Carb mod question? - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 18 Old 01-31-2007, 11:13 AM Thread Starter
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Carb mod question?

I just did the Dynojet carb mod at the Petaluma tech day. I have a question. What does the drilling of the slide do for you?:?:
It was recommended that I don't do it. I went the stage 2 route, 150 main jet, 4th notch from the top, and 3.5 turns out on the mixture screw. The bike runs great, no more popping when I let off the throttle, and it pulls really hard in the mid range.
I have a Big Gun exhaust Quiet Series with the spark arrester, K & N air filter and I have drilled 6 1" holes in the air box and put little snap-in foam filters in the holes. Before the mods I was getting 48 - 50 miles per gallon. Haven't check the mileage yet with the new set up.

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post #2 of 18 Old 01-31-2007, 12:59 PM
 
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I'd like a definitive answer on the drilling thing as well. I hear some say to do it... other's say leave it alone.
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post #3 of 18 Old 01-31-2007, 01:14 PM
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Drilling the slide allows the slide to go up and down faster, giving you more throttle responce.

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post #4 of 18 Old 01-31-2007, 03:52 PM
 
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So it doesn't just use up more fuel on it's own accord?

We're talkin' about that tiny hole that people enlarge?
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post #5 of 18 Old 02-28-2007, 10:29 PM
 
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The tiny hole is the place where the vacuum created by the engine goes through to act on the diaphragm, raising the needle. Open the hole up, and when the butterfly valve opens, the drop in the pressure on the intake side of the carb goes down, sucking the diaphragm, raising the needle. This is the whole idea of a cv (constant velocity) carb. Open the hole too much, and the needle flies up too quick and kills the engine when you rev. It will not make the engine run ritcher or use more gas, but it will give you more response (which may make you more throttle happy, which may make your mileage go down). Find the balance that suits you. I drilled my carb a little, and it is more peppy.
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post #6 of 18 Old 11-21-2012, 08:06 AM
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Just so I don't mess up. My bike is down right now. Carb is apart to a degree. I have the slide out. Can someone post a picture as to where exactly the hole is people are talking about drilling out to 7/64ths for better throttle response? I think it's the one next to the needle but want to be sure so I don't mess up! And a picture is worth a thousand words! Thansks, And May God bless you! P.S. I found out a dremmel tool works best when drilling out that 7/64ths hole in that metal seal to get to the air screw! I did that and put the end of a chainsaw file in it, leaned it over gently and it just popped out! No damadge! Praise Jesus!
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post #7 of 18 Old 11-21-2012, 08:53 AM
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Quote:
Originally Posted by Homealone777 View Post
Just so I don't mess up. My bike is down right now. Carb is apart to a degree. I have the slide out. Can someone post a picture as to where exactly the hole is people are talking about drilling out to 7/64ths for better throttle response? I think it's the one next to the needle but want to be sure so I don't mess up! And a picture is worth a thousand words! Thansks, And May God bless you! P.S. I found out a dremmel tool works best when drilling out that 7/64ths hole in that metal seal to get to the air screw! I did that and put the end of a chainsaw file in it, leaned it over gently and it just popped out! No damadge! Praise Jesus!

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post #8 of 18 Old 11-21-2012, 09:42 AM
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Quote:
Originally Posted by hinquik View Post
What does the drilling of the slide do for you?:?:
You've received some valid answers; the desired/presumed effect of enlarging the vacuum port in the slide is, improved throttle response.

If you're interested in the HOW and perhaps the WHY, I commend to you:

Google: "Care and Feeding of the CVK 40."

(Irrelevant note: Our Harley brethren hog out the vacuum port to 1/8" diameter on the similar CV40 Keihin carb.)
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post #9 of 18 Old 11-21-2012, 10:02 AM
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I've often thought that the 7/64" recommendation came about because the first guy to write it up in KLR-dom didn't have a 1/8" drill bit....

T

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post #10 of 18 Old 11-21-2012, 10:03 AM
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Homealone777 -

I would recommend you look in the Common Mods and Issues thread and follow the links under '22 cent mod' for pictures and such like that.

T

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