Replacement engine for BCS 948 tractor/tiller.

[oughtsix]

The (new) BCS 948:

I ran the GX390 one time for about 5 minutes. Here is the puddle it left:

Below is the leaking valve cover. I think the previous owner also messed with the valves and disabled the compression release which is why it is such a bear to turn over. The threads in the block for the valve cover retaining bolt are stripped so the valve cover can no longer be tightened. For $500 I can put a new more powerful engine on this 948 which I think will be worth it.

Top view:

The broken dead mans switch/paddle:

The clutch control cable looks a little questionable. I will have to see how much a new one is to decide to replace it or not:

The cables on the other (right) handle. One for brake and one for releasing the steering column so it can be repositioned. I think the outside one is the brake which looks like it should be replaced. Again I will have to see how much a new one costs.

The rest of the right hand handle:

A shot from the back:

Here is the 948 looking longingly at todays snow just itching to go out and play!

 

[oughtsix]

********************************** 735 ******************************************
Here is my first BCS, a Mainland 735 just in time for the first snow of the season today. I think it dates back to the 70's:

The original motor was an Acme 10hp. About 25 years ago I bought the engine swap kit and put a GX390 on it. A couple years ago the GX390 lost compression so I put a Predator 420 on it. Those extra CC's made a huge difference in how it handles the snow blower. The Predator 420 doesn't bog down like the GX390 did.

It is wearing the handles from a 715 which do not have a differential release lever or brake levers. Having the differential locked when blowing snow is a MAJOR disadvantage. This is the proper 735 handles:

The toggle switch is my version of a dead mans switch. Forwards is run. I can grab the switch and pull it back quickly to kill the motor.

This is the control shaft from the 735. The internal rod and cone shaped piece rusted through. This is the control column:

I have welded it back together a couple times. I think it is time to make a whole new column with a new disconnect rod and new cone shaped piece.

Here is the old 715 parts tractor still wearing its ACME 8hp engine. The ACME does run but has low power. A few years ago I scored a engine swap kit on ebay for a couple hundred dollars because I figured I could use it some day. I might put a new engine on this 715 and sell it.

This is the tiller gear box from the 735:

There should be a similar stud on the other side of the gearbox but it snapped off several years ago. So I put the gear shaft in the lathe and drilled out the stud (not really a stud because it is cast as a single piece) so I could rep0lace it with a bolt:

Right after doing the operation on the tiller shaft I found the 715 on Craigslist for $200 and bought it. I used the 715 tiller on the 735:

The rear cover plate for the 715 tiller (on the left) fell off in the middle of my garden somewhere. I need a buddy with a metal detector to find it. I will probably just order a replacement.

The 715 came with wheel extensions which I will remove before selling it.

How am I doing for a picture thread? (I like threads with lots of pictures to so I might have gone overboard a bit).

 

[Topzide]

You can put a heli-coul in valve cover bolt hole to fix that issue. Would be worthwhile to see if you can get the Honda working. If you had already budgeted for the other motor, put on the shelf if you get Honda running. Money in the bank down the road if it goes belly up on you. Who knows, another project may drop in your lap for the Predator motor. Great find and a beast of a 2 wheel tractor! Played with a lot of Gravelys and work on a couple BCS's with BS.

 

[oughtsix]

You can put a heli-coul in valve cover bolt hole to fix that issue. Would be worthwhile to see if you can get the Honda working. If you had already budgeted for the other motor, put on the shelf if you get Honda running. Money in the bank down the road if it goes belly up on you. Who knows, another project may drop in your lap for the Predator motor. Great find and a beast of a 2 wheel tractor! Played with a lot of Gravelys and work on a couple BCS's with BS.

Good advice. I had a heli-coil in the back of my mind. I have never done one before. I am a little worried about the compression release not working. I "think" that this might be fixed by adjusting the valves? I think it was over 40 years ago that my father showed my how to adjust the valves on out 63 Falcon but have never done it myself.

P.S. I was considering putting the GX390 on the 715 since I have a spare ACME to BS conversion kit including the new clutch then selling it.

 

[oughtsix]

I just spent a couple hundred on cables and a dead man handle bar lever. They should be her next week.
All new cables should go a long way to getting her back in good shape. New motor and new cables should make is close to a new tiller.

 

[otsegony]

Joel DuFour of Earthtools does a good job of explaining how to adjust Honda GX valves here:

 

[oughtsix]

It has been a little while. I forget where I left off. I went with the Harbor Freight 459cc Predator motor. The deeper I dove into the Honda motor that came on the tractor the more I found wrong with it.

3 of the studs were broken off of the engine adapter so there were only 3 left to hold the engine to the rest of the tractor. I drilled the broken studs out as carefully as I could but inevitably buggered some of the threads in the adapter plate. My local Napa fixed me up with some helicoils (or their version of them) and the proper metric replacement studs. That one guy on the end counter always goes out of his way to help me and was happy to dig through the parts shelves to find the right studs.

It took me a fair bit of Kroil and persuasion to get the screw out of the center of the clutch that holds it on to the GX390 motor shaft. To my horror I found that the shaft on the GX390 had a taper on it! I didn't know they made such a beast. Luckily I had a spare clutch for the straight shaft 459cc. I got it all put back together only to discover that I put the clutch too far onto motor shaft and the clutch lever was no where close to touching the clutch.

I went in for the night and looked up some of the Joel videos which told me exactly what I needed to know, the flat face of the clutch bearing needs to be 4 1/2 inches from the flat of the engine adapter plate for the clutch lever to engage properly. I ALSO found in the same video the the newer BCS clutches come with a spacer for a motor shaft and a tapered collar that clamps the tapered clutch to the straight motor shaft. The next morning I looked at the old GX390 and sure enough it had the spacer and tapered collar which I mistook for a tapered motor shaft. I removed the motor from the transmission, replaced the clutch with the original clutch using the spacer and tapered collar and sure enough everything fit together perfectly! It did take a fair bit of wiggling and pulling to get the 6 studs into the holes on the transmission and the clutch onto the transmission shaft.

I fired it up yesterday and it came to life nicely. I put the 30" HD Combo mower on (I used bolts because the studs were missing. I ordered new studs). The mower fired up nicely and took down my 2' tall overgrown grass. I was surprised when it bogged some on the taller wetter grass then I realized that the throttle was in the lowest position. After going to full throttle there was not really any more noticeable bogging down.

There is a 3" pto extension that came on this 948 tractor and with that the heavy 30" mower balanced very nicely. I am confident the even heavier 33" tiller will balance well to. My 24" snow canon will be where the extra weight of the motor will test the balance of the tractor. The snow thrower will be easy to add some weight to if needed.

I still have some more cables to replace (already have the replacement cables) and a few more tweaks and it will be good to go.

I did notice that my old blue version of the 30" combo mower is quite noisy. I found a video of the same mower online and it had the same scratchy noise. I need to take my deck apart to attend to some rust around the seams before it starts to cause some real damage. I will take a close look at the gear box at the same time. I know Joel doesn't like the combo mower but it is going to suit my purposes just fine. I did order and received a replacement blade that has swing tips on it in case I get into rougher ground where I might hit a rock or big stump. I will probably put this swing blade on when I rebuild the deck.

So far I am very happy that I went with the 459cc Predator engine.

 

[WesKootenay]

Thanks for the detailed post. Good to hear it has worked out OK.
I must look at the clutch on our 732, I had Earthtools rebuild it several years ago, now I need to adjust it or get a bigger left hand
I'm in the middle of replacing the 250cc B&S (blown) engine on our Ariens snowblower with a 420cc.

 

[jbradley]

The 948 has built in (add-on) weights that are on the engine side of the axle. I found that the balance on my tractor made it almost unusable for anything other than the 34in tiller box, so I took the weights off and had the tires foamed. The balance is much better now.

 

[jbradley]

In regards to replacing the engine, is it as simple as removing the 4 bolts to the clutch housing and pulling the engine off, or is there a bolt/screw that secured the clutch to the engine shaft?