Since you are in the South like I am have you considered Rotella 30w? I've been running Rotella 30w for the last few years too and change oil every 100 hours or so. My 25hp Kohler is a 2002 motor and it is as strong as ever.

I actually had good results with both synthetic oil (Mobil 1) 10w-30 and grease with my last two motors, both were Kohlers (25,27). BW told me I should use conventional oil the first two changes and then I could switch to synthetic.

I use Lucas grease in my lower and Rotella 15-40 in my engine with Wix filters. I change it often though. Every 20hrs or so.

I took the boat out today for the maiden voyage. Right off the bat I'm not liking the factory throttle lever. When would open it up the angle with my wrist did not let me hold it down with any kind of comfort. So when I would release pressure with my thumb the throttle backed off on its own. So I need to look at some other kind of throttle lever.

Also at low to mid throttle the cavitation plate rode just like it should have....right at the water line with very little if any "fight" with my hand to hold there. But when I opened it up to 3/4 or full throttle the cavitation plate was a few inches above the water line and I was not gaining any speed like I thought I should. Do I need to shim it? I don't think I broke 15 mph at full throttle. Just me and no load what so ever.

Overall I like the motor just need to tweak a few things.

Does your mount have the pin/stop or bump stop? See my review today. I dialed up the bump stop and took out a shim, left one in, and it runs really well. If your cavitation plate is running that high, I believe you must shim it to ride a little deeper; that said, your pin/bump stop could also be the culprit!

Is the bump stop the pin with a choice of 4 holes?

It's the orange bumper with the adjustment on top.


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Mine does not have that red bump stop thingy but I did pull the pin and switch to a hole that does allow the prop/plate to be lower. But its sitting in the driveway now so will have to wait a few days till I can get back on the water to test it out.

Ok let me add some info. When I was trying to go full throttle and was looking back and seeing the plate to far above the water....I tried like hell to pull up on the handle to get the prop lower in the water. Would not budge. Was that the pin holding it or does the prop/plate have that much gusto to keep me from lowering that dam prop down into the water?

I am guessing the pin is stopping you...try running without the pin.
hawilson, did you tinker with the small threaded bolt that pushes the throttle plate? I am tempted to advance it so it pushes the plate farther and gain some rpms?? I will be getting a 9x6 prop also, should get to that 20 mph plateau.

More rpm at idle??

If it's opening all the way 90 degrees of the inlet that's all you're gonna get as far as upper RPM.

I just checked the throttle plate. It can travel another two inches of arc. If I loosen the nut and forward the bolt most of the way, it should travel most of the way. This should increase top end rpms, I only worry this can damage the EFI settings? hawilson, any ideas?

Does it not have a rev limit built into the programming being EFI? If it does, I'd advance that screw till you can get it 100% open. Let the ECM do the rest.

If you're getting high teens without full throttle, and still working on that cav plate, that's pretty impressive.

Someone here said the EFI upper limit is something like 4700 rpms? I think I will advance the throttle, thanks for the encouragement, I am impressed with this motor. I also think by moving to the 9x6 prop I will also improve.

I'm not sure where the Kohlers are set at. The big block Briggs is 4750.

The ECU max rpm is set to 4500. From the Kohler service manual (you can download the service and owner's manual from the Kohler site):

To prevent engine over-speed and possible failure, a rev-limiting feature is programmed into ECU. If maximum RPM limit (4500) is exceeded, ECU suppresses injection signals, cutting off fuel flow. This process repeats itself in rapid succession, limiting operation to preset maximum.

I actually bought a longer screw, the one you alluded to, and turned it in more. I believe it increases tension on the governor spring making it harder for the governor gear/arm to pull against it thereby raising the upper RPM's it can reach. My gov now engages around 4350-4400 rpm. The max rpm in water is now about 4150-4200 with the BW 9x6 prop. Running 20 mph with one man fishing load and can touch 21 or 22 if all the stars align.

Again, I am no expert.

Thanks, man! I will definitely turn it farther! I hit 18.4 mph at 3470 rpms (tinytach2A) with the 9x7 prop!

Ok, threaded the small bolt forward and now,out of the water, hit 4100 rpm. There is still about a 1/4" of more travel available but I will play it safe and see what I get.

I got 20 mph with me and son. He's 6-2 200 lbs and I'm 5-11 195 lbs. No load though, just us. A few ripples on the water. 23hp backwater light . 15ft flat jon.

Is that speed about right?

If accurate, that's a REAL good speed.

Dang good! Welcome to the 20 mph club. I had to officially take off my hat and stow it or I'd of lost it. Going to have to start wearing something else to keep my baldpate from getting burned! longboman, get you some gatorglide or steelflex on the bottom of your hull, it will feel like a small airboat!

HA HA beat you Glades. I put gator glide on it when I was re finishing it. I downloaded a speed app on my phone and me and son have tested it in our trucks. Spot on. We mostly got 19 mph but hit 20 a few times. The boat was loaded out though, all life jackets plus 2 spares, throw able, tool box, push poles, walking stick, collapsible paddles etc.

I'll post up pics later of the rig.

Good for you! Just make sure you keep the bow clip on when backing down the ramp! Hey, there's a 1648 riveted Lowe jon (275#) down here with a 20 year old GD 25 HP LT. I have clocked it with the father and two sons on board- all well over 200# each plus hunting gear- going 18.5 mph. Stock motor, tweaked throttle, synthetic oil and grease, well worn GD prop...I have to figure the motor internals are so smooth from wear is why they are so damn fast! I wish my hull was that light!

First pic is the day i got the boat. Second is the day i mounted the motor. Last is the finished boat. I stripped the boat out when I was re finishing it. Welded new deck, beefed up the transom. Camo is nat gear. Also re finished the trailer.

longboman, glad you mentioned the trailer! We usually talk about everything here except the trailer. I found that both of my boat bunks were soft so I replaced them last time I ran the boat, much easier to do with the boat off the trailer. I also noticed my transom tie downs need replacing; the tires still are good but I bet another season will warrant a change. The original tires were load range B, I moved to load range C and make sure I have it at the indicated inflation pressure, guess for years I was under-inflating the others and caused excessive wear. I run exclusively in fresh water, I am sure there would be more maintenance if it were brackish or salt.
Your boat looks good! Are you adding a floor? I'd recommend aluminum if you do.
Did you ever try the versa mount "inboard style"? One thing I have noticed with this motor, compared to both GD and MB, is that generally the BW design is more back-weighted. I will still have to move it to the rearmost hole to adjust the balance point forward a notch. The positive trade-off of this design is that the cavitation plate and prop ride at the surface and you get max performance.

No floor. This is a transport boat (unless I see an unusual amount of divers in the center of the lakes)! I hunt backwater timber areas mostly. I like the 2nd floor beam forward from the rear....makes a good foot bench while standing. I did not try the versa mount inside. I wanted the motor as far back as possible. But I to have noticed the rear weight of the motor....my tie down straps keep coming loose during trailoring. Both transom and the dam strap for the motor. But I just bought a newer tie down for the motor and its rated for more weight than my old one. You would think a rinky dink 300lb strap would keep the tail down but it won't. I got me a 660lb strap now! I mounted an eye hook on the rear beam each side and the strap connects there and goes around the tail shaft. I had to get 2 transom straps that were rated higher also. And they have the wire clip so that even if they come loose they can't just come unhooked and you loose them. They might come loose now but there staying strapped on! As far as my trailer only thing I need to change now are the carpet bunks. Tip I got here on mmt. The carpet can wear on the gator glide I guess so I'm going to remove the carpet and put gg on the wooden bunks. Only thing I noticed so far about the motor is...I put my gas tank up front under the bow. So I have a long gas line now. Sometimes when I start the motor it wants to try to sputter a little. Never dies though. Once I lower the motor she picks up steam. Not sure if that is related to the long gas line though. All in all I'm very pleased with the job. Seats are cheap coolers. They act as somewhat dry storage also. Guns will hang along side the gunnels with straps (another tip here on mmt) Decoys will strap to the front and hang over bow deck. Blind bag stays near me in the rear. Push pole and walking sticks strap on top of the rails.

Can't wait till duck season!

I understand, since I hunt out of the boat, I got tired of tripping on the ribs. Always good to have a "fail safe" strap in addition to the others. On my previous motors I always trailered the longtails with the tail out, took a chance there, always drove carefully and added a light for other drivers. With the new motor, as it is mounted, it trailers best with the tail in the boat, just added a wooden "shoe" and it holds firm and the hydroturf does not let it slide much. I love the shorter turning radius of the 59" inch drive, and it is about 5" less than that because of the inboard mounting.