62t 61x reverse engineering/billet machining

[BallsJohnsonDance]

How bout machining molds for a plastic hull similar to the sea doo spark but a freestyle ski? Maybe too big?

Thats big money in material. We had a machine on the floor for the last year that could do it, but it just shipped to texas. You need a real exspensive mold press as well. Your startup cost on that would only be justified in the hundreds of thousands or millions of individual piece parts.

 

[BallsJohnsonDance]

How bout machining molds for a plastic hull similar to the sea doo spark but a freestyle ski? Maybe too big?

I was more thinking case modifications. I see people epoxying cases, not real sure why. Also i have heard the read angle on the stock 62t cases should be adjusted.

 

[Quinc]

You could make the cases a little deeper so they would be ready to run for a stroker. Not sure how this would effect a stock stroke engine with more case volume though? @waxhead @Jr.

This pic shows the area that is epoxy'd and ported.



This pic is cases that are not ported or epoxy.


Here is a video that explains and shows the porting process:

 

[Quinc]

read angle on the stock 62t cases should be adjusted.

Bun Freestyle made/Makes cast cases that have the intake aiming 30% more up. @CARBONX2

 

[Storbeck]

I think the highest level of development in two strokes is found in dirt bikes and snowmobiles (well really two stroke gp racers, but it's hard to find pictures of those and they did lots of goofy stuff for packaging purposes), so I would be looking to those for inspiration.

Also the 66e Yamaha is on a higher level than the 62t.

There is a general theme here of pointing the reeds tangent to the top of the crankshaft and having a big clear path to the bottom of the cylinder and the transfer ports...which is basically what case porting does within the constraints of the 62t architecture.

When looking at case porting it's important to keep in mind the crankshaft is there blocking things and the bottom of the cylinder/sleeve/piston. The Polaris twin and the 66e both use a "porkchop" type crank that opens up the area from the reeds into the case during most of the rotation of the crank. Polaris takes this to kind of an extreme. I think they use a very low balance factor, there are reasons for doing that having to do with the belt drive on the snowmobile, and weight, so it might not all be motivated by flow in the case.

If you're doing both the cases and the cylinders the thing you probably could gain from most is opening up the transfer port area as much as possible. Look at the 66e Yamaha or any of the billet watercraft cylinders and they all stretch out the transfer ports to some extend. Dasa takes it to the extreme.






Some examples:

 

[BallsJohnsonDance]

I think the highest level of development in two strokes is found in dirt bikes and snowmobiles (well really two stroke gp racers, but it's hard to find pictures of those and they did lots of goofy stuff for packaging purposes), so I would be looking to those for inspiration.

Also the 66e Yamaha is on a higher level than the 62t.

There is a general theme here of pointing the reeds tangent to the top of the crankshaft and having a big clear path to the bottom of the cylinder and the transfer ports...which is basically what case porting does within the constraints of the 62t architecture.

When looking at case porting it's important to keep in mind the crankshaft is there blocking things and the bottom of the cylinder/sleeve/piston. The Polaris twin and the 66e both use a "porkchop" type crank that opens up the area from the reeds into the case during most of the rotation of the crank. Polaris takes this to kind of an extreme. I think they use a very low balance factor, there are reasons for doing that having to do with the belt drive on the snowmobile, and weight, so it might not all be motivated by flow in the case.

If you're doing both the cases and the cylinders the thing you probably could gain from most is opening up the transfer port area as much as possible. Look at the 66e Yamaha or any of the billet watercraft cylinders and they all stretch out the transfer ports to some extend. Dasa takes it to the extreme.




View attachment 398274

Some examples:

View attachment 398271View attachment 398272View attachment 398273

Perfect, i can make that happen.

 

[Storbeck]

For what it's worth, I should point out that I don't actually know anything lol, was just posting my observations. So follow at your own risk.

 

[BallsJohnsonDance]

so correct me if iam wrong. It appears the the epoxy is being used to fill in the ribbing to allow for larger ports, which means o dont have to mess with epoxy, i should just try to get the reed angle as perpindicular to the axis of the rotating assembly and as high as possible.

 

[BallsJohnsonDance]

For what it's worth, I should point out that I don't actually know anything lol, was just posting my observations. So follow at your own risk.

You know more than me!!!!

 

[Storbeck]

so correct me if iam wrong. It appears the the epoxy is being used to fill in the ribbing to allow for larger ports, which means o dont have to mess with epoxy, i should just try to get the reed angle as perpendicular to the axis of the rotating assembly and as high as possible.

The thing about the epoxy yes you are correct, that is only used because people are carving out the cases further than there is aluminum to carve in, so the epoxy fills in the hollowed out parts of the case to make it solid.

The rest about the reed angle, well see above comments

 

[BallsJohnsonDance]

 

[BallsJohnsonDance]

View attachment 398275

Why have i seen epoxy here on some cases, whats the deal with the ribs in the reed port

 

[Mobile Chernobyl]

I would imagine that the material thickness (walls) you see being epoxied are also somewhat related to the cooling rate of the casting after the pour - i.e. trying to achieve a relatively uniform cooling rate so the material doesn't crack and so that material crystal formation is what the engineers intended it to be for the strength goals... etc. etc.

It can get quite advanced at that point and you have to ask yourself if it's easier to scan, clean and edit then test or just design from scratch in SolidWorks and do a lost wax mold created from additive 3D printing?

I'm no expert in metal casting - I did study at a relatively high level material properties and such in my mechanical engineering academia days though.

 

[Storbeck]

View attachment 398275

I think it's partially to kind of redirect the flow over the crank, partially to reduce case volume.....and in some cases it's because they saw that other people put epoxy there.

 

[Storbeck]

So that would be an area that the epoxy is actually being used for shape, not just to fill in the hollow parts to allow more carving.

 

[AdzUK]

You could also open the intake up for snowmobile reeds like a lot of the motors run.
the new bun case porting is very different to the new bun cases, they look real nice.

 

[Jcary85]

Epoxy is the fingers of the Intake area (creating a ramp) Is to INcrease air velocity as I understand it and many builders think it’s pointless.

 

[BallsJohnsonDance]

I would imagine that the material thickness (walls) you see being epoxied are also somewhat related to the cooling rate of the casting after the pour - i.e. trying to achieve a relatively uniform cooling rate so the material doesn't crack and so that material crystal formation is what the engineers intended it to be for the strength goals... etc. etc.

It can get quite advanced at that point and you have to ask yourself if it's easier to scan, clean and edit then test or just design from scratch in SolidWorks and do a lost wax mold created from additive 3D printing?

I'm no expert in metal casting - I did study at a relatively high level material properties and such in my mechanical engineering academia days though.

I understand that, i plan on modifying as much as really makes sense, i am not trying to make the most powerfull motor possible at any cost. im wanting something somewhat reliable that works with the current aftermarket available parts. the nice thing about the scans is i know everything will fit, i dont have to keep track of bolt patterns etc. i am drawing solids over an stl file. I am just using Autodesk powershape instead of solid works. Also my company sells cnc machines, not jet ski motors so me asking you guys is all the "R&D" they are willing to pay for! i am trying to make some thing solid that is a reliable improvement over stock to start with, i can always continue to modify these models. I have a partner in this project that owns a multiaxis cnc shop in kentucky that will most likely be taking this over and produce and modify whatever we actually wind up making. We are scanning a b pipe as soon as i get it and will be doing a billet clamshell welded head pipe and billet manifold, chambers are still up in the air. we are clam shelling the head pipe to get around casting, its way easier for us to machine than cast. that being said if it does not work our we will be machineing patterns and casting head pipes. Me and my partners sole reason for chosing this motor/pump/pipe for this demo is due to the absolute ridiculous prices that superjets and thier aftermarket have climbed too. fact of the matter is i will never do a backflip, dont even really want to try. i like carving turns and jumping cornrow waves during t storms here in the midwest. i just wnat to do it on a superjet instead of a 800. Any help you guys can give me on how to do tastefull modifications will be greatly appreciated, just keep in mind i am not trying to start with a hand grendade!

 

[Jr.]

For what it's worth, I should point out that I don't actually know anything lol, was just posting my observations. So follow at your own risk.

This is something very worth pointing out!
While the guys that truly care admit to “Not Knowing” So not to mislead you in your work thinking its gospel.
There is a lot to be said to that. In the contrary, there is a tremendous amount of really bad info Spread via all forms of internet postings and especially youTube. Some of this has been offered to the OP here in this thread.
Please, before you take this hard work to the next level, Verify what parts of it you want to use?
In my years of building and dealing with performance motors. I see much of what the general community thinks is true? Is in reality, passed down poor, misleading Information. Many base what they do off it, and find themselves with poor running, unreliable setups. Please don't make that mistake with your re-engineered parts. I like your desire to build something of value to this community. I would enjoy nothing more that to see you succeed! Be Smart!


Ski ya, Paul

 

[Storbeck]

Epoxy is the fingers of the Intake area (creating a ramp) Is to INcrease air velocity as I understand it and many builders think it’s pointless.

I've always been pretty skeptical of the ramp thing, but see aforementioned comments about not knowing lol.