So this exists....
I've been working on an intake/reed combo for my hobbit and wanted to make a 16.16 sha work. Very quickly I learned there is not a lot of room. So I designed this. This is just a prototype but worked pretty well. There's a few adjustments to be made and then hopefully I can place a large order and offer them to you kind folks.
To get this to work you gotta canabilize a plastic sha top for the metal bits.
These three pieces
Here's everything together
Hoping to have these available asap. Already made the needed changes to the design. I will post in here when they are available. Thanks!
Damn, this is a SMRT idea.
Love it!
Nice, no cable bind on throttle return?
> The Dude Wrote:
> -------------------------------------------------------
> Nice, no cable bind on throttle return?
I was curious on this too. I guess it would be best if your carb is facing backward too. Or like my garelli and facing forward but in front of the cyl.
Great work. I just dont trust myself on getting the metal bits on there properly and permanently.
I haven't gotten to do a whole lot of testing besides making that "the choke works" video. But the cable never seemed to bind up. My concern is what an hour of riding on and off the throttle is gonna do.
There is a small plastic chunk to guide the cable out of the metal guide and slowly bend down instead of a harsh 90* angle. This is my concern for the "fail point." Either the cable is gonna slide nicely for a long time over that plastic hunk, or saw right through it and cause problems.
The plan is to test it through out the week and see what it takes to make it fail.
Have you seen the malossi ones for Hobbit, how they fail? I had thought of this a few years back (for phbg) and maybe trying to embed the metal bendy inside the plastic?
Sha might be a lighter return spring so that might help
> LGN Bruiser Wrote:
> -------------------------------------------------------
> There is a small plastic chunk to guide the cable out of the metal guide
> and slowly bend down instead of a harsh 90* angle. This is my concern
> for the "fail point." Either the cable is gonna slide nicely for a long
> time over that plastic hunk, or saw right through it and cause problems.
>
this would likely require a 'slight' redesign , but ,
maybe consider replacing that plastic chuck with a set screw holding a pin with a slide/sleeve . That sleeve would move/roll with cable movement .
Of course all three would have to be size appropriate .
Cut a brake cable apart and stick the wound steel liner inside on the bend to give a wear surface?
Ready to buy when ready to sell!
That slide is working great! Even if the top only lasts a season I’d still buy it!
Doing great stuff
Graham - I've only heard about the malossi tops and that either they fail and/or eat cables. If you have a more detail description of where and why they failed I'm all ears. I'm hoping this design will take advantage of pa12 having a low level of friction.
PD- have thought about doing a small wheel or pulley inside to guide the cable; at that point I think its over-complicating something thats supposed to be simple. Personally I'd probably abandon the project at that point even though it would work.
I did a lot of testing last night. For about an hour and a half I set the carb up and just tugged the ever living shit outta that throttle cable trying to break it.
I tried:
1. Pulling with a stupid amount of force
2. creating friction by going back and forth super fast
3. Pulling till full throttle and then slowly and gently letting it down and trying to get it to hang up or get stuck
4. Choke on. Pull throttle till choke off. Repeat 50x as fast a possible
All of this is over and over with different combinations of force, speed, and amount opened and closed.
And after all that abuse...NOTHING HAPPENED
Cable looked fine and so did the top. Never got hung up once. I feel pretty confident in this. My goal was trying to recreate an hour of heavy rally riding and see if this fails. It didnt and thats while being put under abuse its never gonna see.
that is sick!
i bet you could send you cad file out and have em cast in aluminum and stop worrying about that potential point of failure
Aluminum wouldn’t wear the cable like plastic will
But who would pay $30 for a carb top
So many people if it meant saving you an hour of time fucking with your carb Everytime you want to rejet/remove
I have a metal float bowl sha, I would totally get a metal top to match. If I can only get the metal bowl to not leak.
Maybe it could be made from delrin, super slippy and durable.
Not sure if that's available for 3d printing though.
What about just sanding down the area super smooth. Almost a polish. That would help lessen the friction, but I think your testing was pretty rigorous for most use.
It seems your testing is fairly rigorous and maybe enough .
Make 2 or 3 and let a couple of hard riders test them for a month in differing conditions and circumstances , to back your findings .
I can test one on my garelli. The way the carb is on the garelli, there is very little room for the cable and requires a super short bendy. This may help things out. I should even have an old sha top I can cannibalize for the needed parts.
are these not a thing? I got one of those style tops on my XKE/trac thing, I just found it in the ol bucket o sha's
I have some tops that have a 45 degree angle for the top and plenty 90 degrees straight up, but not one that is level.
Pics of your found top!
Awesome design
Yeah I got a couple from the shorty intake tomos 14:12p that are really low profile, got one on my Peugeot, but this is even lower looks like
gotcha, sweet. I definitely have use of it haha
Update: The original is now on a DS50 and doing great. Also got a batch of these in...
I tried to hit up anyone who expressed interest so they could receive the holy honor of dibs. Otherwise pm if you want one. $12 shipped on this first batch. (edited)
thats awesome! thanks for bringing rad shit to the community... this one might even be popular outside mopeds, maybe with some of the tweaker bike guys or kiddie dirtbikes/pocketbikes that use them?
I got mine in two days wow so fast. I was able to pull the pin out with just some small pliers so my OG top is still intact.
Yeet.
Got mine today and some sweet stickers too! Thanks guy!
I'm going to install it tomorrow, I expect everything to go smoothly. I have a few spare tops I can cannibalize for the needed parts.
Alright so the first three that went out will all have the pin stick out a little bit. I drilled the rest in my possesion so the pin will sit in all the way. Also updated the design to reflect the correct sizing.
After talking to Emil about getting the pin out and them using pliars to get it out; I took a crack at not ruining one to get the metal parts. I used an o-ring pick and pushed through the plastic just enough to push the pin out a few mm and grab it with pliars. Top is still usable.
Thanks Graham! I think you're right but I never felt like posting on their forums. I thought the same with the slide and once treats started selling them I hoped they'd find them there.
(edited)
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