Nissan 9.9 prop ??

[goblerblaster]

I have been working on a 9.9 Nissan 2 stroke 1997 model that was having carb issues. I got it running good in the water barrel, so I took it to the lake on an aluminum 14x35 flat bottom boat. The motor will start right up and not miss but it will not plane off the boat. I thought it must still be a carb issue. Break down the carb again, got it running good in the barrel, back to the lake and it doesn't miss but will not plane off the boat.
I got to noticing that it almost felt like the prop was slipping - especially when motor was in reverse. I have looked at the prop and cannot see any signs that it has "spun a hub", but don't really know what I am looking for. I can put the motor in gear and turn the prop and it turns the motor over without slipping. I put a wooden block between the prop and cavitation plate and can't get the hub to spin without the blades in sync.

How do I test for prop slippage or any other ideas that might help.....

 

[goblerblaster]

I should add that the existing prop is an 8.5 pitch, which I think is a "standard" or middle of the road pitch for this motor.

Also...everytime I try to post to this website, I get and error that says "you are not authorized to creaet a post" o r a message that says " Server error" . If I try 5 or 6 times, it will finally post. Whats up with that???

 

[steelespike]

A spun hub usually is a total failure as power is increased the hub will slip,motor revs and boat slows.
This will happen over and over at less and less power.You can check for slip by putting a waterproof line across the hub and body of the prop and test.
Unfortunately running in a barrel only proves the motor will run.Often the prop will be fouled with exhaust in reverse making it lose its grip.
Are you sure both cylinders are firing.You wouldn't be the first to not realize your on one cylinder but for the lack of power.

 

[goblerblaster]

Thanks for the response. I just went and checked and it is getting good blue spark on both plugs. It doesn't hesitate or miss when in gear in the barrel. It doesn't miss on the water, just acts like it can't get the boat to plane. I did get it to plane out one time and it ran perfect for about 1/2 mile. When I slowed down and came off plane to make a turn around. I could never get it to plane again. I have replaced the fuel pump diaphrams, changed gas line and bulb, new gas, etc. and it is still doing the same thing. When I bought it a few weeks ago, it would not start, but after I cleaned the carb and put fuel pump diaphrams in it- it starts easy and runs good...except when on the boat at the lake !!

Any ideas appreciated.........

 

[steelespike]

I should add that the existing prop is an 8.5 pitch, which I think is a "standard" or middle of the road pitch for this motor.

Also...everytime I try to post to this website, I get and error that says "you are not authorized to creaet a post" o r a message that says " Server error" . If I try 5 or 6 times, it will finally post. Whats up with that???

That server error pops up a lot just click ok or what ever it says.Server error appears to pop up for no real reason.
Heve you seen then "restore" (auto save) tab at the bottom of your post if you lose your post somehow.
Auto save updates as you write. It will save text if you leave the page for some reason.I've come back the next day and the restore tab is still there.
Maybe if you leave the page when not authorized comes up it will work when you come back and click restore?
I'm on a fairly new MAC.
At the very bottom of the rules and guidelines there is a phone number and a contact us tab.

 

[Sea Rider]

Some issues :

-Standard delivered props performs awful in reverse compared to same forward motion, that's the spirit of those props.

-A 9.9 engine is a very poor performer for such a large 14 footer, can play with prop pitches all you want but will be ekeptical if you can plane that combo rated for a at least 25-30 HP engine, worst if heavily loaded, or badly trimmed and engine not sitting at its best height position.,

-You can bump that 9.9 into a 15 HP for peanusts cost, which will better the overall performance of that combo, even going afterwords for a prop maximization to get all the juice out of that 15.

Happy Boating

 

[steelespike]

A 14 X 35 doesn't seem large to me.
Is that a bare boat?No floor or live well etc.If it is then a 9.9 should;d jump on plane and approach 20 mph.
When I was a kid about 100 lbs we had a full size14 ft Crestliner utility not a car topper.
With 2 of us 100 pounders in the rear seat it got on plane easily and ran about 20 mph.
It planed easily with 3 or 4 of us kids aboard.
I would say the 8.5 pitch is on the nose for typical small boat operation.Now if 2 or 3 200 pounders are going out
you might need a little less pitch.

 

[goblerblaster]

The boat is a very light 14 foot long 35 inch wide at the bottom of the transom. It is rated for a 20 HP max motor. I use to run it with a mid 80's 9.9 evinrude and it would plane out with 3 adults and a 100 pound Lab duck dog !! I can't seem to get it to plane with just me and 3 gallons of gas in the tank with this 9.9 Nissan. The one time it did plane, it ran great and at full throttle with no missing. This is a short shaft motor-15 inch- and I have tried it at the full "tucked under" position and it still won't plane. It may be a gas issue, but it sure runs great in the barrel even in gear- that is why I thought it might be a prop issue.

 

[Sea Rider]

If that boat was easy to plane out, you could have a prop on its wat to become kaputt, near spun hub failure, check. Bumping that engine into a 15 with a new prop would be ideal.. Running great on muffs or on barrel it is no guarantee engine will run as expected once is pushing a boat under load.

Happy Boating

 

[steelespike]

You need to go through the motor for other problems. You say spark is good, Is running on 2 cylinders. You know a 9.9 will plane the boat easily.
Check the link n sync. Be sure the throttle opens all the way.Be sure the timing advances as it should(link n sync) be sure the timing doesn't advance too far.
See if it responds when you tickle the choke.
Is the idle strong and steady?
Have you done a compression check?

 

[Sea Rider]

Speculating about engine condition is the best way to lose precious boating time when first thing you need to do is troubleshoot the current prop to know its working condition. If found ok work from there..

OTHO, he's running a boat rated for a 20 with just 50% of the required power. Where did the near cast on stone that states min 70% of the required HP went ? Besides don't know max achieved wot rpm when trying to plane, definitely he's at the ultra lugging side of the wot range,

Prop Hub Test :



Remove prop, turn upside down, mark a straight line across hub or 2 front marks as seen in pic, put prop back on
shaft, go for a wot spin lighty loaded for a short time, remove prop, if marks have moved from where originally marked you have a kaputt hub, buy a new prop if was working ok or go for one less pitch size to have better hole shot with weight.

Happy Boating

 

[steelespike]

The 14 ft Crestliner we had when I was a kid was rated for 35 hp. It did fine with 10. A 14 ft boat is ideal for a 10 hp.
The Crest liner was 185 lbs.
Now if your going to put 3 of todays men aboard with gear then your going to need more hp.
He is running a "very light" 14 footer I'm guessing 145 to 165 and a flat bottom And it won't plane with he and his son aboard.
and It planed fine with a 9.9 E/J.
It's my experience (66 years) that when a hub starts to fail there is no partial fail.The motor will simply over rev until you reduce power.
Sometimes the friction will heat the hub enough it will work normally for awhile. But each time it lets go it is total like shearing a pin once you slow the motor it will work until you apply more power. It will begin to fail sooner and sooner.

 

[Sea Rider]

Seen cases where engine did't over rev with spun hub due to being on its first initial spun procedure, over revs badly when completely KO and that takes a bit of time if with less HP. The white prop pic previously posted had same issue, didn't over rev but didn't plane the combo either. Tree shade mechanics fingered the whole engine with no positive avail. After conducting a conveniently prop test, new same pitch curred the patient instantly. Not saying a 9.9 will not work, will work ok if engine and prop are both healthy, but at the moment prop is uncertain.

Happy Boating

 

[goblerblaster]

Thanks for the input. I've been out on a trip, but intend to do the prop test for spun hub today. I have re-soaked the carb in Berryman's carb cleaner for 4 hours. Installed new plugs and tried the boat again while putting a 15 inch tire and wheel in the front of the boat for extra weight. I was able to get the boat to plane off- although very slowly- and once it planed out and ran WOT with no misses or skips. I ran it for about a mile and then came off plane, and never could get it to plane out again.. This motors has good compression and idles as long as you want it to.

I'll update once I try the slipped hub test and see what happens. I think I am also going to put the motor on a 16x48inch flatbottom that I have and see what it does on it. This bigger boat is so wide that it hardly has any bow raise when starting off with a 25 hp on it.

 

[steelespike]

longer boats sometimes plane easier than a shorter hull and the 48 inch width would surely help it to plane.
Our old Gale 25 did much better on a 18ft bare utility than on a similar 15 ft utility.That big footprint got up on the water much easier.

 

[goblerblaster]

OK, I tried the motor on a Lowe 16 foot long 48 inch wide bottom aluminum boat. The motor planed off the boat and ran like a champ !!.. There was a SLIGHT hesitation when going from idle to WOT, but I don't think anyone would notice except for me coz I was looking for it. There is very little bow rise before the motor planes off this boat. I am now wondering if the smaller boat is getting so much bow rise when trying to plane off that it is tilting the engine to the extent that it is not getting enough gas. It continues to act like it isn't getting enough gas on the smaller boat, but if I scoot as far forward as I can while still being able to reach the tiller- I can sometimes get it to plane out on the small boat. Once planed- it runs great.

I even put my 225 pound buddy in the front of the 16 foot boat and the motor has no problem planeing and running great.

I think I will put some weight- car battery and a couple of wheels and tires - in the front of the smaller boat and see if it will plane out better. At least I know the prop is not malfunctioning now !!

 

[Sea Rider]

What's the issue of doing a prop slip test and confirm if 100% operative ? old prop hubs are not eternal. The smaller boat probably achieves more hull drag than the longer one and slower to get out of the hole faster. It's normal to have some "hesitation" between idle to wot, you must warm that engine for 20 seconds at mediun throttle, then go full throttle if liking. Once engine has rached its ideal operating temp, no issues throughout the whole throttle range. Bow up doesn't have anything to do with carb not receiving the proper amount of fuel. Carb will always receive what needs provided pump fuel is in good working order.

The timing cam and carb restriction will never let you be set at 180 deg butterfly opening, for that will need to passs that horse to 15 HP with a new carb cam along sync. Both 9.9 & 15 HP are same 250 CC engines, bieng the 9.9 HP a factory restricted model.

Happy Boating

 

[steelespike]

What is the gps speed with the 16 planed out and the 14?
Buy or make a tiller extension for your single operation.
Long ago we had a flat bottom 12' steel boat that popped on plane with a 5 hp Gale
and a 180 pounder in the middle seat. The 5 was rated for 12 mph I think speed was about 10 or 12 mph.

 

[goblerblaster]

Sea Rider, I did do the prop test as you recommended and the prop is not slipping. Thanks for the pic and info on how to do it.