EZGO ST350 Motor Swap

[cking494]

New to the golf cart world and recently picked up a 97 ST350 with dump bed. Appears to have a blown motor, shows no oil pressure and sounds like it has a knock when trying to start. I believe the cheapest/easiest will be to swap to a 440cc Duromax motor, but not exactly sure what all I would need. From looking, I believe I’ll need a motor mount plate and should be able to use most everything thing else from stock parts.

Help would be appreciated.

[slonomo]

Go to the Big Block section, much more info there. Those EZGO's have tons of room in the engine compartment so a 440 engine would fit nicely.

Check out the Vegas Carts site in the site sponsors page. The kits there will give you an idea of what you need. I don't think they'll have a kit for that model year, but all the other components will be the same.

For Key Start (like a car):
1. Engine
2. Engine mount plate
3. Primary clutch
4. Belt
5. Ignition switch
6. Wiring and fuses

For Starter/Gen:
Add a V pulley behind the clutch

To Use Stock Primary Clutch:
You'll need a clutch adapter and you have to cut the crankshaft down and drill and tap the center for the clutch bolt. I'm not a fan of this route, but if you must, it is possible. Stock clutches aren't tuned right for the big block engine. Also if the crank isn't done properly and the adapter isn't spaced and tightened down properly, the clutch can slip.

[JPonLKN]

As for oil pressure, generally need it to start to generate pressure to activate the sensor and kill the light...The knock is possibly just a loose rod bolt. They have a tendency to loosen up and back out on their own, usually causing a failed rod. You could pull the plugs out, and turn it over by hand slowly and with a flashlight, see if the pistons are moving up and down. If not, its a broken rod. If you are going to remove the engine for a swap, might as well split the case and take a look see at the condition of the rods. Direct replacement should be under $800 with delivery if you buy a rebuilt replacement and send in your core. For someone never having done one, a long afternoon to remove and replace an engine...no more than a day. Depending on what you do to it, and if the case and internals are good enough for a rebuild, under $300 if you do it yourself. I've rebuilt a 295 (identical to yours except displacement) and done a Predator 670 swap with the Vegas carts kit. With a swap, you will end up with a loud cart. The options are endless with your cart though, and only limited by your budget, skills, and what you want out of it.

Good luck.

[cking494]

Originally Posted by slonomo

Go to the Big Block section, much more info there. Those EZGO's have tons of room in the engine compartment so a 440 engine would fit nicely.

Check out the Vegas Carts site in the site sponsors page. The kits there will give you an idea of what you need. I don't think they'll have a kit for that model year, but all the other components will be the same.

For Key Start (like a car):
1. Engine
2. Engine mount plate
3. Primary clutch
4. Belt
5. Ignition switch
6. Wiring and fuses

For Starter/Gen:
Add a V pulley behind the clutch

To Use Stock Primary Clutch:
You'll need a clutch adapter and you have to cut the crankshaft down and drill and tap the center for the clutch bolt. I'm not a fan of this route, but if you must, it is possible. Stock clutches aren't tuned right for the big block engine. Also if the crank isn't done properly and the adapter isn't spaced and tightened down properly, the clutch can slip.

Thanks for the info. I looked at the kits, just wasn't sure if I need a whole new swing arm, or if the engine mount plate would work. I pulled the original motor last night and looks like the motor mount plate from Vegas Carts would work fine.

[cking494]

Originally Posted by JPonLKN

As for oil pressure, generally need it to start to generate pressure to activate the sensor and kill the light...The knock is possibly just a loose rod bolt. They have a tendency to loosen up and back out on their own, usually causing a failed rod. You could pull the plugs out, and turn it over by hand slowly and with a flashlight, see if the pistons are moving up and down. If not, its a broken rod. If you are going to remove the engine for a swap, might as well split the case and take a look see at the condition of the rods. Direct replacement should be under $800 with delivery if you buy a rebuilt replacement and send in your core. For someone never having done one, a long afternoon to remove and replace an engine...no more than a day. Depending on what you do to it, and if the case and internals are good enough for a rebuild, under $300 if you do it yourself. I've rebuilt a 295 (identical to yours except displacement) and done a Predator 670 swap with the Vegas carts kit. With a swap, you will end up with a loud cart. The options are endless with your cart though, and only limited by your budget, skills, and what you want out of it.

Good luck.

I am moderately mechanically inclined, at least with cars/trucks. I don't have much knowledge about the small engines like these, but they seem to be similar. The current Robin 350 has over 2300 hours on it; I'm not sure how long they really last. I pulled the motor and I am going to start taking it apart to evaluate.

Long story short, I got the cart from my brother-in-law who is a dealer for John Deere. He took it in on trade for next to nothing and was told it did not run/was seized. It is not seized as I can turn it over by hand.

[slonomo]

Yep you won't know what's making the sound until you take it apart, but something isn't right. Any bolt that might be loose can be tightened, but you have to ask what damage/wear has occurred and for how long? Who knows right? That's the problem.

Doing an engine rebuild is not difficult work, but it is highly technical. If you don't have any experience with this type of engine, be prepared to get a factory repair manual and read everything....twice.

I just sent the same engine you have out to a rebuilder in Georgia. With a new crank, pistons, connecting rods, and machining and labor....it's going to cost just over $1000. But....the end product will be stock, quiet, and very drivable. I got the cart for $400 so it's worth the cost for me. I couldn't buy a running driving cart for $1400 let alone one with a rebuilt engine with a warranty. And, there will be no fabrication involved or guesswork to get it installed and running. Bolt it in and go. Consider it.

A 670 swap is not going to be easy unless you get a full install kit, but now you're talking about big money. Yes, you'll have more power. Doing the engine swap on a small budget is not a good recipe for success. It "can" be done, but it's not easy.

I'm not trying to sway you one way or the other. Only trying to tell you the truth about each option. Once you have gathered all the facts, only you can decide what you are capable of and what you really want to do.

[JPonLKN]

Originally Posted by cking494

I am moderately mechanically inclined, at least with cars/trucks. I don't have much knowledge about the small engines like these, but they seem to be similar. The current Robin 350 has over 2300 hours on it; I'm not sure how long they really last. I pulled the motor and I am going to start taking it apart to evaluate.

Long story short, I got the cart from my brother-in-law who is a dealer for John Deere. He took it in on trade for next to nothing and was told it did not run/was seized. It is not seized as I can turn it over by hand.

Here is the engine manual for it.
Robbin engine manual.pdf
It gives pretty detailed instructions on how to disassemble, evaluate (verify if parts are to spec or not), and re-assemble. Search this forum for others that have re-built these 295 and 350 engines, and pay attention to what the "Guru's" offer. Things like re-using original o-rings at the oil pump and top of the case, as the ones that come with the re-build kits don't fit properly, and cause oil pressure issues, or verifying the bearing journals on the crank are within spec, as the engine will loose oil pressure at the rod when it heats up if the journal is out of spec. Good luck and let us know how it goes.

[kgsc]

If it matters I believe the st350 is a long wheel base txt aka workhorse with a 4” lift. Engine cradle is the same as a txt but pushed back roughly 11 inches. Following because my Robbins is aging. I live about an hour from the company slo is using so I need to call them as well.

[JPonLKN]

Originally Posted by kgsc

If it matters I believe the st350 is a long wheel base txt aka workhorse with a 4” lift. Engine cradle is the same as a txt but pushed back roughly 11 inches. Following because my Robbins is aging. I live about an hour from the company slo is using so I need to call them as well.

They absolutely are...the 295 and 350 can be directly interchanged between a TXT or ST, either 800 series or 1200 series. 800 series has a 800 lb load carrying capacity, 1200 has a 1200 lb carrying capacity. 800 series is a TXT frame with heavier suspension. 1200 is a longer machine by about 11 inches, but it is all in front of the cross bar at the front motor mount. Motor mounts are the same, belts, spacing, bolts, etc. For the record, even the 2009 and newer MPT with the Kawi motors have the same frame spacing. Drop the Kawi motor mount and transaxle, and you can direct bolt in the older Robbin motor mounts and transaxle. There are some alignment issues that come into play at the shifter, and bump stops, but it works. Just got done doing exactly that.

[kgsc]

Ezgo actually sells a kit to do this. Includes the motor, rear transaxle and all the other goodies to switch to the newer version as well as going from electric to gas.