JTH's HD 883 Dual Sport'ster conversion

[JimmyTheHog]

Here it is. This tank requires a bracket to be welded to the top frame tube to hold a bolt that holds the tank. I'll post pic's when I get to that point...

[johnwesley]

Sweet!!!!!!

[Kleetus]

JTH,
Love what you're doing with the Sporty. I've been trying to get the wife's Sporty for a year so I could do something similar but she won't give it up. I had a KLR but sold it. It wasn't a good dirt or street bike in opinion for me needs. I'm planning to keep watching you and Johnwesley's builds. I've known John a few years and he always comes away with fresh ideas and out of the box thinking. any thoughts on what that swing arm will cost?

Thaks...Kleetus

[JimmyTheHog]

Originally Posted by Kleetus

JTH,
Love what you're doing with the Sporty. I've been trying to get the wife's Sporty for a year so I could do something similar but she won't give it up. I had a KLR but sold it. It wasn't a good dirt or street bike in opinion for me needs. I'm planning to keep watching you and Johnwesley's builds. I've known John a few years and he always comes away with fresh ideas and out of the box thinking. any thoughts on what that swing arm will cost?

Thaks...Kleetus

Thanks Kleetus. I dont know what the swingarm will cost yet. We are waiting for the billet to arrive, then we start cutting metal. Once we get into it and find out how many hours of cutting, then we'll have a better idea. I plan to put it thru some rigerous testing to confirm its structurally ok, then make it available if anyone may want one. It will be a bit pricey though. The billet alone costs ~$500.

[Kawidad]

Don't get me wrong, I love billet, but wouldn't it be cheaper and easier and just a good to use tubular steel ala Ducati?

[JimmyTheHog]

Originally Posted by Kawidad

Don't get me wrong, I love billet, but wouldn't it be cheaper and easier and just a good to use tubular steel ala Ducati?

Cheaper / easier - As a 1-off prototype, Im sure tube steel construction would be much less expensive. Half the billet gets removed which is not economical. In a production run though, it may be a different story - there would be less billet waste if you nest the rough cut arms, and once the cnc program and tooling are done, its a pretty straight forward process to machine.

Just as good - Depending on the design & material, the billet arm can be less weight. The 7075 aluminum has a very high yeild strength (higher than alot of carbon steel tube materials) and is ~1/3 the density (.1 vs .286).

For this design, I went very strong (low stresses) and kept the walls thick. Estimated weight is 13 lbs. Not the lightest but I want it to take off-road abuse without worry.

Ok - enough BS - the real story ~ I just love billet

[JohnBoy777]

Hey JTH,

Which tank is that? Seems to work well w/ the design.

Have you entertained the thought of offering a kit?

Cheers
John

[JimmyTheHog]

Originally Posted by JohnBoy777

Hey JTH,

Which tank is that? Seems to work well w/ the design.

Have you entertained the thought of offering a kit?

Cheers
John

The tank is from Storz Perfomance - alloy dirt track tank. Its super light, weight is kept low, and doesnt interfere with the tripple clamps when turning. Holds 2.75 gal.

http://www.storzperf.com/jpgs/page27.html

Yes - Im thinking about doing a kit. I have wanted an HD DS for years and wished someone had a nice dual sport kit that I could start from, but never found one. Just kept seeing one-off builds that kept my interest going.

My thoughts are that it would include the swingarm and the other brackets/components I made shown in this thread, and then my build notes for all the other purchased components and how they get assembled / modified. The challenge will be to see how low a cost I can offer the swingarm & components. If its too expensive, it will be a tough sell. Theres still some work to do on the exhaust, rear frame, and seat, so it may be a while - the day job gets in the way of going faster.

[JimmyTheHog]

Started the seat mock-up today. I want a single seat that is narrower and a bit taller than the stock sporty seat, and uses the same stock mounting. So, Im starting with the stock seat pan and foam and trimming to my likes.

Here is the seat pan trimmed...

[JimmyTheHog]

The other side - still has the stock mounting brackets...

[JimmyTheHog]

Now shaping the foam. Its not quite tall enough, but the shape is pretty close to what I want.....

[JimmyTheHog]

Looks pretty close. Now just need to work with a local seat builder to take it from here - They can do a much better job than I - and make it available to others....

[JimmyTheHog]

...And my sad attempt to cover it. I used the stock cover and stretched / stapled it on. The professsional seat will look much better, but I wanted to get an idea of how it would feel and look......

[Lutz]

Originally Posted by JimmyTheHog

Cheaper / easier - As a 1-off prototype, Im sure tube steel construction would be much less expensive. Half the billet gets removed which is not economical. In a production run though, it may be a different story - there would be less billet waste if you nest the rough cut arms, and once the cnc program and tooling are done, its a pretty straight forward process to machine.

Just as good - Depending on the design & material, the billet arm can be less weight. The 7075 aluminum has a very high yeild strength (higher than alot of carbon steel tube materials) and is ~1/3 the density (.1 vs .286).

For this design, I went very strong (low stresses) and kept the walls thick. Estimated weight is 13 lbs. Not the lightest but I want it to take off-road abuse without worry.

Ok - enough BS - the real story ~ I just love billet

One thing that is often totally overlooked (even in fairly highly engineered designs) is that aluminum does not have a fatigue limit, but steel does. What this means is below a certain level of cyclic stress, a steel part will last literally forever without failure due to fatigue. On the other hand, there is no minimum level of cyclic stress that an aluminum part can take without eventual failure due to fatigue.

In practical terms, it might take so many cycles to failure that the aluminum part will last virtually forever, i.e. it might never get to the number of cycles required to cause a fatigue failure. And just because steel has a fatigue limit doesn't mean that a steel part won't be designed such that it is stressed above the fatigue limit.

Does any of this really matter in here? Nah, let's just see this beast run!

[JimmyTheHog]

Originally Posted by Lutz

One thing that is often totally overlooked (even in fairly highly engineered designs) is that aluminum does not have a fatigue limit, but steel does. What this means is below a certain level of cyclic stress, a steel part will last literally forever without failure due to fatigue. On the other hand, there is no minimum level of cyclic stress that an aluminum part can take without eventual failure due to fatigue.

In practical terms, it might take so many cycles to failure that the aluminum part will last virtually forever, i.e. it might never get to the number of cycles required to cause a fatigue failure. And just because steel has a fatigue limit doesn't mean that a steel part won't be designed such that it is stressed above the fatigue limit.

Does any of this really matter in here? Nah, let's just see this beast run!

Lutz - Good point - I'll be doing the fatigue analysis soon.