Help solve this one

[texaswildman]

I can't get a 15 pitch prop to run on my C60. I rev a 11 pitch, and a 13 runs on it fine (high rpms) but I put a 15 pitch on it and it will not get out of the hole for nothing. Just bogs down and stays there. Prop shop dude said it is a engine issue.

Boat is a 18' panga (hull weight 628lbs) Motor is 228 dry weight and another 400lbs or so with two people and fishing gear.

A 15 pitch prop should run fine on it. The book calls for a 13.5x15

Any suggestions?

[jb123]

weight distribution, motor height.

[texaswildman]

The Johnson 50 hp I had on it ran it before ran 33mph and motor weight was 30 pounds more than this yami 60

Weight distribution: with the 15 pitch I even put a 200lb man in the bow and it still would not come out of the hole. It just ran bogged down. After looking at props on the internet, it seems that a 15 or 17 is the standard pitch for that motor. It is strange that a semi v to 11 degree transom would not run with a 15 pitch.

How do you test a motor to see if you are getting optimized power from it?

The prop guy said it was a motor issue not a prop issue. The 13 pitch runs it fine but still when I trim out it pushes 5800 or 6000 rpms at 28-30 mph. Seems the 15 would be perfect if I can get the motor to push it.

[jb123]

the motor does get up to 6k so it is not a motor issue.

[texaswildman]

Yep. Motor will pull up to 6k or better I think but as soon as it hits 5800 or 6k I back out of it.

Problem is the load with a 15 pitch prop. A 15 pitch starts to load the engine to the point to where horse power or something gives

[texaswildman]

Morning bump.

Still looking for why a 15 pitch would load a motor to the point of not coming out of the hole but a 13 will run the motor to red lining if I ran it that hard

[99yam40]

Did you pull and clean the carbs, and then do a sync and link?
Did you check the timing to be sure it is correct at WOT?
These will effect the power.

[texaswildman]

Yes sir. Link and sync done, timing manual, idle and wot all set in specs.

I did pick up some torch on the link/sync but still not enough to push the 15 pitch.

Strange because the 13 is screaming.

[99yam40]

If you cleaned the carbs , how did you do it, soak in a cleaner, ultrasonic, or just blow out with compressed air? Did you check timing with a light?
Sounds like not getting enough fuel or air movement to develop the torque needed. Are you sure the main jets got back into the proper carb? some of these motors have different size jets in the different carbs.
Have you decarbonized the motor? maybe you have some type of restriction in exhaust.I have seen small 2 strokes get restricted with carbon but not something this large.
If it has good compression,spark,timing, and plenty of fuel,it only leaves air/fuel mix.
But that is just my opinion, for what that is worth.
Do you have any history on the motor, how it ran before, on what, how many hours, etc.

[texaswildman]

If you cleaned the carbs , how did you do it, soak in a cleaner, ultrasonic, or just blow out with compressed air?

Carbs were not torn down complete. I soaked them without bowl, and seats. Did not pull the jets.

Did you check timing with a light?

Light timing is spot on

Sounds like not getting enough fuel or air movement to develop the torque needed. Are you sure the main jets got back into the proper carb? some of these motors have different size jets in the different carbs.

Never broke the carbs down that far (I'm too scared)

Have you decarbonized the motor? maybe you have some type of restriction in exhaust.I have seen small 2 strokes get restricted with carbon but not something this large.

I have not decarbonized the motor. How is that done?

Do you have any history on the motor, how it ran before, on what, how many hours, etc.

History is this is a new rebuild from a local guy (respected mechanic but not trouble shooter) Replaced the #1 piston and all new rings and stuff on the other two cylinders. Other than that I do not know a thing about the motor, only that he rebuilt from the cam to the fly wheel and replaced the water pump and parts. I have a one year warranty on labor and parts.

He said that he can put parts together but can't trouble shoot the problems of timing/load on the motor

Compression after break in period on the new rebuild is

#1 - 123
#2 - 123
#3 - 123

[99yam40]

The biggest question is what happened to the #1 piston in the 1st place.
I have read from others that a lean condition will get a piston and a lack of oil will get the bearings and shaft,but take that as you may, it is just something I read before.
If he did not correct the condition that cause the problem the first time, you may still have the same problem.

These carbs are not that complicated, but to clean properly they do need to be taken completely apart and done right to make sure they are clean. That means all passages, not just some of them. Its the only way to be sure.

[texaswildman]

The piston burn because the previous owner ran it premixed too lean at 100:1 instead of 50:1 is what I was told.

It is a premix motor so there is no issue with too much or too little oil. 2.6 oz per gallon.

[chadbro]

man i'm having the same issues out of my F60 it will not turn a 15 either and it will scream with a 13 it will only run 30mph and i was fine with that until i got smoked by a boat bigger than mine with a 50hp mercury he is running 42 i just don't understand it is a yahama just that much weaker than a mercury