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Thread: Help with new yamato 331

  1. #1
    Team Member Chad Morgan's Avatar
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    Default Help with new yamato 331

    I have just got my hands on my first yamato engine from the importer. It came in the yamato box with new prop, manual, pull rope and a few spares and it says its a 331

    I put choke on and turned the timing handle towards exhaust side and screwed idle in a bit and it started straight up. Gave it a few seconds then turned it off. Its temporarily just clamped to my minimmaxed as I dont have a race boat yet but have some plans here from Don Nyberg.

    Is there an easy way to put a water hose onto the motor so i can run it longer. Prop is not installed. I dont know anything at all about these yamato motors but used to race 2 stroke bikes 20 years ago at the local motorcross track so have a little understanding of 2 strokes in general.

    Any tips or ideas about how to wet this motor ? The pickup area looks a bit tricky to get a garden hose to stick there while its running.

    Thanks
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    Team Member DeanFHobart's Avatar
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    Quote Originally Posted by Chad Morgan View Post
    I have just got my hands on my first yamato engine from the importer. It came in the yamato box with new prop, manual, pull rope and a few spares and it says its a 331

    I put choke on and turned the timing handle towards exhaust side and screwed idle in a bit and it started straight up. Gave it a few seconds then turned it off. Its temporarily just clamped to my minimmaxed as I dont have a race boat yet but have some plans here from Don Nyberg.

    Is there an easy way to put a water hose onto the motor so i can run it longer. Prop is not installed. I dont know anything at all about these yamato motors but used to race 2 stroke bikes 20 years ago at the local motorcross track so have a little understanding of 2 strokes in general.

    Any tips or ideas about how to wet this motor ? The pickup area looks a bit tricky to get a garden hose to stick there while its running.

    Thanks
    First and foremost do not run that motor on a MiniMaxed… the boat is way to small for a 30HP motor and it is too heavy.

    Yes there is a way to run the motor out of the water… call the owner of this site…Ron Hill…714-608-7147… he can tell you how to do it.
    Dean Hobart

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    Team Member Chad Morgan's Avatar
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    I am from Australia and have zero experience with race motors or boats. I built the minimaxxed and put a 15 merc fishing motor on it and with a solas prop it does 50 km hr along side a jet ski. That felt pretty fast in that boat but it feels a bit dangerous and really gotta watch the water for waves or it chops them off and straight into your face haha. I wont run this motor on the minimaxxed. I just want to start it up and listen to it and daydream a bit untill i build my first race boat.

    The class here is osy400 and uses stock yamato and stock prop.
    I just felt like building a second boat after the minimaxxed was fun to make and drive.
    Took a long time for this yamato to arrive but its here at last and looking forward to learning all about them. Fastest boat ive had is the minimaxxed so im a total noob haha. All help appreciated. I cant call overseas on my phone plan unfortunately.

    Tried uploading a picture but its saying the post has to be approved

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    Team Member Chad Morgan's Avatar
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    There is 2 hose barbs coming out of exhaust cover on side of engine. One faces forwards and has a hose on it and the other faces down and has no hose on it. Does the same amount of water come out those ? Without pulling cover off I cant see how its supposed to flow. Tried sticky taping a garden hose to water inlet near prop but it failed to stay there when i turned hose on. Do these have a thermostat like a fishing motor?

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    Team Member Chad Morgan's Avatar
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    Figured it out and got it running with water. The cone end off a silastic gun refill tube was the right size to screw over a 1/2 inch garden hose and chopped a bit off small end and worked great with a bit of duct tape

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    Team Member DeanFHobart's Avatar
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    Quote Originally Posted by Chad Morgan View Post
    Figured it out and got it running with water. The cone end off a silastic gun refill tube was the right size to screw over a 1/2 inch garden hose and chopped a bit off small end and worked great with a bit of duct tape

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    Good old duct tape fixes everything….. don’t rev it too high as there is no load on it.
    Dean Hobart

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    [QUOTE=DeanFHobart;158824]First and foremost do not run that motor on a MiniMaxed… the boat is way to small for a 30HP motor and it is too heavy.


    +1.........Don't even think about running that engine on that boat in the water !!! If you're just putting it on that boat as a motor stand.......than fine. That motor is capable of 70 mph + on a compatible hydro. I'm sure you'll have a lot of fun with it, but make sure you have the proper safety gear for yourself. If you don't plan on racing it, at least get a good helmet and a suitable life jacket. Also, it would be good idea to have someone present that can retrieve you if you get into trouble out on the water.........seriously!!!
    Yamato engines are about as good as it gets for the price.

    Stay safe and have a great time !!!

    Here's a great video of riding in a proper hydro with basically the same engine:
    https://www.youtube.com/watch?v=M6FqIpSVShg

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    Team Member Chad Morgan's Avatar
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    All good advice so far, I donít plan on running the yamato on the little minimaxxed. Its purely a motor stand. It doesnt corner very well with the 15 merc on it but is is a fun little fishing boat.

    Iíve got 3 sets of boat plans here. Ones called the whippet from Don Nyberg, and his jack rabbit. Also got a set of desilva plans from the 90ís for his comet tunnel boat but those ones are a bit vague for a rookie builder like me. Im thinking to build the whippet with 4mm ply and carbon fibre. Iím only 50kg so might need a bit of tweaking to stop me flying away lol.

    Iím hungry for any info

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    Team Member zul8tr's Avatar
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    Quote Originally Posted by Chad Morgan View Post
    All good advice so far, I don’t plan on running the yamato on the little minimaxxed. Its purely a motor stand. It doesnt corner very well with the 15 merc on it but is is a fun little fishing boat.

    I’ve got 3 sets of boat plans here. Ones called the whippet from Don Nyberg, and his jack rabbit. Also got a set of desilva plans from the 90’s for his comet tunnel boat but those ones are a bit vague for a rookie builder like me. Im thinking to build the whippet with 4mm ply and carbon fibre. I’m only 50kg so might need a bit of tweaking to stop me flying away lol.

    I’m hungry for any info
    Whippet II is a good choice for the 321

    https://nybergdj.wixsite.com/nycraft

    If you build do not use fir ply to heavy and will grain check a lot unless fiber glassed then way to heavy, use Okume ply and thickness per plans. If carbon fibre out of your budget(?) replace with Okume on: 6mm on bottom, side non trip chines and all of sponsons, main girders, gussets, and 3mm on deck. Do not know what fasteners Nyberg uses in his designs and what brand epoxy let us know.

    Post build pics
    Great project
    " Three may keep a secret if two of them are dead" Ben Franklin

    Location: SW Orlando, Fl

  10. #10
    Team Member Chad Morgan's Avatar
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    The plans for the whippet offer a couple of different ways to do the cockpit sides. Okume is specified for the ply due to weight. A recent discussion with Don reveals a new idea for the bottom that he is having luck with which I may use those ideas. I will be using our Australian Bote cote epoxy system as It was great to work with in my last build.

    Don questioned me about me mentioning the standard 2 blade prop and said that wouldnt be competitive where he is so I may have to re check those rules for over here. I thought I read the yamato has to be bog stock but cupping stock prop is allowed. I will double check the rules.

    I cant help but wonder about the use of Paulownia timbers and if anyone is using it for boats? Maybe its not suitable but It sure is light weight.

    My nearest boat club is hundreds of km away so talking with others about racing/building is a bit hard.

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