Hi Im new to the page and i just got a 6.5 gdlt. the motor and frame had satfor a few years. It has a briggs 6.5 intek pro on it and after rebuilding the carb i got it to run. The motor sounds great out of the water but once you put it down into the water it boggs down to about an idle and struggles to run. there is no change when you move the throttle but it will push a 1448 jon slowly with 2 guys. I know that neither of the props i got for this motor are right as it came with a 9x6 3 blade gd prop and a 6x5 2 blade that is worn to about 4" and the 3 blade is worn to about 7.5" .. i have access to a new motor that is a 7hp kohler .. any suggestions.

Call go devil and get the correct prop... once you are good on that front look at your throttle, will it rev up out of the water?

The BackH20 site recommends a 6x4 prop for a 4-7 hp motor and a 7x4 prop for a 7-10 hp engine.
Sounds like too much prop and it is bogging the engine.
Hope this helps

Mudde

Decent chance it's the prop as others have said.

How confident are you that the carb is completely clean and providing full fuel flow? If you choke it when it bogs down, does it pick up any? I've seen similar behavior out of an engine that ran great out of the water and bogged when put under a load. Choke it and it smoothed out, but lacked power. Wasn't getting enough fuel due to a piece of trash in the carb. Cleaned it up and it ran like a top.

I had a coil pack going bad on my ol 25 GDLT that would run great out of the water, but spit n sputter in the water. Check the coils and check the gap.

Well i got the motor from a guy that i work with and i saw him run it a cpl of years ago with the 6.5 briggs intek on it and he was getting about 12mph outta it. When i got it the carb was gummed up bad. I rebuilt the carb and thoroghly cleaned it along with fresh fuel and plug and filter. i also changed the lower bushing and all seals. The motor runs great outta h20 but once it is submerged it pulls the tail down deep and just boggs down to nothin. The prop that is on it is a worn out 9-6 old 3 blade go devil prop but its worn to about 7" it did come with a 7-5 2 blade bu that one is worn to about 5" i went ahead and put the new kohler 7hp on there and am gunna try it this wknd with both props and more than likely will end up getting a new prop for it .. are the backwater props good replacements.

Sounds like your biggest problem besides the prop is that your motor is running too deep in the water. Bend the cavitation plate down towards your prop, grab a hold of it with a crescent wrench and bend it dow. This creates "lift" and will bring your prop closer to the surface of the water and will allow your motor to turn at higher RPM's. Longtails are not designed to run deep but right at the surface of the water. If your motor wants to blow out of the water then bend the cav plate up. A small hp motor doesn't have the torque to run that deep or you really loose RPMs. Good luck. BTW your kohler will bog too if you don't move your cav plate down.

Sounds like your biggest problem besides the prop is that your motor is running too deep in the water. Bend the cavitation plate down towards your prop, grab a hold of it with a crescent wrench and bend it dow. This creates "lift" and will bring your prop closer to the surface of the water and will allow your motor to turn at higher RPM's. Longtails are not designed to run deep but right at the surface of the water. If your motor wants to blow out of the water then bend the cav plate up. A small hp motor doesn't have the torque to run that deep or you really loose RPMs. Good luck. BTW your kohler will bog too if you don't move your cav plate down.

Sounds like your biggest problem besides the prop is that your motor is running too deep in the water. Bend the cavitation plate down towards your prop, grab a hold of it with a crescent wrench and bend it down. This creates "lift" and will bring your prop closer to the surface of the water and will allow your motor to turn at higher RPM's. Longtails are not designed to run deep but right at the surface of the water. If your motor wants to blow out of the water then bend the cav plate up. A small hp motor doesn't have the torque to run that deep or you really loose RPMs. Good luck. BTW your kohler will bog too if you don't move your cav plate down.

i just bent the cav plate the other day as it had neve been bent prior to me getting the motor i bent it down a bit but will adjust as needed .. thanks for all of the information guys i really appreciate it