Burnt tips on fiber reeds..why?

Omc 15hp small bore, fresh rebuild cause metal reeds had reed tips broken. So I use fiber reeds, jetting slightly rich and never any case explosions, or sneezing of one prefers.

I did some case cleanup, and behind the liner mods and so forth. With tach it spins 7400rpm with 10p4blade prop. I don't run it that fast but upon occasion when I'm with a buddy.... 8)

But by the end of the year it was spitting back and hard to start. I knew the cause so i just pulled it down today and found burnt reed tips on all 4 reeds. What is my next move to fix this issue?

Well yea..but the steel ones crapped out also. I was wondering if there was a good reason for it.

I use the boat 1.5 hours a day from April to November on average. Was using cc reeds and now will try Boyesen for this summer.

I figure the results will be the same come November. I guess its the price to be paid to go fast

I have a lot of experience with 2-stroke motocross bikes, not so much outboards.

OEM reeds work great, I never liked the aftermarket.

Also make sure there are no air leaks at the intake.

Multitudes of 2-stroke engine problems are caused by leaky crank seals. I've replaced a lot of crank seals in my day, and once I started replacing crank seals regularly, all the burned and seized pistons stopped happening, the smoking was cut down, jetting made sense, and everything was right in the world.


Good seals are critical.

I might have left out the fact that the steel reeds failed cause the screws came loose holding them down The reed "stop" then was hitting the crank along with the reeds. I got the motor in a box couple of years ago cause of the loose reed damage.

I was hoping for 10 extra HP from the fiber reeds. jk.. :roll:

DaisyCutter said:

I have a lot of experience with 2-stroke motocross bikes, not so much outboards.

OEM reeds work great, I never liked the aftermarket.

Also make sure there are no air leaks at the intake.

Multitudes of 2-stroke engine problems are caused by leaky crank seals. I've replaced a lot of crank seals in my day, and once I started replacing crank seals regularly, all the burned and seized pistons stopped happening, the smoking was cut down, jetting made sense, and everything was right in the world.


Good seals are critical.

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^This^

Same here, two stroke dirtbike engine experience, not much outboard. The Boysens I used always worked but would warp a little bit so they did not seal good. Steel reeds always sealed unless the ends chipped for some reason or another. I did have some good long term function from a set of Aktive brand carbon fiber reeds in my "96 YZ250.

7,400 RPM :shock: not doubting ya , but did I read that right??

Charger25 said:

7,400 RPM :shock: not doubting ya , but did I read that right??

Click to expand...

Okay..yes according to my Chinese tach.

Older 75' higher comp head

"D" cut behind the liner so called and slightly cut piston to match. Flowed the intake path in the liner and around the intake ports. Use no gasket except loctite gasket maker to close area up behind intake cover alittle keeping velocity up.

Had CC reeds. Boyesen this year, river still frozen

Meg exhaust tuner, shortened 1/8in.

opened up area at ends of the reeds on block half

Opened up the exhaust port facing down, 1 on each cyl to make better use of the return wave. no liner cut but port is much larger, can stick thumb almost in it all the way. Trumpeted other 2 ports per cyl, aiming them down the best I could.

Modded and flowed older intake manifold to the newer post 93 design.

Running minimal water in the mid section, manual adjustable motor temp adjust on head, no thermo

Polyurethane home brew motor mounts.

Running 4b10p blade, sharpened for weed cutting

Atom point eliminators, older ign system

Using Walmart oil at 20/1 mix, alcoholfree gas, B5 plugs with rich jetting.

And 7400 rpm alone in a 1232jon with 3" side pontoons extending a foot past the transom. With 8' bimini top flapping in the breeze.

I only run it at 7400 when my buddies are listening or racing for pink slips. Normally my wife is with me so...not so fast.

I like the way you think. :mrgreen: