my 2009 Mudd OX

[mudslinger]

After reading all the comments on sooty exhaust, backfiring, and slow throttle response it seems the sooner Kohler comes out with electronic fuel injection for this engine the better off the Ox will be, especially for you high altitude folks. I wonder if they will be able to make an EFI kit for all you Ox owners with carbs that would like to upgrade to 21st century fuel management.

[Roger S]

I doubt this is a chronic problem.. all the years I saw Matt's machines in development they always ran perfectly with none of the problems listed in this thread. There's plenty of argo and max discussions with these same complaints. One thing I like carbs over electronic fuel injection, is you can change a jet or make an adjustment. With EFI, you are stuck with the programming it came with. EFI is great when it works right, esp for altitude changes.

[travisch]

I agree with Roger - I just happen to live at 5500 feet above sea level and will operate the machine from here to 10k. Just like you needed to jet and possibly clutch an argo to get them to perform at their peak I suspect the Mudd-ox will be the same.
EFI isn't the perfect solution but it is a better all-around solution in most cases. I've got an EFI Polaris 800 that runs ok at high altitude but not perfect but I'm stuck with Polaris programming. A friends Yamaha 700 EFI runs great - better programming.

The problem with the 40HP Kohler big block is that its so new and a jet kit doesn't exist yet. Matt has been working with Kohler on developing a high altitude kit. I also only have 5 hours on my Mudd-Ox so it needs to be run more for break-in.

[hancock]

The engine issues I have described are not really troublesome to me, and I consider them, at least at this point, minor. I'm not a dealer, nor a dealer to be.......nor am I a disgruntled owner, so I have no vested interest in slanting information one way or the other.....I just tell it like it is. I'll keep you guys posted if any of the issues I have described become chronic.

For one thing, I agree with Travis that a little breaking in time is due. The backfiring seems to be handled as long as you rev the engine a bit while shutting down, as recommended by Kohler. The rough running/unresponsive throttle is extremely rare, (its only happened three or four times and every time has been during restart after it was already warmed up. It fixes itself within about 15 seconds or so). The vast majority of time it is actually quite responsive to throttle input. Time will tell if it ends up needing a little carb adjustment, but this I'm writing off to break in time right now. I haven't really had any exhaust soot problems, (not sure whats up with that).

Overall, I'm pretty impressed with the performance of the engine and especially it's start-up history during cold temps. If I had to pick a complaint at all right now, it would be that I don't think it is hitting top end speed as advertised. But, I have to caveat that by stating I haven't confirmed this. My "eyeball" picture of 24mph may be off. I'll confirm this one way or the other when I put my gps on board. (I keep forgetting to do this).

Hancock

[tbunce7]

muddox speed

Hey eveyone,

I asked Matt about the speed of the machines. He told me that the standard
gearing allows for about 21 mph, and low gearing kit is about 17 mph. I don't know if think Matt ever told me that 24 mph was top speed. Not to argue, I just never heard that number. Matt did tell me that with the tires aired up to 5 psi he thought that it might go 25 mph but I think that is an estimate. I have about 10 hrs on my ox and I'm very satisfied with it's performance. My son is an avid 4 wheel atv enthusiast but he is all about the Mudd-ox now.
Have fun

Terry

[hancock]

Features check out the link

Actually, Terry, that 24 mph is straight off of the official website. I also had a conversation with Matt early on where that was offered as the top end speed. I did, however, have a conversation with Matt fairly recently where he said that was fully inflated tires on flat pavement, so driving environment could affect it somewhat. And, as I stated earlier, I haven't really confirmed that it isn't going at that speed yet. That's just my best guess so far, but from the first time I ever drove it, I was surprised when I reached top end. (I should also add that I am used to four wheelers and the top speeds are dissimilar and for obvious reasons). I suppose I'll answer the question once and for all when I put the gps on board.

I'm sure it varies slightly from vehicle to vehicle and all of Matt's stats and specs come straight from hands on testing.

In regards to that previous post, I made it because it seemed like the tone of the last two pages from a few of us was geared towards engine complaints, and a few guys reading and responding seemed to maybe take it the wrong way. I think our comments weren't really meant to bring up serious concerns but rather "gee whiz" observations. Overall, I think it runs like a champ!!

Hancock

[tbunce7]

muddox speed

Hancock,

I stand corrected,I found on the muddox site abut the speed. I guess I must have read it with my bad eye. I understand your other concerns I love this machine. I have never owned a 4 wheeler of my own, but have been around and ridden many. I was always waiting for an aatv, since I was a kid. Matt happened to build the machine I was looking. I like the videos you've posted.
I post some as soon as I decide on the vid cam I want. Where in Mo. are you?
Tame that Ox.

Terry

[hancock]

Terry,

I was always waiting for an aatv, since I was a kid.

Sounds like a similar story to mine. I had a neighbor when I was about 7 or 8 years old that had a Hustler, and I've been jonesing for one ever since. (sheesh, that was almost 40 years ago, I must be old ).

When I starting looking, I initially thought I was going to buy a Max Buffalo, then almost bought an Argo....first the six wheeler and then an eight wheel Frontier. Actually had the Frontier bought, but it fell through for dubious reasons. I'm glad it did, because it gave me time to give the Ox a second round of consideration. It was quite a bit more $$ than I originally planned on investing, but after the smoke cleared I'm happy with the purchase. I figure, if you are going to do it......might as well do it right the first time.

I'm located in south central MO. Small town, in the Ozarks, not far from Current river. God's country, land of the hillbillys

Hancock

[hancock]

I post some as soon as I decide on the vid cam I want.

Incidentally, I'm not an expert on camcorders, but the wife and I bought a Panasonic not too long ago and are very happy with it. I can't remember the exact model, but if you are interested I will find out for you. Price wise, for the functions and zoom strength it provided, it was very competitive. The software it comes with doesn't interface very well with my Mac, but if you are a PC guy, no problems. It is very small and compact and the presentation is great. The fuzziness on my videos, I think, is more a component of the upload, and not the camera itself.

Hancock

(feel free to merge those two posts, Mike)

[AussieMax]

Carburettor jetting

I don't know if it is the same for the 40 hp Kohler, but some Kohler carburettors have jets identical to weber carburettors. We re-jetted an Avenger carby with these jets commonly available from an auto parts store. You can get them in any size. Kohler don't sell many sizes, and depending on the altitude you are at, you may need to change jets to get the best performance. We have had a Mudd-Ox here in Australia since September, and in the tropical heat we live in the engine bay fan is a must. It is there to stop the heat from the exhaust from boiling the fuel in the carby after shut down resulting in vapour locking problems. We also changed the exhaust to a smaller system with heat wrapping to keep the engine bay cooler. All in all a very capable machine.

[hancock]

We also changed the exhaust to a smaller system with heat wrapping to keep the engine bay cooler.

Interesting. Do you think that would be necessary here, where the temp gets to 90s or so in the summer, and around 100 once in a blue moon? Average temps in Aug probably run low to mid 90s.

Hancock

[AussieMax]

exhaust

The standard exhaust was quite large and very close to the drive belt. It held a lot of heat. The new system is a lot more compact and has reduced the heat in the engine bay quite drastically. I guess when the temperature rises over there if you are having problems it might be something worth looking into. We are in the tropics over here where the temp is 90 and above all year round with very high humidity at this time of the year. The new system is a little bit louder than the standard one, but it does sound good. I believe Matt was woking on a different exhaust in the factory to minimize engine bay heat.

[Roger S]

I'm located in south central MO. Small town, in the Ozarks, not far from Current river.

If you find a place for a group ride in your area, it would be centrally located for a bunch of us. We rode at Flat Nasty offroad park, south of Salem. Nice, but mostly hard pack/rock, and not much mud and soil. Beautiful area though.

[tbunce7]

location

Hancock,

I'll checkout the panasonics, I've just started looking. I've been to Springfield and Branson several times over the years. My wife has a cousin in Rogersville, Mo. and one in Jasper, Ar. I see Roger suggested a ride in your area. I'd be up for that. I'm just south of Des Moines and I'm looking for some places to have a ride.

Terry

[hancock]

We rode at Flat Nasty offroad park, south of Salem.

I've never been to Flat Nasty, but have driven by it numerous times. Lots of rocks in the Ozarks......hills, trees, and rocks. You can find mudholes/mudbogs after a good rain, but other than that they aren't just real prevalent around here. There is practically unlimited state and national forest as well, and some of those old woods roads through the forests have nice long rutted out mud holes, but the g-men have gotten pretty restrictive on atvs and such in these areas. The wife and I ride down buy the creeks and rivers on the county roads and MARKED woods roads, (I emphasize "marked", because those are the only legal ones), and yep, believe it or not, we sneak off on the unmarked ones, too, and it makes for a very fun and scenic afternoon. You would have a hard time pulling that off, however, with several vehicles on an organized ride. It is easier to stay under the radar with just 1 or 2 vehicles, and if you do get caught, they are less likely to hassle you as long as you aren't getting off the roads and carving up the woods. She and I are a little more into the scenery these days, anyhow, and not so much into the mudbogging and maxperforming of the vehicles. The latter interferes with our beer drinking. If I do ever come across a venue for a group ride, though, I will definitely throw it out there and see what interest it generates. I think Moallen, up to the north of me, has some big area he rides in that has mud, hills and all the good stuff, and if I'm not mistaken, atvs are allowed in there.

Hancock