Any motorheads out there???

[jcmseven]

I debated about whether to place this question, in the ATV area or the JD forum. From its presence here, we can tell that I felt this question might be best answered in this forum, due to the vast experience with the Yanmar engines which exists here. I have a JD XUV Gator with the indirect injected Yanmar three cylinder 854 cc engine. The machine is great, but I would like to have a bit more power. The engine is rated at 24.6 HP and pulling the accessory-laden XUV at about 1700 pounds is at times challenging on our steep grades, especially when loaded. I otherwise like the machine and was looking into replacing the current engine with one 5-10 hp stronger. Does anyone know which Yanmar diesels would be compatable in this case from a size perspective?? I would like to stick with diesel if I do this, although my JD dealer says he thinks the gas engined one would be easier to upgrade. My only other issue is that the Yanmar diesels seem quite expensive. Any thoughts and/or reputable resources would be welcomed.

John M

[RollTideRam]

Could you add a turbo? JC

[AKfish]

If you're interested in more power -- you might consider changing the gear ratio in the rear differential.

The cost would be considerably less than a new engine and the pulling power could be greatly improved, especially with a load.

The downside of course, is the gator will have less speed.

My $0.02 sense.

AKfish

[AKfish]

Your dealer (shop foreman) hopefully, will be able to determine what the different gear ratios are for the various models of gators that JD offers.

I'd like to believe that the various models would have interchangeable ring gears and also have lower/higher gear ratios depending upon the model and engine.

Best of luck with this, John.

AKfish

[CATMAN]

How many hours do you have on your gator? Have you installed a new belt on your transmission lately? The reason I ask, is because as the sides of the belt wear, you lose some mechanical advantage during initial accelaration and most people assume it is the engine's fault. It will feel sluggish and low on power.

A really worn belt is like starting out in 3rd gear on a 5 speed manual tranny in a pickup leaving a stop sign.

My experience is all on snowmobiles, but the transmissions are very similiar. Note: one can visually look at a evenly worn belt and swear it is ok, but once you measure it with calipers and watch where it rides on the primary and secondary clutch sheaves is when you know it needs replacing. Some secondary clutches (on snowmobiles) have adjustment screws w/shims to correct/adjust for worn belts, but it is easier just to install a new, correct lenght belt. There are many other issues to getting these types of belt transmissions into optimal operating conditions, I have a 68 page performance manual just for snowmobile clutches/trannies and many of their tips and suggestions would apply to any belt style transmission. I hope this may help a little.

[jcmseven]

Fellow Posters:

Thanks for the replies thus far. For the turbo, I looked on the internet and was unable to find a reputable turbo source for this engine. I know that Yanmar offers a turbo for its engines, but I am unsure how to procure one of those a somewhat of a reasonable price. I also wonder just how much it would really add. I use the 3320 to 3520 comparo with only 4.5 hp separating the two. As for the belt, I am sure it is possibly worn, but with only 90 hours on the machine and not in water or grungy usage I doubt this is it. Finally, the axle ratio sounds appealing. I really have no desire to go faster, I just want more performance climbing and pulling. Unfortunately I do not know where to begin on finding this one. My dealer reports he has never done this type project, as he is where it is more flat, and this problem is not an issue there. I am sure my 27" tires hurt me here, but I really find them handy for the nasty terrain, etc. I find myself going into frequently so I would hate to get rid of them for the stock setup again.

John

[shot_gun]

I'm not sure if it would work but maybey a driven clutch from a older 6x4 diesel. Change that and a belt. It will probably knock off 5 mph but should give you lots more tourque. I've never tried it personaly but it seems like it would work. The driven clutch on an old 6x4 is bigger in diameter.

[kennyd]

It seems to me that with the larger tires, a gear ratio change is the best, most cost effective solution, Just like the 4x4 guy's do to the trucks when they run the big tires.

[CATMAN]

Originally Posted by shot_gun

I'm not sure if it would work but maybey a driven clutch from a older 6x4 diesel. Change that and a belt. It will probably knock off 5 mph but should give you lots more tourque. I've never tried it personaly but it seems like it would work. The driven clutch on an old 6x4 is bigger in diameter.

If shot_gun is right about that larger diameter driven clutch, and if it fits on your gator without interference, I would think that is the cheapest improvement that you could make. Another trick, that snowmobile racers use for increased low-end performance, is to close down(tighten up) the sheaves of the driven clutch to the point where the belt(at idle, 0 mph) sits above the outer lip of the sheaves a little bit. This gives an improved, effective starting gear ratio to the belt transmission. Requires a different lenght belt just has shot_gun's suggestion does. Now, if you could do both ideas and not interfere with any framework or brackets, that should compensate for the larger tires.