I need your all's opinion

[Stumpys]

I have a 85 HP Javelin. Last year I got 42 mph @ 4000 RPM's. This year I'm getting 35 mph @ 4000 RPM's. I have checked it with a GPS, and I do have all new Faria guages, so I know they are right. I can get 4500 RPM's if I trim the motor up until it starts to rooster tail, but the boat starts hopping and the ole lady hates that!<br /><br />Also, I went to a 17 pitch prop last year from a 19 pitch to get a better hole shot, which worked. I know from all the experts here to check the carbs and fuel pump, which are both rebuilt from last fall. I did take the carbs out and cleaned them. Anyway, when I pump the bulb, it never gets hard and when it's running, it get semi hard. Also, how can I reach 5800 RPM's?

 

[Dunaruna]

Re: I need your all's opinion

Check me on this:<br /><br />You had a 19" and you got 42MPH @ 4000RPM.<br />You went to a 17" and got 35MPH @ 4500RPM.<br />Your reccomended WOT RPM is 5800 - yeah?<br /><br />It that basically the story so far?<br /><br />Aldo

 

[umblecumbuz]

Re: I need your all's opinion

Don't think that's exactly right Aldo.<br /><br />According to Stumpys, he was getting 42 at 4000 revs, then 35 at 4000 revs. Presumably the 42 was with a 19" pitch, and the 35 was with a 17" pitch.<br /><br />Can't see where the 4500 revs comes in yet - unless the motor tops out at 4500, and Stumpys is just comparing revs with revs for comparing props.<br /><br />Presumably if the motor will hit 4500 revs under load, then the 17" prop will top out at 39 mph, not 35mph. <br /><br />Stumpys - more detailed info needed.

 

[Dhadley]

Re: I need your all's opinion

Stumpy, what setting is your tach on?

 

[OBJ]

Re: I need your all's opinion

Stumpy, you should've picked up around 400 rpm dropping to a 17* prop. Did you? The trade off for the hole shot was speed.<br /><br />You really need to get those rpms up above 5500rpm or the motor won't last long lugging it. Stillfishing is right, we need to know how the engine is set up on the boat...where the anti-cav plate is in reference to the keel.<br /><br />Maybe Dhadley will see the post and give some pointers.....Mr. D is good at settin' up engines.

 

[Stumpys]

Re: I need your all's opinion

Dunaruna... Both those numbers are from the 17 pitch prop. <br /><br />Dhadley... I believe the tach is set on 13 pole if I remember right.As soonas I get off work this morning, I will make sure I'm correct. <br /><br />Stillfishing... Again, all the rpms is from the 17 pitch. I can get 4500 rpms if I trim all the way up to when it starts to rooster tail, but the bow starts hopping bad.

 

[OBJ]

Re: I need your all's opinion

Well...I guess Mr. D did see the post..... as I was typing.....

 

[Stumpys]

Re: I need your all's opinion

OK... Click on the links and see what you think.<br /><br />Oh yeah.. don't make fun of my ugly boat. LOL<br /><br /><CENTER><A HREF= URL>http://img.photobucket.com/albums/v379/Stumpys/Transom.jpg</A></CENTER><br /><br /><CENTER><A HREF= URL>http://img.photobucket.com/albums/v379/Stumpys/RearView.jpg</A></CENTER>

 

[Dhadley]

Re: I need your all's opinion

Cant see the pics Stumpy. Probably this ol computer. We need to verify the tach is set correctly before we go any further.

 

[lark2004]

Re: I need your all's opinion

ok, can't see photo's<br /><br />how old is your boat?<br />it is possible that your underfloor foam is waterlogged. this can weigh a boat down a fair bit and will make it run slower.

 

[Straightup]

Re: I need your all's opinion

Yeah, along the same lines as Lark, make sure nothing is clogging your drain hole. Went out with my brother in his Mirro Craft once and couldn't even get on plane. Took his plug out and no water came out. Looked further and turns out drain hole was clogged with leaves ect. Once the clog was cleared it drained for a long time. Went normal speed after that.

 

[RPJS]

Re: I need your all's opinion

If you are turning the same RPM with the same prop and nothing has changed on the setup you must be carrying more weight or have more drag acting on the boat

 

[ddbyrd3]

Re: I need your all's opinion

Originally posted by lark2004:<br /> ok, can't see photo's<br /><br />how old is your boat?<br />it is possible that your underfloor foam is waterlogged. this can weigh a boat down a fair bit and will make it run slower.

How would you check this, let alone fix it if this was to be (a) the problem..... Just curious.

 

[REELSPORT]

Re: I need your all's opinion

a good wax job on the boat might help and if you have a local prop repairman you might want to get him to cup the prop might give a couple more mph

 

[Stumpys]

Re: I need your all's opinion

Sorry, I must have forgot how to post a link. Anyway, it is a 1980 Fiberking Bomber. The bummer is that it is a tri-hull. I know that slows it down some. <br /><br />The tach is set for a 4 cyclinder.<br /><br />Also, I know it is draining fine cause it has been raining about everyday here and I did forget to pull the plug. It drained for over an hour.<br /><br />I know a good ole wax job may be needed too. The only thing new I did this year was replace both batteries with the same size it had, same weight. <br /><br />I really believe it has to do with the bulb not getting hard. It does have a new bulb, new fule lines, new filter, and rebuilt the pump last fall. <br /><br />See if this works... <br /><br /><a href="http://img.photobucket.com/albums/v379/Stumpys/Transom.jpg"<br />target="_blank">Click here</a>

 

[Stumpys]

Re: I need your all's opinion

Oh.. here is a couple of more pics.<br /><br /><a href="http://img.photobucket.com/albums/v379/Stumpys/RearView.jpg"<br />target="_blank">Click here</a><br /><br /><br /><a href="http://img.photobucket.com/albums/v379/Stumpys/Guages.jpg"<br />target="_blank">Click here</a>

 

[walleyehed]

Re: I need your all's opinion

First thing I see is what I think is a Raker prop, designed to surface........ with an engine mounted all the way down....this sin't "really" a good combo. and Rakers are even numbered pitches...I can't tell if it has vent holes...if not, it may not be a Raker.<br />It does however, look as though we could start raising the engine a hole and testing for starters...

 

[muskyone]

Re: I need your all's opinion

how much gear have you added to the boat i wouldn't wax the bottem i sanded mine with 220 grit

 

[OBJ]

Re: I need your all's opinion

From the one picture, there are no vent holes....can't tell what kinda prop it is. And I'm not real crazy about what appears to be a speed sender mounting either. You might consider moving it over....you want "clean" water coming at the prop.

 

[G DANE]

Re: I need your all's opinion

The numbers in Tach setting does not refer to cylinders, but alternator poles. As I remember your tach should be set on 6, which will change your RPM reading radically. Recheck in your owners manual.<br /><br />I know its hard to see in a photo, but pitch looks higher than 17" to mee.