Yamaha 989 Billet Cylinder

[Brooks]

Here are some pics of our new 989 Billet Cylinder in progress:

[Brooks]

More:

[Brooks]

Here she is!

[Brooks]

Closeup of the exhaust port:

[Brooks]

Transfer ports:

[holeshot]

Is that with the stock crank or stroker to get 989?

[Brooks]

This cylinder will not work with the stock stroke crankshaft. It is setup to be used with a +5mm with stock rods or a +8mm with +8mm rods. With the +8mm setup you will use a spacer plate on the bottom of the cylinder.

Here is the easy way to figure displacement:
Bore x Bore x Stroke x .7854 x # of cylinders

The bore is stroke need to be in cm to get the decimal point in the correct place.

So, with an 8mm stroker:
9.1cm x 9.1cm x 7.6cm x.7854 x 2 = 989cc

[JimTMich]

That looks sweet! What pistons and sleeves does this use?

Now, How about a 1000cc twin cylinder for my kawi ;) Do you have one of those in the works?

[Brooks]

The cylinder will include sleeves, which are in the process of being made. It will use Sea Doo 951 pistons.

A Kawasaki cylinder is a possibilty in the future.

[waxhead]

That looks awesome
some quick questions

Do you have to have a head designed for this cylinder only ??

Are the bolt holes for the head below deck height ??

My reason for asking i am wondering how the salt water will effect them if the bolts are exposed to the water

I cant wait to hear of one going and see how well they preform
well done ADA

[Brooks]

Yes, the head is designed specifically for this cylinder. The head studs are below the surface, but we make the studs from stainless and we roll the threads, not cut them.

[puppi350]

Is this for the 701/760 cases?

Need some info. thanks.

[learsrx]

Why the 3mm spacer for the 8mm stroker? You guys are CNC machining these things. The billets can't be that much more of a cost in the larger size. You are adding one more interface that needs to be sealed and subsequently an addtional failure mode. Thanks for any replies.

[madoyster]

That thing is shwwweeeeeet. It may have to go in my build off ski. Price and when is this available? I have just the engine buider in mind. (PAUL L) whoops my bad