1801 owners with 2 Stroke Yammie prop questions

[In2Deep]

Just picked up a 1999 1801 (no T-top but does have a polling platform)with a 1999 Yammaha 115 (that uses premixed fuel) and the previous owner changed the prop to a stainless one. On the sea trial the rpms maxed out @ 4600 with the motor trimmed down,and 4900 with the motor trimmed to the sweet spot(better mph via GPS). I did a search and what I found out was that wot the rpms should be 5000? Some other 1801 owners here have posted much higher rpms(6300) @ wot?? What should I be seeing,roughly?
I think the prop is too tall for the setup? I dont think the 2 stroke motor is hitting its sweet spot/power band.
Thanks in advance.
What size prop are you running?
Jerry

 

[In2Deep]

Oh I did a search but didnt find much pertinent info?

 

[In2Deep]

wow no love from the 1801 owners?

 

[In2Deep]

Ok the prop on the boat is a "Rapture" 13.25 X 19 stainless steel, wot was @ 4600 RPM with the motor untrimmed and 4800 rpm trimmed. After reading a bunch of posts here I feel I should be running about 1000 rpm higher. Where should I start? Prop? Carbs? Linkage? Compression??
thanks.

 

[In2Deep]

Ill be checking the compression /linkage in the am.Ill post the results.

 

[erichins]

I would drop down to a 17 or even 16 pitch taking into account how much weight you'll have in there when you are fishing not sea trials. i've got an 97 1800 it had 115 yamaha when i got it. 17 pitch prop worked great. just used a hell of alot of fuel. found a 2005 mercury 115 4 stroke now i use less than 1/2 the fuel of the 2 stroke.

 

[In2Deep]

so I guess I should look for a new motor? Hmmmmm....

 

[In2Deep]

Compression was great 125-130 all 4 cylinders. Throttle linkage looked good also. I guess Ill have to try a different prop. Anyone got one?

 

[Megabyte]

I think erichins is correct. A 19p is too much.
Do you have a prop shop near you that will allow you to try different props?
Check the owners manual for that motor and see what it should be turning at WOT, then take your direction from there.

 

[mthomas]

I have an 89 model with a 89 yam 115. It had a m19 prop originally and it was a great prop for the boat.It would pull a skier with a boat load of people. That is the stainles yam prop (not the Salt Water series). The back side of the blade is staight as compared to the teardrop backside. I spun the hub and replaced with a aluminum merc prop of the same size and it is too much prop for the motor. Can't wait to gret to the coast and get my yam prop hubbed.