Prop Vent Plugs for 4 stroke

[tnbassin]

I was just looking around trying to learn more about props. My 2017 Ranger RT188C with 115 Mercury with command thrust uses a 23p Tempest Plus prop. The prop has the PVS plugs with the large hole in them. I think I just saw that the 4 stroke motors should be using the solid PVS plugs, not the large hole ones. Anyone know anything about this? The plugs are cheap and but what do you think it will change on the performance of my boat to use the solid plugs? What I would like to improve on my prop is to get a faster hole shot and stop the porpoise over 5000 rpms.

Also, do you think cupping would help?

[n2ratfishin]

If you are getting excessive prop slip coming out of the hole then I can see it helping. If not it might hurt hole shot.

They won't have any effect over 5000 RPMS.

Cupping the prop may help? I thought that was the benefit of the CT lower unit was running the larger Tempist. You are going to lose rpm when you start cupping.

[gonefishin555]

Solid PVS plugs will kill your hole shot. The hole in the prop when the proper one is in use; lets it blow out enough to keep RPMs up for hole shot. Too large an opening in the PVS plugs will cause cavitation and slippage on hole shot.
Not an expert; but have had about 10 bass boats and helped setup many more.

Good Luck

[Tim Kelly]

The hole shot on an RT188 should be pretty much instantaneous, very different to a heavy glass bass boat.

[Skeeterbait]

Solid PVS plugs will kill your hole shot....

That is generally true of a two stroke motor. Two strokes tend to have a power band high in the RPM range that must be reached to get proper torque from the motor. Vents in the plugs allow enough slip so the engine does not lug and can spin up enough RPM to reach its power band.

This is usually different on a 4 stroke. Mercury recommends solid plugs or minimal openings on 4 strokes. This is because 4 strokes develop torque at much lower RPM, normally enough to plane a boat without venting the prop. It is quit possible that his large vent holes are over venting causing his prop to loose too much thrust and causing him problems planning the boat with his 4 stroke. In that case plugging or reducing the size of the vents will give his 4 stroke better thrust and plane the boat better. Only way to know for sure is to test it. Plugs are cheap and easily replaceable. By all means should test and see what results he gets.

[johnsobo]

I have a 115 4s ct on a Z6. Using no plugs worked the best for me, motor spools up to 3500 rpms then I am off. With solid it would chug along to 3500 then get on plane.

[model70man]

I took the plugs out of my X7 Spitfire. Holeshot is much better with the vents wide open.

[eliteangler]

Triton bass boat owner here... chiming in on an old thread. I just took my motor out today for break in. It is a 250 Suzuki 4 stroke. The prop is a Mark Croxton Razor 4 blade, 26 pitch. He sent it with the solid plugs. I asked him before running it and he said to try it with them in first. The holeshot was horrible. I do have some different size plugs lying around. I wonder if I should go wide open, or start with the small hole plugs first.

[gatorglenn]

Well I would go open and see what happens. You can always put the plug back. Until you get the others.

[eliteangler]

Yeh... I will try it. I read somewhere that the vents don't help the 4 strokes like they do the 2 strokes.

[gatorglenn]

Yeh... I will try it. I read somewhere that the vents don't help the 4 strokes like they do the 2 strokes.

I would say that’s true on HP 115 and under. But 150 hp and up, can spin up pretty fast. So for me it will depend on the characteristics of the hull, load, power for a hull. To determine whether they will work or not.

[eliteangler]

I would say that’s true on HP 115 and under. But 150 hp and up, can spin up pretty fast. So for me it will depend on the characteristics of the hull, load, power for a hull. To determine whether they will work or not.

Agreed

[born 2 fish]

My hole shot did not change going from large plugs to solid. I prefer the solid plugs

[tobin01]

My hole shot did not change going from large plugs to solid. I prefer the solid plugs

Just changed mine to solid as well...no change. As Skeeterbait mentioned earlier, solid plugs for the 4-strokes. Mercury has also made the statement that the PVS system has little to no effect on the 4-Stroke motors.

[n2ratfishin]

If you want to REALLY dial one in for your load get all solid plugs. Load the boat for your normal day. Find a ramp with little traffic. Take a cordless drill and some drill bits. Launch with the solid plugs and time your hole shot. Make notes as you go. Take the boat out and drill one plug 1/4” and try again. Keep doing this one plug at a time going up one size in bits until you find the optimum sizes. If you have a jack plate this process can take a while because you’ll be making those tiny adjustments as well. But, you can really dial in a particular hull. When I had a “team boat” I may do this all day going through ten props before I got exactly what I was looking for.

This time I bought Rangers national dealers meeting boat and haven’t touched a darn thing on the set up. I know it has more in it, but I’m happy with the little boat. Ten years ago me and a guy named Tom (Flyswatter)spent no telling how many hours tweaking on Cat Sabers. That was a riot playing with those 70 MPH 18’ glass rigs.