Yamaha SR250 - A clean standard build

[xb33bsa]

but that bellmouth is actually only at its efficiency when in open air or well inside a large box
clamping a filter to it negates much of its effect and intended efficiency
it is designed to let air spill in smoothly from all around it ,hence its form with the scuplted round as apposed to a thin sharp bellmouth that you see on lots of stacks

 

[jpmobius]

but that bellmouth is actually only at its efficiency when in open air or well inside a large box
clamping a filter to it negates much of its effect and intended efficiency
it is designed to let air spill in smoothly from all around it ,hence its form with the scuplted round as apposed to a thin sharp bellmouth that you see on lots of stacks

Well - yes . . . to all of that but . . . . There is still value! Certainly the length of the tube (trial and error seems to be the means to get the best balance despite the calculations - temperature is your enemy!) can come into play, and the entry curve (seems to be unclear as to the best ratio) will still be useful even inside a somewhat claustrophobic air filter (agree a big box would be better of course) - but hey - it's a motorcycle, and style points are important. Pretty girls are preferred. I already know how to cook!

 

[JadusMotorcycleParts]

but that bellmouth is actually only at its efficiency when in open air or well inside a large box
clamping a filter to it negates much of its effect and intended efficiency
it is designed to let air spill in smoothly from all around it ,hence its form with the scuplted round as apposed to a thin sharp bellmouth that you see on lots of stacks

You might be right, but as jpmobius says, there will hopefully still be value. Besides, if I dont try, what have a I learned?

I read the K&N website guidelines for filter placement and distance and the recommendation is a miniumum of 1.5'' from bellmouth edge to filter cloth. This is the information I used to base my filter purchase decision on. According to the attached images (pictured is the 3D printed prototype), using this filter, do you think it would still be an issue? I personally don't, or if it did, it would be a poofteenth of a poofteenth. I have read that the gauze that some people use over intake trumpets is much more detrimental to flow than a correctly sized, proper air filter. You are right that this set up will not be ideal though, but hopefully, a good compromise...

I would rather not delve into this discussion for a second time in this thread though! Haha. Lets just see what happens on the dyno

 

[JadusMotorcycleParts]

In other news I received the first offtool samples for the ABS seat base. It looks awesome and fits perfectly. I had three thickness options to choose from from the supplier and checked them all to see which was the best.

I was really stoked that it fit first time and no expensive tooling modifications need to be done. However I needed to make a revision to the drawings and update the mounting hole position - which just means tweaking the milling program that cuts out the seats straight off the mould, so hopefully no additional costs there. I also added some holes for water drainage. Even though the foam is closed cell foam and wont absorb any water, if the seat is ever exposed to torrential rain, there may be some water that gets in and in that case it would be nice if it can drain/dry away from both the top surfaces and the underneath

 

[grcamna5]

Nice seat base.Did you use the thickest ABS ?

 

[zap2504]

Quick seat question - How did your upholsterer fasten the cover to your prototype? Glue, staples, pop rivets, separate seat panel that fastened to the pan?

 

[JadusMotorcycleParts]

Hi guys, to answer your questions, they actually go hand in hand...

The upholsterer I am using swears by the stapling method - the long stainless ones with a pneumatic operated gun. But ABS is so tough that the stables wont go right into the thickest of the bases. So I shot for the middle thickness (which is what I spec'd in the drawings). The reason we tried the thicker sheets was because I was concerned that the form of the seat would pull a lot of thickness out of the part on the high spots during the forming process. But this was not so much the case - wall thickness deviates .5mm max and the base is plenty strong in all areas. It actually gains some rigidity with the foam part on top too believe it or not

 

[JadusMotorcycleParts]

Its all coming together for the seats now! I received these metal seat components from the Swedish supplier yesterday

Overkill on packaging? Bit of a joke really. I'm quite pissed at how much I paid for the pallets and the freight now. Could have been packed in a shoe box with some bubble wrap if you ask me! Wonder who makes these calls???

 

[Eleganten]

That should almost be illegal to do. Ridiculous size on those pallets. Who makes your molds?


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[xb33bsa]

hay man i think you are doing a fantastic job with everything my point about the stack was only to suggest that its best use with that type of rounded bell edge
anyway i do have a killer idea but it may make you want to take up smoking
if you had a section of say 3-5" long crystal clear plastic tube between the bell mouth and filter you could sit there all day entertaining yourself and shop guests
simply remember to keep one lit at all times and blow smoke onto the the filter whilst you free wind and panic rev the motor up and down ;D and everybody will be hooked watching the flow stream

 

[Tune-A-Fish]

Do I need to buy something from you again :-X

 

[xb33bsa]

Do I need to buy something from you again :-X

: chimp lips shrink slips ,pilgrim

 

[JadusMotorcycleParts]

That should almost be illegal to do. Ridiculous size on those pallets. Who makes your molds?

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Agreed. I have since contacted them and it seems like one of those 'big company' type situations where they have tried to put a system in place for assessing packing and shipping, but in the end, its just easier to do the same for all customers, and these guys do a lot of big stuff and a lot of large quantity orders...

The bases are made by a company in Nyköping called StegoPlast. They're pretty big and do some quite advanced stuff. The actual mould though, I'm not sure sorry - they outsource all their tooling work and then focus on the plastic moulding side of things I believe.

 

[JadusMotorcycleParts]

hay man i think you are doing a fantastic job with everything my point about the stack was only to suggest that its best use with that type of rounded bell edge
anyway i do have a killer idea but it may make you want to take up smoking
if you had a section of say 3-5" long crystal clear plastic tube between the bell mouth and filter you could sit there all day entertaining yourself and shop guests
simply remember to keep one lit at all times and blow smoke onto the the filter whilst you free wind and panic rev the motor up and down ;D and everybody will be hooked watching the flow stream

Thanks man! That sounds like a sweet idea - would be real entertaining!

I set up some of my stuff for display at a Start Up Fair yesterday in Lund - a sort of interaction with students. Most of the people there were working with app development or some kind of web based start up. So I stood out a bit, but sadly, no one seemed interested! Kids these days huh. At the very end, three dudes came to chat to me and they were studying mechanical engineering and they really appreciated and loved the stuff. That made the whole day worth while haha. But perhaps it was the wrong kind of crowd for this kind of stuff.

Check out a snap from the display - I made up some engine plates/stands to show everything clearly. Its starting to look a bit like a hot rod engine ;D

 

[Luugo86]

Looks great man

 

[grcamna5]

Looks great man

Yes

 

[Eleganten]

So bummed out I missed the fair, would have been fun to have a chat. Came back home later in the day and saw your post on Instagram.


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[JadusMotorcycleParts]

Thanks guys.

Man you should have said hi!

 

[Eleganten]

Yeah, but I missed the whole thing. Been working on my BFA project since January and it's suppose to be done in like 3 weeks so I'm stuck in Nybro until end of May.


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[JadusMotorcycleParts]

I found a couple of images/diagrams I took screenshots of from my CAD file to see what the spark advance increase would be with re-positioning it. Cant remeber If I have shared these or not yet...

Anyway, by moving it forward 6-7mm, the advance will increase by 4-5degrees