Mercury 25 HP Help

**freeclimber** · 01-13-2019, 07:25 PM

Hi Scream and Fly!

I was referred over from microskiff! I was looking for suggestions or help on my outboard. I pulled it apart this weekend and found out it was .030" over, wasn't warned or advised it had already been rebuilt. I tore it apart due to low compression, poor idling, and difficultly to start.

There is a little scoring on the #2 cylinder. Is there any possible outcome to bring it back to life? I have seen pistons that would go up to 0.040" over but the rebuild manual doesn't recommend more than the 0.030" over.

I would like to get it back to a reliable fishing machine again! I have looked into the new Yamaha but I don't wanna swing ~$4k

Thanks for your help in advance!

**XstreamVking** · 01-13-2019, 07:35 PM

It's probably used up it's 9 lives. Keep an eye on e-bay and crsigslist. My son found and bought a mint 2002 25hp bare powerhead for 300 bucks a while back. It may also be a good idea to look for complete motors in the sub 1000 dollar range. We got a 20'' 2000 mariner 25 for 700. Real nice. They are out there. People are moving to the 4 strokes and selling the 2 strokes.

**freeclimber** · 01-14-2019, 07:24 AM

Thanks Vking!

Going to see a machinist here in town for another opinion. I am hoping that my set of calipers are jacked. If not I will be running on the spare motor for a while. Any idea what the ideal compression is for these motors are? I have heard the gantry of responses.

Thanks

**XstreamVking** · 01-14-2019, 07:55 AM

About 125-130 is what we are seeing in a healthy one. My sons 2002 was 130 when fresh.

**FORBESAUTO** · 01-14-2019, 08:51 AM

You could resleeve it, but like the king said you can pick you up a nice one for less than you can get this one back in tip top shape I would imagine. Then ya got a nice spare parts mota too.

**WillySteve** · 01-14-2019, 06:49 PM

Don't know about now but back in the 80's the 25's used Mercosil Cyls! My '85 was!

**FMP** · 01-14-2019, 07:13 PM

All those made more hp than 25. I've heard 28-30, I have a couple, tough motors but I've replaced coils wires pumps etc , gears. They still start first pull every time, every time. Just choke prime three or four times and high idle , pull and it's running.

**freeclimber** · 01-16-2019, 11:14 PM

Yep this one has the Mercosil block! I should be seeing the machinist tomorrow now! I'm hoping for some good news. I don't know if the .040" will be needed yet but it would be a great backup if I do!