Talk Me Into a Big Block Swap

[KRAZYMATT]

Originally Posted by Springbok

Thanks for all the info guys! I'm feeling pretty good about tackling this with all the support and advice available here. I've been on this site for 8 years and have primarily resided in the Gas Club Car forum helping our members with their old KF82 flatheads. Half the time when I'm looking for info about the KF82s I find my own posts and images showing up in the search results...lol

Come to the dark side! I used to always be in the gas cc section too until I just got sick of not having the *** to get through some of the trails and sand. I swapped my kf82 for predator 420 about 6-7 years ago and haven’t looked back. I used the stock club car clutches with the taper adapter and honestly I feel like that was the weakest link of my setup. Once the crankshaft is cut you can’t run the comet clutch. If you do swap I would recommend using the comet clutch! My cart did 23mph with the stock clutches and 6” lift and 23” tires and had tons of torque! My stock cc driven clutch was machined with the power spring installed.

[Springbok]

Originally Posted by KRAZYMATT

Come to the dark side! I used to always be in the gas cc section too until I just got sick of not having the *** to get through some of the trails and sand. I swapped my kf82 for predator 420 about 6-7 years ago and haven’t looked back. I used the stock club car clutches with the taper adapter and honestly I feel like that was the weakest link of my setup. Once the crankshaft is cut you can’t run the comet clutch. If you do swap I would recommend using the comet clutch! My cart did 23mph with the stock clutches and 6” lift and 23” tires and had tons of torque! My stock cc driven clutch was machined with the power spring installed.

Thanks Matt! I remember you helping me out with info on KF82s when I was a newbie back when I joined here in 2012. Yeah...since I put a rear seat on my '90 Club Car and started hauling more people I've really been exposed to the limiting weakness of the KF82. For me, for years, the KF82 was plenty for just myself and my young daughter, and even my wife...but hauling anyone beyond that would bog the cart down, especially on hills. My '87 still has a good running KF82, so I'll leave that alone for now. If the swap goes well on the '90 I'll probably upgrade the '87 when the motor eventually fails.

Glad to hear you've had a Predator 420 in your cart for that long. Yes I do plan to run the Comet drive clutches and VC rear clutch rather than permanently modify the crank in order to run the stock ones.

[KRAZYMATT]

Originally Posted by Springbok

Thanks Matt! I remember you helping me out with info on KF82s when I was a newbie back when I joined here in 2012. Yeah...since I put a rear seat on my '90 Club Car and started hauling more people I've really been exposed to the limiting weakness of the KF82. For me, for years, the KF82 was plenty for just myself and my young daughter, and even my wife...but hauling anyone beyond that would bog the cart down, especially on hills. My '87 still has a good running KF82, so I'll leave that alone for now. If the swap goes well on the '90 I'll probably upgrade the '87 when the motor eventually fails.

Glad to hear you've had a Predator 420 in your cart for that long. Yes I do plan to run the Comet drive clutches and VC rear clutch rather than permanently modify the crank in order to run the stock ones.

Good plan. Only thing I’ve had to do is put gas in it and change the oil every once in awhile. ALWAYS starts right up and no issues driving. Never cuts out very reliable machine. Your speed will be in the mid 30s with that clutch setup even with the govenor! I used the club car starter generator just for charging. Put in a 3 position/5 pole off-on-start ignition switches and start it using the predator factory geared starter, no belt slipping!!!

[KRAZYMATT]

The clutches are the most expensive part of the swap and the exhaust is the hardest part. Vegas carts says their header doesn’t work with the predator 420 motors but it bolted right on mine without any issues. I don’t know if they changed the motors at some point since mine is so old but it bolted right up without issues. The part they say doesn’t work is the support bracket doesn’t line up with the mounting boss on the motor- I guess I lucked out it lined right up on mine!

[slonomo]

There are two different Predator 420 engines. The Hemi head version is the odd duck. Parts won't interchange to that engine, so I don't recommend that one. Any GX390 clone exhaust should bolt up to the standard Predator 420. Supports? Yeah that's more of a custom thing. Plan on doing a little fabrication on your exhaust pipe to get it right.

[Shepard]

Originally Posted by Springbok

Talking to (I think) Geoff at Vegas Carts on social media and FB messenger. They don't seem to have much love at all for the Predator 420 or any of the clones. What do you guys think?

He said that I would be better off rebuilding the KF82 with performance mods (not sure what can be done there besides boreing it out) than go with a Predator 420. I told him my main desires in a motor swap were increased low-end torque, and the ability to keep the motor quiet. I'm not interested in higher top speeds.

lf your looking for increased torque the Predator 420 Hemi has 1.5 more foot pounds of torque the the standard 420. The Hemi has bigger valves and a better valve train system compared to the standard system with stamped steel rocker arms. Since you said you weren't looking for increased speed just torque I don't think you'd have any problems getting parts. The parts suppliers NR Racing have everything you may need for any repairs. The main block takes standard GX390 parts [cam - crank - rod - gaskets - seals]. The top end is covered by NR [heads - valves - gaskets - valve cover]. Don't be afraid of the 420 Hemi Predator.

[BIKERMIKEYBLACK]

Wat Shepard said is true about the hemi

[KRAZYMATT]

I don’t think you will ever have trouble finding parts for the clones as the Honda gx390 is used for all types of equipment. It will be around for awhile.

[sho305]

I put in two lifan 420s, one is stock I think did in 2010 the other in 2012 now has a cam and rod and other things on it. Both run fine. The stock 420 is like twice the power it does not go faster than stock really both stock and clone engines valvefloat at around 4300 rpm. It gets to 25mph in half or less the distance, it has a lot more torque than stock G9 did. IT can spin the 22s in dirt it will pull the front end in the air going up steep ditches that almost stopped the stock engine. The stock one does have a cut secondary sheave rebuilt clutches and is jetted with a car muffler and airbox otherwise all stock. The honda is said to be a better engine however they may have a new model now idk the v twin is all new. The 10 bolt block is more HD. But for normal stock use you wont need any of that to enjoy more power and a new engine. Getting the exhaust quiet will be some fiddling around there are big threads on it here. The pedal start works fine on them however you have to keep a cart clutch with the belt pulley or install the vegas behind pulley. The CC clutches will work but substandard 1" skinny belt is not good and worn out old clutches are not going to work that well. It should be upgraded to a 1 3/16 belt clutches as most other carts use. You can put a comet on a cut crank clone, you don't need the whole crank to mount it, unless someone cut it way too short. 1 1/8 is the minimum you can cut for adapter anyway. The hemi has a different head on it with a square cover on rockers, the rest is the same as other clones. Its said to be slightly better but will you notice running it stock I doubt it. Most of the hp ratings are suspect anyway the clones are based on a honda gx390 13hp and you don't get tons of hp with a bore and stroke increase. 2hp is a stretch unless honda under rated who knows. If you really want it to fly get the 460 vegas and put that together. Vegas like anyone wants to sell what they have. The $300 420 and vegas mount/parts you need is the cheapest way you can go and significantly more power than tired stock cart engines. You really should get new larger clutches on it but that is up to you and your budget. A cart will shift and run better with properly working clutches and I think the small Cc clutches have less ratio range but I'm not positive. Personally I prefer the lifan they are the largest maker of small engines in the world, I got mine from home depot online on sale. Some other clones don't use the ut2 electronic ignition yet, the ut2 does advance the timing some it is better but also includes the rev limit at 4K rpm I think it is and you have to buy a new coil without the limit to get around that, assuming you upgrade your valvetrain and put a rod in so you can rev it harder. I ran mine to 5100 on stock rod and cam but I didn't do speed runs that often it was under 4500 most all the time. I can't go that fast on trails. In my cart that was 38mph, now I hit 41mph gps with the cam and rod. 4500 was about 34 mph I think which is all I do on trails I ride and just short spurts over 30mph. If you run it at 5K for too long or more rpm the stock rod will fail.

[Springbok]

Thanks for all the great info! So the Lifan 420 and the (non-hemi) Predator 420 are the same motor just made by different manufacturers?