That is a C25.
Single carb twin cylinder (500cc or thereabouts). It was a "cheap" 25 HP from back in the day. For a long time, Yamaha offered 3 different 25's. One (and the most popular) was the 25ESH, which was twin cylinder (395cc) twin carb, could be had in electric or manual start, short or long shaft and had oil injection up unti IIRC, 2004 or 2005. Then they were 100:1 premix. Then there was the C25 which was a price fighter 25. Long or short shaft. 90% were manual start but there were some electric start versions too. Rougher running, 50:1 only, a little louder. It was cheap and competed with Mariner/Mercury and OMC. Then there was the 25MSHU2 and 25MSHV3. Both were 3 cylinder manual start only but popular with guys who like to go fast. Can be modded to around 80 HP give or take. I've seen one on a dyno make 85 HP but they were spinning it close to 9,000 RPM. Sounded wicked.
Anyway...that picture is of the C25. It wasn't as nice as the oil injected 25's but they are ok. Still a reliable Yamaha outboard. Very simple and not much ever goes wrong with them due to their simplicity. Same powerhead as a C30, if I remember correctly. Carbs different and tuner (muffler) different.
I wouldn't give much more than $1000 for a NICE C25 electric start and probably $800 for a manual start. It's just not as sought after as the oil injected or later model 25 was; but nonetheless they're good motors.
Compression should be right around 125 psi on both cylinders.
Seems like I've seen that pic on Craigslist a while back. Might have been another one. If it's the one I'm thinking of, it's been for sale for a good while, IIRC.