Replacement engine for BCS 948 tractor/tiller.

[oughtsix]

Next Sunday I will be picking up a BCS 948 with a bad Honda GX390, tiller attachment (33" I believe) and a brush cutter for $1000. I have been investigating options for a replacement engine:
1) Rebuild the Honda GX390 - 69lb
2) Harbor freight 420cc 13hp Predator engine - 76lb - $389
3) Harbor Freight 450cc 15hp Predator engine - 80lb - $499
4) Harbor Freight 670cc 22hp V-Twin - 110lb - $999
5) Chinese Diesel engine - 406cc 10hp - 96lb (shipping weight others are actual weight.) - $630

My first thought was the Chinese 406cc Diesel but it is quite a bit more of an unknown quantity and I also am very nervous about all the extra vibration from a single cylinder diesel. I am sure the torque would be fabulous to have though.

The HF 420cc I am currently running is really nice and the extra power over the Honda GX390 is very noticeable with the snow blower. It rarely bogs down like the Honda did (which is what probably killed my Honda GX390).

For $110 more I am really thinking the 450CC Predator is the way to go. A bit more power is always a good thing! One of the things I love about bigger engines is that I can run them at a slower RPM while tilling and they don't bog down due to being at part throttle. The high tine speed is nice sometimes but it is also REALLY nice to have a lower tine speed sometimes, especially when breaking ground.

I fear that the 22hp V-Twin will be too much for the tractor and liable to to cause something to break. I really cherish the idea of the smoothness of a V-Twin though and being able to run it at a very low speed and still have enough torque to get the job done sounds VERY tempting. I also like the idea of running an engine at a fraction of its rated power rather than full out for stuff like snow removal.

I have 5 acres with 1 acre vegetable garden. I use the 28" snow blower a few times a year after a heavy storm as my main snow removal. I look forwards to finally having a brush mower to tame some overgrown spots on the property. I do not do any work for hire or do any commercial work with my BCS. Fuel usage isn't really a concern for me.

What do you guys think?

P.S. I have had a BCS tractor with locking diff and wheel brakes for about 30 years now. When I bought it is was already ancient and no BCS repair person has been able to identify it from the model number stamped on it (Very old Italian tractor). I replaced the 10hp ACME with a Honda GX390 decades ago (with the adapter and a new clutch) then again with a HF Predator 420cc 13hp, which is really nice, a few years ago. But the whole tractor is getting VERY old. The threaded lug for retaining the tiller blades to the tiller drive shaft on my tiller attachment broke many years ago and I replaced it with a tiller from a 715 with a dead acme (which I also have the rest of stashed in a shed). My 28" Snow blower attachment is quite a bit newer and I am currently using a spline to 3 dog adapter. The 948 should have the 3 dog adapter and it looks like it comes with a quick connect.

 

[super55]

Been years since I worked on a BCS but very similar story. Had replaced an old acme motor with a honda because the acme was like just like the looney tunes cartoons. Pull on it forever to start and then just stop for no reason whatsoever.

In small engines Im a fan of the saying no replacement for displacement and would go with the largest Predator motor that fits. Those motors are essentially Honda clones to the point where parts are interchangeable. Diesel small engines I'm not a particular fan. Reason being they are hard to pull start and require pressure relief. If your BCS is running long hours like running a chipper shredder I might consider diesel due to longevity and fuel economy.

 

[oughtsix]

I like the HF Predator engines and they have a great reputation. The 450cc Predator is really looking like the way to go. I am thinking the Predator 670cc V-Twin will be too heavy and possibly too powerful. At half the price I am thinking that the 450cc is going to be a perfect upgrade without being too much weight and power.

I appreciate the feedback! I don't have a shredder and doubt I would acquire one.

 

[super55]

I think you are right. That upgrade is going to move you from 9 to 15hp. With the gear reduction to the PTO I doubt you will find few if any situations where you are going to say you wish you had more hp.

 

[jbradley]

I have a 948, and its balance tends toward the engine side. I have had to rig weights on my snow thrower, and the 45" oil bath sickle mower is a bit light in the front, though not unusable. Putting a heavier engine on is going to throw that balance off even further. I'd rebuild the GX390.

The above comment is after I removed the 948's weights. It was much worse when they were in place. I had the tires foamed to regain the weight.

 

[oughtsix]

I have a 948, and its balance tends toward the engine side. I have had to rig weights on my snow thrower, and the 45" oil bath sickle mower is a bit light in the front, though not unusable. Putting a heavier engine on is going to throw that balance off even further. I'd rebuild the GX390.

The above comment is after I removed the 948's weights. It was much worse when they were in place. I had the tires foamed to regain the weight.

Good point! Do you have a battery on your 948? Balance is something I will definitely evaluate after I pick it up before I decide on an engine.

 

[jbradley]

I did add an electric start to mine, but I had the balance issues even after I added the electric start. It is so nice to not have to pull start that engine.

 

[oughtsix]

I picked the tractor up this after noon. It was about a 5 hour round trip drive.

Man this thing is a beast! I have an old BCS tractor sold by Mainline WAY back when. I have had it for 25 years and it must have been at least 20 years old when I bought it. I thought is was a big 2 wheel tractor with the locking diff and the steering brakes but this 948 is just an order of magnitude bigger in pretty much every way. The tiller attachment is MASSIVE! I had to take the tiller attachment off to get it into my truck and it took the two of us to lift the tiller up into the bed of my pickup. It is SERIOUSLY heavier than my tiller which is great because I broke the tiller that came with my old BCS/Mainline. The brush cutter is beefy too!

I think the GX390 on the 948 is pretty much toast. It has a new carb and a new head gasket and no compression. I think I will start by taking the Predator 420 engine off my old BCS/Mainline tiller and putting it on the 948 since I missed Harbor Freight this evening. I will try to post some pictures when I have it back together.

 

[super55]

If you get some time. Post a few pics. Love following these kinds of projects and seeing the end result.

 

[oughtsix]

Well here it is before I unloaded it. I thought I took more pictures after unloading but I guess I didn't

Not shown is the 30" combo mower and several accessories like a furrower.

After I got it unloaded I took the air cleaner off and disconnected the oil shutdown wiring. Man does this thing have compression (I am pretty sure the compression release is not working properly)! I checked the oil level and it was full to the point of just overflowing out of the fill hole with the engine level. I put a little starting fluid in the carburetor and it fired up after about 5 pulls. The seller showed me that he had stripped the valve cover retaining bolt and sure enough it was spattering out a fair amount of oil from the valve cover. After running it for 5 minutes I shut it down and wasn't able to get it started again.

I started pulling the GX-390 off of the transmission. The lower right engine bolt is completely rounded off and I wasn't able to get it to budge. So I started dismounting the engine adapter instead of the engine. There we 3 nuts on 3 adapter studs. 2 of them were very loose and the third one is under the metal piece that retains the plastic handle bar shaft cover. That is as far as I got.

The dead-mans switch lever is broken. There was no wiring or cables going to the engine. The cable for the throttle is missing the little knob that goes into the throttle lever. The dead-mans switch was not wired to the engine. The clutch feels like it might be stuck but I am not 100% sure.

I am guessing that the GX390 has a compression relief that isn't working. I bought a Predator 459cc engine to replace the GX-390. I haven't opened the Predator engine box yet so I can still return it. I think I am going to spend a fair amount to bring this tiller back to factory functionality. New throttle, clutch and brake cables. New dead man switch paddle. And a few other odds and ends.

Where is the cheapest place to get parts? Earth tools? I could not find the 948 on their site. Does the 948 take the same cables as the 850?