GT750 reed intake idea's

[Suzukidave]

Kris , have you already machined off the intake side of your 750 block ?

[durgam]

nope.

[tz375]

Kris,

It's best with a single plate all the way across, but of course that means the small stud to the inside of the right cylinder is no longer accessible.

Use 6mm screws, 2x top and 2xbottom to retain the reed boxes.

On a street bike it's best to keep inclination angle down to avoid weeping into the crankcases. Stock motor is roughly 10 degrees, so machine the back of the block parallel to the bores ( perpendicular to the bottom face) for the adapter plate.

No point in doing all that work for small stock carbs, and 34's are typically deeper from centerline to the bottom of the drain bolt that BS40 or VM32's from a J/K.

The best solution would be to angle the face to more closely match port downdraft, but that requires an angles rubber intake manifold.

So let's think about a 15 degree angle to the reed boxes to get the flow right, and a 10 or 15 degree angle on the manifolds. If there isn't a suitable Arctic Cat angled manifold, I'd suggest an angled "cover" to the reed cage onto which a stock Mikuni manifold would mount. In other words a wedge shaped plate to which a standard Mikuni intake rubber could bolt.

If you can draw it up and send me a 1:1 print I can check it on the motor on the stand here with 34, flat, 38 flat and 38 rounds or with 36mm Lectrons which are slightly shorter IIRC.

38mm throttle bodies for EFI can go on at the port angle, so they can use OEM AC rubbers.

Hope that makes sense. if not, PM or email me.

[Suzsmokeyallan]

Richard you can weld on the plate as one piece then make an access cut away at the lower section to the stud you speak of.
The Artic cat intakes did have an inclination on the rubber as far as i can remember, the inlet did not enter perpendicular to the reed cage.

[Suzukidave]

If there isn't a suitable Arctic Cat angled manifold, I'd suggest an angled "cover" to the reed cage onto which a stock Mikuni manifold would mount. In other words a wedge shaped plate to which a standard Mikuni intake rubber could bolt.

something like this

[Suzsmokeyallan]

Was i wrong to think we were using the Artic cat intake rubber piece and the reed petal case, fitting these parts into a reed box Kris was making to accept it.

[durgam]

A second, angled piece is very similar to wht I had in mind when we started talking about the boxes being angled. A piece like that one pictured would bolt through the reed cage mounting holes, and into the boxes im making. And like shown, a manifold could bolt to that.

[tz375]

A/C manifolds are near as damn it straight. Where Polaris come at two different angle.

If there was a motocross reed cage/box with a more angled manifold, it would obviate the need for the angled plate.

Anyone ot a 125 RM or YZ lying around they could photograph?

A/C reed cages are fine, and come in sets of 3, but if we are making boxes from scratch it might be better to use a different one.

[durgam]

ive got a KX125. What do you want pics of? the cage itself or the manifold?

[tz375]

Answer (D). All of the above. Final Answer.

Comparison to the A/C reeds would be good to give me a perspective on their relative size.

Thx.

[Buffalo-guy]

The AC reeds and manifolds are all I have. Anything else will be more difficult, and expensive, to acquire 3 of. If Kris is willing to provide a mounting plate as well, then the easiest approach for carb clearance would be to adjust the angle when the block gets milled. I'm all for keeping it as simple as possible for Kris, and all involved. Does this fit with everyone's expectations? Thanks Kris, for your attention to the details. Cheers.
Fred

[durgam]

Fred makes a good point about milling the cylinder on an angle that comes close to the down draft of the ports. How thick should the plate be thats welded to the cylinder. Thick aluminum takes a lot of heat to weld. Lots of options here.

[tz375]

OK. Let's stop for a moment and take a deep breath. We are trying to design a "product" that meets the needs of several different applications.

Fred has a set of 3 A/C reeds so would like boxes that use them. Dave has A/C reeds and a set of crankcases. other people don't have either. The simplest solution for most people might just be to go with the majority.

Milling the block at an angle is possible, but harder and more expensive than just lobbing it off straight for a number of reasons. Simplest and cheapest solution is a straight cut.

Downdraft angle is not very important on a reed motor, so don't worry about it.

Packaging (making it all fit) is crucial.

Mounting plate is a simple 3" by 1/4 inch plate with three holes in it for ports plus the all important drilled and threaded holes for the reed boxes.

From a flow perspective, the reeds have to be close enough to the piston, so that they respond to small pressure changes, and they need to be far enough back to provide good flow into the crankcase and the new transfer boost port(s).

Demand for these will always be small, so maybe the way to go is Arctic Cat reed cages, a paper template (pdf file perhaps) for people to make their own mounting plate, and a simple angled manifold mounting plate.

But the first step is to draw it all up. Kris offered to do that and I offered to check it on a motor and to provide input.

I would also like to see that KX125 system to see if it is more suitable. In the meantime, I'll probably go back to the Polaris cages I have already. They flow more.

[Suzukidave]

[tz375]

I remember that one. That is basically what they need to look like to get the right port angle AND the right carb angle.

Dave, do you have a photoshop to CNC interface?