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HSR 45 Manifold

billy2billy2 Member, OS Professional, Mentor, Developers Posts: 1,355 PRO
edited January 13 in General
So my triumph quit running and it's my favorite commuter bike.

These had to go:

These are CV carburetors and they're not the best in the world for racing. I've been wanting to replace them for some time now.

This is a Mikuni HSR45:

Most would agree this would be an improvement.

2 intake ports and 1 carburetor now what?:

I've spent a lot of time on this little project and it's almost done. Those who follow this forum know I like customizing bikes using onshape and every additive method available on this planet. How do you connect 1 carburetor to 2 ports?

Like this:

How do I know it'll fit?

Like this:

and this:

At rustyshed.com, I've incorporated "quill" a web editor for creating reports. Let me know what you think.



  • billy2billy2 Member, OS Professional, Mentor, Developers Posts: 1,355 PRO
    HO, HO, HO!

    Christmas came a little late for me:

    My good friend recommended I roll my bike outside before trying to start it for the first time. He's afraid I'll burn the garage down.

  • billy2billy2 Member, OS Professional, Mentor, Developers Posts: 1,355 PRO
    edited January 12
    It freak'n fits!

    It won't start because the battery is dead. You'd think I should've hooked her up to a battery tender; that's what she gets for breaking down. 

  • john_mcclaryjohn_mcclary Member, Developers Posts: 2,323 PRO
    Nice work!
  • billy2billy2 Member, OS Professional, Mentor, Developers Posts: 1,355 PRO
    John- Thanks

  • matthew_stacymatthew_stacy Member Posts: 10 PRO

    Great work on that intake plumbing!  I'd love to hear more details about the fabrication.  How was this part manufactured?  Any challenges with fitup, sealing, etc?



  • billy2billy2 Member, OS Professional, Mentor, Developers Posts: 1,355 PRO
    edited January 15
    The fabrication was fairly straight forward. It's a MJF print off a HP printer. It's 4mm thick and fairly stout. There was really no other things to do except pay for it. It wasn't cheap. I do paint them before use because the dye they use fades to blue in sun light. I use a special plastic paint; you can't tell it's on the part and it keeps the parts black for a long time.

    I've had plastic parts on bikes for over 2 years and they show no signs of degradation due to being outside. Theres a lot of plastic parts on motorcycles these days so I don't worry about using plastic on a motorcycle.

    As far as sealing goes; I just clamp it down. The hose clamps seem to pull the plastic together and form a seal. I'm running a .2mm clearance gap. Once it's running better; I'll spray a little ether around the joints while it's running to see how good the seal really is performing. Right now I think it's pretty good.

    I'm still worried about temperature on a hot day. May need a rev 2 to stop heat transferring from the head. Being an engineer; it's more of a challenge than a problem and there's gotta be a solution. I'm not going to fix it until I have the problem. I will keep an eye on it so I can always ride home. I don't want to have a droopy carburetor!

    Dividing up the flow was another challenge. I did use CFD, simscale and 100's of "what if" tries before coming up with something that worked. The brief run I show in the video; my gas tank was a tiny funnel; each cylinder was popping nicely better than the individual carburetors. I don't think the carbs were balanced before. I think they're much better now. A test run around the block will prove this out.

    I still need to make throttle cables, attach the choke, assemble all the hoses, design a new velocity stack and then take her out for a ride around the block. I know I'll need to re-jet everything but this is fine.  

    The biggest deal was getting the geometry correct. I've been working with onshape & meshes for a long time and I'm getting better at it every project.

  • owen_sparksowen_sparks Member, Developers Posts: 2,575 PRO
    edited January 16
    Just out of interest when you say "It wasn't cheap" have you looked at the Markforged metal printers?  The slicer helpfully lets you know how much the material costs.  The difference between their carbon loaded nylon and metal wasn't much, and the result can be polished if that's your thing. 
    I'd image the hard part is finding someone who has one who will let you use it at material cost plus a bit of profit, as opposed to silly money because he has one and most people don't!  I seem to recall a chap who makes off road wheelchairs (yes that's a thing) having one.
    Owen S.
    Production Engineer
    HWM-Water Ltd
  • billy2billy2 Member, OS Professional, Mentor, Developers Posts: 1,355 PRO
    edited January 16
    We have a couple of markforge printers at work and use them a lot. They're great printers but I prefer the isotropic properties of the MJF. SLS & MJF printers are coming down in price, hopefully reducing the job shop pricing. The material cost is surprising nothing and the reason for the 4mm thickness. Volume is the cost driver, how big is the part.

    My wife has approved me buying one, but I'm not sure I want to run a print machine.

    We had desktop metals in a couple of month ago. Saw a demo of markforge metal printers about 6 months ago. Turns out getting permits to run these things in California is problematic.

    Yes, I want to redesign hand grips on motorcycles and I think metal is the way to go. Why do mountain bikes have such cool looking levers and motorcycles have cow horns from 1950's?

    We have 5-axis at work and I'm helping these guys set that up. 5-axis machining is pretty cheap. But I'm not sure I want to run a mill either.

    It's an exciting time to be an engineer.

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