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Another Honda hp50 Tach / prop issue - + an internal image of HP-0243-001 tach (not easy)!

E

eeberhar

New member
Hi ,


My knowledge is basic++ - just getting into boating and having fun :)

- bought boat with 75 2 stroke evinrude
-2000 HP50 4 stroke installed
-princecraft 18.6 foot boat


-original evinrude 75 tach

- bought HP-0243-001 http://www.ebay.com/itm/161131128624?item=161131128624&viewitem=&sspagename=ADME:L:OU:CA:3160&vxp=mtr

It appeared to be running dble the revs, knowledge increased to the concept of 'poles'. Max rpms went above 7k

Based on this info - should have a 6 pole tach
http://faria-instruments.com/site_manuals/IS0012u.pdf


This post lead me to believe there was a switch in the 243-001 part http://www.marineengine.com/boat-forum/showthread.php?290603-Honda-tachometer --- I started to wonder if my honda tach was the wrong one given the double revs.

I took it apart, not easy/ probably a bad idea but I was curious..... and there is a little slider switch but i had to peel the bevel off. The boat reads 1.5/1.6 rpms at idle at the lowest when I play with the internal switch. There is no obvious 2,4,6,10 pole type switch in it. (see photo below)

I looked at the original tach and there is a circle switch to show 'poles' and it was set at 6. I read this and thought I should just try and use the old tach http://forums.iboats.com/mercury-mariner-outboards/tach-question-4-stroke-2-stroke-470254.html

It revs at 800+/- at idle, seems good.

I have no idea about props, other than the motor was on a pontoon boat then I bought an oem honda prop 283/330 mm basically a 11 pitch. They seemed similar. The boat will rev out to max on the old tach on both the orig and oem prop at 4k. Even when I get the prop spinning 'beyond' where its cutting/pulling into the water it still max's out at 4k.

So I know I should get an rpm meter...or....I dont have easy access to help or more gear.

Ideas?

1. Which tach is right? the old one set at 6 pole with 4k max or the new honda reving out past 7k. It sure seems at idle the old tach right.

2. from there I will need to investigate the proper tach, probably less pitch given the boat is slightly underpowered....not sure? how does one guess on the next prop as I have to buy to try.

3. If a motor prop stops pulling water (cavitation or whatever the term is), should the motor rpms max out and the motor cut out with the rev limiter?

thanks

(see the philips plastic screw, it modifies the rpms by about 500 rpm - the lowest I can get it is 1.5k which seems to high based on it being almost at stall level)
photo (11).jpg
 
First you need to get the correct tach. I would not mess with the evinrude tach set at 6. The setting is for the # of cylinders. If you are running a 50, then you don't have 6 cylinders. It is not possible to prop the boat correctly without a functioning tach.
To answer the other question, yes, the engine should rev up once it cavitates and may redline. Why are you cavitating? Are you trimming the engine up when this happens? Is the engine mounted too high? I am sure one of the Honda guru's will chime in, but it will help to have basic info on the situation, and for you to have the right tach.
 
Helpful thanks, I thought maybe the numbers on the evinrude where pole settings.

1. I was trimming the motor up to see how high I could get the rpms - while maintaining suction for engine cooling - only for a few seconds.
2. The engine has 4 or so bolts and its mounted to the second lowest hole, it doesnt cavitate unless I do something to try and force it like a big corner or trim.

The motor runs excellent, and based on the fishfinder/speedo I get almost 30 mph which is fine for my use.

Should one expect to run the motor at 3500-4k rpm for an ideal cruising speed?
 
In most cases, 3500-4k would be optimum for cruise rpm. You should be propped to turn near the maximum recommended wot rpm for that engine. Most engines are in the 5500-6k range, but I would double check that with the owners manual to be safe.
The settings could be poles, but you said it was set at 6 to get the rpms where you thought they should read at idle. Maybe you could try it on 4 and see what it reads, but 800 may be high at idle. Was that in gear or neutral? Most seem to be set at 5-600 in gear.
 
The motor should be mounted so that the anti ventilation plate (the horizontal fin above the prop) should be approximately even with the bottom of the boat. It should be within one inch of the bottom.

If the boat is fairly light, it would probably be able to take a 13 pitch prop. As an example....a shallow v 18' 8" Carolina Skiff with a loaded weigh of 1360 lbs tachs out to 6000 wot with almost 32 mph using a 11 1/4 x 13 prop. So you are probably not too far off.

Mike

Unless you use the resistor, that I mentioned, you will probably not get an accurate tach reading with any tach with that motor.
 
thanks again

1. i will order the resitor
2. i reinstalled the honda tach, i think at lower revs it off but maybe the high end one are closer. It will rev to 7500
3. i reinstalled the 11 1/8 by 13 prop, the pontoon boat one has no numbers on it but its larger in diameter.
4. the anti ventilation plate from eye balling looks about even with the bottom of the boat
3. the fish finder speed is more like 23-24 mph at wot right now not 30, but i need to verify with a gps

the boat is a princecraft jumbo which is supposed to be 335 lbs, motor 220lbs, stuff/wood/gas etc guessing 400 lbs so its in the 1200+ lbs range.

"This Princecraft outboard utility has a aluminum hull, is 18.33 feet long and 80 inches wide at the widest point. The boat weighs approximately 335 pounds with an empty fuel tank and without any gear or passengers. The maximum horsepower we have listed for this outboard boat is 50 hp"

question

1. when would the rev limiter kick in?
2.If the motor is spinning to 7500 right now , I can see why a pitch of 13 might be a good idea. it might bring the revs down 500-600 rpms?

thanks agaiin
 
Generally, you will hit the rev limiter around 6200 - 6300 rpm.

I do not think the motor is really rev'ing to 7500.

Idle rpm in neutral should be 950 rpm plus/minus 50. I usually set them close to 1000 rpm.

Mike
 
Sorry for jumping in so late but I just had to ask where the "maximum horse power list" came from? It seems to me that 50hp would be condidered a minimum power source for getting this hull on plane. It is my guess that this hull would require a substantially larger outboard to plane a boat that obviously could carry 3+ passengers and their gear.

Witness the fact that it had a 75 on it. Like I said, I'm guessing but I don't think i'm wrong. And, if i'm right, you may never achieve "desired" performance "readings" with the 50.
 
Hi,

Its stamped on the boat...and if I got that quote off the web when you google princecraft jumbo. Most jumbos have a 75 though, so I think you have a point. The evinrude was having problems and I found the honda so I just swapped. I am just river running, fishing around here so I dont need optimal but I want to be respectful of the engine and rpms...

The honda is soooo quiet and the fuel usuage compared to the evinrude is unreal. All and all I am very happy....

except I have to choke the motor at the base as the remote choke/engagement doesnt seem to work.

thanks for the input
 
Hey, as long as you're happy with what ya got, then that's all that matters. As far as that choke goes, most of those aren't too complicated and you can probably get it fixed after you sort out your tach.
Happy boating....it's what it's all about!
 
Hi,

Update - resistor installed

Tach indicates idle at 1500-1600 rpm. but the reality is its close to stall so I would put it at 800-1200 - probably closer to the lower number though.

I think the tach needle doesnt jump around quite as much but I can still rev it out to a bit beyond 7000 rpm with the 11 1/8 by 13 prop.

No rev limiter is kicking in and it runs very well...so I guess to get a true reading I will need to take it somewhere.

Now I have a bigger issue...will start a new post :)

thanks
 
If the resistor worked somewhat then I would say that's a path you could continue on. Resistors are CHEAP so it is easy to experiment with some different values and find what works. They can be temporarily installed and easily removed and replaced as you "feel" your way along. You can also place them in series with one another to INCREASE resistance...ie; 10 ohm + 10 ohm =20 ohm and place them in parallel to DECREASE resistance.. .ie: two 10 ohm resistors in parallel= 5 ohm resistance (approximately).

Although any decent electronics store oe even Radio Shack should have the exact values you need. I keep little 5 count bags of a wide range of resistors in my soldering box for doing work arounds like this. What was the resistance value that you installed?
 
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