Yamaha SR250 - A clean standard build

zap2504 said:
Did you give it a "test sit" for an extended time? It looks to me like the upper part that would actually provide the most support is fairly narrow and I would be suspect of the sharp transition angles on the sides.

I sat on it for a bit to see how it feels, and it feels pretty good! Its a bit hard to test the comfort of an unfinished seat on an unrideable bike ;D I guess I could set it up on a bench in front of the tv or something though right?

The seat is pretty soft foam, so the transition angles just mush when you sit on it. The area that you actually sit on is the widest point of the seat so your ass is pretty well supported. Good links there for future reference for comfy seats. Cheers.
 
Beautiful work man. I think the hard angles on the top are ok. Are you going to have a seam there in the cover to maintain the visual edge? I think that would look good. My $0.02 is to remove the body line in the middle of the sides and replace it with a smooth curved shape so the seat styling better matches the styling of the tank. Another thing about trying to make corners or hard edges in the foam for styling purposes is that it is often very difficult to keep that body line sharp and straight looking after the padding and cover are done. If there is not a seam on top of it to help teach the eye that the corner is fair and straight, it can look lumpy and wavy - especially over time. Otherwise I think the shape is right on. Gonna be a nice motorcycle when you are done. Kudos for documenting!
 
jpmobius said:
Beautiful work man. I think the hard angles on the top are ok. Are you going to have a seam there in the cover to maintain the visual edge? I think that would look good. My $0.02 is to remove the body line in the middle of the sides and replace it with a smooth curved shape so the seat styling better matches the styling of the tank. Another thing about trying to make corners or hard edges in the foam for styling purposes is that it is often very difficult to keep that body line sharp and straight looking after the padding and cover are done. If there is not a seam on top of it to help teach the eye that the corner is fair and straight, it can look lumpy and wavy - especially over time. Otherwise I think the shape is right on. Gonna be a nice motorcycle when you are done. Kudos for documenting!

Thanks man. Yeah the original idea was to have a seam at each transition, but then I realised it would be too 'busy' and expensive to make - because of all the seam work. Then I decided to just have a seam along where I have drawn the black lines on the white foam. You make a really good point about the angles/transitions/curves. I think much more will get lost than what I was originally thinking. So its better to design for the process/material rather than trying to fight it. It will be interesting to see what has happened when it comes back from the upholsterer :D
 

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Just got mail! A billet machined rear loop in aluminium to be screwed in place, plus the ignition relocation bracket I designed ;D

I couldnt find anyone who could bend 7/8'' tube as tight as I wanted to suit my design, so I designed the rear loop to be machined instead - hence the half round, half flat profile (only the half round will be seen). This allowed me to do it in solid aluminium and to fasten it in place with M6 screws and lock washers.
 

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Decided I like the new trend of actually having side covers... So I modeled up some super slim ones that hug the frame much better and fit the form of the frame rails and new seat :D

In the past I have been a big fan of the 'emtpy/clean triangle' but my tastes have developed haha. Now that area does just look, well, empty? Plus it means you miss out on the opportunity of giving the bike another design detail/more character. Case in point:
 

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3D model to be prototyped:
 

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Yes to well designed side covers. On mine I just moved them forward to line up with the rear edge of the tank, made them 2" less wide each and made them out of carbon fiber. They worked out OK but not as nice as a 3D print or machined prototype would be.

The point is that side covers can look good and there are many ways to make them look right. Yours should look really nice. Good work.
 
A mint day here in southern Sweden so it was out for a ride with the rat bike. Already got plans for it for next winter ;D
 

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JadusMotorcycleParts said:
Decided I like the new trend of actually having side covers... So I modeled up some super slim ones that hug the frame much better and fit the form of the frame rails and new seat :D

In the past I have been a big fan of the 'emtpy/clean triangle' but my tastes have developed haha. Now that area does just look, well, empty? Plus it means you miss out on the opportunity of giving the bike another design detail/more character. Case in point:

That CB360 is a great looking bike
 
Picked this up today... Liking it 8)

Will have to see how it looks/fits on the bike.

Oh yeah, I had some embroidered labels made too - in anticipation of a small production run ;)
 

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Was really hoping to get this bike done in time for this riding season, but it is looking more and more like it will not be complete until winter, autumn at best. So I was looking back through some photos of my fist SR build to get some inspiration to keep at it!

Thinking about producing some of these 'melting/dripping' Yamaha decals as well. Inspiration came from Alice in Wonderland believe it or not! That scene from 'paint the roses red'!
 

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Tested the fit of the seat and the prototype side covers today. The seat is pretty awesome for a first off sample. However I would not be satisfied if it were from a batch production run, so I have a little work to do there.

The side covers on the other hand were a different story - at the front and the top sides they fit well, but the back sides did not match the frame at all. Oh well, just need to make some adjustments to my 3D model then try another couple of prototypes I guess!
 

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Very good first efforts! I think your second photo is very telling - it looks like neither the seat nor the side panels follow the bike frame's vertical plane (i.e., seen from above) and so look out of place. The seat looks like it needs to be narrower at the tank end and flair out more at the shock mounts. Likewise, the side panels look fairly good at the rear (except for not following the frame downtubes completely) but protrudes too much at the front. [Edit - I went back to your 2-D drawings and you can see it there too.] Probably due to the frame plane twisting inward in that area. The side panels may also look better (less visual weight) if they did not extend as low. Try it in a drawing first to see which way you prefer.
 
zap2504 said:
Very good first efforts! I think your second photo is very telling - it looks like neither the seat nor the side panels follow the bike frame's vertical plane (i.e., seen from above) and so look out of place. The seat looks like it needs to be narrower at the tank end and flair out more at the shock mounts. Likewise, the side panels look fairly good at the rear (except for not following the frame downtubes completely) but protrudes too much at the front. [Edit - I went back to your 2-D drawings and you can see it there too.] Probably due to the frame plane twisting inward in that area. The side panels may also look better (less visual weight) if they did not extend as low. Try it in a drawing first to see which way you prefer.

You are right zap. However, with the SR250 frame and designing a seat for it, its a bit of a tricky task. Just because the frame rails come so tight at where the rear of the tank connects to the frame. So then it becomes a decision (personal preference maybe) as to whether or not to follow the frame rails the whole way (and end up with a very very thin seat at the front - and possibly not even cover the tank bolt - ala attached), or only follow the frame rails at the rear (like I have done) and then match the edges of the tank at the front of the seat instead. Personally, as nice as the La Corona custom is, I am not a fan of the seats shape/form.

Another option, which would probably be ugly, would be to design the seat so that it hangs over the frame rails and covers them - thus creating a clean uniform line. But I kinda like seeing the frame rails there at the rear.
 

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Zap you got me all curious now! Just been checking what other builders have done with the SR (some I like much more than others). Also checking some aftermarket seats for the Triumph Bonneville and the Scrambler... Its seems some of the cover the frame rails entirely and look pretty good!
 

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JadusMotorcycleParts said:
You are right zap. However, with the SR250 frame and designing a seat for it, its a bit of a tricky task. Just because the frame rails come so tight at where the rear of the tank connects to the frame. So then it becomes a decision (personal preference maybe) as to whether or not to follow the frame rails the whole way (and end up with a very very thin seat at the front - and possibly not even cover the tank bolt - ala attached), or only follow the frame rails at the rear (like I have done) and then match the edges of the tank at the front of the seat instead.
Right, but what I'm proposing is only a slight change to your original design - just slightly narrower at the tank (will not affect comfort as you will be sitting further back), and slightly wider at the shock mounts (just enough to match the frame). The padded tank overlap you have designed at the front will take care of the tank rear/seat front issue. The side panels may be a different story. Maybe more of a curved slope at the top/front edge so as to better match the frame coupled with either a higher bottom line or a stepped design so that the panel is the same overall height but has more of a visual "thinness".
 
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