Doug. It depends on your tire and the track, but generally less than 10lbs. We have run ours as low as 4 and as high as 6.5lbs this year. You'll need a tire gauge that goes to single digits to do it.
As for pulling with a hydro, just put it full throttle at the sled, ease into the forward lever and then push it all the way up til you stop. Unfortunately, hydro's don't have enough pressure to really get down the track. You'll usually pop the relief valves so the pump doesn't kill itself. Just be sure to get back to the stop position when you stop moving forward.
And give both the engine and hydro 5 or more minutes of idle time after to cool down before you park it.
Thanks Nic. the pressure gauge is no problem. were running tru powers loaded with washer fluid. Yes I realize track conditions will play a roll in tire pressure.
On the hydro I was going to keep it under 1/4 speed to try and mimic a "low gear" we will try your way
A hydro only has 1 gear. speed is determined in how fast you turn it. So going slow doesnt "change" your ratio, your just literally turning it slower. Pulling with a hydro is directly related to how much resistance you put on the pump. The more resistance, the closer you get to popping a relief valve. So momentum will be your friend. Try to get going as fast as possible and let the weight of the sled push itself a few more feet.
Think if you had to pull it by hand. If you go really slow when you get tired the sled just stops. But if you could run with it and you stop pulling, the sled keeps sliding a few feet. Cause your body only has "one gear", its just a matter of how fast you run. Understand?
Now pulling with a gear drive is different, cause you can choose a gear ratio to pull with. Ideally, we would pull in third gear, but we don't make enough power to really get moving. So we have to pull in second to not kill the engine.
Typically, if it doesn't dump you just stall the engine. Those pump are tough, I doubt you'll tear it out. Most likely the engine will start to bog down and you'll either spin out or stop moving forward even though you pushing on the control, which means you should let off...
On a hard pull you will kill the engine or spin out before you ever hurt the hydro....like Nic said, they are tough.
I have been plowing and flogged them until I have accidentally killed the engine.....start up and keep right on plowing.
Push the hydro lever until you have the engine pulled into the max torque range, but don't "get under it" and over do it right off the bat. Stalling the engine 10 feet into the pull won't win....you need to practice finding the line between pulling it down to max useable torque and pulling it down so far it won't recover....and then ride the line until it spins out or dies.....
Momentum is your friend with a hydro, and it's the only "advantage?????" the hydro has......get the speed up quick, so you can "ride it out" as long as you can........you are losing at least 2 hp to running the pump and the fluid coupling....so make the most of the infinite speeds while you can (early in the run).
Plowing with a hydro offers great insight into how hard they will pull and where they run the best......sinking a 12" plow 7" deep and moving along at a good clip will teach you a lot about the limits of the hydro (and the momentum benefits when you hit a tight spot).
I've been meaning to post how the wife did in the pull at the Sky Valley show back in August
On sat. her first attempt she went too quick on the speed control and stalled. Because she hadn't gone fifteen ft they let her go again. Her second attempt she went fifty one ft.
On sun. I signed up to pull with the 149 to show her how its done and stalled at about thirty ft. Then she got on the 149 and schooled me on how to pull with a Hydro and pulled to seventy five ft.
typically when the put bike motors in Cubs they use the clutch on the bike motor. they use a live rear axle and run a chain back from the bike trans output sprocket to a sprocket on the rear axle. that's the most common way. if you want to keep the cub tranny then you have to come up with a driveshaft that hooks to the bike trans output. alignment is critical when coupling the engine to the cub tranny unless you build something with u joints. the first method I mentioned is common because its easy and cheap but
I'm not a fan of locked rearends either