I just bought my first mud motor a few weeks ago and I'd like to know at what RPM's do most of you run your engines at? The motor I bought is a Mud Buddy Black Death 5500 with a 4300 RPM Rev limit and the motor can reach 4300 rpm quite easily. Most of the time I run it at about 3700 or so since I care more about engine life that going another 2-3 miles faster but I'd like to hear from all of you. So please let me know at what RPM's you usually run at and how many hours you have on your engine along with any mods you might have. Thanks.

i run anywhere from 3700-3900 when im WFO where i liked it trimmed on a stock briggs with almost 100 hours goin strong. could turn higher RPMS if i wanted... try using the search feature, be surprised what you will find on this topic already

from 4600 to 5050

4250+ on a CDI with carb, heads w/ valves, rockers, cam, and re-pitched prop.

You are not going to damage anything running it up near the rev limiter on that motor. If you are worried about it then add more load (have Hopkins add more pitch to your BB prop).

4600-5300.

3800-3900 wide open running stock.

3900-4200.

3700-3750 with my heavy arse barge

3500 to 3700 Stock GTR. Depends on load. I can turn 4200 but loose alot of speed. Around 3600 is my sweet spot.

Usually right around 4500-4600 on a stage 3 prodrive.

4150 is my sweet spot right now.

6000, WFO

I try to stay between 4100-4250.

I usually run around 3700 - 3850.

4000-4200

4100

WFO

6950-7100

I guess I've been running mine a bit slow compared to all of you. Have any of you seen a stock engine crack the block? I've done a few searched and it seems like the only ones that have had issues with the cracked blocks are the modded motors.

Isn't a 5500 is a modded motor?

Yes the 5500 is a modded engine, and yes there have been many stock motors that have cracked. If the bolts holding the case together get loose, it will cause the block to crack...

Higher rpms can cause more vibration that would work the bolts loose... But it does happen on stock motors.

The case bolts. The ones that go all the way around the motor and hold the block to the oil sump. Yes they can be checked and tightened. I don't know the torque spec on them for the briggs, but I would say its a good idea to keep an eye on em. Should be able to download a service manual from the manufacture's website.

I'm sure there are many things that can cause the block to crack. The case bolts seem to be the most prevalent reason for cracking. They get a little loose and the block can shift putting extra stress on certain areas. An out of balance prop can cause it also. Those bolts do not have to work loose for it to crack. Any kind of bad vibration can stress the block to a point where it cracks. Higher rpm's can amplify these vibrations. I'm sure there have been other reason's also, but I would say that's the main two reasons I've seen or heard about. Bolts worked loose, or vibration, or both...

Basically, what Cb is sayin is that he tries to keep his nuts tight & only plays with his vibrator @ home. At least that what it sounded like anyhow.

Heres a quick tip to check nuts/bolts that may cause concern. Use a paint marker and put a line on each nut/bolt and the motor. It's alot more simple to see if the line are straight than to put a torque wrench on each nut/bolt. I do this on my outboard for the lower unit, transom, and oil plugs.

Took my boat out today and ran it at 4000-4100 the whole time and it ran great. I went out before sunrise and couldn't see the tach and noticed the engine was missing but it turns out I was on the rev limiter. With these CDI engines the only think you hear is a light popping sound and that's it, sounds like a slight misfire so I'm going to call hopkins to see if I can add an inch to my prop. Thanks