How to replace Jets on M50D for Hi Alt

[towtruck1]

Hello

I am considering replacing the main jets on my 91 M50D(3E3) for better hi altitude performance. The engine runs fine at 5000' as is, but I could use a bit more top end.

Is is possible to replace the jets w/o removing the carbs? I looked at a CLYMER manual which is not really that great, and had me a good stare at the engine w/cowl removed and it looks like more work than its worth for one week a year unless there is some trick I don't know.

Also, does anybody know where I can get better instructions if I decide to go for it? I'd rather not buy the official shop manual if I don't have to.

Thank You to All!
Andy

 

[TOHATSU GURU]

Re: How to replace Jets on M50D for Hi Alt

You have to pull the carbs to get to the jets. The Clymer manual is awful, but more than adequte for this task. Keep in mind that boating can be an expensive sometimes. Your talking a 15% to 25% performance increase by changing the jets. For a week of fishing it may not be worth it. For a week of watersking you don't have a choice.

 

[towtruck1]

Re: How to replace Jets on M50D for Hi Alt

Thank you Tohasu Guru

I was afraid of that.

The 15% to 25% numbers you quoted surprised me. I know I definitely get a drop in speed & pulling power up at 5000', but I don't recall seeing much (if any) drop in RPM at 5000' over what I checked out a week ago down here. Does that sound reasonable? Could the fact that down here I tested in salt water have something to do with it? I've heard it can have an affect, but I wouldn't expect such a big one.

The manual says to discard the carb gasket and put on new ones. Are those stuck on with adhesive or simply sandwiched in. Do they come right off? I don't I want to do this if I have to scrape adhesive off the mating surfaces. Do I have to replace weeks-old gaskets again when I get back from the lake and re-jet for SL?

Thank you again for all your help.
Andy