425 Engine Swap idea

[ldabe]

45 degrees and lower with the Robin, and my prayer life kicks into auto-pilot!

Once I get it started, I would say it is a pretty decent engine (gas consumption, power, torque), and after running a while, when I shut it off, it does not seem to be quite so "fridged".

But that initial start, it is very hard on the starter and the battery!

Btw, I have the 22hp.

 

[ernemats]

I also have a 422 with Robin engine and it starts pretty easily at 40 + degrees, even at our recent 20 degree days and teen nights it has started without any problem.

 

[BobRip]

I also have a 422 with Robin engine and it starts pretty easily at 40 + degrees, even at our recent 20 degree days and teen nights it has started without any problem.

That is different from my experience. I have trouble starting below about 45 degrees. I am not sure of the exact temperature. I have put Mobil 15W50 synthetic oil in the hydraulics. I suspect that makes it worse than the original 5W30. I always park my PT in a heated garage. The PT does climb hills better when hot with the 15W50 and that is why I use it.

 

[ernemats]

I have the original 5-30 oil in the hydraulic system , the original battery(8 years old) and my garage where I keep it is unheated. Today it was 32 degrees and it started first attempt.when it gets down below 20 I quite often put a magnetic heater on the oil tank.
I took it out and pushed some snow off our driveway and then took a ride up over the hill to see if I could see any bear or deer tracks as we have about 4 inches of snow on the ground now.

 

[Gravy]

My Robin 25hp doesn't like to start when it's cold, even with the free starter upgrade. Much below 50 and it may need help. I suspect it still doesn't spin fast enough for the magneto to make a good spark. I use a magnetic block heater on the hydraulic oil tank and sometimes still need jumper cables. It would be nice if the small engine manufacturers would move their ignition systems out of the 19th century.

My comment about the diesel wasn't entirely fantasy. Google "Punsun Diesel" for a Chinese air-cooled V-Twin that looks like it might fit. It's around 750cc/20hp (depending on which advertiser you believe), but there have been press releases promising a new version closer to 1000ccs. I kinda doubt we'll ever get it in this country, and then there's the legendary Chinese quality issue, but it sure sounds good.

 

[ldabe]

Ernemats,

Could you give us a run through on how you go about starting yours?

The throttle and choke position, how long (seconds) do you hold in cranking position before it starts?

Do you have to keep cranking, even if it sounds like it has ignited, but if you (I, in my case) stop, it dies.

Anyone else who wants to give there starting sequence would be appreciated. Maybe we can see a pattern of what is best, good, or worse.

 

[SnowRidge]

My comment about the diesel wasn't entirely fantasy. Google "Punsun Diesel" for a Chinese air-cooled V-Twin that looks like it might fit. It's around 750cc/20hp (depending on which advertiser you believe), but there have been press releases promising a new version closer to 1000ccs. I kinda doubt we'll ever get it in this country, and then there's the legendary Chinese quality issue, but it sure sounds good.

As suggested, I Googled Punsun Diesel. One of the hits I got led to this engine. I don't think it is a Punsun, but it does look interesting.

Another hit led to this photo, which I thought was a hoot. That's a B&S/Daihatsu engine stuffed into a Harley Softail. JD freaks are everywhere.

 

[woodlandfarms]

If you want pure brute power, the diesel wins. They are used in just about everything, except planes.

They are now

Diamond Aircraft

 

[Gravy]

As suggested, I Googled Punsun Diesel. One of the hits I got led to this engine. I don't think it is a Punsun, but it does look interesting.

That's the Punsun, or at least one of it's clones. Variations of that same ad copy and a handful of photos show up on dozens of sites. I'm pretty sure they don't pass requirements for import into the USA, but they seem to be somewhat popular in Australia for generators. I think it's intended to be a drop-in replacement for various gasoline v-twins.

 

[MossRoad]

Anyone else who wants to give there starting sequence would be appreciated. Maybe we can see a pattern of what is best, good, or worse.

For our Kohler (or any 4 cycle gas engine we have, for that matter) we do this:

Full choke.
Full throttle.
Turn the key to crank until it fires up or 10 seconds, which ever comes first.

If it doesn't fire, stop cranking so you do not cook the starter. Let it rest for 30 seconds and try again. If it doesn't work on the third or fourth try, get out the starter fluid and go that route. Give in one 3 second blast in the air cleaner and repeat the above procedure. If it won't fire on starting fluid there is a spark problem. If it fires and dies, there are fuel problems, like filter plugged, ice, etc....

If it fires, release the key to the run position and decrease the throttle to 3/4.
Decrease the choke until it sputters, then increase choke a bit. Monitor the sound of the engine while it warms up. Keep adjusting the choke until you no longer need it. At zero degrees, that can be 5 - 10 minutes for us.

Keep you battery fully charged. We keep a 1/2 amp charger on ours all the time, winter or summer, because it can be weeks between uses.

I also put Stabil in our fuel during the winter and we have a clear fuel filter.

I can honestly say that in the 7 years we have had our PT425 with the Kohler engine that it only failed to start once, due to the original battery croaking. I have used starting fluid on it a few times when the temps were well below zero, but less than half a dozen times in those 7 years. I have never pulled the spark plugs to inspect them. I have changed the air filter and pre-filter foam last year. I change the engine oil every year. We use Mobil1 since the first oil change. We have about 350 hours on it.

I beat the snot out of it yesterday pulling firewood logs out of the woods for 5 hours. I probably shut it down and started it 50 times as I hopped off and on over and over. I am really impressed with the Kohler's durability and cold weather starting. Let's see how I feel in another year, and so on.

 

[cqaigy2]

Moss's method of starting sound very familiar, except i couldn't find the starting fluid and used carb cleaner and a shorter shot of it.

 

[BAGTIC]

My Robin has not been that reliable. The starter failed while it was still under warranty.

The engine froze up over three months ago and has not run since. Every time my tech calls he is told replacement engines are not available at this time.

I have also had to rebuild two wheel motors and replace the ignition switch.

Diesel Vs. Gas? Some of the larger two cyclinder gas engines (B&S, etc) can if derated and run at less than full power almost match a 25 hp class diesel in torque. Running at 65-75% rpm also makes them much more fuel efficient.

Hydrostatic drives don't need high torque engines, that is what the hydraulic pump is for, to produce increased torque.

 

[J_J]

My Robin has not been that reliable. The starter failed while it was still under warranty.

The engine froze up over three months ago and has not run since. Every time my tech calls he is told replacement engines are not available at this time.

I have also had to rebuild two wheel motors and replace the ignition switch.

Diesel Vs. Gas? Some of the larger two cyclinder gas engines (B&S, etc) can if derated and run at less than full power almost match a 25 hp class diesel in torque. Running at 65-75% rpm also makes them much more fuel efficient.

Hydrostatic drives don't need high torque engines, that is what the hydraulic pump is for, to produce increased torque.

The hydraulic pump has to be matched up to the engine, or you will not see the pumps potential. You can over HP and just loaf along, but if underpowered, sometimes it just will not cut it.

 

[BAGTIC]

My point is that if you need 25 hp you can put in an engine that produces 25 at max continuous rpm or you can use a larger engine rated 35 +/- hp with 25 hp at the peak torque curve, where the best fuel efficiency is, and still have have as much hp and more torque that the straight 25 hp model and at very little more initial coast and better fuel efficiency.

Of course the pump must match the engine. The pump should be selected to fit the engine, not the other way around.

 

[J_J]

My point is that if you need 25 hp you can put in an engine that produces 25 at max continuous rpm or you can use a larger engine rated 35 +/- hp with 25 hp at the peak torque curve, where the best fuel efficiency is, and still have have as much hp and more torque that the straight 25 hp model and at very little more initial coast and better fuel efficiency.

Of course the pump must match the engine. The pump should be selected to fit the engine, not the other way around.

I tend to disagree for this reason. First, you have to plan for what you want the machine to do. Say you want to be able to lift 2000 lbs, and move the machine at 8 mph.. That will determine the thickness and type of metal you use in fabrication. Next you want to know what size cylinders will lift this load, by selecting the correct pump size. Moving the load will take a certain hyd motor for the speed desired, which will dictate the pump size. The HP necessary to drive this pump is calculated, and added to the list of HP necessary to power all the pumps. Then you look for an engine with the available HP to power all the pumps on this machine. If you can find an engine that will fit the frame, you are almost there, however, if you can not find an engine to fit the proposed frame, maybe widening the frame might work.

From all this, you determine the hyd GPM's, pressure, and HP required to power all this, with a safety margin.