Yamaha hot up tips

**bullshot** · 03-13-2008

I am setting up a 14'6" tunnel deck mono and am going to build a hot 130 Yamaha. Just wondering if any body has any idea of port heights and head cc,s or any other tips to upgrade the Yamaha,s. I am located in Australia and good bits are hard to find in Oz. Also wondering if anybody knows where to get velocity stacks. Any help would be great.
Bullshot racing

**Rusrog** · 03-13-2008

Originally Posted by bullshot

I am setting up a 14'6" tunnel deck mono and am going to build a hot 130 Yamaha. Just wondering if any body has any idea of port heights and head cc,s or any other tips to upgrade the Yamaha,s. I am located in Australia and good bits are hard to find in Oz. Also wondering if anybody knows where to get velocity stacks. Any help would be great.
Bullshot racing

If you have access to any decent welders or machinists then you need to go ahead and build a horizontal reed V-4. No sense messing with the verticle reed stuff as you are giving away a bunch of power.

If not... Find some 34MM carbs and add some compression. Depending on what you want it to do and how many RPM's you are wanting to turn... You may or may not need to port the motor.

I may have a set of velo stacks that will fit but they will not add much more than some cools looks. But I like cool lookin stuff too so I run them.

Russ

**bullshot** · 03-13-2008

Russ, thanks for the response. As you say looking cool is good thats why I want the stacks. The boat I need to beat is the same hull with a stock 130 Yamaha. It is doing 75Mph running a 26 laser 2. I work at at Yamaha wrecker so parts are not the issue just need specs to work to.

**Rusrog** · 03-14-2008

Originally Posted by bullshot

Russ, thanks for the response. As you say looking cool is good thats why I want the stacks. The boat I need to beat is the same hull with a stock 130 Yamaha. It is doing 75Mph running a 26 laser 2. I work at at Yamaha wrecker so parts are not the issue just need specs to work to.

If he's got a stock motor, just remove the rev limiter, add the bigger carbs and compression and you have him beat. I'm not sure if your Yamaha would ahve come with 32mm carbs or smaller. If it has smaller carbs then I would go with 32's. They are easy to get a hold of. I think I have a couple of them in my stash of parts. Also you can modify the emulsion tubes on the carbs by shortening them and the bottom end will really wake up.

I don't know what your boat looks like or what it weigh's but if ya'll have the same boat, same motor then you should run right by him with carbs heads & the rev limiter removed.

What kind of gas are you running? 93 octane? 87?

Russ

**bullshot** · 03-15-2008

This is the boat I am setting up. Not sure about the weight but it can be picked up by two people.

**Rusrog** · 03-15-2008

Originally Posted by bullshot

This is the boat I am setting up. Not sure about the weight but it can be picked up by two people.

COOL RIG! I like the looks of it.

RUss

**bullshot** · 03-15-2008

I will be running 100 octane pumped fuel. I also used to run a mix of methyl bezine but I guess it depends on how far I can bump the compression.Hydro tech Marine in the U.S make hp cylinder heads but I,m not sure what comps they give. Maybe I,ll just machine some myself but would love to know what cc to achieve. I may run a EGT probe and just experiment with that and jetting. I would really like some info to work with but nobody seems to have played with these engines very much. I may just have to play around and see what works. lucky I work at a Yamaha wecker

**bullshot** · 04-17-2008

Still looking for port heights and any further tips

**bullshot** · 10-12-2008

Finally got the boat running. New paint job. Rebuilt Yamaha 130 running 140 heads, 140 exhaust plate and a mild port job. First time in the water 73MPH running a 26 laser II @ 6000 RPM. Also tried a 26 Yamaha drag but only 71MPH @ 6500. More engine height and set up to come.