Yamaha 130 V4 Project Build.

[Mr. Demeanor]

It already is. I never get water inside the rear vent after I vented the front but it sure crawls up the back.

[powerabout]

We have a long history of trashed outboards on cats in australia from living on a salt water diet.
Many get used in commercial applications so higher decks
Maybe tunnels are better?

[Mr. Demeanor]

Its alive!

Some interesting things. With the new heads just decked 50 thou and squish left stcok angle I have a little less compression than I had before (must have just a little more CC) but, the 10 psi difference I had side to side is a little less

Just for kicks I did a compression test with the engine running at about 1500 rpm and I got 173-175 psi across all 4 cylinders. It must be either a small difference in the exhaust port relief notches that only shows up a slow cranking speed or some filling issue at slow speed. Either way, I now know my compression is the same side to side when it running.

To the water.....!!!!!!!

[Mr. Demeanor]

So here the results with diverting the water. I still have a LOT of water coming out by the propshaft so I dot think there will be any issues with heat.

To me it sounds snappier with the different heads.

[1FASTLASER]

Snappier....LMAO!!!!!!!!!!!!

[Mr. Demeanor]

Snappier....LMAO!!!!!!!!!!!!

You know how a rick motor sounds "soft". Mine always sounded like that to me. SOund crisp now.

[Dave Strong]

Sounds like time to get it wet and see how it works.

Dave

[Mr. Demeanor]

Ran great all day. Ran across Charlotte Harbor in a some chop and the mid is fine. The amount of water coming out the hose for the poppet is huge. Its like a garden hose.

[Mr. Demeanor]

The new heads are giving me a much cleaner and readable piston wash. I am definitely rich now. This is a before/after of the same piston which was cleaned of all carbon before the new heads went on. If you click on the first pic you can see I circled the area shown with my borescope in the second pic.

Red circle:


Blue circle:


Time to jet it down a little and bolt up the 32

[Mr. Demeanor]

Boat launches MUCH better with the wedges and I also finished my tunnel tabs. Leaves nice and flat and I have the tabs set even with the top of the tunnel right now.

[baja200merk]

I like the setup. Tunnel tabs as far from the prop as you can get is a good idea. Especially for holeshot. Well done, we need to have a little test/tune/party on tarpon it was slick out there today

[Wayne Cammidge]

What is the piston to bore clearance? Looks like a lot
Also what is your piston ring end gap like? That also looks a bit big?

[Mr. Demeanor]

What is the piston to bore clearance? Looks like a lot
Also what is your piston ring end gap like? That also looks a bit big?

If you can see thousands from a pic you got some damn good eyes !
I dont recall off my head, Gordon set all that up.
Motor has 48 hours on it now since build.


Heres a video I made playing with the $20 ebay borescope last night. Love this thing.
Judging from this chart (domed piston side) I think the jetting looks pretty close on that cylinder

[Mr. Demeanor]

Have read a lot of different opinions on what the piston wash should look like on a domed piston. The chart i posted shows it should go almost all away around the piston which is what I have but it seems rich to me.
Not sure why i didnt think of this before but i went over to a local place (Outboard Connection) that rebuilds powerheads and always has a lot of Yamaha stuff laying around. Found a whole box of used domed Yamaha pistons with nice piston wash. This is what it should look like and be nice and safe.
The tip of my thumb fit perfect. From a stock motor.

[Mr. Demeanor]

Looked at some flat top pistons and it was about he size of the tip of my pinky finger.