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2-Minute Mod Jet Kit

Tour1

Member
Member
Hi Steve,
I've had your rebuilt carbs in for a year or so but still haven't gotten around to tuning the foam insert.  The way I ride I'm getting good performance without the foam, I figure it's running leaner if anything, and when I get some riding time I'd rather go somewhere than ride in circles around a cloverleaf testing acceleration.  So I'm thinking for a winter project I might try using my 3D printer and an old fashioned choke cable to make a Dial-A-Foam project (no dials expected for now).

My air box has a venturi-ish restrictor on the back, with an open area equal to about the diameter of 1 carb.  The simplest dial-a-foam would be to put a butterfly across part of one side of this venture so it would max out at the same restriction as the uncut foam block.  If it needs to have an echo effect (I recall this as a Helmholtz resonator) then it could be a slider thing but it would get more complicated.

Anyway the question is, since the opening in the present restrictor is about the same as a carb, is the 2-minute mod supposed to be used with or without the restrictor?  I'm attaching a CAD sketch of it, which in my case was quicker & easier than tuning the foam block.

PS I've been careful that the foam block is always singular in this post.  I saw an old thread where a guy "put both blocks in and still had no power".  Yep I'm pretty sure we only use 1 block at a time. ::)
 

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Steve in sunny Fla

Iron Butt
Industry Vendor
you must be a very easy rider, as acceleration without the foam is almost non - existent. it's very lean without the foam, and that's not good.

  The easiest thing you can do is just cut 1/4" off the side of 1 block and stuff it in there. easy  - peasy, and you'll probably be so close to perfect you couldn't tell the difference. And yes, it needs to be in the STOCK airbox, with the stock inlet in place. and there's WAY more airflow capacity on one side than one carbs worth... in fact I would guess it's closer to 3 carbs worth of flow.

  Years ago, Jim Snyder came up with a sliding restrictor door for the airbox inlet. You could do something like that. Or you could just cut the 1/4" off the side of one of the blocks and install it the way it was designed, because it actually works, and only takes about 2 minutes to do it....

    Steve
 

MAN OF BLUES

Guest
Guest
:)) :)) :)) :)) :)) :great: :rotflmao:

I can say for certain, that SolidWorks 3D model took wayyyyyy more time to create, along with measuring the snorkle, than it takes to jamb the foam block in... :rotflmao: :rotflmao: :rotflmao:

so much for "2 minutes"...  :D :D :D
(and in reality, the cross section of the open area of the snorkle is more than 4x the open area of a single carb, when the butterfly plate is half open....)...

yeh, I have SolidWorks and AutoCad 3D on my computers...  :rotflmao: :beerchug:
 

connie_rider

Member
Member
Tour 1, I build the sliding restrictor door that Steve mentioned.
Mine was installed with the Airbox Inlet in place.
I think Jim removed the Airbox inlet completely and build something similar.
Both worked but with Steve's help I removed mine and went to the foam. Never went back to my sliding restrictor door.

With all of that said, everyone that is replying here, "love's a project".
We're just saying that the foam works great, takes no time to install, and there may not be a way to improve on how it works.

I suggest you install the foam as Steve say's. {with 1/4" removed}
It will be very close to perfect.

PS: {after installing the foam} If I had a 3D printer and if I still wanted to see if I could do it, {just for the heck of it} I would next look into building a slider door that duplicates what the foam does.
                                                                      >:D

Ride safe, Ted
 

Steve in sunny Fla

Iron Butt
Industry Vendor
I received this email this AM, I did these carbs about a week ago.

"Steve,

Just a quick note to let you know that I've reinstalled the carbs and have performed the airbox tuning with the foam blocks. Wow! No more sluggish acceleration! First, I noticed the bike running more smoothly at idle and in general with the new refurbished carbs. Prior to the airbox tuning, I did a test ride and when attempting quick acceleration, there was a huge hesitation and bog-down until eventually it would start to pick up speed. When I put the foam block into the airbox intake, then did a test ride, the hesitation was gone and man did it get up and go with smooth, fast acceleration! I then took a few more rides with trimmed versions of the block, 1/4in at a time, with a test ride each time I trimmed (as you've instructed). When trimmed down to 1.5in, I noticed the hesitation come back a bit. I've put the full 2nd foam block in and will ride for a while with it. If my gas mileage is bad, I may go down to a 1.75in block, but with the full 2in block, it really performs! "

  Obviously he nailed it with a little testing. BTW, the full block is probably better in the cold months and 1/4" off for the warmer months. it's not huge, but I can tell the difference. Most probably wouldn't, but aggressive riders are more likely to.

  Steve
 

Tour1

Member
Member
I'll send a pm about the adjustable plate, though it will take some of the wind out of my sails on the design project.
I learned to drive sometimes in a box truck, my habits don't usually require all the C10's power.  I find the acceleration can be scary, I guess because I don't want to spin the rear out from under me just when I'm needing to get out of trouble.  Seems like stuff happens 4 times sooner when I only go twice as fast, too.
  I wanted to ask, what is the usual power band for the bike, then?  Without the 7th gear mod 6th gear is about 4000 rpm at slab cruising speed.  My tachometer doesn't have green & yellow stripes & I usually don't use high rpms except getting on the parkway where the ramps were sized for 35 mph speed limits.  Then I'm grateful it spins up without blowing up.
 
 

dc-concours

Guest
Guest
I have never had the bike spin out under me. I don't think this bike makes that kind of power even with the 7th gear mod which is for cruising.
 

bajasam

Scooter
everybody has a different range, for me i spend 95% of my time between 3K-5K rpm.if having a slippery rear end scares you,try finding a nice hardpack dirt road and practice accelerating til you feel it start to spin,after and hour of playing around you'll know what it's gonna feel like and wont be so scary. same senario that dirt bikers do for those who fear hitting deep sand at speed, best thing i did was take my dirtbike to the beach in mexico, after a weekend riding in sand was not even a concern anymore.
 

Tour1

Member
Member
Tour1 said:
...My air box has a venturi-ish restrictor on the back, with an open area equal to about the diameter of 1 carb...
I have to wear the dunce cap for a while.  I calculated the area of one carb using the square of the diameter instead of the square of the radius  :mad:
So the corrected figure is the stock restrictor has about 3.8 times the open area of one carb.
On a brighter note, I did the super-quick mod by snipping off 1/4" of foam and installing it in the right side intake.
Then I rode to work & back.  I tried to make it "whuff" but couldn't, although it's only about 15 minutes each way and I had to ride like an idjit just to open the throttle.  With the winter weather I'm still indoors working on the adjustable intake.
Life goes on  :motonoises:
 

jim snyder

Member
Member
Tour1 said:
Tour1 said:
...My air box has a venturi-ish restrictor on the back, with an open area equal to about the diameter of 1 carb...
I have to wear the dunce cap for a while.  I calculated the area of one carb using the square of the diameter instead of the square of the radius  :mad:
So the corrected figure is the stock restrictor has about 3.8 times the open area of one carb.
On a brighter note, I did the super-quick mod by snipping off 1/4" of foam and installing it in the right side intake.
Then I rode to work & back.  I tried to make it "whuff" but couldn't, although it's only about 15 minutes each way and I had to ride like an idjit just to open the throttle.  With the winter weather I'm still indoors working on the adjustable intake.
Life goes on  :motonoises:

I would mail you mine for the postage if you want to save some time.
 

MAN OF BLUES

Guest
Guest
Tour1 said:
Tour1 said:
...My air box has a venturi-ish restrictor on the back, with an open area equal to about the diameter of 1 carb...
I have to wear the dunce cap for a while.  I calculated the area of one carb using the square of the diameter instead of the square of the radius  :mad:
So the corrected figure is the stock restrictor has about 3.8 times the open area of one carb.
...
Life goes on  :motonoises:

:))

I was hoping you would go back and re visit those calc's...

now, factor in, as I also noted, the  actual downstream restrictions applied by the butterfly plates, and the actual slide cutoff... before, and as it opens....

the air is flowing baby...plenty of it, and the basis for Bubba's enlightenment...
 

Tour1

Member
Member
Jim Snyder said:
...I would mail you mine for the postage if you want to save some time.
I it fits in a flat rate box and you can't find a more deserving individual I'm willing to pay the postage.  Meanwhile this sketch is what I think I can do:
 

Attachments

  • DialAfoamSketch.jpg
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jim snyder

Member
Member
Tour1 said:
Jim Snyder said:
...I would mail you mine for the postage if you want to save some time.
I it fits in a flat rate box and you can't find a more deserving individual I'm willing to pay the postage.  Meanwhile this sketch is what I think I can do:

The one advantage to my design is it has been tested and works like a charm.
 

Daytona_Mike

Guest
Guest
DC Concours said:
I have never had the bike spin out under me. I don't think this bike makes that kind of power even with the 7th gear mod which is for cruising.
Mine would..and repeatable...and with a 7th gear mod.  All you have to do is install a Metzler 880 tire on the back and 3rd gear WOT at about 6k would break loose everytime. In wet weather...you only had to sneeze and the tire broke loose
 

jim snyder

Member
Member
Daytona_Mike said:
DC Concours said:
I have never had the bike spin out under me. I don't think this bike makes that kind of power even with the 7th gear mod which is for cruising.
Mine would..and repeatable...and with a 7th gear mod.  All you have to do is install a Metzler 880 tire on the back and 3rd gear WOT at about 6k would break loose everytime. In wet weather...you only had to sneeze and the tire broke loose

I remember when you burnt the rear tire off on Push Mountain Road.
 

Steve in sunny Fla

Iron Butt
Industry Vendor
Jim Snyder said:
I remember when you burnt the rear tire off on Push Mountain Road.

No kidding, that's an absolute fact. The tire literally melted and went flat. I would not have believed it had I not seen it with my own eyes.
 
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