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Discussion Starter #1
After viewing some recent posts about what I consider "performance-enhancing mods" (I call them Steroid Mods) I wanted to throw this out there as kind of a poll, if you will.

We all have our opinions, largely based on what we read here and what kind of riding we do. Some push our KLR's harder than others, both on the street and off-road.

Not knocking what anybody else does, but I personally don't push my KLR that hard and tend to stay away from "performance-enhancing" mods because I just don't think they're necessary for the way I ride my KLR.

I believe the doohickey and brake and clutch safety switch bypasses are "must-dos" but I think these fall more into the "dependability" category.

My mods largely tend to lean toward either dependability or riding comfort; i.e. raising links, peg-lowering brackets, windshield, means of carrying more tools and supplies, etc.

So, let's hear what you think about some of the following mods, or feel free to add any I've overlooked but please don't bring up the Thermo-Bob. If you've done these mods, I would like to know why you chose to do them and how they enhance the experience with your KLR.

Feel free to bring up the big bore kits, but they're definitely something I'm never gonna do, not because I think they're pointless, but because I'll never be able to afford doing one.

.22 Mod: Haven't done it. See no need to, but might if I ever detect any pronounced symptoms of the bike running too lean: haven't noticed any yet.
Guess this could fall into the "dependability" mod considering long-term effects of a too-lean condition if present.

L-Mod or other airbox mods: Haven't done it. See no need to. Bike pulls and runs plenty good enough for me with regular filter cleanings.

"Premium" Air Filters: Same as above

Needle Changes: Same as above

Brake Line/Pads Upgrade: Haven't done it: see no need. The thing stops plenty fast enough for me. When replacing pads, I might go with "premium" pads since I'm already doing it.

Exhaust Change/Mod: Haven't done it. See no need. Bike runs fine with the stock exhaust and I don't care what it sounds like.

My "dependability" mods on the slate for this Summer are:

-Clutch and sidestand safety switch bypasses.
-Petcock "no vacuum" mod.
-Carb drain tube mod.
-Relocate choke control to carb instead of handlebars.
-Extra lights as backup for headlight circuit/bulbs & for more light at night on country roads.

Opinions, please.
 

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I've got the KLX needle kit and airbox opened a bit. It made a slight difference. I think you either like the KLR or you don't. You definitely can't make a silk purse out of a sow's ear power wise.
 

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...


.22 Mod: Haven't done it. See no need to, but might if I ever detect any pronounced symptoms of the bike running too lean: haven't noticed any yet.
Guess this could fall into the "dependability" mod considering long-term effects of a too-lean condition if present.

...

-Clutch and sidestand safety switch bypasses.
-Petcock "no vacuum" mod.
-Carb drain tube mod.
-Relocate choke control to carb instead of handlebars.
-Extra lights as backup for headlight circuit/bulbs & for more light at night on country roads.

Opinions, please.

You want to do the .22 mod. The bike is lean stock on the low spead carb circuits stock to meet emissions. You will definetly notice better throttle response, wakes it up so to speak.

I haven't had any issue with the vacuum petcock. If you bypass it you'll have to remember to turn off the gas everytime you stop or risk gas getting past the float needle and hydro locking the motor.
 

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I did the .27cent mod (.22cent adjusted for inflation) and drilled the slide. It worked fine for me, seems to have stopped the backfiring the bike had been doing.

I will be putting on the larger brake rotor since I am going to be adding some more weight and commuting in the DC area, there are a lot of idiots out there. I find the stock rotor to be a bit lacking.
 

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Discussion Starter #5
You want to do the .22 mod. The bike is lean stock on the low spead carb circuits stock to meet emissions. You will definetly notice better throttle response, wakes it up so to speak.

I haven't had any issue with the vacuum petcock. If you bypass it you'll have to remember to turn off the gas everytime you stop or risk gas getting past the float needle and hydro locking the motor.
Ah, didn't realize that about the petcock mod. Sounds like the risks of that one outweigh the potential rewards, especially as much as I forget stuff.
 

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I see where you are going with this…. I like my bike and I enjoy adding little things and tinkering on it… But at what point do some of these thing become “You must do” verses “when I have time and want to tinker – do’s”
 

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Discussion Starter #8
I see where you are going with this…. I like my bike and I enjoy adding little things and tinkering on it… But at what point do some of these thing become “You must do” verses “when I have time and want to tinker – do’s”
In a way. I certainly don't want to come across as critical of people who do these mods (or any other) and don't want to imply they're wasting their time and money. They all seem to be pretty widespread and thus there must be some benefit to them otherwise people wouldn't do them: I just don't see any of them improving the performance of my KLR the way I ride it. I may be wrong, but just really don't think I'd notice a difference.

I think most folks would agree that the only thing close to a "must-do" is the doohickey upgrade unless you're willing to take your chances with it if you don't.

I was really thinking hard about upgrading my rear shock, but then decided "What's the point?" The raising links took out all the sag I need under my weight. I don't jump the thing or go flying over rough desert terrain or whoop-de-doos or rocky trails: my rear tire never even comes close to contacting anything else on the bike. The only real plus I see is that maybe a performance shock (or the stock shock with a bigger spring) might last longer, but I would imagine my stock shock will last for quite awhile the way I ride.

I would say every mod is suited to an individual's riding style, how they use their KLR and demand of it and some just like to tinker for the hell of it and there's certainly nothing wrong with that and I think it's a bug most of us have been bitten by.
 

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I bought a decent pair of BarkBuster aluminum guards and feel it is worth the money spent. Not because i plan on riding tons of single track where the trees are 28" apart, but because I've dumped bikes numerous times, jamming the grips into the dirt and would have tweaked the levers/controls had it not been for the Busters. Trick I learned from trail riding was to leave the lever perches slightly loose so they have a chance to spin freely for when your unlucky enough to dump your ride. Maybe I should just learn to ride better...
 

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I did the KLX needle, uni filter, rejet, FMF Q4, de-snorkel, slide drilling, etc. How much actual increase in performance is netted from these changes is debatable, and with the relatiively expensive exhaust, $/hp or $/ft-lb its not a lot of bang for the buck on paper. That being said, my bike will now wheelie in 1st easily, and with a fair amout of clutch abuse can be hoisted up in 2nd. Major improvement in throttle response and general rideability and it sounds good without being loud. Money well spent? Perhaps not, but if i bought another KLR i would do the same mods to it too.

Moab rear shock & Progressive front springs: Expensive but worth every penny to me. If you have spent years riding MX bikes and sport bikes with actual competent suspension, the KLR's boingers just dont cut it.

Pro Taper Evo's: Taper section bars are the bomb. Seriously, i had no idea how much difference they can make in how a bike feels in terms of feedback thru the bars. A friend had them on his MX bike and raved about them. I decided to try some on his reccomendation and have been hooked ever since. I will not own an offroad bike without them. They seem to damp vibrations better, and if you crash hard enough to bend or break them, its probably not a crash you are going to walk away from, they are hell for stout.

Fork Brace - Steel brake line: Brake line improved front braking by maybe 10%, but every little bit helps. Fork brace benefits are arguable, but it looks cool and I have convinced myself that it adds something useful, so in my make believe world, its an awesome upgrade.

I guess I could have ridden my KLR in stock form, but to me its a lot more fun with the upgrades i have made. 20 more HP would be nice, but seeing as its not up for sale, i must be pretty happy with what its got now.

A friend of mine asked me why I use a $1000+ .375 H&H mag instead of a 250$ Wal-mart .30-06 when the only things i hunt are deer and feral hogs. My answer is that my rifle is more interesting, more fun, has more capability, is a challenge to shoot well with the recoil, and to me, its just more "cool". I guess its like the KLR, I just like to blow $$$ on cool stuff for no damn good reason.
 

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I betray my ignorance, planalp!

What is the, "Carb drain tube mod?"

Its purpose and function?

Or are you referring to the "Tee" or "Wye" mod, providing an alternate path for the carburetor breather hose?
 

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I completely understand not modding a klr and riding it stock for street use.
For a guy like me who is much happier in the dirt and gravel the suspension was the fist thing to go.

Out with the stock stuff and in with the Cogent Dyn parts.
I also crave a little more mid range grunt
685 kit
.5mm over sized valves with mild porting
Leo vince exhaust with the usual carb mods

Honestly for me, my klr runs better and has more pep than it ever did and I got rid of the oil burning problem in the process.

I have 18000 miles on my 09 and most of the engine mods were done about 10000 mile mark.

Zero reliability problems
This is not for every one but it has worked well for me.
 

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Discussion Starter #13
I betray my ignorance, planalp!

What is the, "Carb drain tube mod?"

Its purpose and function?

Or are you referring to the "Tee" or "Wye" mod, providing an alternate path for the carburetor breather hose?
No, the ignorance applies to me: I mean to say carb "vent" mod, not carb "drain" mod. Sorry. Yes, the T Mod, I believe it's called.
 

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Discussion Starter #14
I did the KLX needle, uni filter, rejet, FMF Q4, de-snorkel, slide drilling, etc. How much actual increase in performance is netted from these changes is debatable, and with the relatiively expensive exhaust, $/hp or $/ft-lb its not a lot of bang for the buck on paper. That being said, my bike will now wheelie in 1st easily, and with a fair amout of clutch abuse can be hoisted up in 2nd. Major improvement in throttle response and general rideability and it sounds good without being loud. Money well spent? Perhaps not, but if i bought another KLR i would do the same mods to it too.

Moab rear shock & Progressive front springs: Expensive but worth every penny to me. If you have spent years riding MX bikes and sport bikes with actual competent suspension, the KLR's boingers just dont cut it.

Pro Taper Evo's: Taper section bars are the bomb. Seriously, i had no idea how much difference they can make in how a bike feels in terms of feedback thru the bars. A friend had them on his MX bike and raved about them. I decided to try some on his reccomendation and have been hooked ever since. I will not own an offroad bike without them. They seem to damp vibrations better, and if you crash hard enough to bend or break them, its probably not a crash you are going to walk away from, they are hell for stout.

Fork Brace - Steel brake line: Brake line improved front braking by maybe 10%, but every little bit helps. Fork brace benefits are arguable, but it looks cool and I have convinced myself that it adds something useful, so in my make believe world, its an awesome upgrade.

I guess I could have ridden my KLR in stock form, but to me its a lot more fun with the upgrades i have made. 20 more HP would be nice, but seeing as its not up for sale, i must be pretty happy with what its got now.

A friend of mine asked me why I use a $1000+ .375 H&H mag instead of a 250$ Wal-mart .30-06 when the only things i hunt are deer and feral hogs. My answer is that my rifle is more interesting, more fun, has more capability, is a challenge to shoot well with the recoil, and to me, its just more "cool". I guess its like the KLR, I just like to blow $$$ on cool stuff for no damn good reason.
I know what you're talking about. Not to infer your nice mods fit only into this category, but about blowing money on cool stuff just because it's cool.

My Ruger 10/22 is a good comparison: it's kind of the "KLR of .22's." It is competent in its stock form, but still I've added Tech-Sight military aperture-style sights which I really like for some unknown reason, trigger job, etc. so it shoots better and I shoot better with it. Quantitative results: with open sights, shoots a dime-sized group at 25 yards rather than a quarter-sized group. Real-life benefits: none, really. What am I ever going to shoot with it that's the size of a dime from 25 yards away?

Sometimes it's just the satisfaction you get of knowing you've done all you can to improve what you've got so you're not always thinking "it could be better."

If I wanted a really accurate, tack-driving .22, I could go buy one that would put all three shots in the same hole at 25 yards, but it's kind of cool to know you've achieved almost the same thing through research on how to do it and then modifying an existing "platform" with your own hands to perform to almost the same standards as something costing a hell of a lot more.

Mod on, folks. It's obviously a deep-seated urge considering the industries that have been in place for years selling performance parts for any kind and make of vehicle you can imagine, guns, whatever: you name it and there are people there selling stuff to make it better.
 

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Discussion Starter #15
22 cent mod was a night/ day difference on my 09. :)
Not to badmouth the .22 mod, but in what way? What difference did you notice in performance? Stopping the backfiring on decel is always noted as a benefit of the .22 mod, but my KLR never backfires. Even if it did, I wouldn't care as long as I knew it wasn't having a detrimental effect on my engine. Maybe it would have a detrimental effect: I don't know. I know backfires can possibly cause air filter fires, valve damage, etc.?

I always hear the term "better throttle response." What exactly does that mean? More low-end or mid-range torque? Less "lag" in the throttle input vs. what the engine does? Is it really that noticeable? Maybe kind of a 2-stroke vs. 4-stroke difference I might be familiar with?

Has anybody ever quantified this by, say, the old "gold standard" of performance in the 0-60 run before and after the .22 mod? It would seem it would be impossible due to rider skill with shifting, etc.

I would like to see somebody measure this, or even do it myself, but it would have to be a more proficient and skilled rider than myself that would exactly duplicate the surface, temperature, wind, timing of shifting, etc. Sometimes I wonder if it's not kind of a "placebo effect" where just because it's been done, a perceived effect is noted by the user. Any good articles along this line available anywhere?

Nothing against it; it's obviously a cheap and easy mod and I really can't see any reason NOT to do it, but am not thoroughly convinced there is a reason TO do it, either.
 

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Discussion Starter #16
As a followup to my last post, I would note that I understand something just "feeling better" after it's been modded without measurable results.

When I put my raising links on, I did it to take out some of the sag caused by my considerable mass. Actually, one of the best results of this mod was making the bike lean over farther on the kickstand so it was more stable while on the stand.

But, after adding the links, it felt like the whole machine was more "nimble," like more weight had been moved forward and it was more responsive to both handlebar and body movement control inputs. Was it? I don't know, but it sure "felt like it" and I still consider it to be true.
 

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I always hear the term "better throttle response." What exactly does that mean? More low-end or mid-range torque?

My 09 felt truly anemic until reaching approx. 30 mph (other ride is a DL 1000). After carb mod definately seems to have more low end grunt. Results are based on butt dino. :)
 

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Not to badmouth the .22 mod, but in what way? What difference did you notice in performance? Stopping the backfiring on decel is always noted as a benefit of the .22 mod, but my KLR never backfires. Even if it did, I wouldn't care as long as I knew it wasn't having a detrimental effect on my engine. Maybe it would have a detrimental effect: I don't know. I know backfires can possibly cause air filter fires, valve damage, etc.?

I always hear the term "better throttle response." What exactly does that mean? More low-end or mid-range torque? Less "lag" in the throttle input vs. what the engine does? Is it really that noticeable? Maybe kind of a 2-stroke vs. 4-stroke difference I might be familiar with?

Has anybody ever quantified this by, say, the old "gold standard" of performance in the 0-60 run before and after the .22 mod? It would seem it would be impossible due to rider skill with shifting, etc.

I would like to see somebody measure this, or even do it myself, but it would have to be a more proficient and skilled rider than myself that would exactly duplicate the surface, temperature, wind, timing of shifting, etc. Sometimes I wonder if it's not kind of a "placebo effect" where just because it's been done, a perceived effect is noted by the user. Any good articles along this line available anywhere?

Nothing against it; it's obviously a cheap and easy mod and I really can't see any reason NOT to do it, but am not thoroughly convinced there is a reason TO do it, either.
planalp, the 22-cent mod remains a simple matter of easily explained and rather universally-accepted physical principles!

SLIDE DRILLING: Doubt you'll Google, "Care And Feeding of the CVK40," but if you did, read and understood the accessible text, you'd understand . . . a CV ("constant velocity") carburetor's slide and needle rise from "vacuum" (differential pressure) applied above the diaphragm. This vacuum reaches the upper chamber above the diaphragm through a little hole, called a, "vacuum port." By hogging out this port (making it larger in diameter by drilling), the vacuum (pressure differential) is transmitted to the upper diaphragm surface more quickly, resulting in faster response of the slide when the air butterfly (throttle) is opened, that is, when one twists the throttle in the "GO!" direction.

More accurately described in technical terms, ATMOSPHERIC PRESSURE on the underside of the diaphragm raises the slide; said atmospheric pressure admitted through a crescent-shaped opening on the input side of the carburetor venturi; take off the hose between your carburetor and air cleaner and you can clearly see this portal for atmospheric pressure.

NEEDLE SHIMMING: The mid-range carburetor circuit's air/fuel ratio is controlled by the needle and needle jet. By RAISING the needle, with one or more washers, the TAPER of the needle evacuates the needle jet more precipitously than without the thickness of the washer(s), making the air/fuel mixture more FUEL-RICH in the mid-range operating spectrum. Since conventional wisdom holds "factory" carburetor settings are skewed toward passing enviornmental standards, in contrast to developing optimum power, men say fuel-enriching the mixture processes more fuel per unit time and thus produces more power.

FUEL SCREW ADJUSTMENT: The idle air/fuel mixture from the factory likewise is said to be fuel-lean; again, for emissions considerations. This screw can be adjusted for maximum rpm at idle (nominally, 1.75 turns out from a soft closure on a stock engine), providing optimum idle air/fuel mixture and perhaps offering easier starting as a bonus.

Now, a CV carburetor characteristically experiences a delay in "throttle response" (slide opening) as a consequence of its DESIGN; delay cannot be eliminated entirely; but . . . throttle response can be improved, made crisper, as it were, by slide drilling.

The conversion of hydrocarbon fuel's chemical energy into mechanical energy is facilitated by a more fuel-rich mixture than KLR's typically enjoy from the factory; thus--shimming a needle produces more power IN THE OPERATING REGIME WHERE THE NEEDLE AND NEEDLE JET DOMINATE AIR/FUEL MIXTURE.

Finally, properly adjusting the fuel (pilot) screw enhances reliable operation, improves starting, and reduces backfiring upon deceleration.

The comments in this post reflect known, proven, demonstrable facts, as far as I know.

You don't want to tune your bike optimally? Your call etirely.

Any questions?
 

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FULL DISCLOSURE:

Now, planalp, before you, or any other reader, runs, SCREAMING, from the room over concerns about fuel economy vis-a-vis the 22-cent mod, I must disclose some unfortunate facts.

FIRST, there ain't no such thing as a free lunch! Fact of life!

SECOND, if an internal combustion engine produces more power, all things besides carburetion being equal, then . . . said engine is processing (aka, "burning") more fuel per unit time.

THUS; making an engine's air/fuel ratio more fuel-rich to produce more power (all other things equal) remains antithetical to making the engine fuel-lean for maximum fuel economy.

"Fact of life."

-------------------

Now, want to talk about "throttle response?"

SERIOUS riders concerned about this issue abandon CV carburetors altogether for carburetors with mechanical (in contrast to "vacuum," or differential-pressure) mechanisms to raise the slide: The throttle handgrip's cable physically opens the slide; thus--the lag from throttle opening to slide opening is ZERO MICROSECONDS (factoring cable elasticity).

BUT; such abrupt opening leaves the jets saying, "What's happening, man?" The lower pressure of the Bernoulli effect doesn't have time to "suck" fuel into the intake airstream instantly, and the engine stumbles and stalls 'til the consequent vacuum effect can feed fuel through the jets for a proper mixture . . .

SOLUTION? ACCELERATOR PUMP! An accelerator pump dumps raw fuel into the venturi when the throttle is opened, insuring enough joy-juice is present to give instant acceleration, while the aforesaid Bernoulli conditions are developed.

Thus, the world knows, "Flat-slide pumpers," carburetors with mechanically-actuated slides and accelerator pumps.

Harleys, who use CV40 carbs (similar to KLR CVK40 carburetors) on some machines , actually have accelerator pumps to improve throttle response.

This material WILL be on your quiz.

Class dismissed!
 

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Discussion Starter #20 (Edited)
Damocles, thanks for the class. You obviously know your stuff when it comes to the CVK40 carb! All these principles make sense to me. I appreciate you sharing them with me and I'm sure a lot of others do, too.

That being said, I kind of feel bad when I continue on to say, after your effort to lay this all out, that I probably still won't do any of the carb mods. I know, everybody's probably thinking, "Well, why the hell did you bother asking about them in the first place?"

I kind of fall into the "if it ain't broke, don't fix it" category as far as my carburetor goes.

I'm getting ready for a trip to ride out in Colorado in about a month and was considering them to boost performance a little, but in the past I've taken two thumpers, a Suzuki 600 and a Honda 650 from sea level and ridden up to 14,000 feet out there with no problems or noticeably-reduced performance in their stock configuration. Since the KLR uses the same 40mm carb system they did, I don't anticipate any problems. I was going to ride out, but my Army-crippled back can't handle the distance: I'm going to truck the KLR out in the back of my Toyota and ride once I get there.

My KLR starts fine, idles fine, doesn't pop on decel and I can't think of a single instance where I found myself thinking "This thing doesn't have enough pep," "wish I had a little more power," etc. I figure as long as I keep the carb and ignition cleaned, tuned and maintained as per the manuals, it's good enough for me.

I do appreciate Glasser's "butt dino" evaluation and kind of explained that in how it just "felt" like my KLR handled better after I put on my raising links. Maybe I would need to do these mods to appreciate the difference myself and maybe I would notice it, but it just seems that I won't miss them if I don't do them and probably wouldn't really notice the difference if I did, or noticeably improve my riding experience.

Mileage isn't a concern for me. Actually, mileage is a mystery to me. Still can't figure out why my KLR only gets about 3x better gas mileage than my wife's Durango that weighs about 10 times as much as a KLR, has a lot more drag and has a 5.9L Hemi in it.

Seriously, though, thanks for the info about the KLR's carb system. I appreciated you going to the trouble to put that all out there. Gotta admit, though, not that this is some kind of challenge and I think everybody's full of it, but nobody's posted anything yet that convinces me these performance-enhancing mods are worth messing with unless the stock system, cared for and maintained per the manual, will somehow decrease the life expectancy of my KLR as opposed to a carb/engine that's undergone these mods. Again, I will note that it also depends on how you ride your KLR and what you expect of it.
 
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