump should push water through the jackets until it reaches and fills the heads...then flow out the thermostat hole. Please let this be right