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View Full Version : Prop pitch vs. re-jetting?



Full_Monte
09-25-2008, 09:48 AM
The other thread about prop pitch was about Hondas. I'm wondering if anyone has experimented with both prop pitch and re-jetting. I often fish at about 7,000 ft altitude. My 25 hp Yamaha oil-injected, electric start 2-stroke uses a 9 7/8 x 13 pitch prop. Doing nothing other than tilting the engine up a bit allows me to troll at .9 to 1.2 mph without stalling more than once every 10 minutes or so. I'm wondering whether I should fool around with prop pitch or changing the carburetor jets to improve it. Thanks for any suggestions.

MackPrince
09-25-2008, 09:53 PM
If you are stalling within 10 minutes check the plugs. They may be running too cold if the gap is fouled and oily. A different pitch propallows you to run the engine faster, but burns more gas and thus more noise. If stalling is as frequent as you mentioned a tune-up at the shop could help adjust for the altitude. Be sure to tell the mechanic how you use the motor, as this could lead to new carb settings and spark plug selection.

Full_Monte
09-26-2008, 03:43 AM
Thanks, MacPrince,

I hadn't thought of using a hotter plug. That makes a lot of sense, as idling a 2-stroke around for hours is probably hard on the plug as well as the engine.
Good idea! Thanks!

TrophyBoat
09-26-2008, 07:57 PM
Props can make a very big difference, my dad bought a brand new boat and we took it out to willard for its maiden voyage and it would barely plane and when it did it only would go 25mph, after doing some research and talking to local shops he rented a different prop and picked up 13 more mph and planed a hell of alot faster,and still ran at the correct RPM, he now runs 3 different props in utah depending on where we go and how many people we hual. we also upgraded th trolling motor that was propped different and it runs a ton quieter with improoved handling/response. I think once you figure out your scenario getting the correct prop would be your best bet seeing they only take 5 minutes to change. You may have other issues if your motor is dying. just my input.

Full_Monte
09-26-2008, 11:07 PM
Yeah...I guess there may be more than one adjustment necessary. Some problems in life often require complex solutions. What I've learned from this is that I should look at a few things: checking the tuneup, experimenting with the heat range of the spark plugs, and perhaps taking my 13 pitch prop to a 12.
If those things don't work out, I guess re-jetting the carburetor might help. I'm surprised there hasn't been someone proposing that. Thank you guys for speaking up! It's appreciated!