Yamaha 130 V4 Project Build.

[Mr. Demeanor]

I have noticed that my first long wide open pass is always my fastest. Made me think it was a little lean maybe but jetting up doesnt change it. The engine can be completely warmed up but my first wide open run is always the best. Its like once I get a real deep heat soak into the motor is loses a little something even if I let it sit awhile. Maybe just coincidence.

I also noticed my flywheel gets really hot. I guess I never put my hand on it after running hard but it was really hot. Engine temps are right about 150. Its got a lot of holes in it thanks to Dago (Mike) that you would think would cool it.

[CharlieN]

Sweet

[1FASTLASER]

Mr D I got some gonads but just don't think they big enough to run 95 in a 13' bote. Lol this has been and continues to be one if the most epic builds I have ever watched. You have done a SUPREME job. You steadily creeping up on triple digits. Be careful buddy

[milkdud]

I have noticed that my first long wide open pass is always my fastest.

I don't know why this is but I usually had the same results when I did my speed runs with my boat as well.

I wondered as the carbs warmed up my L6 lost a tiny bit of power. My 1500 really wakes up on cold mornings and the first run.

Conrad

[Mr. Demeanor]

I think I finally have a good number for the results of this build at a 7mph gain. Thats with the exact same prop and setup and very similar weather conditions on the same lake. That works out to about a 25-30hp increase.

If you have ever used the Crouch Calculator, its always been very accurate for us. If you know your HP, speed, weight, you can figure out your hull factor (efficiency). Then using that hull factor, you can change the HP figure to calculate your projected HP. The Yamaha 130 is supposed to make closer to 140hp in stock form.
Playing with the figures it puts me at about 165 - 170hp and I have a very good increase in power across the entire powerband.

http://continuouswave.com/cgi-bin/crouchcalc.pl

Time to break out more pitch and cold air.

[71V153]

Time to break out more pitch and cold air.

Well it looks like yer gonna get your wish cold air wise at least. Been outside lately? 65 brrr!

[baja200merk]

Time to break out more pitch and cold air.

u can run mine at suwannee as long as u dont wake me up before 10

oh and gopro the 97.1 mph pass

[Mr. Demeanor]

Ran 91.3 at the Suwanee with my 30 ET. After the run I found my airbox had come loose and was laying sideways in front of the carbs. The screws has come loose before so I hit them with blue locktite and they still came loose. Luckily I found 4 screws. I gutted the airbox and its flexing allowing the screws to loosen. Ill try some red.

Since the airbox ws off, I did a little test and ran without it (jetted up one size) and it really leaned it out. Not much piston wash at all.
I still dont understand why a motor is not stronger without the airbox if removing it allows more airflow and you add the correct amount of fuel. I do understand the scavenging effect of the airbox but its not that much or the fuel would pouring out the lower cowl. I just get a little dribble under the carbs. My airbox has no integral velocity stacks or anything.
My airbox is pretty gutted so Im really surprised at how much it leaned it removing it. It wasnt even much louder.

Interesting I am also getting more wash at the finger ports than at the transfer ports.

[Mr. Demeanor]

I also pulled my reeds to inspect them since I just ran nearly 200 miles on the Suwanee river pretty hard. I was going through Boysens every time I held them wide open more than a few seconds. I have about 15 hours on these Chris Carsons reeds now on the same ported cages and they look like new.

Huge thumbs up to Chris

Attachment 287821

[CharlieN]

If the engine leans down that much without the airbox I would sure want to try jetting it up and see what the numbers show. Obviously the flywheel has the air moving about so I would want to check each cylinder.

[Mr. Demeanor]

It was pretty much spot on with the airbox on. Always trying for more though...

Need to get back to this:

[syclone01]

I think I finally have a good number for the results of this build at a 7mph gain. Thats with the exact same prop and setup and very similar weather conditions on the same lake. That works out to about a 25-30hp increase.

If you have ever used the Crouch Calculator, its always been very accurate for us. If you know your HP, speed, weight, you can figure out your hull factor (efficiency). Then using that hull factor, you can change the HP figure to calculate your projected HP. The Yamaha 130 is supposed to make closer to 140hp in stock form.
Playing with the figures it puts me at about 165 - 170hp and I have a very good increase in power across the entire powerband.

http://continuouswave.com/cgi-bin/crouchcalc.pl

Time to break out more pitch and cold air.

Chris, what's your "hull factor" number and weight? I assume you are using total weight with you in the boat? We are figuring Sean's 150 motor is prob about 170ish hp and he's just cracking 90mph, I'm pretty sure he will get a little more speed once he actually tries another prop.

[baja200merk]

Remember the transfers come in at a pretty sharp angle.

Beefs is still 4 stroking the whole time, once the 1.62 sporty goes under it we will lean on it a bit.

[Mr. Demeanor]

Chris, what's your "hull factor" number and weight? I assume you are using total weight with you in the boat? We are figuring Sean's 150 motor is prob about 170ish hp and he's just cracking 90mph, I'm pretty sure he will get a little more speed once he actually tries another prop.

I think we worked backwards with known numbers to get the hull factor. I want to say we went with 1000 pounds for the boat then used 140hp for the stock HP that got me to 85mph. That gave me the hull factor then we worked back to get the HP needed to go 91.5mph.

Cold air has moved in and its time to drill some bigger jets. I am still amazed at how much air this motor is moving with such conservative port work. Both Neudecker and Kottman said I would be at around a 1.95mm main jet and I'm at a 2.48mm.

I have another intake I am going to play with. I plan to pack the outside with epoxy and then make an almost straight bore from the carbs to the reed blocks. You end up breaking through the aluminum intake runners into the epoxy you put in the outside. We used to do this on the dragbikes to straighten the intake runners.

[Capt.Insane-o]

Your at the point now where some calls should be made to Brucato.