The 460 motor is bolted on the utility in the video I did and it's been raining all day here but I weighed the 2 different motors before I put the 460 on and the difference was 500 grams but i don't trust that as completely accurate as I don't know how much the castings can change between different PT's ,the bigger boss is 50 mm in diameter and about 33 mm long the standard boss is 39mm in diameter and about 33 mm long , I would say 300 grams to 500 grams should do or just machine up a steel bush so it's the same size as my measurements or I may be able to find another on a motor tomorrow and remove it to get the weight.
500g is quite a bit and it's wider which when combined should make quite a difference to the spinning mass. Time will tell if that's what the 600 slashers need.
I had another whoopsey yesterday, I made up a cast iron disc and it was obviously a bit tight because it cracked when I was pressing the boss into it. Wouldn't have that problem with steel but I didn't have anything here that I could use. I would prefer steel so that I can weld it to the boss so it can't come loose. I have to come up with something because I want to drop the slasher off there that I have here and then I can pick the 600 and bring it back here Ok so here is another thought, please tell me if it is a dumb idea. I'm thinking of sitting a boss in the pulley and pouring lead into it. Not sure how many grams I could get into it, I might also have to weld a ring to the top of the pulley so it comes up close to the underside of the fan wheel so I can fill that as well. This idea is going to make it very hard to remove the boss if it ever has to come off. This will prove our theory one way or another Thoughts?
Cast iron should be ok Norm as long as it slides over the boss and just silver solder it to the boss or braze it , I would assume you would remove the boss for welding so heat doesn't melt the lower seal.
The standard oval blade plate is about 1300 grams without blades so an extra 300 to 500 grams on the boss should be no problem.
If you have got a bigger standard boss on a motor already it would be easier to use that ,just look for a PT with a straight intake manifold instead of the standard offset one.
Hi Max, I think I am going to struggle getting much extra weight in there, thinking about it there is not a lot of clearance between the standard boss and the dished pulley that comes back up toward the underside of the fan wheel
Hi Max, well there you go, always a fix out there somewhere. I just weighed a big boss at 398 grams and the standard boss weighs 185 grams so quite a big difference. Is it enough, only one way for me to find out, off to Fawkner
I suppose there is no chance you could get an ordinary blade disc on there as well without blades of course . Pulley probably comes upwards to far. Turn the centre out of a blade disc and weld it to the pulley maybe Probably still height problems I think a bit of weight further out would give more momentum.
Obviously try the 460 pro boss first if you can find one.
Max,
Do all the straight inlet motors have the big boss. Isn't that the right motor for a 600.
I'm waiting with great interest on Norms results here.
The Victa Utility mowers with PT's I have ,all have straight inlet manifolds , the Power Torque with more power has a High compression head and a straight manifold and a different jet in the carby and with the heavier boss ,the motors with the heavier boss have straight manifolds but not all straight manifold motors have the heavier boss. I haven't looked at all the latest PT's but I would think all the newish ones have the straight manifold.
Hi Max and Jeff, The motor I just pulled the big boss off had the offset manifold. All the mowers with the gray curved tops have the straight manifold, you can't fit the standard plastics with the straight manifold because the fuel tank hits the carby. This is the first big boss I have come across and I have no idea what mower it came off. I am picking up the 600 in the morning so I should have an answer tomorrow afternoon. Jeff, there is not much room above the pulley was thinking maybe a 1/2 inch thick piece of plate to make a disc out of. Will see how tomorrow goes
Well there you go, problem solved the extra 223 grams on the flywheel boss, hard to believe but it is something that is very important. No attempt to kickback. Apart from that they are still a HOS and I would never bother with one ever again unless it was for the base or for the motor but as a combination as I said a HOS, really bad setup. Sure you can now start it, so bloody heavy to turn over, pull start design is a big factor, have to pull it half a dozen time to get it started but at least if your arm is strong enough you can get it started. They are a real DUD and to be avoided
Sounds like you have solved the kickback issue at least. Did you try it with belt a little looser. Might be easier to pull over. They have to be harder to pull over because of the belt. We are not really cplaining about that.
At least you can send it back to its owner anyway.
Hi Jeff, belt is not tight, just enough to stop it slipping. I also tried it with an unrestricted decomp and it kicked back. One major issue is that the pull start most times comes out about 200 mm before it catches, but in this situation it is that first 200mm that is important. Nothing I can do about that, and I believe it is the gearing in the way the pull start has to turn the motor from the center of the crank pin does make it harder to pull over. This added to the extra weight of the belt and disc make this design very heavy to start. It is a hell of a heave to get it spinning fast enough to fire. I also think the extra weight of the heavy boss is a bit marginal and another 50 grams would help. I have asked the seller with the heavy pulleys to weigh one so I can see how close it is to what I am using now. Sure I can send it back to the owner but I'm not sure he will be able to start it, he isn't a big bloke. I was also thinking of fitting a longer pull start cord and somehow set it up like the mowers that have the guide on the handelbar so you can stand behind it and really put your shoulder into it to get it spinning. Once it fires up it is fine, just getting it fired is the problem
Hi NormK and JFB, I read that even the full crank 160 can have problems over time due to the side force on the crank. That's another reason it pays to have it as loose as allowable. Can a FC be made to go on a 600 and I wonder how well a 125cc would perform? No worse than a four stroke I expect. You do have the 2:1 ratio belt drive.
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!
I think you could get an FC onto a 600. It could be no worse than what I did which was exactly the opposite. It's quite a bit of work though. A 125 might be Ok.
My PT is mounted side ways like a normal PT. Perhaps that helps us get our weight behind it when pulling it over. We aren't big people either and my brothers only complaint about the 24 is that it's heavy to push up his hills.
Hi Jeff and MF, a F/C will bolt straight on using the adapter plate. Jeff, the pull position might also have something to do with it, the way they are setup in the factory position means you are almost doing a vertical pull which is not that different to a sidepull but I'm sure the gearing of the sidepull makes it easier. Also with the cup pull starters I have come across none of this heavy pulling required to get them spinning. I'm convinced it is the way the pull start design works, pulling off the end of the con rod, not directly on the end of the crank
Hi We aren't big people either and my brothers only complaint about the 24 is that it's heavy to push up his hills.
Jeff
A pair of full ball bearing 7" wheels from a later Victa on the front would help a bit and it would be good to be able to convert the rears to at least partial ball bearing like the older Victa wheels.
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!
I don't think bearings in the wheels would make much difference in the big rear wheels, it is just the overall weight of the machine that makes them a bit heavy on hills. On flat ground that are easy to use, they have a very good balance point so a lot of the time the front wheels are off the ground anyway
