help finding cause of over heat

[mattdd]

is it possible that only one cylinder wouldnt be getting oil. my no. 2 cylinder went out, and has been rebuilt, and now iam looking fo rthe original problem. i took the carbs off and oil dripped out of the line going to the no. 2 hole, dont know if that even means that it was getting oil, maybe just residual, but it was fresh oil. gonna work on some more stuff. oh yeah, '86 90hp yamaha

 

[mattdd]

Re: help finding cause of over heat

ok....heres where iam at. no. 2 cylinder definatly overheated, but 1 & 3 were fine except for very minor scuffs in the cyl. wall closest to the no. 2 cyl. 1. checked water pump, it was in perfect shape, but while its out iam putting in a whole new kit. 2. so i moved onto the oil injection....no problems there. all 3 lines b/t carb plate and oil pump where clear. took those lines off of the pump and oil came out of all 3 ports when i cranked the engine. so its getting oil. so theres really not much left that could have caused it to overheat, right? 3. i took off the head cover, to check those passages and they are clean. but what is this at the top of the cover? is it a thermostat. it looks like its in bad shape. no part of the very top piece moves, like i think that it should. could this be my problem?<br /><br />

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[Ray Neudecker]

Re: help finding cause of over heat

It is a thermostat at the top and a popit vave below it and either could well be the cause of overheating.