Conversion to Pod Air Filters?

[Bumboo]

New to forum but not new to motorcycles! I just acquired a 2004 XII that had been sitting for several years...about 18K on the clock. It's pulling a Daytona sidecar. I pulled the carbs, cleaned thoroughly, removed all the smog crap (CA model though I'm in VA) replaced sans air box, and synch'd them. The engine starts and runs ok though without the surge air box and filter it seems to so lean as to need moderate some choke to run. What a PIA to remove and replace the carbs and air box. It's doable but much more aggravation than the same procedure on a GW1500 or injector service on the k series BMW's. I'm considering just doing away with the air box and going to K&N or other pod type air filters. Generally this requires some new jetting and mixture changes to get it right. Has anyone done this before with success? Best, MM in VA

[cranky]

... NOT a wrench, but read.... with success = NO! Someone with knowledge
will be along directly... methinks Ya need the airbox for smooth / good
running.... JM2C

[Bumboo]

Thanks. I'd agree. Without some experience I wouldn't try this at home. I am just hoping to discover someone who's sorted it out so I could avoid some of the trial and error in getting it dialed in. It's completely feasible but they normally don't just bolt up and give flawless performance without changing jetting and usually needle positions. I've done dozens of conversions from stock to free-flowing filters but this was usually to enhance performance and required fettling to get smooth running across the full power band. In this case I just want to make removing the carb's a much simpler and easier proposition; performance is secondary. With ethanol fuel having to remove and clean carbs is an almost an annual service regardless of how we try to manage the damn stuff. The trade offs are usually less fuel economy and sometimes issues with riding in prolonged rain; something to consider with a touring bike.

[cranky]

... I run Seafoam in my tank to keep'er clean....

[SgtSlag]

Pod air filters will never work on the OEM carb's: they are CV, or Constant Velocity carbs... The OEM air box was designed around the needs of these CV carbs -- pod air filters will never give the carbs the constant air flow properties they require. End of short answer.

Start of long answer... I owned a 1979 Honda CB750K, with CV carbs; owned it from 2006-2012, so this is relatively recent information (my XII is a 1993). I, too, was intrigued with pod air filters. I thought they would improve performance, and make the bike look nicer. I belonged to a CB750 forum. On there, I learned about the CV carbs which debuted on the CB750, in 1979 -- the year of my bike. The moderator, a genuine wrench, and guru, of the CB750's, warned everyone that the 750's from 1979 on, had CV carbs, and pod filters were a bottomless money pit -- don't go there, keep the OEM air box, and be happy with it. One gentleman did not listen. He claimed he had found the Holy Grail, after extensive trial and error, with many different jets, and settings.

When Tools, the moderator, asked him if had eliminated all flat spots in the throttle response, he admitted he could not get rid of one... Tools laughed, and told him, "I told you so..." End of long answer.

Carl Leo, the XII guru, factory trained technician, on this site, has rebuilt many carbs, but he has never discussed replacing the air box, or the carbs. He steered clear of this topic because he knows that the CV carbs will only work with the OEM air box. This is a touring bike, not a rocket. It can be quite fast, if you tear off the Tupperware, but then it is no longer a touring bike.

The OEM air box feeds, and regulates, the air pressure, into all four carbs, per the design engineers' calculations. It is tightly tuned to work as well as it can. They knew what they were doing, per their desired outcome. Mess with it at your peril

Alcohol-free gasoline (E-0) is sold by many gas stations. You pay more, but it is worth it, IMO. I have not had a carb issue since I bought my bike, and had it professionally cleaned, and tuned, in 2010. I store it for around five months, each year, with a full tank of SeaFoam'ed gasoline. I run SeaFoam through the tank, in the summer, around once per month, as a preventative measure. Zero carb issues in nine years...

I run E-10 if the stations I stop at, don't have E-0, when touring. Around home, I run E-0. It's available all over town.

Take the XII as it is, or get something different. There are ways to improve the performance, a little, but nothing that will turn it into a rocket. Not trying to rain on your parade, just trying to spare you time, hassle, and money. Throw away the OEM air box, and you will have a parts bike. Cheers!

[Mr Jensee]

He is talking about a 2004 model. I am sure there was no 2004 model. Last XII to roll off the assembly line was 2003.

[Bumboo]

Thanks for the generous and detailed comments. They are well received and conversion to a simpler intake system may be a bridge too far just now.

Correction: as someone pointed out, the bike is a '94. I guess my head jumped time when I wrote the original inquiry. Actually the side car the bike is tugging is a 2004.

My goal is not to improve performance but to simplify the process of removing the carbs for cleaning and service; a genuine pain with the exiting air box. Ethanol free gasoline is not an option in this area or anywhere along the Eastern Seaboard with a few rural exceptions. Ethanol gas is a scourge regardless of how it's managed. I own a business that is a full Honda/Tohatsu Outboard and Mercuriser dealership and probably 40% of our work is ethanol induced. Generally ehanol in older carbureted engines requires periodic cleaning of carbs regardless of how much Seafoam or Lucas or whatever is used; especially if the motor is allowed to sit idle for more than a month or so....a real likelihood with specialty sidecar rig.

While there is no technical reason why CV carbs can't be made to work with a less restrictive intake system, mod's, sometimes significant, are normally required to get them sorted out. I had wondered if someone had done so with any success. I guess not.

You are certainly right in pointing out that Kawasaki engineers did a remarkable job of getting it to run at all with all the emissions crap on the CA model I have.

I am an old, as in age 69, rider with a lot of builds and racing time. As for CV Carbs, I have used them with K&Ns, foam pods, and velocity stacks on CB 160's, CB500s, Benellis , and singles like the Yamaha SRX6. And I've fitted them to several BMW airheads for racing performance.
In most cases I was tuning for performance on the top end though they had to get up to speed without too much fuss. On the singles we tuned for better acceleration for shorter tracks or quick sport riding.

As you suggest, for now I'll probably stick with the air boxes, wrestle them back in place in and make it work.

Since my inquiry I have "almost" sorted out the issue with some K&Ns, new jetting, and a restrictor baffle. Performance is powerful and linear to about 80mph faster than I will ever ride with a sidecar. However, it's still so lean when cold that it's a difficult, if not impossible to start. If I "strangle" two of the K&Ns with a rag it lights off OK when cold. So, I have more thinking to do on this since starting is pretty important! Oddly, acceleration from idle is OK with no hint of running lean. I've ordered a set of salvaged carbs to experiment with to see if I can arrive at some solution.

Thanks again for the detailed reply. I'll keep you posted. MM in VA

[Mr Jensee]

Sir Carl Leo a man on here who owned a Kawasaki Dealership and sold more Voyager XII models than anyone in the nation recommended to me when I visited him to use an outboard motor gas treatment to keep your Voyager carbs clean so you wont have to constantly take them off (a real pain) to clean them. Start the bike at least once a month and rev it up after warm up a couple of times to circulate the treatment. 6 oz per 6 gal. tank.

You mentioned that it runs cold at start up. Japanese engines are all pretty much cold at start up and will stumble without the choke on. Once warm the bike should idle at 800 rpm. Fuel injection has pretty much eliminated cold running at startup on modern bikes but these aren't modern bikes. I found the hardest part of getting the carbs back on was reinstalling the cables and getting the air box boots back on. I have used a hair dryer to heat up the plastic to make it easier to slip on the carbs.

[cranky]

.. brand? Anything better than Seafoam? TIA

[triton28]

The gas treatment is probably Star Brite Star Tron Fuel Treatment.

[Bumboo]

Success in converting to K&N filters with removal of air box! 1994 Voyager XII. Starting with a California Model (in Virginia) I removed all the emissions components and the air boxes, capped all vacuum ports on the carbs and bolted it all up with 3" K&N pods. I also installed a K&N crankcase vent filter to the crankcase nipple that once was connected to lower air box. While it ran I found the mixture way too lean and starting was tough without "suffocating" two of the K&N's with a rag to richen the starting mixture. I then went to 115 main jets and 42 pilot jets vice the 108 mains and 38 pilots that were installed. That was much improved with easier starting but it still seemed lean at idle through modest acceleration. I then upped the pilot jet to a 45. This allowed to it start instantly when cold with the carb enrichment circuit engaged and it quickly settled down to nice idle with no enrichment circuit after about 20 seconds of warm up.

A test ride was satisfactory with linear acceleration to about 90: as high I was willing to take it. After about 25 miles of mixed riding the plugs were beginning to brown slightly. I noted some slight hesitation above about 70 mph. After renewing the CV diaphragms and moving the needle up one "lift" washer" this vanished.

Since I had not ridden the bike before I can't say whether performance is better or not. I can say that now I can now remove the carbs in about 10 minutes without suffering through the agony of wresting with the air boxes. Service and cleaning is easy now and I can fine tune again if I need to. After about 125 more miles all seems good. I am hoping the side covers and fairing will provide adequate rain protection. We'll see about that. The bike is fitted with a Daytona 2+2 sidecar with is about 300 lbs. The hack was not on for the test runs. I'll let you know how it goes once it's all back together. MM

[Lucasind]

Congrats on your conversion to a "airbox-less XII ! I spent a Saturday 4 years ago " experimenting " with this idea on one of my Voyagers . I figured since I had the carbs off , and 2 other Voyagers to ride .....go for it. I have a drawer in my workshop filled with various used jets from working on bikes over the past 40+ years, and could not get it perfect,mostly due to not having a endless supply of various sized jets ( times 4 ) . So I ended up putting it back to stock , and the bike ran perfect . Yes , that 2 part Kawasaki air box is one of the biggest PITA's in existence , ! The more times you do it , the faster you get at it, but not something most guys want to practice ! Being over 6ft tall , I always wished the frame be a bit longer , giving a couple more inches of room behind the airbox, giving a guy some room to work on the carb area , and stretch my legs out more when riding ! by the way , where did you order your selection of jets from ?

[Me Again]

I did this to my KZ1000 LTD back in 1977.
Bike ran like a raped ape but MPG dropped from 50mpg to 35 mpg.
Not a good thing when you only have a 3 gallon tank

[cbrfxr67]

Great to see somebody doing mods and succeeding! awezome!