Getting new prop have question

[steelespike]

Re: Getting new prop have question

Will it plane with you alone.And what rpm and speed? This will give us a more accurate indication of what you need.It is possible it won't plane with 2 because the pitch can't get enough speed.If we can get an rpm and speed on plane
We can get a better idea of what pitch.I think on plane the rpm should be in the 6,000 range. Don't be afraid to let it rev to top speed.

 

[logain]

Re: Getting new prop have question

No it will not plane with me alone in the boat.

 

[logain]

Re: Getting new prop have question

Ok by myself I was getting about 5850rpm and 13-14mph.

 

[logain]

Re: Getting new prop have question

I decided to bump this thread instead of just starting a new one. Got busy with school and this kinda got forgotten. It is getting close to that time of year to be getting my boat out so I thought I would come back to it. With the info I have given, what prop do you guys think would be best? I was kinda thinking the OEM 10x7 or 10x5 to get some more rpms out of the motor.

 

[steelespike]

Re: Getting new prop have question

You mention the 8" is a little rough.Is it really dinged up or possibly worn to a point its actually undersized diameter?In my opinion it should plane and the motor rev freely.I don't think you need less pitch.A 1" change on a little motor is more like 2 or 3" on a larger motor.
If you go to youtube and search "9.9 on jon boat' you'll get an idea what a 9.9 can do.Granted your boat is likely heavy but it should plane and likely rev to the top end of its range,with a 8" prop your hole shot should be instant.
Are you absoutely sure it is running on both cylinders.Do both plugs look the same?is the throttle opening all the way.Don't assume because its smooth that it is on 2 cylinders.
Do we know that the compression is good?

 

[logain]

Re: Getting new prop have question

It is dinged up mostly. It is running on both cylinders. Throttle is opening all the way. I have no way of checking compression. Both plugs looked the same last year when I checked them to make sure the gap was correct. I have not run the motor at all yet this year. My boat is heavy and I think is the cause of most of it considering I see more rpm and speed with just me in the boat vs when a friend is in the boat with me. It is rated for a 25-40hp. This 9.9 is all I had access to for now and almost all the lakes in the area are 10hp limit anyway so a bigger motor wasn't really a priority. The motor is strong. It worked great on my dad's boat, despite the shaft really being too long for his boat, but his is also much lighter.