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Airfilter airbox performance?

4K views 22 replies 8 participants last post by  Gary Gregory 
#1 ·
I have a 1999 K1200 LT I was wondering if anybody has ever changed the airfilter airbox to one off a 2003 K1200 RS they look like they have larger air velocity stacks going from the box to the throttle bodies, I know it would probably move the HP and torque numbers up the RPM range would the computer be able to handle it anyone know and what difference in gas mileage and power?
 
#2 ·
I doubt it would give much since the RS has higher compression pistons, a different fuel map, different throttle bodies (still 34 mm) and cams. Just changing the air stacks would not give a noticeable difference.
 
#3 · (Edited)
Of course the air-box is different on K1200RS, however this only a small part of the equation:
1) K1200RS have higher compression pistons

2) K1200RS have different camshafts (intake and exhaust)

3) K1200RS have larger throttle-bodies (34mm for early K1200LT, 36 for K1200LT 2004-2009 , 38mm for K1200RS)

4) And OF COURSE the Motronic-EFI sysetn is tuned differently according to effects of all above items.

In my opinion, you will achieve noting (or very little) by changing only a single small part of this whole system. Unless you modify all the above items, or install a K1200RS engine (with its matching ECU) you are on wrong track ;-)

The 2005-2009 K1200LT horsepower is somewhere in between the early K1200LT and a K1200RS, because they have increased compression , changed Camshafts profile, and increase the throttle-bodies by 2mm. Not enough to acheive the full 130HP of the K1200RS, but better tuned for low end torque - something a 900 lbs beast needs...

P.S.: Did all this typing for nothing.... as I saved my message I just saw Jzeiler has given you roughly the same answer ;-)
 
#4 ·
Unless you modify all the above items, or install a K1200RS engine (with its matching ECU) you are on wrong track ;-)
Early on, there was a dealer in Texas who swapped an RS engine into an LT.

Several of us were quite interested, and I spoke with the dealer who said it wasn't worth the time and expense as the LT actually did much better tuned for torque than top end HP.

YMMV...
 
#6 ·
Update I purchased 03 k1200RS air box the box would not fit so I pulled the velocity stacks off and installed on my stock box rode around the block wow I think it is going to be great no lagging great throttle response I will give update on fuel mileage and performance I had rode with 3 other bikes so I will know when I race again, I do think the bigger velocity stacks will help.
 
#7 ·
I'm struggling to understand this. My 08 LT has absolutely no lag and just as good of throttle response as any bike I've ridden. My last bike being a CBR1100XX.

On a normal day my mileage is:
80mph=38mpg
70mph=44mpg
55mph=50mpg

I recall reading the newer LTs have about 5mpg less than the 04 and older. I think there may be a bigger problem with your bike that's causing the throttle response and mileage issue.
 
#9 ·
Update on 03 RS air box I purchased it from salvage yard when I had the Tupperware off and gas tank for other maintenance I tried to install the complete air box it would not fit so I took the velocity stacks off the RS box and installed them on my LT box reinstalled on throttle bodies any way here are seat of pants results throttle response is still good it might be a little flat at 2500 rpm in 5th but it still pulls when you get to 4000 to 4500 it starts pulling hard I was running on the freeway @ 70 rolled the throttle wide open I shut it down at 125 and it was still pulling on this same ride went about 60 miles averaging 80 to 85 I was getting 36.5 mpg driving normal I think it will get around 40 to 45 mph I did unhook the temp sensor in air box I had followed a couple guys racing before I installed the velocity stacks they pulled away from me I will give them a run and see how they do now I took the trunk off and I weight 175 lbs will I put the stock velocity stacks back on no way.
 
#13 ·
throttle response is still good it might be a little flat at 2500 rpm in 5th but it still pulls when you get to 4000 to 4500 it starts pulling hard
Have you looked at the stock curves for the LT?
 

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#10 ·
Oy! That is the longest run-on sentence I've seen in quite awhile.
 
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#11 · (Edited)
I'm glad it worked for you. One thing I will add in is an experience I had when I was just getting in to motorcycles at around age 17.

A friend of mine just got his new ZX-6R (his first bike) and felt it didn't have enough power, so he went to a guy to get it jetted. You may remember the ZX6R was one of the last 600 supersport bikes to go fuel injection. The carbs worked great, and it had the most power of any of the 600s out there.

I had a Ninja 250 at the time and he encouraged me to jet mine to. Being in Colorado, I thought this couldn't hurt.

So my friend comes back with his newly jetted bike. Not even 1000 miles on the odometer yet, and now it it's jetted. Well, it basically wouldn't run under 6000 rpm. It would bog down and backfire in the exhaust, it was running so rich. But he said, "WOW does it have a TON MORE power up top!"

My bike was jetted about 3 sizes too rich as well. The pilot screws were completely screwed up too. So I did some research and put the proper jets in. It ran great for the next several years.

My friend went back to the bike shop after about 3 months of barely being able to ride in the city. The mechanic eventually got it running right after six months on. My buddy then decided he needed a GSXR750 and traded his bike in for one.

I maintain you can learn a lot from motorcycling.
 
#15 ·
On the pulling hard I am sorry I should have said it started pulling harder. Throttle response is good maybe better than stock, I payed around 27.00 dollars for box and shipping A lot better than for a $100.00 plus for chip and would have had to purchase a different computer to put it in, I have personally tried chips whit no difference on cars, As far as dyno charts it depends whose dyno and what conditions and altitude. I have not had a chance to do the comparison yet with other bikes I will let you know. Factory dyno charts have to stay in certain parameters to be able sell there vehicles and meet standards world wide.
 
#17 ·
I concur I run a 2.82 vs. stock 2.62. Now I hit the rev limiter at 57 MPH in 1st where before I hit it at 62 MPH. Did it primarily for two up, trailer pulling to get off the line easier.
 
#18 ·
Thanks for the info on the gear changes. I am sorry for the long sentence no excuse I hope the guy that was reading it did not run out of breath. I think I had a few beers. Also I thank everyone for the advise . I am new to the KLT and I am finding I really like it. The only thing is the foot pegs are a little close in am getting use to them , I have my seat on the high setting any way :smile: thanks for all your help. Oh I am a old kid at 73.
 
#21 ·
I have a set of the Suburbans on Carpathia. Just perfect for those of us a little longer in the leg. Well constructed. Look great. Easy to install. No complaints,

DW
 
#22 ·
Will I ordered the suburban machinery lowering peg kit. Well my bike is still running great, I guess I should be careful I ran it up to 8500 thru 3 gears with no issues, I am going to take it easy on the old gal being 21 years with close 53000 miles. I will let you all know how the pegs work out.
 
#23 ·
Re: Airfilter airbox performance? update

The bike is running great with new velocity stacks. Installed the suburban peg lowering kit, easy install working great more relaxed riding legs not cramped. Installed a excel XXL seat cover 11 bucks Amazon love it. New tires sinko 777 rear sinko verge11 radial front love them. Galfer SST break lines and fluid flush. new plugs fluid change. Rock led in low beam can see at night. plus a lot of other service, what a adventure. Thinks to Illinois club video's and you guys on this forum. Gary
 
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