RPM of XP150 too low?

[farginicehole]

Re: RPM of XP150 too low?

So the functionality of the gray wire for the tach is NOT independent of the charging circuit (red wire, right?) of the rectifier/regulator? That is, if it is putting out the correct charging output, then it is definitely not what is causing my erratic tach operation? Thanks for the replies!

 

[MGuckin]

Re: RPM of XP150 too low?

Testing it that way will only determine if it is putting out voltage not if the correct amperage. A trickle charger will show output voltage with a meter but not amps.

 

[farginicehole]

Re: RPM of XP150 too low?

Got it, Mike. Your thoughts on my last question regarding the relationship(?) between amperage output and the signal going to the tach?

 

[MGuckin]

Re: RPM of XP150 too low?

Don't really understand your question.<br />Have you read this yet? Great troubleshooting for tachs. Found this in my old listings links favs. I don't remember whom submitted it. Tach Troubleshooting.

 

[farginicehole]

Re: RPM of XP150 too low?

Thanks again, Mike! Sounds like I need to verify that my tach has a good ground. Not positive, but it seems like I've seen it not zero all the way when the ignition is turned on (the times when it reads over 6K at WOT). Back when it was reading 5000 rpm (which I think is probably right) at WOT, it was zeroing when I turned the ignition key on. I'm anxious to get this issue resolved so I can move on to Dhadleyizing my motor setup!

 

[farginicehole]

Re: RPM of XP150 too low?

Think I may have found the reason for my erratic tach readings. . . I think I might be the root cause! Found the gray wire was attached to the "sender" post for alternators, instead of the J/E post. Now I am getting readings of around 5500-5600 rpm, and this agrees with my uncalibrated ears. I used to get around 5000 rpm, but this was before I replaced timer base and powerpack so I'm guessing I was dropping a cylinder or two and therefore the 500-600 rpm. Does this sound about right? Problem is, at 5500-5600, I'm still only getting about 40 mph with that 15x17 aluminum. What next? Raise the motor up? I'll get a jack plate if I have to, but I don't want to spend the $$ and time if there are still other issues that need to be addressed first. Thanks!

 

[walleyehed]

Re: RPM of XP150 too low?

That's about 16% slip....I think we can lower that some with some heigth adjustments.<br />I didn't look back but is the 15X17 in good shape???

 

[MGuckin]

Re: RPM of XP150 too low?

Stop worrying about the top end speed for the moment. Lets get the rpm's up as high as we can with what you have. Hold off on the jack plate too.<br />Lift motor 1 hole and try it. You don't need to worry about sealing the bolts completely unless you are keeping it in the water. We can do that later. Record your Wot Rpm, observe holeshot, check handling at turns and watch for porpoising. PLay with your trim settings a bit. You may be surprised what it will do. The object is to get the rpm as high as you can and still be able to handle the boat with a comfortable ride. I do not believe you will over rev but if you do these motors can take it for a short time. Actually you may be surprised what they are capable of turning, but that's another story. Report back.

 

[MGuckin]

Re: RPM of XP150 too low?

Sorry Walleyehead you beat me to it.

 

[farginicehole]

Re: RPM of XP150 too low?

Yeah, I'd say it's in reasonably good shape. A few small dings, but not all bent or chewed up. If I'm looking at it properly, I think I just need to loosen the two bottom bolts (holes in bottom of mounting bracket are slots, and bolts are currently all the way at top of slot) and then pull the top two bolts out to slide the motor up. I think I may have nearly 2 inches to play with here. Now I just need to find a way to raise the motor up. I may have to find a marina somewhere that will do it. With my current motor height, I can trim the motor all the way up without cavitating. Of course, I do have to trim down if I take anything more than a very gradual turn. Walleyehed, how do you calculate slip and what should we be shooting for? Thanks again!

 

[MGuckin]

Re: RPM of XP150 too low?

As low as possible.<br /> Slip Calculator

 

[farginicehole]

Re: RPM of XP150 too low?

Cool, thanks Mike. Guess I'll have to have a look in my manual to see what my gear ratio is.

 

[MGuckin]

Re: RPM of XP150 too low?

Easiest way to lift it is using a flywheel puller. Don't believe your crank is tapped. If it is use an eyebolt. For mine there are 3 tapped holes in the top of the flywheel that are threaded. You may be able to work off of them as I did using a hub puller and a winch.<br />If you can trim all the way up without cavitating, the motor is definately too low. Maybe go as high as you can. You can always drop it back down.

 

[MGuckin]

Re: RPM of XP150 too low?

1.75 I believe but not sure.

 

[farginicehole]

Re: RPM of XP150 too low?

The three holes in the top of my flywheel are tapped, and I used these with a cheapie harmonic balancer puller to remove the flywheel. So this is a safe place to lift the entire motor? I'd hate to damage my flywheel - those things are shockingly expensive!!

 

[farginicehole]

Re: RPM of XP150 too low?

You posted your last one at the same time I was posting. Anyways, I'll check my owner's manual but if 1.75 is correct, your calculator gives me a slip of 21-22%. That's pretty bad, huh?!

 

[MGuckin]

Re: RPM of XP150 too low?

Actually if you look in your manual that is exactly how they tell you to move it. I just yanked 1 off about an hour ago myself.

 

[farginicehole]

Re: RPM of XP150 too low?

Man, I sure hope you're still talking about boat motors here. . . .

 

[MGuckin]

Re: RPM of XP150 too low?

I suspect the ratio may be wrong. Kenny is usually very accurate.

 

[MGuckin]

Re: RPM of XP150 too low?

Yes, I am talking about motors. I just pulled a 150 cross flow off a boat to part it out. But I guess if you are a little off you may have read different.