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I was just following others advice for this bike thus far... ?
When I get into it again I think I'll try my klx300 needle. It LOOKS like a happy medium between the stock and the JD one. I'm still baffled by the very minimal taper to it.


What if I were to remove the snorkle and the pc of plastic with all the holes in it prior to changing the needle again?
Can the snorkle be put back in if I don't like it?
Thanks!!
 

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Well, I was running the stock needle with the shim and now I've gone ahead and installed the JD needle and jet kit, after a ride on KLR-zin's bike. I noticed that his bike had usable power at LEAST 800 rpms lower than where mine would be lugging, if not 1000.

That's pretty useful for the way I ride.

When I get a chance to flog mine for real, I'll report on the diff.
 

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Discussion Starter #43
If I were going to go into the carb at all, I'd make sure I dropped a larger main in to richen the 3/4-WFO circuit.
If I rememeber needle discussions from off road sites, the taper gives it a "mild" fuel inrichment. Some have steps for different fuel intakes.
(just take a needle and place it in a tube abd slowly pull it out, you can see how it will deliver the fuel)
It you have a blunt less taper, it gives you a "hit" as more it gives more fuel suddenly.
All rocket science.
I've used needles on my KTMs and trials bikes that made it from a friendly machine to a animal "hit" and vice versa.
It's all trial and error, (a lot of error), once you go down that route!
These bikes are set REALLY lean, (as most, no check that, ALL bikes from the factory), so the first thing I do to all of them is richen ALL the circuits up when I get it. (even fuel injected machines).
If your gonna unplug the exhaust, you've done zip, IF you don't let it get more air/fuel, just scavage the cyclinder more of burnt air/fuel mixture, letting that piston and exhaust valve get hotter,
(think breathing through a straw instead of a garden hose, or farting with your cheeks pressed TIGHT together!!!!!
IF your gonna do just ONE, richen the carb, but I'd do the air box AND the jetting.
Best thing for that motor, do all three!
Joe
Just one old guys advice, take it for what it's worth!
 

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I removed the snorkel, and drilled 3 1" holes in the top. If you don't like it it's easy to plug it with 1" plastic plugs. I also modified the stock exhaust with the frugal exhaust mod. I drilled the slide re-jetted to 142 (c-clip on the second notch, washer always on top), turned the mix screw 2 1/2 from the bottom. I use a UNI filter, no gain with a K&N.

It's all a balancing act. If you open up the air box, you should do something with the exhaust. If you do the air box and exhaust, you should give it more gas or it will be too lean and run hot and surge. Heck, the stock KLR's come with the mix screw set too lean IMO.

Just try removing the snorkel (better eat your Wheaties that day) and adjust your mixture screw and see if you feel the difference.

Since I wasn't happy with the .22 mod on my stock bike I thought I'd try something similar to your suggestion. Since I don't know if I could put the snorkle back in or not I decided to just remove the air filter door and go for a spin. (Went for a spin and felt the bike out prior to removing it)
Then removed it and put the side panel back on. Went for a spin, got on it in 2nd from 20-30 mph and felt a nice difference. It's spooling up faster now and "getting on the pipe" quicker.
After doing the .22 mod and prior to removing the air filter door the bike just felt flat (worse than stock) on the top end. Opening it up at 75 mph and it didn't do much. Now with the filter door removed it just kept pulling and pulling on the top end. The bike finally HAS a top end!

I can't think of any reason why I should put the door back on and remove the snorkle and cut holes in the box? I'm not doing any water crossing and the air filter is going to get more dusty no matter where the added air is coming from...

Here's the big problem though. I feel the engine has more potential now and on 1 hand I'd like to pep her up, on the other hand I sold a badazz hotrod of a dual sport to get a more laid back bike that is more comfy eating up road miles. Tell me to not go any further please!
 

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Discussion Starter #45
Your not making it a "hot rod", your letting the engine do what the engine was designed to do!
Just cuz your truck is a V-8 doesn't mean you have to pull 3 spark plug wires off it cuz you don't want to go fast!
IF you open the air box, richen the jets up, open the exhaust, your letting the motor not work so hard, and the most important thing, run cooler!
How fast you wanna spin the tires depends on how hard you wanna twist the throttle!
Isn't it nice to have that power on tap, incase..........
Joe
A wise old mechanic (he was a grease monkey and proud of it), told me, "better to have a elephant doing a pony's job, than a pony doing a elephant's job". Wisw words to live by!:animal0019:
 

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That's true.

What I don't want to do is make my bike vibrate more and be too loud. I really like how quite and smooth it is.
 

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What joe28 and savage are doing is fine but... for the others be very aware that the KLR650 engine was not designed to create horsepower but was designed for torque. If you want horsepower and a short life engine and 30-35 mpg then follow the above.

There have been many KLR experts over the years though only a few stand out. KLRCary was the Master. Cary was concerned more with performance than horsepower. He designed the 685 and 705, enhanced the head in different stages, and had an ongoing transformation of the stock muffler. He also ran a shop that was known for drag racing. He knows through experience what worked and what didn't. Oil, chain lube, valves, rings, pistons, bearings, carburetors and parts, gaskets, air cleaners, mufflers, and such are parts he worked with. A couple years ago we lost Cary to a drunk driver. Godspeed Cary.

Hopefully this keeps modifying a KLR engine in perspective. The stock KLR engine with its heavy piston and restricted head and valves were designed to do only so much. You don't get something with giving up something.

Please read a lot before modifying your KLR engine.
 

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What joe28 and savage are doing is fine but... for the others be very aware that the KLR650 engine was not designed to create horsepower but was designed for torque. If you want horsepower and a short life engine and 30-35 mpg then follow the above.

There have been many KLR experts over the years though only a few stand out. KLRCary was the Master. Cary was concerned more with performance than horsepower. He designed the 685 and 705, enhanced the head in different stages, and had an ongoing transformation of the stock muffler. He also ran a shop that was known for drag racing. He knows through experience what worked and what didn't. Oil, chain lube, valves, rings, pistons, bearings, carburetors and parts, gaskets, air cleaners, mufflers, and such are parts he worked with. A couple years ago we lost Cary to a drunk driver. Godspeed Cary.

Hopefully this keeps modifying a KLR engine in perspective. The stock KLR engine with its heavy piston and restricted head and valves were designed to do only so much. You don't get something with giving up something.

Please read a lot before modifying your KLR engine.
Sorry to hear about KLRCary.

I don't like your backhanded compliment. I'm a KLR newb. Please link me to the tried and true KLR info so I can study up and see what exactly I've done wrong with light mods that is going to net me 35 mpg and a blown engine. I don't want either one.
Thanks
 

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So, as promised, I've had a chance to flog my machine. Throttle response is pretty much the same, but I have more useable power down low, just like I described with Zin's bike. Still a dog on the top end though, but I'm almost never riding above an indicated 80.

Most importantly, it doesn't lug in the corners like it used to do. Less shifting, with the klr's clunk box, makes me happy.
 

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So, as promised, I've had a chance to flog my machine. Throttle response is pretty much the same, but I have more useable power down low, just like I described with Zin's bike. Still a dog on the top end though, but I'm almost never riding above an indicated 80.

Most importantly, it doesn't lug in the corners like it used to do. Less shifting, with the klr's clunk box, makes me happy.
Make sure the diaphram is not damaged.
 

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It's only a dog in fifth gear, it revs freely in the lower gears, should I still tear it back apart?
I was planning on ordering and installing the carb mounted choke. I guess that would be a good time to open it up again.
If you have the same basic engine as zin and installed the same upgrade parts as zin then you should get the same performance + -. Not sure what parts you replaced but I am guessing you replaced the needle and jet and ? The diaphram is the only part I have experience with that could have been easily damaged during the instllation.
Did you drill the slide? If so what size drill bit did you use?
Did you mess with the airbox?
Did you change the air cleaner?
Is the choke functioning properly?

Ride 100 or more miles and check your gas mileage.

Think about the parts you replaced and touched during the JD upgrade.

Hope this helps.
 

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Sorry to hear about KLRCary.

I don't like your backhanded compliment. I'm a KLR newb. Please link me to the tried and true KLR info so I can study up and see what exactly I've done wrong with light mods that is going to net me 35 mpg and a blown engine. I don't want either one.
Thanks
I haven't heard anything yet. Can someone please explain how removing the airbox door is any different than removing the snorkle and drilling 4 big holes in the box?
I like my carbs to remain in the sweet spot as much as possible throughout the powerband.
Thanks
 

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Still frustrated by the undefined phrase, "throttle response" (i.e., are we talking about optimum air/fuel ratios across the operating spectrum, or the time required for slide elevation upon openining of air butterfly ("throttle") ?), I offer the following irreverent and irrelevant comment:

Sometimes folks expect too much from "jetting," perhaps envisioning a super-hero with a "jet-pack" strapped to his back, flying off to do deeds of derring-do.

Carburetor-wise, "jetting" only affects air/fuel ratio; and . . . this ratio is sensitive to many things, including rpm regime at which the ratio may be considered.

Now, chillun, one the OPTIMUM, or DESIRED, air/fuel ratio at a given rpm/load/altitude/etc., is achieved, ONE CANNOT IMPROVE UPON IT!!!!!!!!!!

Doesn't matter WHOSE aftermarket "jet kit," or whatever substitution/cannialization needles, jets, etc., might be installed . . . once the preferred air/fuel ratio occurs, ain't nothin' any better . . .

What GOALS surface? MAXIMUM POWER at all throttle openings/rpm, or MAXIMUM FUEL ECONOMY?

Or are we talking about throttle response, shortening the interval the slide responds to the throttle (facilitated by enlarging the vacuum port in the slide)?

SERIOUSLY interested in your air/fuel ratio? Hie thee, then, to a dyno shop and order a dyno run with a plot of your air/fuel ratio from their exhaust gas analyzer. Then, competent tuners may adjust your "jetting" for the optimum results you seek.

Wasted keystrokes for those who enjoy proclaiming at the coffee shop, "I just JETTED my bike!"
 

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I'm after optimum air/fuel ratio. I get what you are saying and appreciate the advice. I had a DRZ 450 E with a pumper carb. That thing had nasty, instant throttle response. This bike will never have that unless I install a pumper which I don't plan to do.

I guess I'm looking for improved power, optimum air/fuel ratio, without losing too much in the mpg dept.
I'm about to run this tank out so I'll see where my mpg is now after raising the needle, opening the pilot and removing the airbox door.
But I'm still searching for optimum! :)
Thanks!
 

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I hear you, Savage!

A CV carburetor (like the KLR's CVK40) possesses an inherent DELAY in throttle response; i.e., a "vacuum" (depression) must build before the slide is raised, uncovering needle jet and main jet . . . only a "pumper" (a carburetor with accelerator pump) effectively eliminates this delay. A "slide carb," without an accelerator pump, cannot match the responsiveness of a carburetor ingesting raw gasoline when the throttle is opened . . .

Everyone must realize, the Harley Hog Keihin CV40 has an accelerator pump . . . while still a CV carburetor, the accelerator pump compensates to some extent regarding throttle response . . .
 

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Will the Harley version bolt in place of the klr version, and is there enough benefit to justify it if it is doable? I realize there may have to be some jetting changes. Would there be a negative impact to fuel economy?
 

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I don't know if one will bolt on or not but a properly tuned carb can get better mpg. For instance, a ridiculously powerful KTM can get better mpg than our underpowered KLR's if tuned right.
When I got my DRZ the carb was way out of tune. I had no clue though because it still ran great. Only got 35 mpg no matter how I rode and how much I changed the gearing. 2 different MC shops said for as many hopups as it had that 35 mpg was normal. I wasn't happy with that, read up on it, got help from DRZ guru's, rejetted it 3-4 times and finally got it to where the performance was just the same (maybe a tad better) but was consistently getting 55 mpg IF I rode it mellow.
So a pumper could be put on our KLR's and mpg could increase along with a huge jump in throttle response. I'm guessing with the weight of the KLR that all the added response would just be wasted on tire spinning though.
However it's a LOT of fun to be cruising along at 55, crack the throttle and shoot gravel and mud all over your riding buds behind you. I did that just yesterday to my bud behind me. The problem is he was riding my bike so now they're both muddy. :)
 

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Ain't no free lunch, guys!

ANY pumper dumps raw gasoline into the venturi when the throttle is opened; raw, unmixed fuel is not the most economic diet to feed an engine!

But, how many times and how often do you "crank 'er on?" The throttle opening event accounts for very little throttle "duty cycle." Thus, I wouldn't expect great mpg difference, should a Harley CV40 be transplantable to a KLR. "Steady-state" operation? Identical, with identical jetting, I'd think.

And, the high fuel efficiency of a KTM compared to a KLR ain't a function of merely tuning alone; the DESIGN of the total power plant (e.g., compression ratio, etc.) exists as the driver for fuel efficiency, IMHO . . .
 
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