Author Topic: Adjustable air box intake  (Read 9053 times)

Offline turbojoe78

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Re: Adjustable air box intake
« Reply #15 on: May 12, 2013, 02:38:06 pm »
Wow, you guys have been busy! Some cool stuff there. I use foam with my kit because it keeps the cost and work to a minimum, and it works as well as any high-zoot restrictions. In fact the name "2 minute mod jet kit " was developed here on this forum several years ago, because we could change the jetting "in 2 minutes". We discussed making adjustable restrictors, and actually Jim Snyder is the first to have done so. Upon reviewing costs, etc on various threads, it seemed that the average connie owner - being a "frugal" guy - would be as happy with foam, as long as it was easy to install and it worked.

What I find most interesting is that when I first introduced the idea of restricting the intake for power, it met with a LOT of questions. Common hotrodding dogma has always been to open the intake, I was advocating to restrict it. Heck, there's even a factory sticker on the intake that says "do not let anything obstruct this airbox intake". Now  Here we are some years later, and restricting the intake is just "the accepted way to do things". Funny how that works... Steve


Steve, I had all the stuff I needed to create my version just laying around asking to be used up. (except the round wood stock, cost me around $3.00)

I think last time I had spoke to you we discussed me changing all the jetting from the 36mm carbs over to the 32's so I knew there was going to be allot more tuning and then dyno runs.  I already had the 36's out to change the fuel rail "O" rings so getting the airbox out to play with it was no problem.  Also had plenty of time to experiment during the long cold winter.
Joe
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Offline kzz1king

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Re: Adjustable air box intake
« Reply #16 on: May 12, 2013, 04:16:03 pm »
Wayne, the cams push the top of the snorkels down to close up the openings on both sides evenly.

The first picture shows me closing one side down by hand to show what it looks like in use, the second picture shows how I cut
the top edge on the 90* side and cut toward the middle of the curved side.
Thanks Joe, I am too lazy to  do it but the next time those carbs are out!  :D Maybe. Well thought out sir.
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Offline Yamahawk

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Re: Adjustable air box intake
« Reply #17 on: July 31, 2014, 04:34:01 am »
Interesting idea... my 1982 Yamaha XZ550 Vision has this idea already, it has a flapper door in the intake opening of the airbox that operates under spring tension and venturi vacuum and later, as a service bulletin fix, a vacuum operated flapper, with a vacuum tube from the replacement top of the front carb as a cure for the Vision 'stumble'... those carbs are down draft and sorta like Weber 1 bbl carbs, with accelerator pumps, so the carbs needed the increased vacuum to flow fuel, hence the restriction of the intake air... with a couple nickels taped to the flapper, it would then give more restriction, to give a better fuel flow... and less stumble under full throttle... hmmm.

Offline RFH87_Connie

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Re: Adjustable air box intake
« Reply #18 on: July 31, 2014, 12:12:59 pm »
Well, since it came back to life, I have a question that I just haven't had the time to diagose.  I have the "power" kit from Steve with pretty much 40% foam blocking (almost one complete snorkle opening).  No engine mods other than the 4 degree advance plate that has been in this thing for years, a K&N filter (properly oiled as far as I can tell), and T-Cro's coils.  When cold, it starts up great with a hit of the choke, I give it a few seconds to smooth out, and away I go.  Runs like a top in all RPM ranges.  If it is an exceptionally hot day, it will sometimes stumble at a traffic light and will sometimes want to cut off if I don't add a few RPMs.  It it does cut off under this condition, it needs a little bit of cranking with absolutely NO throttle.

So, does is this mean I need to ADD a little bit more of the blocking foam?  Is it better or any difference to split the blocking to each snorkle opening?  For those running foam blocks, how much are you using (as a percent)?
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Offline turbojoe78

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Re: Adjustable air box intake
« Reply #19 on: July 31, 2014, 06:49:33 pm »
Well, since it came back to life, I have a question that I just haven't had the time to diagose.  I have the "power" kit from Steve with pretty much 40% foam blocking (almost one complete snorkle opening).  No engine mods other than the 4 degree advance plate that has been in this thing for years, a K&N filter (properly oiled as far as I can tell), and T-Cro's coils.  When cold, it starts up great with a hit of the choke, I give it a few seconds to smooth out, and away I go.  Runs like a top in all RPM ranges.  If it is an exceptionally hot day, it will sometimes stumble at a traffic light and will sometimes want to cut off if I don't add a few RPMs.  It it does cut off under this condition, it needs a little bit of cranking with absolutely NO throttle.

So, does is this mean I need to ADD a little bit more of the blocking foam?  Is it better or any difference to split the blocking to each snorkle opening?  For those running foam blocks, how much are you using (as a percent)?

How many turns out are your idle air screws?   If it only does that when it's really hot my thought is it could be running a little rich at idle.

An easy test could be you turning your idle air screws in 1/8 turn and see if it still runs like that when hot.
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Offline RFH87_Connie

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Re: Adjustable air box intake
« Reply #20 on: August 01, 2014, 05:13:54 am »
I have them out 2 turns per the "kit" instructions (I think that is what it said).  I'll give it a try.  So is 40% blockage a decent or standard amount of "blocking"?
“I can truly say I had rather be at home at Mount Vernon with a friend or two about me, than to be attended at the seat of government by the officers of State and the representatives of every power of Europe.” - George Washington

Offline turbojoe78

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Re: Adjustable air box intake
« Reply #21 on: August 01, 2014, 05:27:24 am »
I have them out 2 turns per the "kit" instructions (I think that is what it said).  I'll give it a try.  So is 40% blockage a decent or standard amount of "blocking"?

I'm guessing that your foam for 40% blockage is around 1-3/4" long, I believe that is what SISF recommends as a starting point and for some it works just fine.

If you have another piece of foam you could try cutting it 1/8" smaller than your current size and see how that works but I would only make one of the adjustments at a time so you can see how each difference affects your bike.

Right now I'm running at 36% to 37% blockage and the bike is running great, but I've got SISF's power cams and very different jetting than his standard 2mm jet kit.
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Offline RFH87_Connie

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Re: Adjustable air box intake
« Reply #22 on: August 01, 2014, 05:28:45 am »
Thank you Sir - Just what I was looking for.
“I can truly say I had rather be at home at Mount Vernon with a friend or two about me, than to be attended at the seat of government by the officers of State and the representatives of every power of Europe.” - George Washington