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Main Area => General GS500 Discussion => Topic started by: halffttime on May 03, 2016, 03:45:37 PM

Title: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: halffttime on May 03, 2016, 03:45:37 PM
I know you'll have to re-jet the carbs and what not. If you did re-jet, did the bike perform to your standards, or perhaps maybe even better than stock? Also, were you able to do it by staying with the stock exhaust?

I hate the stock airbox with a passion. It's so bulky and I'm always struggling trying to jam it down there.

I already have the lunchbox and also a rejet kit from buddha. I tried switching it out a couple of years ago but had to switch back to stock because the bike had problems starting and running with the lunchbox. I never did figure it out...

halp pls.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: lucas on May 03, 2016, 04:19:59 PM
Check back with Buddha to ensure you have the optimal size for your setup.

If you change the airbox without also putting on a free flowing exhaust you may have trouble jetting it properly.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: halffttime on May 03, 2016, 06:12:05 PM
Quote from: lucas on May 03, 2016, 04:19:59 PM
Check back with Buddha to ensure you have the optimal size for your setup.

If you change the airbox without also putting on a free flowing exhaust you may have trouble jetting it properly.

i'd love to run an open pipe, and i have one all ready wrapped and everything... but damn thing is so loud. also, i found the bike doesn't perform that well with it.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: lucas on May 03, 2016, 10:34:00 PM
Wear ear plugs and have fun  8)
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: Big Rich on May 04, 2016, 05:02:44 AM
There's a difference between "free flowing" and "wide open". Free flowing is pretty much any aftermarket exhaust, wide open will get you attention from the police and neighbors.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: The Buddha on May 04, 2016, 05:42:27 AM
Airbox -> K&N is a standard swap. But K&N with stock pipe makes for lots of issues.
Anyway K&N also is pretty dirty for the motor, I tend to push people away from it if I can, however K&N with pipe, or pipe and air box or all stock is all jettable pretty easy.

K&N and pipe gives you some extra revs on top about 500 or so under load (6th gear with my 250#) and makes extra power all the way across. Maybe 3-4hp (10%) all the way across.

Stock airbox and filter with pipe you get maybe 200 rpm up high, if that, and 2-3hp up top, but all the way through the rev range, it still gives you that 2-3hp. Essentially its on par with the K&N and pipe all the way through to maybe 3/4 throttle. Makes it very very useable in real life.

Both these setup's should give you rideability and useability. As in cold starts, quick warm up's and better running all across the all weather and conditions. They also run cooler than stock. That is your biggest gain. I hate the airbox too, but I look at it as 1 time pain for long term gain. Helps the motor live longer.

Cool.
Buddha.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: halffttime on May 04, 2016, 06:07:26 PM
Quote from: The Buddha on May 04, 2016, 05:42:27 AM
Airbox -> K&N is a standard swap. But K&N with stock pipe makes for lots of issues.
Anyway K&N also is pretty dirty for the motor, I tend to push people away from it if I can, however K&N with pipe, or pipe and air box or all stock is all jettable pretty easy.

K&N and pipe gives you some extra revs on top about 500 or so under load (6th gear with my 250#) and makes extra power all the way across. Maybe 3-4hp (10%) all the way across.

Stock airbox and filter with pipe you get maybe 200 rpm up high, if that, and 2-3hp up top, but all the way through the rev range, it still gives you that 2-3hp. Essentially its on par with the K&N and pipe all the way through to maybe 3/4 throttle. Makes it very very useable in real life.

Both these setup's should give you rideability and useability. As in cold starts, quick warm up's and better running all across the all weather and conditions. They also run cooler than stock. That is your biggest gain. I hate the airbox too, but I look at it as 1 time pain for long term gain. Helps the motor live longer.

Cool.
Buddha.

What pipe are you talking about in both set ups you've mentioned? Are you talking about stock, aftermarket, open pipe... Thanks for the reply Buddha, I read it over and over again but couldn't understand what pipe you were trying to mention.

Also, are you a buddhist by any chance, lol?
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: TeamSky1975 on May 06, 2016, 09:37:51 AM
I recently removed the airbox and fitted a K&N lunchbox. Because I'm building a cafe racer-something I also fitted a nearly open Megaton exhaust. I had to rebuild the carbs completely and had to fit pretty big jets to find a nice balance in the fuel/air mixture. Currently the bike runs nice, except at the very lowest revs, it feels a little "unsure". Which is normal, because of the size of the jets, it's hard to find a perfect setting... I might try a Dynojet kit later on... Is it worth it? Yes and now, it depends on what you're looking for...
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: halffttime on May 06, 2016, 06:16:15 PM
Quote from: TeamSky1975 on May 06, 2016, 09:37:51 AM
I recently removed the airbox and fitted a K&N lunchbox. Because I'm building a cafe racer-something I also fitted a nearly open Megaton exhaust. I had to rebuild the carbs completely and had to fit pretty big jets to find a nice balance in the fuel/air mixture. Currently the bike runs nice, except at the very lowest revs, it feels a little "unsure". Which is normal, because of the size of the jets, it's hard to find a perfect setting... I might try a Dynojet kit later on... Is it worth it? Yes and now, it depends on what you're looking for...

Let's see your cafe racer. I want to compare it to my own cafe racer.  :cheers:

I'd like to see your wire tuck in particular. My wires are a mess, lol.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: TeamSky1975 on July 25, 2016, 12:08:47 PM
(http://i.imgur.com/uF0ZVEr.jpg)
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: chornbe on July 25, 2016, 12:53:12 PM
Quote from: halffttime on May 03, 2016, 06:12:05 PM
Quote from: lucas on May 03, 2016, 04:19:59 PM
Check back with Buddha to ensure you have the optimal size for your setup.

If you change the airbox without also putting on a free flowing exhaust you may have trouble jetting it properly.

i'd love to run an open pipe, and i have one all ready wrapped and everything... but damn thing is so loud. also, i found the bike doesn't perform that well with it.

Open pipes are, pardon my french, completely idiotic for on-road, typical use. A measured amount of proper back pressure is all but required for proper low-rpm use... irritating noise aside.

Don't be in such a hurry top fully open up the breathing unless 90% of your engine's time is spent at WOT, way up in the revs.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: Weedy64 on July 25, 2016, 01:43:42 PM
Yes...all done with a Vance and Hines header with a dB killer, good performance no longer excessively loud with dB K.  Sounds like a real bike.

Never even tried it with the stock muffler and Cat.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: lefty1615 on July 25, 2016, 11:04:43 PM
Just fit a lunchbox on my bike and threw 150 mains into it per buddha's advice (canadian model so the pilots are already 40's, if i remeber correctly after a few beers) and the bike is running fine if maybe a bit sluggish. I am getting it into the shop on Wednesday to get a yoshi pipe on there that I bought on craigslist so i think that will sort out the throttle response.

Anyone experience some wicked noise from the lunchbox when you open the throttle up? I'm thinking it got dislodged or something just cant look at it until Wednesday morning before I give it to the muffler guys but since this popped up maybe someone has some insight.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: Mr. BIGGZ on July 25, 2016, 11:56:09 PM
Quote from: lefty1615 on July 25, 2016, 11:04:43 PM
Just fit a lunchbox on my bike and threw 150 mains into it per buddha's advice (canadian model so the pilots are already 40's, if i remeber correctly after a few beers) and the bike is running fine if maybe a bit sluggish. I am getting it into the shop on Wednesday to get a yoshi pipe on there that I bought on craigslist so i think that will sort out the throttle response.

Anyone experience some wicked noise from the lunchbox when you open the throttle up? I'm thinking it got dislodged or something just cant look at it until Wednesday morning before I give it to the muffler guys but since this popped up maybe someone has some insight.

I'm interested in hearing how things turned out.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: Big Rich on July 26, 2016, 06:37:31 AM
The stock airbox has a couple functions - one of which is to control noise from the intake side of the engine. Back in the 70's, they discovered that making a bike quiet not only came from the exhaist, but also the intake. So with a K&N, you will definitely hear a loud roar from the engine.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: Mr. BIGGZ on July 27, 2016, 12:22:06 PM
Quote from: halffttime on May 03, 2016, 03:45:37 PM
I know you'll have to re-jet the carbs and what not. If you did re-jet, did the bike perform to your standards, or perhaps maybe even better than stock? Also, were you able to do it by staying with the stock exhaust?

I hate the stock airbox with a passion. It's so bulky and I'm always struggling trying to jam it down there.

I already have the lunchbox and also a rejet kit from buddha. I tried switching it out a couple of years ago but had to switch back to stock because the bike had problems starting and running with the lunchbox. I never did figure it out...

halp pls.


It's been a few months since you posted this, did you give it another go? How did things turn out? Did you swap out the exhaust?
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: Mr. BIGGZ on August 09, 2016, 12:34:21 AM
Bumping this thread looking for more feedback. I've checked the wiki and read countless posts about jetting, but I still see a lot of posts like this on where people can't seem to get the bike to run right with the lunchbox, reject and an exhaust.

Does anyone have a good running setup with a lunchbox, rejet and slip on?  :dunno_black:
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: Weedy64 on August 09, 2016, 12:16:52 PM
These things go better as a matched system.  The oem exhaust with its T shape pipe joint instead of the smoother Y transition of a full system kinda of precludes the use of the high flow intake provided by the lunchbox.  The two things are fighting each other instead of helping each other and you would be trying to mediate by jetting.  :cheers:
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: halffttime on September 03, 2016, 10:05:37 PM
Quote from: Mr. BIGGZ on July 27, 2016, 12:22:06 PM
Quote from: halffttime on May 03, 2016, 03:45:37 PM
I know you'll have to re-jet the carbs and what not. If you did re-jet, did the bike perform to your standards, or perhaps maybe even better than stock? Also, were you able to do it by staying with the stock exhaust?

I hate the stock airbox with a passion. It's so bulky and I'm always struggling trying to jam it down there.

I already have the lunchbox and also a rejet kit from buddha. I tried switching it out a couple of years ago but had to switch back to stock because the bike had problems starting and running with the lunchbox. I never did figure it out...

halp pls.


It's been a few months since you posted this, did you give it another go? How did things turn out? Did you swap out the exhaust?

Hey. I just got to trying to start the bike again, I have the lunchbox on with slip on delkevic muffler. I have't gotten the big to start yet. I was thinking there might be too much air flow and not enough backfire, but stuffing the muffler while i start the bike still doesn't help. I'll get back to you when i figure it out.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: Endopotential on September 04, 2016, 01:51:54 PM
Quote from: Mr. BIGGZ on August 09, 2016, 12:34:21 AM
Bumping this thread looking for more feedback. I've checked the wiki and read countless posts about jetting, but I still see a lot of posts like this on where people can't seem to get the bike to run right with the lunchbox, reject and an exhaust.

Does anyone have a good running setup with a lunchbox, rejet and slip on?  :dunno_black:

In case you were still working on this....

K&N lunchbox filter and new exhaust.
Total beginner's luck, but I was lucky to get it spot on with 20 / 60 / 147.5 jets following Buddha's advice.  Also 2.5 turns out on the air mixture screws; 2 washers on the jet needle
http://gstwins.com/gsboard/index.php?topic=70953.0

The bike idles well, and seems to have even power across the throttle curve
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: GTiRolla on September 23, 2016, 11:34:34 PM
I'll post some more details about mine when I can, but I have a 2008 with box filter, Iridium plugs, Yoshi slip-on and its been rejetted.

I got the local guys to check my tune on the dyno whilst doing a service and new rear tyre and luckily enough was pretty spot on :)
(http://uploads.tapatalk-cdn.com/20160924/b9a059bc277b3dea9bc9021716df8737.jpg)

Sent from my Nexus 6P using Tapatalk

Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: Mr. BIGGZ on October 09, 2016, 11:19:26 PM
Quote from: Endopotential on September 04, 2016, 01:51:54 PM
Quote from: Mr. BIGGZ on August 09, 2016, 12:34:21 AM
Bumping this thread looking for more feedback. I've checked the wiki and read countless posts about jetting, but I still see a lot of posts like this on where people can't seem to get the bike to run right with the lunchbox, reject and an exhaust.

Does anyone have a good running setup with a lunchbox, rejet and slip on?  :dunno_black:

In case you were still working on this....

K&N lunchbox filter and new exhaust.
Total beginner's luck, but I was lucky to get it spot on with 20 / 60 / 147.5 jets following Buddha's advice.  Also 2.5 turns out on the air mixture screws; 2 washers on the jet needle
http://gstwins.com/gsboard/index.php?topic=70953.0

The bike idles well, and seems to have even power across the throttle curve

Hey Endopotential,

Saw your build thread and your bike looks pretty cool. You don't see too many GS500s in our neck of the woods, let alone a custom one. I really like the paint scheme, your tail section, and how clean your bike looks. I've been offline lately with grad school obligations, but worked on the GS this weekend. I finally got around to installing my R6 shock, Lunchbox and rejetting. Being that you're in CA too, what did you do with all of the extra hoses? Like the PAIR hose and the Evap box under the battery?

I have hoses hanging everywhere and don't know if it's okay to remove PAIR hose or to plug it? I jet to 22.5, 65, 147.5 with the lunchbox and the slip on exhaust. Feels rich and I have a tough time getting it started. The bike dies with choke, unless it's warmed up and I need to give it throttle to start and keep it from dying.

Anyways, looking forward to hearing from you.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: Endopotential on October 16, 2016, 09:15:51 PM
Biggz - PM me if you want to drop by and work on your bike.  I'm over in Pacifica.

Your jetting does seem to be richer than mine, esp if you're running a slip on.  I cut off the distal half of my pipe and welded on a pretty free flowing exhaust, so that's even more of a difference.

And if you're running rich, doesn't quite make sense why you'd have to give it more throttle to keep it running...

One thing I learned on my bike - the metal bar linkage on the front of the carb that controls the chokes can bind easily.  I had to put some plastic washers on mine to level them out and make the whole system slide easily back and forth.  If the system binds, you may not be in the choke on/off state you think you're in.
Title: Re: has anyone successfully replaced the stock airbox with a k&n lunchbox? or pods?
Post by: mr72 on October 17, 2016, 09:34:49 AM
Quote from: Mr. BIGGZ on October 09, 2016, 11:19:26 PM
Feels rich and I have a tough time getting it started. The bike dies with choke, unless it's warmed up and I need to give it throttle to start and keep it from dying.

So, if I can parse what you are saying:
- it won't start on choke
- it dies on choke unless the engine is warmed up
- it requires throttle to start and run until it's warmed up

My questions:

when it's warmed up, does the idle speed increase when you turn on the choke?

have you checked the plugs? what do they look like?

did you recently replace the pilot jet?

This is opposite of how it should work, as I am sure you are aware... so I have to ask a really dumb question... are you sure you are turning the choke on and off in the right direction? Towards you is choke-on, and away from you is choke-off. I get this mixed up every once in a while.

If you verify you are indeed working the choke correctly, and indeed it is behaving opposite of normal, then I would think that it's rich when you start it and gets very lean when it warms up. To me this sounds like it could be either a vacuum leak, or a clogged fuel passage in the carbs.

I think your jetting is probably ok. I would go through the carbs looking for leaks and ensure o-rings are good, passages are clear, and then once you know there are no vacuum leaks or clogged fuel passageways then you should reset the idle mixture until it will start with the choke on (should be factory -2.5 turns) and go from there.