More snappy throttle please - Kawasaki KLR 650 Forum
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post #1 of 37 Old 06-21-2018, 09:38 AM Thread Starter
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More snappy throttle please

I just got into the KLR game and bought a 2008. The only things it had on it when I got it were a nice set of paniers and an uni air filter.

I know these things aren’t speed machines and I didn’t buy it for that (my speed triple does that trick) I am looking for a little better throttle response and snappier acceleration.

I’m guessing that I’ll hear a lot of jet kit and exhaust mods but I’d like to know if there are any tricks to help out.
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post #2 of 37 Old 06-21-2018, 09:50 AM
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Boring a 7/64" diameter hole, hogging out the vacuum port (q.v., 22-cent mod) may improve throttle response. Yet . . . CV carbs by nature have an inevitable delay in throttle response. Our Harley brethren compensate to some extent with an accelerator pump on their CV40 (NOT CVK40) carbs.

Installing a slide carburetor with an acceleration pump definitely will improve throttle response.

Plain ol' slide carb (without accelerator pump)? Better throttle response, but . . . some unwanted consequences, in some situations.
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post #3 of 37 Old 06-21-2018, 10:10 AM
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Smaller front sprocket if you haven’t already.

Could be the PO put a larger.

2016 KLR 650
2017 BMW S1000RR (traded in for
2018 Ducati V4S
1983 GL1100 Goldwing
2017 Yamaha R1

Last edited by dan filipi; 06-21-2018 at 10:34 AM.
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post #4 of 37 Old 06-21-2018, 10:40 AM
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KLX jet kit from Eaglemike, drill the slide 7/64ths and pull the snorkle.....done and done.


Dave
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post #5 of 37 Old 06-22-2018, 07:30 PM
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Again, throttle response time may be SHORTENED with a CV carb, but cannot be eliminated, IMHO. The slide opens only when the pressure differential between the bottom and the top of the diaphragm exceeds the force of the slide spring. Hogging out the vacuum port may help some, but . . . creation of the venturi "vacuum" transfer to the chamber above the diaphragm takes some finite time.

Alternative: Slide carb (favored by one or more website inmates). Down side: Initial snap opening results in immediate fuel-lean mixture.

Work around: Slide carb with accelerator pump, squirting raw fuel into the venturi upon throttle opening.

My own final analysis: The CV carb, as a compromise, tries to cover all the carburetor requirement bases. The result: Adequate in most cases, but not ideal in all.

Summary: "There ain't no ALL-PURPOSE anything!"
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post #6 of 37 Old 06-22-2018, 08:21 PM
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Quote:
Originally Posted by Damocles View Post
Again, throttle response time may be SHORTENED with a CV carb, but cannot be eliminated, IMHO. The slide opens only when the pressure differential between the bottom and the top of the diaphragm exceeds the force of the slide spring. Hogging out the vacuum port may help some, but . . . creation of the venturi "vacuum" transfer to the chamber above the diaphragm takes some finite time.

Alternative: Slide carb (favored by one or more website inmates). Down side: Initial snap opening results in immediate fuel-lean mixture.

Work around: Slide carb with accelerator pump, squirting raw fuel into the venturi upon throttle opening.

My own final analysis: The CV carb, as a compromise, tries to cover all the carburetor requirement bases. The result: Adequate in most cases, but not ideal in all.

Summary: "There ain't no ALL-PURPOSE anything!"
Good post. IMO; you can spend a bunch of time and money on KLR carb conversions to fix a problem that is largely non-existent......sorta like trying to get a bunch more power out of the KLR......from a functional improvement perspective you'd be 10x farther ahead doing suspension upgrades. The other pce of the puzzle is that the CV carb is largely self adjusting for altitude which for me is a much bigger advantage than quicker throttle response.


2 pennies,
Dave
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post #7 of 37 Old 06-26-2018, 10:30 AM
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Is pulling the snorkel really worth it on a stock bike or just makes more dirt and more noise?
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post #8 of 37 Old 06-26-2018, 10:52 AM
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Originally Posted by shoebox1.1 View Post
Is pulling the snorkel really worth it on a stock bike or just makes more dirt and more noise?
The snorkle does little to nothing; it certainly doesn't "make more dirt" as the opening in the airbox is in the exact same location with or without it. Noise? .....it is supposed to quiet intake noise but I've never noticed a difference; if it does reduce intake noise the effect is minor IMO.

If you rejet using the KLX kit, Eaglemike recommends removing the snorkle otherwise you'll be running too rich.

and finally, what difference does removing it make? I give you the following from the late, great KLRCary (Cary Aspy) - I've bolded the most important bits;

A lot of missunderstanding with airbox issues.

First, the screen. Airflow gains are not linear. Removing the screen with an otherwise stock KLR airbox will only gain you 2 cfm. The engine won't know the differance. However, with a heavily modified airbox, the gain from removing the screen is 8 cfm. Depending on what else is done to the engine, you may make more power. I doubt that you'll feel it, but a dyno will show it. Butt-dyno's can detect very small low rpm changes, but don't detect higher rpm changes very well at all. You'll likely not detect it, but that does not mean it's not there.

Comparing screen removal to other models is wrong, particularly with the newer sportbikes. With them, the screen often serves another purpose as well. Air distribution in a 4 cyl sportbike can be a real problem, particularly with "ram air". Removing the screen on them can cause very real losses, depending on the model. That does NOT apply to the KLR.

Same thing with air filters. There is only about 2 cfm differance from the best filter (UNI), to the worst (K&N). With a modified airbox, that differance grows to 9 cfm.

Here is the flow chart:

Completely stock - 64.8cfm
Same - Remove snorkle - 74cfm

Same - With UNI filter - 76.2cfm
Same - Remove screen - 78.6cfm
Same - Small "L" cut - 85.1cfm
Same - Large "L" cut, open snorkle area further - 92.4
Same - Remove door - 103.2

Alternate - UNI filter, No snorkle, With screen, No door, No "L" cut - 95.4

All at 2" of water, tested at 1 1/2" and 3" and averaged to 2"

To answer the larger question, how much air can the KLR really use?
....................
A stock KLR about 70-80cfm. With a good pipe about 75-90cfm
. A modified motor about 90-100cfm. Having a bit more capacity than you you need will not hurt anything. The effects are not linear though. Going from 65cfm to 75cfm you will likely notice, but going from 75 to 85 cfm you likely won't.

Part of the confusion might be due to the effects of the carb shimming. Since that mod is for a stock needle, the snorkle removal serves not just to add air, but to lean out the top end. The stock KLR till 07 is rich on the top. ( The 08 has a smaller main jet.) Airbox mods have much more effect on top end mixture, so, with the stock needle it also helps straighten out the fuel curve.

Finally the airbox door. You've got to carefull there. You don't have clean air there. It's flowing past that door when riding. You can easily create a partial low pressure area there, depending on wind direction, and where you place your leg!

Cary"


I do not recommend removing the backfire screen (PITA) or running without the airbox door for reasons that should be obvious.

Though a KLR isn't going to have a bunch more power no matter what you do, a KLX kit combined with the snorkle-ectomy and L mod or 4 - 1" holes will have it running properly. don't bother with the little 1" foam filters if you drill the holes - they are useless.

Cheers,
Dave
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post #9 of 37 Old 06-26-2018, 10:53 AM
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...all that said do NOT pull the snorkle if you haven't corrected the factory jetting using a KLX kit or, at least, the 22 cent mod or you'll exacerbate the factory lean condition.

Dave
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post #10 of 37 Old 06-26-2018, 11:26 AM
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Quote:
Originally Posted by shoebox1.1 View Post
Is pulling the snorkel really worth it on a stock bike or just makes more dirt and more noise?
If you live at 5000 feet+, probably no rejetting of any kind will be needed & every bit of unrestricted air flow is an improvement.

If you live nearer sea-level some carb re-jetting might further improve / smooth the power delivery or not.

Pulling the snorkle is totally FREE & if for some reason you aren't happy with your results it is totally free to Re-Install.

I prefer to have a little louder intake 'honk' and not any louder exhaust noise.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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