Hey guys,

Picked up new motor last Thursday and am running best speed at 3900-4k RPM's 24/25mph light. Running Voodoo exhaust and gen IV lower. This is on a 1754X series PD that had a gen III motor on it previously that would run best speeds at 4350-4400 26/27. To get RPM's over 4k motor is trimmed up too high and loses speed. I've talked with Prodrive and they're usually very helpful, but didn't have anything to troubleshoot on this one. Not knocking them here, just wanna get right.

Anything worth checking out to see what could be causing the issue? If I'm running at 3900RPMs there still is more HP and torque left on the table.

Really want to get this thing dialed in right, thanks.

P

Still in break in period? I believe these are programmed to be gentle for the first xx hours

sounds about right to me. it ain't gonna turn up as much as the gen 3, different gear ratio.

Stock prop?

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Yes, stock 2 blade. Definitely looks much different from the gen III two blade. I didn't know that they were designed to go easy during break in.

Seems common for folks to report increased power after 10 or so hours. Aside from normal breakin I figured they pull a bit of timing in Ecu . I don't kno this for fact

Wonder if there is any issue with throwing on AM exhaust with only a couple hours on motor. Maybe input to ecu as baseline is jacked up?

What about valve clearance?

My motor has this apparently:

Stay calm as far as adding the pipe, Your not the first guy to add a pipe to a stocker. Wait for Owen to respond about the prop

I know bud, you know how it is you want to be excited about your new motor and if there are perceived issues at the start itll piss you off in a hurry. I will say that I ran my last motor hard as hell in salt water and didn't have one issue except for a solenoid issue that in hindsight was probably a loose connection but PD replaced it anyway.

I don't know if the gen IV vs gen III is the difference, when I would cut it hard and lay on the throttle in a corner it just felt like my last motor had a lot more balls

That just seems a little low to me on the rpms. A stock carb motor with an exhaust on a gen 2 lower usually turns around 4150 or so, and being yours is efi, I would expect a little more probably. I'd put 10-15 hours on it and report back.

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Also I would check to make sure you are actually getting full throttle at the throttle body, as it might be a linkage issue.

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Check valve lash. My 37 had some waaay outta whack clearance after 8-10hrs

When my gen 4 36 hp was stock it would only run 25-26 at 4000-4050. That was on my 18-48 uncle j. I'm also 285 pounds Honestly sounds a little low on mph and rmp.

Would a prop issue cause this by any chance? Bad oil?

KP gave me a call late yesterday to help me figure out what was up, which again shows their dedication to customer service. Feels like the most likely issue is over tightened valve screws so I'll check clearance this weekend when I get back to the coast.

Now only getting 2k rpms out of motor. FML.

Bring it in for warranty work.

It's in now.

Rocker arm came off pushrod, nut was sitting down in valve pocket. Adjusted valve lash on all valves. Hopefully that fixes the issue. I opened up the valve covers prior to dropping the pushrod and noticed that the #2 intake rocker arm was not lifting as far as the others. This was with the nut on, not sure if putting the nut on and setting lash would have anything to do with lift. Wouldn't that be a cam lobe issue?

Yes, or it's set way too loose.

I'll run it after work and will let y'all know how it runs.

God damnit! Still only getting 3900-4000 trimmed right, will run higher when trimmed way up and blows out. Then had issues with idle running high at 1500rpm, and motor cutting off due to low idle when shifting into reverse. I don't know what the hell is going on. The thing that drives me nuts it is seems that Briggs has no clue how to check how things work under load. They run it at the shop without load and it doesn't have issues, but I'm telling you this motor is not making full power. The other BS thing is I'm close rpm wise within a couple hundred RPM so it doesn't seem like a huge issue to these guys.

Top speed is 23mph

Where are you located?

I'm in Raleigh, NC and float around the coast of NC/SC.

Might send a pm to SCmudder7071. I don't know how close he is to you, but he's pretty knowledgeable himself and may also be able to help you find a better shop to look at it.

Will do, thanks

It shouldn't be that tough, I mean engine isn't making enough power to spin wheel higher than 4k at proper trim. Engine is not making enough power, so you might not be getting enough air in, intake valve may not be opening up enough, because rpms are all over the board at idle might have a fuel pump issue or sensor issue. Those are what come to mind for me, any one else have any thoughts? Throttle cable seems to be working correctly.

You get it from muddy bay?


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