Rpm issue 70 hp Yamaha

[Nickm]

Hello all I am a new 170 owner with yamaha 70 2 stroker 2002.
I have read W. O. T. Is 5500 6000 rpm
I am only getting to 3300 on my tack and it's getting aroumd 35mph.
So to me it seem legit but why only 3300 rpm
It idles at 800 and all soumds good.

 

[NCangler]

Hi Nick. What size prop do you have on the Yamaha? Also what mounting holes is the engine attached to on the transom?

 

[Shallowminded]

Have you had it since new? Those rpm's sound pretty low to be tooling along at 35. Maybe your tach is not accurate? My tach sticks every now and then but I have so many hours on it, I don't need the tach to tell me. If the reading is way off, I wrap the tach with my knuckle and it bounces around a bit and settles down to the correct reading. One day when it completely dies, I will put a new one in. Does it take a while to get on plane? Maybe it is a prop issue.

 

[Nickm]

13.25 x 17

Hi Nick. What size prop do you have on the Yamaha? Also what mounting holes is the engine attached to on the transom?

 

[Nickm]

13.25 x 17 prop
See. Pic for. Mounting wasn't sure where you meant

 

[Nickm]

Have you had it since new? Those rpm's sound pretty low to be tooling along at 35. Maybe your tach is not accurate? My tach sticks every now and then but I have so many hours on it, I don't need the tach to tell me. If the reading is way off, I wrap the tach with my knuckle and it bounces around a bit and settles down to the correct reading. One day when it completely dies, I will put a new one in. Does it take a while to get on plane? Maybe it is a prop issue.

No I just bought it and I was gonna try a new prop because this one is original and has some dings but I'd like to know where my rpms are to judge what prop to try.

It jumps on place quickly and seems to be purring fine even sounds like it's close to max rpm.

I was stumped because other than that the tach seems fine.

Just figured I'd ask before I look at a new tach.

 

[Shallowminded]

This website has a prop finder wizard.
https://turningpointpropellers.com/

It might give you an idea if you have a good match with yours. As for the dings, if it is aluminum you can clean it up with a file pretty easily. Just don't be overzealous - and learn from the contours that are still showing on your prop. It helps me squeak an extra season or two from mine. Those oyster bars are murder on a prop.

To double check your tach, you could use an external tach like this one. I have not used it so can't vouch for the product personally.
http://www.ebay.com/itm/like/121656487781?lpid=82&chn=ps&ul_noapp=true