Yamaha 130 V4 Project Build.

[Mr. Demeanor]

I odered a set of Bobs transom wedges. They will give me the 1.5" setback I need at the top, more negative trim for holeshot, and should be lighte than the jackplate. The extra wedge will also open up some space giving me a little more adjustment room between the top of the transom and the tilt tube and more steering clearance when trimmed up. Should work out very well.
Marty will have my mid tomorrow. I would like him to weld in a set of struts in an "X" running from the bottom motor mounts up and across to the opposite side. Theres enough room for them between the tuner and water tube so I sent the tuner/adapter plate with as well. I think that would significantly increase the side to side strength.

[Mr. Demeanor]

Talked to Marty and he has a bunch of work in front of mine so it will be next week before he can even really look at it. First he is going to V out the crack, drill the ends, and see how it welds. If it doesnt blow apart we will go from there. I have a couple other little things I can work on since it going to be down awhile.

[Dave Strong]

Jusr let the man do his thing, paint it, put it back together and run it.

Dave

[Mr. Demeanor]

Wanted to add some info for prosperity.
And I know I wont be able to find it when I need it so Ill put it here. Im cleaning my desk and just came across my notes.

Powerhead = 128.5 pounds fully dressed with as much extra weight stripped off as I can find with lightened flywheel.
Bracket/short mid/trim/tuner/adapter/etc = 98.5 pounds
Inshore Lower Unit = 43 pounds with short drive shaft
Upper cowl = 18 pounds lightened
Lower cowl = 13 pounds lightened.

[albypine]

Hmmmmm what's a 12 inch 300 drag with a speedy weigh someone in the north land needs to build a fast little tunnel maybe after my 22 is done

[Mr. Demeanor]

Already in the works. Theres a 12" 300 Drag going on a Biel. I have offered to help set it up since it will be very similar to mine in weight/balance. Transom will have to get cut down for sure.

[Mr. Demeanor]

What am I missing?

Since the powerheads off i decided to go though and check things out. Pulled the heads and all look good. since i had the heads off I decided to try and figure out exactly where my 10psi difference in compression is from port to starboard.
As stated many pages ago, I have 145psi on one side and 155psi on the other. The previous owner of the block found the same when it was stock.
Today I made up a little bridge to measure directly over the center of the piston. I moved the bridge side to side several times and came up with a .002 difference.
Hard to measure the exhaust port height but best I can tell there dead on side to side.

Cleaned up pistons tops for a good read. Chemi Dip did the trick.

[Motv18]

My v4 is the same some yammy thing. Guy that built mine in 86 just took a extra cc off that side. Even today yammys doing it some 20-30 psi less on two cylinders why no clue.

[baja200merk]

That tiny battery you have was a bit tired when you swapped the gauge to the other bank.

It takes quite a bit of port height to notice a compression difference on your gauge. If anyone else ported it I would suspect that

I will give you 2 gauges make sure you use the correct gauge on the correct bank

[200valeroyt]

I realize your pistons have a slight dome, but is the left hole a bit rich? Just curious.

[Mr. Demeanor]

Gordon didnt touch the port height other than bevel the edges after it was bored. We were both concerned about losing bottom end with the big props I have to use.

On the stock heads, theres a difference between the top and bottom cylinder squish band of about 20 thou. so you end up with different compression to to bottom but this block also has different port to starboard.

I have another set of stock 6E5 heads. Going to cut them to Hydrotechs race head specs which is 50 thousands off and not recutting the squish and see how she runs. I could always use a little better bottom end.

Talked to Marty and my mids almost done.

[Mr. Demeanor]

I realize your pistons have a slight dome, but is the left hole a bit rich? Just curious.

Maybe a little. I went up a size before the St. Johns run to see how it looked. The domed pistons get more wash than your flatties. Im also a little leaner on the starboad side which has 10 psi less compression. Must be the crank spin but its a pretty significant difference.
One thing I read from several sources is that a loose squish will have dirty piston tops and make reading wash difficult which is what I have been up against. The angle Gordon used reduces the chances of detonation but Im ready to lean on it a bit more so Im going to try the stock angle. If it pops he can say I told you so

This is the starboard side.

[Mr. Demeanor]

Getting back to compression. I love a good mystery and just trying to figure out where the difference is coming from. I have swapped heads side to side of course with no change so its not in the head.

So how do I figure out how much to take off one head to bring it up to the same as the other?

Three posts in row....Im pulling a Parker....

[powerabout]

Getting back to compression. I love a good mystery and just trying to figure out where the difference is coming from. I have swapped heads side to side of course with no change so its not in the head.

So how do I figure out how much to take off one head to bring it up to the same as the other?

Three posts in row....Im pulling a Parker....

you could do the old
put some modelers clay in there and squeeze it on both banks then measure the thickness...

[Mr. Demeanor]

I may throw a piece of plastic gauge in there but I really dont think its in the deck height. Its big enough I would be able to see it at TDC and measure it with my little bridge.

Heres a pic that will drive Dago crazy. My redneck deck height bridge. I did lap the back side of it on a mirror with 400 grit like you would lap a reed cage to make sure it was perfectly flat and got the same measurements 3 times moving it side to side.

The center hole is in the center of the piston. Angle of pic makes it look off.