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1992 115 hp Yamaha carburetor float height

E

erich

Regular Contributor
I have a 1992 V4 115 HP outboard with two carbs. Each carb has 2 floats and 2 needle valves. I have removed and cleaned the carbs but would like to set the float height. Any idea what that spec is?
 
Get a service manual. In the meantime, before yours arrives,



Do you know that if you were an aircraft mechanic and you got caught working without the manufacturer's data that you could be fined or lose your license?
 
boscoe said:
Get a service manual. In the meantime, before yours arrives,



Do you know that if you were an aircraft mechanic and you got caught working without the manufacturer's data that you could be fined or lose your license?
Click to expand...

boscoe,

I would get a repair manual if this were my motor but it is my brother-in-laws and he is in the process of selling the boat/motor/trailer. Is that 16.0 mm spec from the 115HP manual? Thanks for posting it.

Erich
 
The reason I asked about the float height is because I pulled both carbs off, took apart everything I could and cleaned with choke and carb cleaner. I put them back in and retested the boat but the original problem remains, but is now a little worse in that I can't get it started without the help of a little starter spray in the carbs first. I have already replaced the fuel pump, but no difference.

The original, and continuing, problem being that the motor runs OK at idle and low speed but when trying to get up on plane it bogs down. It doesn't stall out but keeps surging until the throttle is returned to a lower setting. I don't know the rpms involved because there is no working gauge. With the boat out of the water and running at or just above idle on a garden hose with muffs, I removed the spark plug wire on each cylinder, one at a time, and detected very little change on cylinder #4. I believe the fuel pump works off of the vacuum pulses on that same cylinder. Compression is OK on all cylinders at about 110.

I removed the carbs again and my brother-in-law took them to a shop but they will cost about $250 each to clean and rebuild with a kit, so he declined. So I will take another look at them later this week and make sure the float level is good, but that cylinder #4 issue bothers me. Plugs are good, but I swapped plugs from #2 and #4 anyway and no change.

Any thoughts and suggestions? Possible bad reed valve?

Erich

Edit: I should have previously noted that thinking the problem was bad gas, I connected a portable container with new gas directly to the motor and no change. It seems like the engine is starving for fuel at high throttle settings.
 
Last edited:
erich said:
The reason I asked about the float height is because I pulled both carbs off, took apart everything I could and cleaned with choke and carb cleaner. I put them back in and retested the boat but the original problem remains, but is now a little worse in that I can't get it started without the help of a little starter spray in the carbs first. I have already replaced the fuel pump, but no difference.

The original, and continuing, problem being that the motor runs OK at idle and low speed but when trying to get up on plane it bogs down. It doesn't stall out but keeps surging until the throttle is returned to a lower setting. I don't know the rpms involved because there is no working gauge. With the boat out of the water and running at or just above idle on a garden hose with muffs, I removed the spark plug wire on each cylinder, one at a time, and detected very little change on cylinder #4. I believe the fuel pump works off of the vacuum pulses on that same cylinder. Compression is OK on all cylinders at about 110.

I removed the carbs again and my brother-in-law took them to a shop but they will cost about $250 each to clean and rebuild with a kit, so he declined. So I will take another look at them later this week and make sure the float level is good, but that cylinder #4 issue bothers me. Plugs are good, but I swapped plugs from #2 and #4 anyway and no change.

Any thoughts and suggestions? Possible bad reed valve?

Erich

Edit: I should have previously noted that thinking the problem was bad gas, I connected a portable container with new gas directly to the motor and no change. It seems like the engine is starving for fuel at high throttle settings.
Click to expand...

Did you ever fix this problem? I have a 96 115txru 2 stroke yam with the exact problem right now. Any help in direction would b great.... missing the blue.....
 
Suggest you start your own thread with details on the motor, symptoms on what it's doing or not and some history. Maybe then we can help you.
 
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