Hello all. Just puchased used Godevil 23hp long tail. Motor starts and runs great out of the water. In the water starts out fine but will only get up to about 3000 rpms. Pick it up out the water and the rpm's instantly jump up to 3600 to 3800. Drop it back in and same thing happens, struggles itself back up to 3000 rpm's. Check throttle at carb and it is wide open.

What size of rig? What size of prop? Speeds?

On a Alumacraft 14x32 hull. Has factory 9x6 prop. GPS says 18mph.

Got measurements on the prop? cavitation plate set correctly?

Verified prop as 9x6. My brother has the exact same motor. We put his on my boat and it did great as I expected. Ran at 3600 and GPS'd at 24mph.

Any work done to the prop? Sounds like it has alot of cup in it.

It is a 9x6 which the godevil site says is the right size for a 23-25. It does hav a cup in it. You think thats what it is? too much propeller bieng that is cupped and not flat edged?

Had cup put in mine the RPMs dropped 300 . You said it works fine with another prop correct? That would point me to cup in the prop


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The other set we had was exactly the same. Both had the 23 with the same exact 9x6 prop and same ammount of cup. It jumps out the water and reached top sped guick and effortlessly.

Im thinking it may be a fuel or electrical issue. Also thinking to do a compression check on both cylinders. I've seen engines in differest applications before run fine without any type of a load on it then they start acting like they are dieing from lack of power. That would be a sign fo possible low compression. No compression/no power???

Compression would be a good place to start, and valve clearances. Also a good idea to make sure you have new spark plugs. Factory recommended ones. I have had similar symptoms on briggs, from using odd ball plugs. Also make sure it's running on both cylinders, you can touch the exhaust manifolds right after you start it from being cold. If one pipe stays cold, you know you have a dead cylinder.
Let us know what you find out.

I had bought a 31 HP vanguard and it ran perfect out of the water but had ablsolutely no power when in the water. Prop was all correct size. Went to adjust valves and found the intake pushrod had jumped out from under the rocker arm, fixed this problem and found it still had no power in the water. Checked spark on both cylinders and found that the other cylinder had hardly any spark, checked resistance in coil and found no problems, ended up being the little diode inside of wiring harness being bad which was killing the spark on that coil put a new coil harness on and what do ya know we had good power. I couldn't believe with these two major problems that it ran and revved up perfect.

do yall have the same transom height on the boats! if so my lt did something simular cleaned out carb and found the air fule mixture to be vibrating back and forth placed new screws and a good carb clean shes been running since for a year or so now cav plates are very picky on a long tail and 18 is what i was getting on a loaded 1448 bymyself dont expect too much more they are not fast..if this is a brand new then go call the manufactor and claim warranty or replace with a 23 mini sd

overhaul carerateur.
check spark.
check kill switch.

Also check timing on the motor. The loss of power could be related to that as well. Motor would show high rpms without load, but struggle when in the water and with a load.