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Discussion Starter #1
Just wondering, anyone know how much of a change in gas mileage after doing the L box mod,.22 cent mod and pilot screw adjust ?
 

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If you tune it properly and ride the same, none.

Efficiency is a good thing. More efficient breathing lets the engine spin easier. Less energy is consumed moving air within the engine itself, less mechanical effort is required to produce a certain amount of power.

Less mechanical effort means less air must be burned, requiring less fuel to burn it. Cruising at a steady speed will take very slightly less fuel than it did to cruise at the same speed previously, with all the restrictions. To realize this gain the carburetor must be tuned perfectly, unfortunately few are.

Most folks will argue this, as they lost mileage when they did the mod. Usually by trying one or two main jets, feeling more power and calling it good, setting the screw at some arbitrary number someone else used, and taking whatever fuel flow change happens from whichever size washer they happened to put on the jet needle. Most riders really don't understand the intricacies of carburetion, some don't even grasp the basic concepts of the different carburetor circuits. And of course there's the wrist factor, nobody does performance mods to a bike to ride exactly the same speed and use the same acceleration as they did before.

If hours and hours of experimentation (days and weeks really for those of us without a dyno) is done to get everything as close to perfect as possible, jets, needles, screw positions, slide cutouts, etc. your mileage could even improve, as the bike is tuned for emissions from the factory, not for maximum gas mileage. They are not the same.

Realistically your mileage will drop just a little bit, as even with all this perfection, if you choose to put forth that effort, in the end there is still the wrist factor.
 

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Discussion Starter #3
thanks tkent02, I don't ride agressively, but do a lot of hiway, so I should be happy with some mods like these.
 

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L mod opens up the airbox intake, 22 cent mod uses 22 cent washers to raise the jet needle, adjusting the idle screw lets you tweak the idle and low power circuit in the carb. These mods, if done correctly basically let the engine run as well as it would if the EPA had no say in it.
 

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.22 cent mod

Does anyone know if there is a posting where someone has done all of this airbox and carb mod and done pictures along the way to make it easier for us newbies? Also, where the heck is the snorkle located on these beasts?
Thanks
Intotheabis
 

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Does anyone know if there is a posting where someone has done all of this air box and carb mod and done pictures along the way to make it easier for us newbies? Also, where the heck is the snorkle located on these beasts?
Thanks
Intotheabis
Not that I'm aware of.

The snorkel is way at the back of the air box on the left side. If you remove the left side panel you'll see it at the back, on the top of the air box. It can be a real sumbitch to get out.

The L-mod looks like this, and when done this way is easily reversed with 1" plugs:



You could also just cut an L-shaped hole instead of poking the holes. That hose next to the battery terminal has been plugged with a large vacuum cap. It was part of the CA evap system.

There are some pictures out on the 'net of the 22cent mod, I just can't remember where I saw them. Perhaps someone else will know.

Tom
 

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This subject is on my mind quite a bit as of late since I can't give a fact based
scientific explanation of the mpg's after the mods. One of the guys here on the forum
pm'ed me and wants to do a full tank side by side comparison ride/ hangout type thing.
Sounds like a great time actually and we may do it this summer.

It's just plain weird that in the early 90's the Geo Metro was advertising 58 highway
mpg, my Harleys both got 50 mpg's one with the 1200 engine, and the twin cam
hadda 1450 cc block. Those Geos had to be between two and three thousand pounds
yet we get the same 50 or slightly better mpg's with the KLR's when tuned carefully
for elevation and taking it easy on the throttle hand.

Why???

By doing the pcv mods I lost a LOT of engine braking under closed throttle
deceleration. That tells me the engine isn't working against itself so hard anymore.
With the intake and exhaust opened up the engine breathes easier, but requires
richening to compensate or risk detonating itself to death by holing the piston.

My engine is slightly richer on AFR, but revs freer and gets the same or better
mpg's. Then again, that wacky Metro is a cage and got the same mileage.
Why is our mpg the same after fattening the mix, and why can't we get closer
to 100 mpg's with our water cooled engines?

I'm obviously no rocket scientist, but intelligent enuff to understand basic
principles. It would be nice to have ammo for discussions like this.
Instead, I halfta say, "I dunno, it just runs better and doesn't use any more
gas than before." The 150 main is because the Great Lakes where I live is not
too far above sea level. (Maybe I should go down to 145.)

CheapMark
 

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I helped my brother do the 22 cent mod, the L mod, new exhaust, UNI air filter and get rid of the octopus from under the right side of the gas tank(to stop the loud popping on deceleration after putting on the new exhaust) on his 08. It runs great but if he gets 40 mpg he is doing good. I bought my 05 in Dec of 07. Had 4 long months of below 0 and snow packed roads so I went to toun and did all of the above and then some to mine before I ever had the chance to ride it. Never did ride it stock. If I get 40 mpg Im happy. I was reading about people getting 50 mpg and I went for my first long ride and ran out of gas at 205 miles on the ticker. Had to stop and lay it on its side 4 times before I finally rolled into the closest gas station at 217 miles back fireing and dieing at the pump. I do think as mentioned above that the WRIST FACTOR probably has the most to do with it. I just dont have the patience to go nice and easy for a full tank to see what it will do. I dont thrash it but I do like to run it up through the gears. I also enjoy passing the slo pokes.
 

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What's the "octopus under the right side of the gas tank"?
 

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What's the "octopus under the right side of the gas tank"?
The octopus is the air pump on the 08 and newer bikes that pumps air into the head pipe for the catalitic converter(I think) in the stock pipe. When you put on an after market pipe you sometimes get a lot of backfireing on deceleration from the air being pumped into the header. It is a little roundish pump with hoses comeing out (therefore called octopus) under the fairing on the right side. You have to disconect all the hoses and cap them off.
 

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Are you refering to the Clean Air System (CAS) vacuum switch?
 

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Don't take this question negatively.

"Which of the many changes did you think would make better gas mileage?"

Start putting these things back on until you get better gas mileage. Then research what to remove and what to expect.

KLRs don't have 'catalytic converters'.
 

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Are you refering to the Clean Air System (CAS) vacuum switch?
I am not sure of the official name. It is a little metal pump with a hose going to the head and one to the header and another that went to a vacume off of the carb or intake?(been a while). Any way after installing the new exhaust it backfired terribly on deceleration. It was bad enough my brother was considering changing back to stock exhaust. We idled it up to 1600 rpm and that helped to cut the backfires doun to one big one on initial let off of the gas but he didnt like living with that high of an idle. I new there must be something causing it and started doing searches for back fireing and came across a post on a KLR site that talked about backfiring after new exhaust install on the newer bikes. The post claimed it was the air injection pump and so we took it off and WA LA the back fireing disappeared. I thought I read somewhere in my research that the new bikes had a catalitic converter in the exhaust. Maybe I am wrong, doesnt really matter though the popping stopped with the removal of the pump.



For tomatocity, Niether my brother nor I did any of the modifications to our bikes in the search for better MPG. Not that I wouldnt like better gas mileage, who wouldnt? Its just that I wouldnt change anything I have done to get better mileage. I am ok with my 38-40 MPG. It just took me by surprise. I was expecting more after hearing of others MPG. I know now what to expect and plan accordingly. I have a 95 ford powerstoke and got an honest 25 MPG in it once following my dad in his old 78 motorhome. Never got over 55 and spent most of the time at something less than that. Did 600 miles of that and had a couple opportunities to check the milage. I have never gotten over 20 mpg since. Most of the time closer to 15. Like the KLR I like the steady pull up to 75 on the on ramp and knowing that when it is time to pass I can and do. As for my own MPG I think that the wrist or ankle factor has more to do with my mileage than anything else I have done.
 

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Tim -

I believe the 08+ does have a cat.

Seventh paragraph of this, http://www.nytimes.com/2007/09/09/automobiles/autoreviews/09BIKE.html.

On the attached, see page 12, second paragraph. Also the engine specs at the end.

Tom
This is good and not so good news. This was recently discussed with some of the smarter KLRistas (me not included) and a couple Kawasaki people. The good news is something more to remove. The not so good news is to get Kawasaki to recognize that they have a catalytic converter.
If this is true, my guess is the Cat can become clogged if it does not stay hot and the new air pump helps do that.
I do want to see a cut-away of the cat. Anyone check part numbers from 2007 to 2008?
 

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Tim -

The odd thing is that these are the only references I have found to a cat on the Gen2 KLRs, and these aren't official sources. Thus I "believe", rather than "know". It does make sense with the addition of the air injection to the Gen2. I'd like to know for sure if KHI put a cat on the Gen2s, so if anyone has more concrete evidence (either for or against), post up!

What I have heard is that the cat is stuck into the front end of the muffler, you can't remove it unless the whole muffler goes. If I weren't such a stickler for being able to put my bike back to stock, I'd cut into the muffler to see. I've looked up the front of the muffler, but wasn't able to see anything that looks like a cat.

Tom
 

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well, whaddya know....

OK, despite wondering about this for the past two years, I never went and checked the Kawasaki manual.

There it is. Section 5-6 "Exhaust System Identification" says the "Muffler Body" is a "Pipe Type Catalyst". The cartoon shows that the mid pipe goes way up into the body of the muffler and has a catalytic converter at the end of the mid pipe. Usage is USA, USA (CALIF), and Canada. Part number is 18091-0465.

The only place where a non-catalyst muffler is used is Australia.

Tom
 
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