proper prop pitch 85 xr2 150

[MFisher]

Here's one for someone to help me with, I have an 85 xr2 150 on a 18' Bass tracker fs1800. This is a fiberglass hull boat with a 27 gallon tank, 5 gallon oil tank, three batteries and a trolling motor. Now when i come up on plane with the motor trimmed in all the way I can get the RPM's to get to the recommened 5600 RPM's but I still have room to push forward on the throttle. It will go upto 6000 pretty easily the pitch on it right now is a quicksilver 21" aluminum 3 bladed prop(no dings perfect shape). I am not as concerned with top speed but am concerned with over extending the motor's range every now and then should I move up in pitch or to a 4 blade? Oh yea one more thing it cavitates at 3500 to 4500 and need to play with the throttle to get up on plane but once on plane she runs smooth and straight there is space to drop the motor down one more hole but that is it.

 

[j_martin]

Re: proper prop pitch 85 xr2 150

Here's one for someone to help me with, I have an 85 xr2 150 on a 18' Bass tracker fs1800. This is a fiberglass hull boat with a 27 gallon tank, 5 gallon oil tank, three batteries and a trolling motor. Now when i come up on plane with the motor trimmed in all the way I can get the RPM's to get to the recommened 5600 RPM's but I still have room to push forward on the throttle. It will go upto 6000 pretty easily the pitch on it right now is a quicksilver 21" aluminum 3 bladed prop(no dings perfect shape). I am not as concerned with top speed but am concerned with over extending the motor's range every now and then should I move up in pitch or to a 4 blade? Oh yea one more thing it cavitates at 3500 to 4500 and need to play with the throttle to get up on plane but once on plane she runs smooth and straight there is space to drop the motor down one more hole but that is it.

What do you mean by cavitate. Do you mean that it won't get a bite on the hole shot? Is your current prop ventilated?

I have the exact same boat, and I run an XR4 with a 24 pitch high five on it. It's on a jack plate, set back 6 inches, and I run the prop slightly surfacing, engine turns about 6000 rpm. The prop is ventilated, so she spools up to 3500 rpm instantly, then snaps your neck when it gets a bite.

The trim motor gets a workout, as I tuck the engine all the way under for hole shot, then trim it out till it almost loses cooling water for WOT. Mid speed, unless I sandbag the bow about 150 lbs, pretty much has to be trimmed in to prevent porpoising.

I go down to 22 pitch to pull skiers, or if the partner for the day is too heavy set.

These engines would rather run 6000 rpm than 5200 rpm.

If the boat isn't waterlogged, it should go around 60 mph properly set up.

hope it helps
John

 

[MFisher]

Re: proper prop pitch 85 xr2 150

Thank you for all your knowledge and help j martin,

The prop is not vetilated just stock replacement prop.

As for the cavitation I do mean it's not getting bite in the water. It doesn't grab the water from hole shots it just spins the rpm's up. It gets up on plane as long as fool around with the throttle in and out. she runs WOT at about 50 to 55 mph by the speedo no gps on boat turning 5500rpm's. One other thing that i notice is that when it hits about 4500 rpm at about 40 mph it almost feels like it grabs better water smooths out even more and you can continue to throttle up to 55mph.

I don't have the money for a jack plate but it would be nice to have one on there, but could dropping the motor down one more hole on the trim plate make a better hole shot with less fusing with the throttle and keep her running smooth.

 

[ufm82]

Re: proper prop pitch 85 xr2 150

I believe you are underpropped- with a 21p aluminum you don't have the "bite" you need and the engine is overcoming the bite the prop has and you blow out. On a boat like that with a 150 you should be running a 23 or 25 pitch stainless with some cup in the blades and proper rake. Try going to a 23 pitch Tempest and see what happens. I'd bet your rpms will be close, your speed will increase and you'll eliminate the blow-out issue at 4500.
You want your anti-ventilation plate about 1"-1/2" above the keel but on a bass boat some people measure the distance of the prop shaft to the keel and adjust accordingly. It depends on how performance-oriented you are.

 

[j_martin]

Re: proper prop pitch 85 xr2 150

Several thoughts.

If you have the small LU, you should look around for a high five in 22 pitch. Xr's are about the only motor around any more that can even turn one. I got mine, reworked, and in like new condition for $100.

You have a lot of motor there, and it really just plain overpowers an aluminum prop. Stainless almost anything would be a lot better.

I wonder how good the pad is on your boat. It sounds like the prop is dealing with some pretty "dirty" water.

That boat is a relatively high performance hull, and it should run well with the motor pretty high in the water. Caveat is that the prop should be comfortable with near surface or even surfacing conditions. Your isn't.

hope it helps
John

 

[MFisher]

Re: proper prop pitch 85 xr2 150

Any good places that either one of you would recomend for buy a reworked hardley used Stainless Steel prop for inexpencive price that might work. I am gona try and do some running and gunning style fishing this weekend so I am going to try and keep an acurate acount of what happens and when. Again thanks

 

[Faztbullet]

Re: proper prop pitch 85 xr2 150

Xr2's have the large lower unit and from what you have posted it sounds that it is set up for sking...

 

[MFisher]

Re: proper prop pitch 85 xr2 150

OK Now I went out this weekend and still have the same prop a aluminium quicksilver 14 1/2 with 21" pitch. The water was glass smooth and the hole shot pretty good a little bog at first but ran strong just that it seemed to ventilate at about 4300 rpm for about 4 to 5 seconds then smoothed out and my speed was down from normal. At WOT 5600 to 6000 it ran only about 53mph. (speed wheel)

Any Ideas as for getting another prop Stainless Steel might just have to wait till late fall. Who has ever bought a used prop online and is it worth it.