DJ530

More recent pic of the updated $30 steering wheel, with quick release I had lying around the shop. The stock steering wheel was like some Fisher Price thing. Not ideal at full clip on the trail lol

Here is a pic of the custom header I made myself, by modifying the golf cart header, just shorted it up, welded it all back up and using the same cheapy muffler, still loud as heck though. Debating a bigger quiet muffler. Quite a challenge basically doubling the power output in these buggies and the tuning needed to make it work, about the same as any other rig. If I had more time for it, I would put larger disc brakes and a power steering rack in it, with better shocks. But it does what we need it to, a little too fast at times, if the trails are a bit bumpy. Not as smooth as the Gator we goof around race with, but it has no problem passing an 800D on the straight and leaving them in our dust Always a riot in our pasture on burn nights lol

Just to note, we noticed an oil leak on the 670 on the flywheel side, the frame would get wet with oil. Upon inspection it was just the oil vapor breather tube came loose and was weeping oil. I thought maybe it blew a seal out since we run it around 4000-4500 rpm most of the time. That's the only issue I have had with the new engine.

It's doing great, far better than I expected even. I haven't really done anything to it for the past three months, except drive it. I was worried we would break the Predator engine, but it takes everything we can throw at it. The engine I replaced was a Robin/Subaru EH63. I am running the same CVTech powerbloc clutch, just with a slightly lighter spring , I believe it is the 400/700 spring. Had to go with a lighter spring as the extra torque of the 670 engine over revved (was annoying) a bit at wide open throttle, the lighter spring holds it around 4000-4500, vs 5000-5500 with the original spring. I put new plugs in it around 40 hours ago, and just change the oil. It runs really well now that the jetting is dialed in. I had to install a wide band O2 sensor to fine tune the Mikuni, but it's about as perfect as I can get it, running around 14.5:1 at cruise, and around 13.2:1 at full power. I have not put any other money into it, aside from a set of LED lights. The Kevlar drive belt has held up extremely well, even after attempting to smoke it by climbing some very steep terrain fully loaded on a 100+ degree day. If it has a weak link, I haven't found it yet lol

Thanks Vaughn. No surprise, but I had never even heard of them until I stumbled upon this one on a facebook marketplace ad, if it weren't so cheap I probably would have passed on it. Glad I did, we have a blast with it, (the wife and family have a ball in it) it is a lot of fun out on the trails, climbs anything we point it at, hauls a half ton with no issue and cruises on the road 45MPH @ 4000rpm - and as simple as a lawn mower to work on. For all around utility, this one is a hit for us. We have tried to blow it up a few times, but nothing has fazed it yet!

-----First my required disclaimer: Don't try this at home!! ----- Now with that out of the way: Here is a 'drivability profile diagram' (Reference: Olav Aaen''s vey informative Clutch Tuning Handbook for the scoop on the math behind all this - or this link: https://web.wpi.edu/Pubs/E-project/Available/E-project-022014-185837/unrestricted/MQP_Timothy_DeGreenia_Edited_Jan19.pdf ) Just to give an idea of the empirical 'shift out' with the CVTech in 7:1 mode, just subtract 10MPH from the numbers shown in this graph. (this graph shows the gear ratio 10.15:1 we are using which adds 10MPH to all ratio points in the graph over stock gears) as stock may be 13.25:1 final drive in these buggies. Stock top speed for most these UTV's is 25MPH at 3800RPM - = .75:1 final CVT ratio with 13.25 final. Full stroke allows it to pull to .45 (give or take a couple points due to belt slippage, heat, etc.) at the shift out RPM. Now this could potentially stall/bog stock engines, (we have not seen this at all) but with a 650cc or larger, should be fine. Not like the clutch is being re-calibrated - just allowed more 'shift out' which holds the engagement or governed RPM more consistent with more pull on top. Of course I don't suggest driving one of these buggies at 50+MPH, (or try!) the idea is full use of the CVT ratios. Much like going from a 4 speed manual, to a six speed manual with some more gears for lugging the engine along.

A quick peak into the guts of the mysterious Dana H-12 rear end in these things, built pretty stout for a 'golf cart/lawn mower' axle!

Update on the swap. Since getting the new engine spun up, and dialing in the Mikuni, we have been putting this buggy to use! After a good snow storm, it proved to be handy to have to go clear broken branches and fallen trees in the area. and on our property. I could tell right away though something wasn't quite right with the CVT, it would 'shift out' and the motor would just wind out (as in 5K+ RPM) too high in other words at an anemic 20 MPH tops. Once all the work was done I learned all about this CVT setup. Here is what I learned, and this should apply to all CVTech PWB50/80 type CVT setups for reference. I did the pen mark on the driver(primary) sheave to see what was up with the primary clutch pully, and it was only climbing out with an inch or more of the pen mark left. So I ordered a new Kevlar belt, turns out the original belt was worn about .032" or more, and the new belt being wider will climb higher up the sheave making it more efficient at least. While I was at it I decided to pull the driver pully off, and clean it up, document the spring, blocks, weight, and make sure everything worked - I suspected it was jamming up on the stationary sheave binding the sheave stroke. But I came to discover these clutches have a "Stroke limiter" ring, that stops the sheave stroke about .250" short of the full stroke. Since CVTech specs these CVT's with a shift ratio of 6.97:1 - (3:1 - .43:1 ratio range), with the limiter ring in there it limits the clutch to a 4:1 shift ratio = 3:1 - .75:1 or so depending on belt, spring, etc. So after reading the service information and some trial and error, mock fitting the belt to the sheaves and checking the belt position to full shift out, I removed the limiter to allow the full shift ratio of 7:1. To make a long story short - not only does it haul wood really well, now it hauls ass! lol The grippy belt with full sheave stroke is a night and day difference. The shift out is slow and mild, but the motor pulls down much better - no more crazy RPM to gain a cruising speed. So for anyone with a CVTech Powerbloc 50/80 (aka series 0400/0600), CVT and you need to gain about ~10MPH net speed increase, worn belt or not just remove that limiter ring. (The REAL benefit of this: will help give the belt more usable life with full sheave stroke, and mellow out the engine RPM) while cleaning the primary pulley assembly -- if you have one of the ASW/Landmaster, BullDog, Land Pride Trekker, etc. utility rigs (not sure what all this clutch setup comes on). I imagine it was up to the manufacture to install some type of limiter or not as the manual says (1 or 0) so it's not needed for proper clutch operation. I don't know why they cripple a fairly decent clutch like that, I imagine for some 'saaaafety' regulation, but it really makes the drive setup very inefficient. Once the weather gets a bit more decent we plan to shoot some video of it running. for the amusement of the five other people that own one of these Has come a long way since dragging it home! Anyway I hope someone finds this tip helpful, especially if you are going through a lot of belts. I attached a diagram showing the limiter and a couple pics of the process.

She's a runner! Waiting on some special tools to get here as I have some tuning to do on the clutch. Clutch stalls the motor a bit high, so I have a feeling it's all caked with mud in the clutch sliders. Runs good though!

Getting it back together. Engine final mockup and assembly done. Needed to bump the engine to the passenger side about 1/2" to line the CVT up inline with the original location on the old engine. The 670 has a longer crank snout where the pulley seats. Just waiting on some parts for the carb (this setup uses a 1.5mm needle and seat for use with a pulse pump), and the moto carb to stock throttle arm cable,- should be here tomorrow - and we are ready to fire. Starter cranks, all wired up. I only ended up with a kill wire for now, (blue wire from UTV, black/red wire on the motor) , and the starter (white wire ), along with the fused hot wires. Will hook up the oil sending unit from the old engine so I have the oil light.

Thanks Travis! No, this new motor hasn't been fired, lubed everything up well, greased the cam lobes, checked the bearing clearances, will delete the governor arm and mechanism and button it up. Couple more pics.

A few pictures (so far) of the engine work - eventually I will share wiring info and other details (if anyone is interested?) should anyone else ever need to swap an engine in one of these. The replacement engine is a Harbor freight $750 special 670cc, (lawn mower/industrial type lump) with a few minor upgrades. Should have it back together soon, bolted in. The cold weather slows me down!

Thanks! Haven't taken it apart yet. I was going to prime the oil pump before first before first fire up. I have some parts on the way so I can run a mikuni flatslide carb I have. The stock carb will be too lean apparently.

Fitting the legos back together.

Small and powerful? Kinda spendy but why not drop a KTM 1290 v twin in it? Will be easier to find parts than a gti lump, water cooled, 100+ HP, chain drive, 6-speed, what more could ya want? Gonna be spendy though, around 3-4K for a wrecker. Any old street bike twin may be good candidate, but many are $$$ and hard to find parts like the gti.

Should be able to find them online, one for example: http://www.scautosports.com/Massimo_Parts/Warrior_800_massimo/ parts for the 800 warrior anyway. Good luck!

Current belt is is CVTech JM52-1253-C I guess its not so much power limitation as much as heat control. Gates has their carbon belts that work pretty good in the RZR rigs, so I should be fine. This one is just old, not much wear in 330 hours. May pop for a new belt to go with the motor. Apparently a pretty efficient drive setup.

So many choices! I did some searches, apparently not many people swap engines in these farm/utility rigs. Golf/club carts ,and go karts, but not these. Another question CVT related, has anyone figured out, or rough idea how much torque the CVTech CVT drive belt can handle? I tried finding info, but im not sure what model this unit is. It looks pretty stout and very little wear in fact. Just wondering how much power I can put to it.

Yeah I guess you could say these heads are 'screwed' lol No cracks I can see, just a bunch of pock marks from steel chunks beating the pistons and heads. To go with all new parts (heads/pistons) just the parts will be over $500 bucks, so I will try and scrounge some used head cores. I can't even remove one of the plugs it's beat so bad! It's going to take a TON of work to get these decent again. To weld them I need to heat them up pretty hot and may do more damage. I may just cut my losses and go with a new engine, this lump seems to be the red headed step child of industrial v-twin engines, not much to find on it. Will see if I can find a used vanguard engine, or pop for something better. Not sure if there is any demand but I can sell off the good parts of this Subaru engine. Will update when I get something going together. For now I'm just learning what options I have for replacement engines.

Update: it came off fine, just a few taps with the rubber mallet. Once that was out of my way, I was able to assess the carnage, pretty bad, was not a rod issue as described after all, looks like the screws that hold the air filter housing on rattled into the engine and banged up both chambers, and pistons. Both intake valves had closed on 2 of the screws, other chunks of piston. Not all bad as the case is fine, save for some light scoring that should clean up in one cylinder. The crank, and both rods seem fine, I need to check the intake valves again, both seem like they may be usable, not sure yet. The heads took the brunt of the damage and will cost the most. Pricey parts. Will see if I can get them tig welded and repair the chamber surface as they are pretty bad. Some more pics

Hi Travis! I think they ran it out of oil. Even though there is fresh oil in it now. Has only 338 hours on it. Mentioned a rod knock and- that they kept using it. I bought it from a guy that works in construction. Didn't get too hot at least. It turned over, but makes clunk noises, when I get the side cover off, the evidence will likely fall into my lap. Paid $1500 for it, seemed like a deal for what we need it for. Just hoping I can salvage what wasn't destroyed. May swap in a Vanguard twin if I need to. I have built many mower and ATV engines over the years, but never this setup.

The engine manual matches mine, very useful information, thanks for the link. Here is one I found for the CVTech drive: https://americanlandmaster.com/pdfs/UTV/Service/CV Tech Cleaning Procedure (2-20662 & 2-20660).pdf They have the tool, it's a bit spendy, hopefully I won't need it. http://usa.cvtech-aab.com/176-extracteur.html

Thanks Travis, here is what im working on, I believe it is a CVTech unit. I soaked it good with some PB blaster. Will see what I can do, I don't want to damage it coming off. Do I need to remove the large nut to remove it? I pulled a bolt out before taking these pics. Engine will be out tomorrow, gotta dig my hoist out in the back of the shop. Thanks again.

Has anyone had to remove the CVT pulley from a Subaru/Robin 653 engine? I removed the long 14mm bolt from the side, but the pulley doesn't budge, im thinking this is a tapered shaft. Do they make a removal tool for these? Thanks