Piston wash pics.

[Mr. Demeanor]

Just took these pics with my $15 ebay scope plugged into my laptop.

1/3 (starboard side) are definitely leaner than 2/4 (port side)

Took two pics in each cylinder.

#1.
292720 292721

#2
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[Mr. Demeanor]

#3
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#4
292726292727

[Mr. Demeanor]

Im thinking #2 is the only one that looks like its getting enough fuel.
#4 needs to come up a jet size and 1/3 need to come up at least a couple jets.

[Mr. Demeanor]

Stock jets were 1.80mm / .70" and I am now at a 2.80mm / .110" ....and still lean....:reddevil:

[tres]

nice...

[rev.ronnie]

In the automotive world, many times, when looking at the chamber, the bare spots are an indicator of the lack of fuel. Often it's a chamber inefficiency that has poor distribution. The bare spots have no carbon because there is no fuel to leave a deposit.

Just food for thought.

[Mr. Demeanor]

In the automotive world, many times, when looking at the chamber, the bare spots are an indicator of the lack of fuel. Often it's a chamber inefficiency that has poor distribution. The bare spots have no carbon because there is no fuel to leave a deposit.

Just food for thought.

The cylinders with the most wash also had the darkest colored spark plugs which supports piston wash.

This is what I am going by. Page 21 addresses piston wash.
http://www.slideshare.net/J.T.A.JONES/carburetor-theory

This is where I was at before the carb mods. Maybe a little rich but I need to get back there.

[ChrisCarsonMarine]

Chris,have you drilled the inlet needle seats in the carb bodys oversize?Long ago when we were working the big crossflows hard they would reach a point where they would run lean no matter how big a main you used... The inlet needle/seat was the main jet at wot.A two barrel carb with one inlet can be restrictive,and might be why your mixture is inconsistent,just an idea from the past,Chris

[bigbluechevy454]

thats great i was gona do some adjusting on ecu this weekend and read the piston tops

[Mr. Demeanor]

Chris,have you drilled the inlet needle seats in the carb bodys oversize?Long ago when we were working the big crossflows hard they would reach a point where they would run lean no matter how big a main you used... The inlet needle/seat was the main jet at wot.A two barrel carb with one inlet can be restrictive,and might be why your mixture is inconsistent,just an idea from the past,Chris

These are the dual float 6L100 carbs so I have a needle/seat for each cylinder unlike the newer Yamaha carbs. Its something worth looking into I guess.

[Dave Strong]

Im thinking #2 is the only one that looks like its getting enough fuel.
#4 needs to come up a jet size and 1/3 need to come up at least a couple jets.

Good place to start, with all the carb mods you have you may need to drill 1/2 sizes to get them all the same.

Dave

[rev.ronnie]

The cylinders with the most wash also had the darkest colored spark plugs which supports piston wash.

This is what I am going by. Page 21 addresses piston wash.
http://www.slideshare.net/J.T.A.JONES/carburetor-theory

This is where I was at before the carb mods. Maybe a little rich but I need to get back there.

I'm on board with that. Piston face in conjunction with plug reading is pretty conclusive.

4 strokes and 2 are definitely different animals.

[baja200merk]

Gordon said jet it so its just barley stops four stroking and it will have a long life.

[Lockjaw]

The cylinders with the most wash also had the darkest colored spark plugs which supports piston wash.

This is what I am going by. Page 21 addresses piston wash.
http://www.slideshare.net/J.T.A.JONES/carburetor-theory

This is where I was at before the carb mods. Maybe a little rich but I need to get back there.

I would have looked at that and thought the opposite. Lean means nothing on the piston, rich means to much on it.

[Mr. Demeanor]

Only took me two months to drill the new jets....

Now if it will stop raining I can see how it goes.

[dagodiver]

Lake was perfect this morning. Tried a few diffrent props.
Still like the big cleaver. Still chasing my fuel issue.
Karl is running alva tomorrow. Windy but no rain.

Dago

[eli]

would you like some snow and ice we have plenty ,I wish it would rain.

[Mr. Demeanor]

would you like some snow and ice we have plenty ,I wish it would rain.

I wish I could go snowmobiling. I really miss that and used to spend some time in your areas.

[Tom Foley]

I would have looked at that and thought the opposite. Lean means nothing on the piston, rich means to much on it.

This is what I am thinking also . Looks fine run it wide open .

[Motv18]

It would be in a car your shooting for 20:1 ish crushing. Outboards though are 12:1 ish as constant power is needed to maintain speed on water. Always want it trying to gain.

You mixing or running the oil system. Wondering if you have oil ash. My 130 will darken up with lame oil.

[baja200merk]

I know on the OMC I was told by a few jetting gurus that you want about a 3/8-1/2" spot on the piston that is washed clean from the transfer. Thats about what all the factory engines I tear down look like. We accidentally set one up real lean luckily it was a 200 with 85psi it ran happily till it was sold and there was no clean spot on the piston :eek:

[Mr. Demeanor]

Domed pistons get more wash (mine are domed) because the fuel actually hits the piston at an angle instead of just blowing across the top. They say a domed pistons should have a pretty good wash all the way around like this:

296465

[6Killer]

Time over speed will always give you the perfect jet.................

[Mr. Demeanor]

Time over speed will always give you the perfect jet.................

Time, something I dont have enough of....

[1BadAction]

Lean it out till it sticks, rebuild, go 2 jet sizes higher. Boom, perfect jetting. :D

[Mr. Demeanor]

Lean it out till it sticks, rebuild, go 2 jet sizes higher. Boom, perfect jetting. :D

I was probably close when I took the airbox off and did my carb mods. I had to go way up after doing this. basically made the carbs smooth bores. I still need to run it with and without the stacks.

[Mr. Demeanor]

Well I am slowly learning. I jetted up on one side and there is no change to the washed area. I am thinking that its not washing off the old carbon. Maybe this works well for jetting down when your going from a large wash to a smaller one but not going up???
I am definitely VERY rich. Pulled the plugs after a weekend at the ranch and the plugs are black. Cut one plug and the entire ceramic is black.
I may pull the heads, clean off the carbon, and start fresh.
Crappy pic. Phone doesn't do macro shots well but you get the idea. Ceramic is black top to bottom.

296898

Piston tops are black but wash area is unchanged. I am seeing a thinning of the carbon right at the center so maybe its being washed off there. Regardless, its rich.
296899

[baja200merk]

Yea I wouldnt expect it to clean the carbon off again. Maybe now is a good time to test some decarb products and see what one cleans the best :D

Beefs is a 4 stroking mess now just havent messed with it he keeps using it. The top cyls are 2 sizes leaner then the bottom 2 and still very safe. Im told its due to the chest on the v6 maybe you have something similar going on.

[Mr. Demeanor]

Ive got 40 hours on her now and I was thinking of pulling a head to take a look at things anyway. Ran great over the weekend. One little electrical issue (fuse holder).

[CharlieN]

I was probably close when I took the airbox off and did my carb mods. I had to go way up after doing this. basically made the carbs smooth bores. I still need to run it with and without the stacks.

One thing I want to touch on with the direction of your carb mods and what you are seeing in your jetting.
As you are smoothing the bores in the carbs, this is reducing the signal, call it the vacuum at the jet. You are reacting to this by increasing the jet size.
The increase in jet size is making up for a weak pull of fuel through the jet, were this jet size being productive you would be seeing an increase of power output which we are not hearing about in your recent reports.
I commented last fall about the taper in your carbs starting well after the jet and increasing to the throttle plate, this taper should start up at the jet itself to provide a stronger pull of fuel. With a stronger pull at the jet you will find you will need a smaller jet for the amount of fuel needed.
As you filled in the bores before the jets you again needed to drill the jets larger without the engine getting richer or a substantial power gain relative to jet size.
I wish I had the time right now to modify a pair of carbs for you to evaluate that would both flow well but will be more responsive to jet sizing. Maybe once I have a few customers car on the track I can take the time to do so.
Have you given thought to installing a wide band and or a fuel flow meter for evaluation?

[Mr. Demeanor]

Charlie, I picked up 1.5mph on the top end with the carb mods. I do have access to a flow bench and have a baseline I just havent tested them after the mods.

[CharlieN]

I need to go back and review your posts a bit better as to what each step provided. 1.5mph at the speed you are running is nothing to sneeze at for sure.
Maybe this is just bringing me back some decades when I was doing allot of carb mods which part of was working on response to jetting and how it related to accuracy of mixture through the powerband.
With road racing we place more emphasis on power under the curve than where you came up on a strip so I expect where my mind is at just may not be relevant here since your goals are just with full wide open performance.
I am close to coming down to do some work in Naples and if this happens I would sure love to let my ears hear a full pass of your boat.