Yamato pipes question

[ZUL8TR]

Your rig

Congrads That is a nice build. I agree with Steve no metal removing from the 302 keep it stock.

Suprized you are running with prop shaft at bottom and no cooling issues? Maybe cause the ignition is set low?

What have you done with the ignition timing? The 302 is 0.200 to 0.250" BTDC and there is a lot of room there playing around. Here is a link that will provide good info how to do. Check out the tech tips.

http://www.yamatoracing.net/

Also there are spark plug inserts that fit the 18mm head to convert to 14mm. The link discusses them and 14mm NGK sparkies available.

Note bottom finsh that is glass smooth is not as fast as a sanded bottom although there is debate over this but Bob Wartinger record holder uses sanded. I have always used flat black paint and wet sanded with 400 fore - aft for a satin finish on the last 36" of bottom and same on about 18" of the sponson bottoms. The flat black is easy to spray and refinish as needed and looks stealthy.

About the Tiny Tach others with the 302 CDI ignition will have to chime in. I have a 1973 Merc 25ss engine with CDI ignition that works fine with the Tiny Tach model 1C that they no longer offer that model. Thay now only offer a single model that you set for the engine configuration, so I do not know how that one works on the CDI systems.

[fcliff]

Tiny Tack now sells what they call there "O" model. It will work just fine on the 302 however you need to make sure you tell them you are using it on the yamato outboard or you will get the standard tach that does not work on the 302. They tell me the new model was developed for there main customer which is Briggs and Stratton. They are very good people to work with and they will make sure you get what you need if you talk to them.

[Little Fork Runner]

Congrads That is a nice build. I agree with Steve no metal removing from the 302 keep it stock.

Suprized you are running with prop shaft at bottom and no cooling issues? Maybe cause the ignition is set low?

What have you done with the ignition timing? The 302 is 0.200 to 0.250" BTDC and there is a lot of room there playing around. Here is a link that will provide good info how to do. Check out the tech tips.

http://www.yamatoracing.net/

Also there are spark plug inserts that fit the 18mm head to convert to 14mm. The link discusses them and 14mm NGK sparkies available.

Note bottom finsh that is glass smooth is not as fast as a sanded bottom although there is debate over this but Bob Wartinger record holder uses sanded. I have always used flat black paint and wet sanded with 400 fore - aft for a satin finish on the last 36" of bottom and same on about 18" of the sponson bottoms. The flat black is easy to spray and refinish as needed and looks stealthy.

About the Tiny Tach others with the 302 CDI ignition will have to chime in. I have a 1973 Merc 25ss engine with CDI ignition that works fine with the Tiny Tach model 1C that they no longer offer that model. Thay now only offer a single model that you set for the engine configuration, so I do not know how that one works on the CDI systems.

yea i didn't really know that much about the 302 much at the begging of the year so i just kept shimming the motor up. i will have to look into the timming. however i bought the motor is whatever it is set at. the thing is, i never run my boat wide open like in a race, since i only run on lakes. the trick to my kind of riding is to go out right before sunset when the wind dies out, and most of the boats are already in. my average speed is only around 40 mph because of the slow no wakes, and waves i have to deal with. that is why i don't think my motor gets beat on as much, and stays a little cooler.

Also i have heard about keeping the bottem finish of the boat rough because it helps break that suction with the water. i didn't know if it was true or not??? I have heard it go both ways, so i am going to have to try them both!!!
Thanks

[Little Fork Runner]

Tiny Tack now sells what they call there "O" model. It will work just fine on the 302 however you need to make sure you tell them you are using it on the yamato outboard or you will get the standard tach that does not work on the 302. They tell me the new model was developed for there main customer which is Briggs and Stratton. They are very good people to work with and they will make sure you get what you need if you talk to them.

Thanks for the info on Tiny Tack. I am just going to give them a call like you said so I know that I am getting the right one. I really wish i could have figured out a way to hook up my Super Tach 3, 5 in drag racing tach buttttttt it wasn't going to work/ be worth it!!!
Thanks

[nelson yela]

Yamato 302 in Ecuador

Official website:

http://www.ecuadorboatracing.com

http://www.facebook.com/ecuadorboatracing (LIKE)

[Little Fork Runner]

Exhauast/Jetting

Will i have to re jet my carb if i put a pipe on, or will i just be able to tune the carb to run right with the new exhaust???

[nelson yela]

This model of exhaust, Yamato 302 motor increases speed of 3 miles.

Official website:


http://http://www.ecuadorboatracing.com

"like" Facebook.
http://www.facebook.com/ecuadorboatracing

[ZUL8TR]

Ecuador Pipes

This model of exhaust, Yamato 302 motor increases speed of 3 miles.

Official website:


http://http://www.ecuadorboatracing.com

"like" Facebook.
http://www.facebook.com/ecuadorboatracing

What top speed are you getting ?

[nelson yela]

This model of exhaust, Yamato 302 motor increases speed of 3 miles.

Official website:

http://www.ecuadorboatracing.com
"LIKE" Facebook.
http://www.facebook.com/ecuadorboatracing

[jeff55v]

What top speed are you getting ?

I can answer that. The fast guys are seeing a solid 70 mph on GPS. This is on a runabout.

[nelson yela]

Hi Jeff, Maximum speed 70.6 mph GPS.

"like" Facebook.
http://www.facebook.com/ecuadorboatracing

[ZUL8TR]

pipes

I can answer that. The fast guys are seeing a solid 70 mph on GPS. This is on a runabout.

What amount of additional hp and torque do the pipes yield?

[jeff55v]

What amount of additional hp and torque do the pipes yield?

That is a good question. The megaphone pipes do yield an additional 3mph vs the stock closed up Yamato exhaust. But I do not have any dyno data to support this. Nor have I compared the megaphone exhaust to the expansion chamber exhaust.
I can say the megaphone pipes are quite loud. So consider this if you plan to play around at the lake. Also, megaphone type exhaust pipes are not legal for racing in all sanctioning bodies.

[Ecuador Boat Racing]

Aluminum material to build the engine exhaust Yamato 302.

[ZUL8TR]

megaphone pipes

That is a good question. The megaphone pipes do yield an additional 3mph vs the stock closed up Yamato exhaust. But I do not have any dyno data to support this. Nor have I compared the megaphone exhaust to the expansion chamber exhaust.
I can say the megaphone pipes are quite loud. So consider this if you plan to play around at the lake. Also, megaphone type exhaust pipes are not legal for racing in all sanctioning bodies.

Here may be away to answer it.

Stock 302 with stock 14:15 gears

best speed (not kilo record run) = ?
rpm = ?
prop pitch x diameter = ?



Maybe Yala can get these answers?

Mod 302 with megaphones and 14:15 gears

best speed = 70.5 gps as stated by Yela
rpm = ?
prop pitch x diameter = ?