Drilling Out Exhaust on 200 Blackmax

**Judge85** · 06-14-2009, 10:55 AM

I have a 21 Checkmate Enchanter with a 1989 Mercury 200 hp Blackmax. The engine is in great condition. I am in the process of upgrading the carbs and heads, and I have always wanted to drill out the exhaust in the midsection of the outboard since I bought it. My only concern is that I have never done a modification like this before so I don't know the correct drilling location, or what size the holes should be. Any information on drilling location, and steps for the procedure would be greatly appreciated.

**Jay Smith** · 06-14-2009, 11:05 AM

WELCOME TO SCREAM AND FLY !!!!!!

Many varied opinions on the subject. Several years back Mercury had 260's mounted on a 20" midsection called a "Bass Mid" they had a cavitation plate at the base of the mid and had 5 1/2" holes drilled at that point on each side and was very popular. The way to drill these point the power head would need to be removed and the inner liner with a long drill bit to drill through the inner part of the ledge from the inside. From the outside it is not visable ( keeps lake patrol off ya butt ) but has a sweet sound. Other methods use hole saws from the out side BUT this mod is very visable and I have seen cracks and failures doing the mods any other way that the stock Bass Mid way..

Good luck,
BTW you sure have a good looking rig !
Jay

**Ranger976** · 06-14-2009, 01:14 PM

great place to BS, meet people and spend a GREAT DEAL OF MONEY!

**outboards4life** · 06-14-2009, 01:20 PM

step by step instructions and you can go back to the original sound if you end up not liking it.
http://forums.screamandfly.com/forum...exhaust+relief