[QUOTE=MrHeadsocket;649588]Ok guys, cheers for all the replies! I will walk away from this one, and cancel it through eBay... I currently have a Mariner 15HP that needs a rebuild and I will most likely get it rebuilt, but if I got it completely rebuilt with 20HP parts (including carbs etc) will this uprate the engine to 20HP and will this cause any damage?[/QUOTE
I did have a yam mariner which was a 15c, when I took it for a service and asked could it be uprated I was told it would be possible to gain a bit more hp by changing the carb.These engines were a favourite for Junior racing ,didnt ask exactly what hp would be gained but you can get some mariner 18hp worth checking with your engineer see what can be changed if anything.