Bought a complete rig from a guy locally and I've ran it once so far other than the test run we did before purchasing it. It ran great then, no issues.

Boat is a 2000 15x48 Weldbuilt Modified V with float boxes. Motor is a 20hp Honda Mudbuddy Longtail. I was looking for a V of some sort since I run some local lakes that do get a little choppy from time to time. I know it's not "ideal" for mudboat purposes but I was looking for a good compromise of everything. The hull is in good shape, no hooks or dents. Just some paint missing from the sand more than likely, no biggie.

I was told by the previous owner to grease the tail and joint before every run. That the lower seal and bearing are "self cleaning" it didn't sound 100% accurate to me for reasons of water and debris intrusion etc. I work on equipment for a living. Seals shouldn't leak by design IMO. Anyway. I greased it up, did the song and dance with the thumb screw etc. Me and my hunting buddy got about 4mi from the boat ramp and POP. Off comes the valve cover... Yes, the entire valve cover fell into the back of the boat. Threads in the head are stripped. Got that back on with the help of a rag and bungee cord. (Never leave home without it) and eased back to the boat ramp. Get it loaded up and notice there's grease that had dripped out of the lower seal/bearing even since it had been on the trailer, maybe 5-10min? No telling how much I slung out of it in the lake. Didn't run it hard, mostly just open water and some lillies. I knew this thing wasn't going to be a speed demon but it seemed too slow (no GPS or Tach) but after measuring the prop, it's worn down about an inch less than spec. I'm guessing its a 9x6 or 7 prop.



Needless to say, I'm not real pumped up about my purchase thus far. I kinda feel like the seller with held some info. I got it really reasonable so I didn't completely get hosed but not cool so far.

So what am I looking at to make this thing right and reliable? I've emailed MB and also emailed BW about a prop. Am I upset about nothing major? I know props are wear items on these things but I kind of hoped I could put off anything like this until after season at least.

Hell of a thing to have happen when teal season opens weekend after next and there's scouting to do...

You may not have to do much. You're probably going to have to tap or helicoil the head for the valve cover issue. Might be able to cheat with some steel mender epoxy, but that's your call. A worn down prop still works; you just aren't going to get top performance out of it.

The seals are another issue. If they're worn out and leaking a lot of grease, then they need to be replaced or you run the risk of getting to replace the shaft when you finally get around to replacing the seals. The grease gets hot when running and expands and a little is going to get by the seals, but if it's leaking a lot, then I'd replace them.

Well - 9x4 is what GD runs on the 18 and 20hp LTs.... A mod-v
is a perfomance problem too so go with a good factory original prop...

Don't go up on the pitch - each inch of pitch is a huge jump in final
gearing on these small motors - the 9x6 was ideal on my 23GDLT and
when I went to a 9x7 it killed performance completely....

Grease coming out of those lower bushings is not necessarily a
big deal - when you get back from a run feel for side to side slop
and as long is that is minimal you can keep pushing grease and
running for a long time.... If you can find a good lawn mower
shop the motor upkeep is pretty basic and similar to lawn mowing
applications....

I hear ya. I just hate having that in the back of my mind when I'm blowing down the river with a half ton of friends and gear, then hearing the awful 'skreech' as the shaft locks up. Then knowing it could have been avoided by me not putting it off LOL.

I know if I grease the hell out of it every trip the thing would probably live thru the season. Just not my usual way of doing things I guess. The grease gun lives in the boat already. I helicoiled the valve cover bolt hole already so that's fixed, just more annoying than anything I guess. If he knew there was damage then I feel I should have been informed of it. Instead of finding out about it on the water.

Changed the engine oil/filter, air filter, fuel filter and spark plugs this morning and filled up with ethanol free 93oct with some B12 in the fuel to clean things up. Greased everything again and plan to run it this afternoon with just me and unloaded (minus a full brute box cooler) to get some GPS speeds. I've got a handheld digital/laser tach too I might bring along to get some RPM readings with. Just want to get baseline info before changing anything around.

Either way around, I'd still like to probably order seals and bearings along with a prop to have on hand if I have to have them.

New LT owner: the previous posts said it mostly and you have progressed quickly. My first LT was a GD and I always took a loaded grease gun- man that leaked but that was GD and Coco himself told me on the phone he'd change out the sleeve bearings at least twice a season! The good news is repair parts are relatively cheap- this is a glorified lawnmower motor after all- and you will get to the ducks pretty much in a straight line but not too quick. Don't be too envious of those fast shorties, when they break down it means a lot more. A worn prop needs to be changed out. Always have a spare everything but especially the prop and have some tools to do the swapout. Put the antiseize grease and clean the threads and do it at least once a season. I have a MB LT now and it uses a lot less grease and is noticeably better than GD- no disrespect intended- and the next one will probably be BackH20 because the others are no longer making them and Back is making a fine product and there will always be a few marshes where the LT is the ticket. On a veteran motor I would suggest to go with synthetic oil and grease for the shaft housing. After I got rid of the conventional outboard I have never looked back, my LT is just fine.

I really like the new stuff BH2O is doing. I'm pretty convinced that will be my next one, in the 25-27hp range. This setup is a compromise for lots of different environments and so far that's not the issue, this Longtail setup is. The Honda runs great, plenty of tq and decently smooth. Those short SD setups are nice but I don't want to have to work on one. I'm keeping it simple for lots of reasons. I've owned this thing less than a week so far and have already learned a ton, but any time there's fluids or lubricants coming from places they shouldn't be, I consider that a problem...

One other note;

That's a big tin furr on the kill switch.

I erred in that I though you have a GD LT but in fact, have an MB! My MB uses a lot less grease than the two other GD's did. The skimpy manual that came with it stated NOT to overgrease the top bearing and U-joint, because that could damage the seals. I grease the shaft housing only every third trip or so, and that very sparingly. Obviously if you have that much frequent grease loss, and excessive play on the prop end, you need to swap out the bearings and seals asap.
My friend had a 24 Honda MB LT and it ran fine but encountered, like a few similar Hondas, problem with the fuel flow- kept shutting off and he fixed that by installing an electronic fuel pump. A simple and cheap "mod" as you may know, is to advance the throttle to around 4100-4300 rpm out of the water and it usually translates into a quick 2 mph gain but if your prop is that worn it won't help much.
Good luck and let us know how it goes!

9x5 for a 20hp

KCCO

Well ran it again today. Had a dry box with life jackets and safety equip, a 55qt cooler, bag of ice and some water, and my 145lb buddy, I'm about 240 lol. Best I saw without moving weight around was 15.5 on the GPS. I'm not entirely surprised given the shape everything is in.

This is the second time I've ran it. Both have ended the same, disappointment. Seems like once its ran for a while, there's a squeeling noise coming from the top of the drive. It's not a Ujoint home spinning on a shaft and it really doesn't sound like a lube starved bearing. It only does it with the prop in the water under load. Unload it and it free revs fine and with no abnormal noise. I did notice the lock bolt on the engine shaft backed out. The threads are also shot in that hole so drilling and tapping will be necessary for that as well.

The upper bearing retainer (? Has the Allen set screws on it) slides up and it seems the whole shaft is moving forward, putting something in a bind and making the noise. I snugged up the collar with the Allen screws and tapped it back down into place.

After further inspection, the previous owner has worm gear hose clamps holding the keys in place like they have previously tried to slide out or vibrate out... Ill have to address this too.

At this point a good once over is all that's going to put my mind at ease. I don't trust the " engineering" I have going on back there as of now. I've got an email into MB and will also try to call them tomorrow. Hopefully we can get this thing lined out... Sooner rather than later.

The biggest positive...

I can find no slop or slack side to side anywhere in the shaft top or bottom so I'm hoping the bearings/bushings (whichever it has) may be alright. I'm not as alarmed about the grease escaping as I was before.

I'll tell you the same thing I tell my buddies who want me to fix or build them a bike. " on the bright side, you own both halves! ". Good luck and don't get discouraged, keep your head up.

Setxlongtail,
If you are doing 15 in a welded 1548 mv with two men and gear with a 20 you are doing great.
A friend had a new mud buddy 29 horse Kawasaki on a tracker grizzly 1648 mv, with two men and no gear all he got was 17.. On a 1648 riveted flat bottom landau he got 21 same load.

Bit of a small update...

Pulled the engine and yokes, got a new U joint out in the yokes and fresh hardened set screws (actual set screws, not regular bolts like I had) put it all back together with the new joint, a new Tiny Tach, and grip on the handle. Touched up some of the camo on the engine and ran it... Idling about 17-1800 out of the water and will rev well over 4K if I let it which seems a bit high on both accounts. Ill get some in the water numbers tomorrow.

Last time I ran it with me and another guy my size I was seeing 14.7mph with a heavy cooler and us upstream, coming back down the river I actually bumped 16.6-16.7 but they are generating hard at the dam so the water was definitely helping. From what I can tell also, my hull is extremely heavy... Which is good. It's built like a battleship but its not gonna get you there in any kind of hurry lol.

Going to run it again tomorrow and ill update. Still haven't touched the prop or drive other than a U joint and screws, seems that was the root of my issues. I hate to be working bugs out with teal opening up in 3 days but it is what it is I guess.

-thanks again everyone for the help thus far.

Hey setex longtail. A longtail is not a speed demon. With that load and boat I'd have to agree 15mph isn't that bad. To be blunt about it would be to tell you if your not happy about the speed your getting. Go spend $5000+ and get a surface drive set up and go race with the best of em'. Oh by the way, take out the jam bolts and drill about 1/8 " deep divit in shaft then reinsert bolts, tighten and install safety wires through bolts.

I'm not really disappointed with the speed, it's right about where it should be I'm guessing. Don't really have much to compare to besides what I'm told here. I've never had a setup like this. Seems like mine is doing ok.

As far as the screws, I did just that. I drilled a pretty good dimple in the shaft and wired the bolt heads. The screws I was given are square headed hardened set screws for exactly this. They are almost cleated on the tip so they bite and don't move... A couple drops of red loctite went in with them. I also loctite'd the keys in their grooves since the previous owner had issues with them walking out, hence the presence of hose clamps on the exposed ends. Safety wired the heads on the jam bolts, pressure washed the frame down since there was years of caked on grease and funk on it and touched up the camo on the frame as well. Going to run it this evening and see what happens. Hopefully fighting this thing for 2-3 weeks will pay off.

And....

Yeah, I'd like to go drop 18/20K on a custom hull and surface drive but its not in the cards for me for a while... I'm getting happier with what I've got, it's just taking time and work to get it right. I realize I'm nowhere near done either. I should get several years of service out of this rig before needing any kind of major overhaul so I feel alright about it. These headaches right off the bat as soon as you purchase something is what had me kinda second guessing myself.

Averaged between 3750 and 3800 wide open in the water. Ran on up to around 4500 out of the water the couple times I had to clean grass off the skeg. I didn't have my GPS with me but I felt like we were doing better than the 14.5 we averaged before. Probably in the 16mph range. Idling out of the water was around 2000 and in the water was about 14-1500.

With those RPMs I can't tell if I just need a fresh prop or a deeper one. Probably just a new one since today was about as light as it'll ever be ran.

Out of the water at about 1700 I've got a vibration somewhere but it's only at that exact RPM and not sustained much. The screws and new U joint smoothed the whole frame up a pretty good bit. The fresh grip probably helped too, the old electrical tape and worn out rubber was rough lol

I didn't read all of the replies, so this may have alreaady been said. if you are spilling grease from the bottom seal to the point u can see it on the ground/trailer after a short run, you need to replace the lower seals.