I should also add that I've checked the butterfly's they open all the way at full throttle. Basically from 3/4 to full throttle nothing changes rpm limits at 4k, no bogging or fouled plugs. I would think if the motor won't Rev past 4k and I add more throttle it would bog down, I just don't hear that in the motor. I've also tried a different prop 14 1/4 X 17 with the only change being that it has lost some top rpm by a couple hundred.

my thought on a rig with unknown history?
check the tach.
find beg borrow or steal test wheel YB1626.
a 2 min run up will tell you if its an engine or a Hull/rigging issue.
beats chasing ghosties and talking to peter cottontail.
with that test wheel it should turn 5350-5500.
if it will, chase hull/rigging issues.
if it wont, fix the engine until it will.

Thanks rodbolt I'll try and locate one.

What's the diameter and pitch on a YB1626 test wheel?

can you not read .

remove the prop.

install test wheel.
back it down.
fire it up.
it will spin at the Yamaha engieers speed or it wont.
then its enigine or hull/rigging.

a real shop will have that test wheel.

other than that, your on your own.
but that's why Yamaha made the test wheels.

It is not a normal prop, it is just for testing motors in a tank or on trailer in water at ramp with boat not moving

Rodbolt 17, I appreciate you helping me out. I can read so lose the attitude. I'm new to the boating world although I was previously a motorcycle/ jet ski mechanic. Its a 1986 Grady White, I didn't buy it from a dealer. Short of someone being a first rate customer it was highly unlikely that I'd lend them much of any test tools.

I get the whole idea of putting a test prop on the boat and doing a load test. I also know that after you've been in the business long enough that certain things tend to lend to a common problem with certain models. That's the kind of thought pattern I was looking for. After working on power sport products for over 13 years I was hoping that someone would have the depth of knowledge to enlighten me to common problems that would possibly pop up with a unit of this age with about 600 hours on it. There are numerous items that I get and understand that may need attention. I just thought I'd get a non smart ass response from someone who could help.

How bout instead of a smart Alex response, you simply state that the test prop has no know diameter or pitch and is used to load test the engine as per the manufacturer specs. I don't have that special relationship with a local dealer to find this test prop and to be honest, most mechanics now a days are nothing more than parts changers. So I don't rely a while lot on there technical ability. In fact when I did used to call in to Yamaha they had a degree of decorum that you have lost. As I've looked upon your other posts I see the same tune, you talk to people like a ****, if you can't tolerate a newbie question then dont sign in to the forum!

Thanks 99yam40, that's the kinda reply I was looking for. I guess it's difficult for some people to respond like not everyone knows what they are talking about. Thank you for dumbing it down for me! Lol

its test wheel.
Yamaha and OMC used them for years.
its designed to produce a known load and a known RPM for a given engine.
the YB1626 fits most V6 Yamaha engines and the RPM it should turn is listed in the tune up spec guide.

on an unknown rig you have no idea was it ever propped correctly.
is it water logged.
is there an actual engine issue.
about the only common issue is the fuel system clogging or lift pumps failing.
other than that every engine is different and the prop is the governor.

on your engine Yamaha states it should turn YB1626 to 5350-5500.
if it will you have hull/prop/rigging issues.
if it wont you have engine issues.
that 220 was a rather unique engine and a crude attempt at ECU con*****ed ign system.
worked well but had some quirks.
not many techs have actually seen one.

I'd love to get my hands on a YB1626 wheel. I've been looking for years. I've got 5 200-225s that could use a run on one to set the timing.

Any place rent them? Does Yamaha even make them any longer?

Yamaha never made them.
kent moore the K and L tool made them FOR Yamaha.