drilling exhaust hole in leg

[naughtybynature]

i have a 1993 25h merc. i want to relieve the exhaust by drilling the leg. i have been told this is done just above the cav plate. my question is can you do this with the lower unit attached? where do the shavings go if so? what size hole do you recommend for this engine? anyone who has done this modification please let me know how you did it... and if the extra niose drives you nuts. thanks.

 

[sloopy]

Re: drilling exhaust hole in leg

take the lower unit off to collect the shreds and thendrill the small holes

 

[MercilessMike]

Re: drilling exhaust hole in leg

Thread the holes, then if you want to make it queit again you can screw in some brass pipe plugs.

 

[ad4par1]

Re: drilling exhaust hole in leg

Why do you need to relieve the exahust? Problems?

 

[sloopy]

Re: drilling exhaust hole in leg

he wants more power

 

[Hooty]

Re: drilling exhaust hole in leg

Don't drill into the water channel. Put a big glob of grease where your gonna drill. Drill slow so as not to melt the grease. The grease will collect the shavings. What few that get into the housing will blow out the exhaust.<br /><br />c/6<br /><br />Hooty

 

[Jim@KSC]

Re: drilling exhaust hole in leg

Any other references on this?<br /><br />Thanks<br /><br />jim@KSC

 

[naughtybynature]

Re: drilling exhaust hole in leg

i want to drill the exhaust more for the sound than anything. it has been said that this can increase your rpm a tad... not sure i'd see any benefit. the grease idea sounds very logical. anyone done this and wish they didn't. i plan on using some sort of plug for the times i have the boat at my cabin as to not bother the "locals" but when i'm out on the big lake rippin it up... ;-) open exhaust!

 

[Dhadley]

Re: drilling exhaust hole in leg

You can drill into the exhaust area without worry as it is an open chamber. However just drilling the hole may not help the rpm's unless its dry stacked also (no water in the exhaust). If all you want to do is create a very annoying sound thats the best way to do it.<br /><br />Good luck!

 

[roscoe]

Re: drilling exhaust hole in leg

This would sound better on a 4 stroke. On a 2 stroke it will only make it sound like an over hormoned chainsaw.

 

[naughtybynature]

Re: drilling exhaust hole in leg

that sound is what i'm looking for. when i used to run the chopper prop i could trim the motor so high that the exhaust sound was really loud.... i liked it. now that i am only spinning the stock prop i have lost that "bad ass" sound. simple as that. does anyone know of a picture that shows the best location to drill? how many holes..1 or 2?

 

[kglinz]

Re: drilling exhaust hole in leg

I'm not sure about outboards, but most 2 strokes have exhaust back pressure matched to the engine ports. Messing with the exhaust can kill your power.

 

[gsnyder]

Re: drilling exhaust hole in leg

It's interesting that you are considering drilling into your exhaust housing because the '56 10 hp 'rude that I picked up at an outboard boneyard has an access plate in the starboard side of the housing in order to reach the shift rod connector. On this particular motor, I noticed the plate had three holes drilled in it, but I thought that might be normal for this motor. When I finally got the motor functioning and started up, I found out that the three holes in the plate were exhaust relief above the water line. I also discovered, once I put the motor onto a boat and was able to crank it up to cruising speed, it was pretty damn noisy for a small motor, and I found that the source of the noise was those three holes in the access plate. Also, this motor is particularly strong, and I don't know if the exhaust relief may have an effect on its power. Maybe, if your motor has a similar access plate, you could save yourself from having to drill into the exhaust housing itself.