Some of you might remember my thread about the cav plate question? The problem was that I had a 9x11 prop and the engine bogged bad. I was advised to trade it for an 8x4 so I did! Now the engine had no problem turning the prop but I've Lost all my speed! I'm guessing I'm getting around 3-5 mph with only me in the boat. Taking a closer look at the engine it seems as I have another gear box behind the engine which I'm guessing is a gear reduction? The original owner was no help as to what ratio the gr is! Only info he could tell me was that my engine turned the prop at the same rpm as a 16 hp engine. If this engine will run better without the gear reduction with an 8x4 I will ditch it I a heartbeat!! Any info is aplreciated!

Got any idea on rpms out of water?

The gear reduction throws a little kink into things - the guys recommended a prop size based on your HP at direct drive.

You really need to know what the reduction ratio is to figure what prop you need to run, either that, or replace your engine with a direct drive and run the prop you bought... You can figure the ratio easy enough by marking the flywheel of the motor and the prop, have someone spin the prop 1 revolution and another count the times the mark on the flywheel goes around...

Most likely, the 9" diameter was appropriate, but the pitch (the distance in inches of forward movement for 1 revolution of the prop) was way too much

Thanks guys! I have no clue what Rpms the engine is turning out if the water. The flywheel is located behind the pull start right? It's a honda gx270 engine.

Turn the engine by hand and count the output revs to engine revs. Gear reduction will multiply your torque by the ratio but will reduce rpms. You will have to select prop size based on torque. Dont expect too much from a 9hp.

And take the spark plug wire off when you do that!

thats not a gear reducer, its a crawfish model with a clutch if its a go devil 9hp. it takes a 10x9

Wow this is confusing

Is it a 9?

Yes it is a 9hp no clutch. It's a gearbox

Pics.....

sent from the former Republic of Texas.

I'm sure it's a crawfish model just as autogateman. It should have an obvious gearbox which has reduction gearing. If I'm not mistaken, you should be able to stop the prop at an idle. Hence, clutch.

Here is something from the archives...

Thanks for the link! I cranked the motor today and jammed the prop on hard ground at idle. It still turns not sure if it supposed to come to a complete stop or what? Not worried about that anyways lol. Again thanks for the link.

I tried stopping the crawfish model we have today. At idle it spins pretty damn good. I stuck my foot against it and was able to eventually get it to stop.

I was pretty sure I could stop it. I thought I remembered it stopping while idling. However, that is with a boat loaded with crawfish and bait.

Yep. Honestly I was waiting for it to suck my foot up.