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Cvk 40 jetting for stock drz400

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I am thinking of putting a cvk40 on my stock drz400s with 3x3 air box mod. Was wondering what should I be doing to jet it properly with the stock exhaust? My mechanic also said it’s too much carb for a stock drz? Any suggestions for jetting and set up would be greatly appreciated

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There is a main thread on doing the cvk40 conversion with all the details about base stock jetting.

 

I think your mechanic forgot that when the drz400 was first introduced it had a keihin fcr 39mm carb as factory equipment. The cvk40 is sized just fine for this application.

 

 

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Thanks bumtarder I can’t find the thread do you have a link by chance?

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Thanks fellas. Just bought the carb and supplies. I only found one video on the install which wasn’t very informative. I want to attempt the install myself if I can. Is it very difficult? Any other videos out there to install diy?

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Posted (edited)

I just put my cvk in a few days ago. The only hard part is wrestling it into the air boots. I used an E intake boot with a KLR650 clamp, but people claim the S boot works as well. I also didn't modify the throttle cable bracket.

Edited by His Dudeness

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How does it work with the bracket not cut?

Mine is in the mail

I’m going to attempt it with the s boot

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1 hour ago, Drzeath86 said:

How does it work with the bracket not cut?

Mine is in the mail

I’m going to attempt it with the s boot

Cut the bracket, it is much better (I ran it worth out cutting, then cut it and it was worth it).

I would at min . do a E head pipe, the motor is a air pump, the more in the more out. I.E> you need to open the exhaust up to take full advantage of the carb upgrade.

 

 

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Posted (edited)
20 minutes ago, MyKLX400 said:

Cut the bracket, it is much better (I ran it worth out cutting, then cut it and it was worth it).

I would at min . do a E head pipe, the motor is a air pump, the more in the more out. I.E> you need to open the exhaust up to take full advantage of the carb upgrade.

 

 

I am curious as to how you modified the bracket and what it improved. I couldnt find a very clear explanation of the mod online so i did my own testing and the stock setup seems to do its job just fine.

Edited by His Dudeness

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Yea that’s the part that confuses me too on how to cut the bracket properly?

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Posted (edited)
1 hour ago, Drzeath86 said:

How does it work with the bracket not cut?

Mine is in the mail

I’m going to attempt it with the s boot

It's a simple cut and doesn't have to be extremely precision. You want about .200" distance left when you're done. The cut allows the carb butterfly to fully open. Otherwise, no fully opened throttle, defeating the purpose of the oversize carb.

1395273663_Convert2Pg22.jpg.e3373494b0066d9af43f8e1170769eef.jpg

 

Edited by 76xtdrvr
  • Helpful 1

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Thanks man they made it so clear

I can def so it by myself now. Also any suggestions on getting the carb in the stock s boots?

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As shown, that's where and what to cut.

No matter what you do, make sure the throttle cable is adjusted to pull the butterfly all the way to the stop.

I was able to get WOT without cutting but in my case I did not like how the cable was sitting / aligned.

By trimming the bracket I was able to get more adjustment and the cable alignment was much better.

 

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30 minutes ago, Drzeath86 said:

Thanks man they made it so clear

I can def so it by myself now. Also any suggestions on getting the carb in the stock s boots?

A lot of installation info is credited to others in the cvk thread(s), but I'll pass on what worked for me.  First, the entire attached thread is very helpful and s/b read. My 2 cents is on page 53.

For ease of installation: Remove the upper subframe bolts and loosen the lower ones to allow the subframe to pivot away. You can file away, rather than machine, the small lip on the air filter side of the carb to allow the air box boot to slide on easier. Install the intake boot onto the carb while the carb is on the workbench. It's a tight fit, but I used some silicone grease (not silicone sealer/RTV) here and on the air filter side.

 

 

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1 hour ago, MyKLX400 said:

No matter what you do, make sure the throttle cable is adjusted to pull the butterfly all the way to the stop.

I was able to get WOT without cutting but in my case I did not like how the cable was sitting / aligned.

By trimming the bracket I was able to get more adjustment and the cable alignment was much better.

The stop at my butterfly was way past WOT, you could turn it all the way past WOT until it was closed in the opposite orientation. I ended up playing with the adjusting nuts until WOT on the handlebars positioned the butterfly perpendicular to the bore. I'm tempted to do that cut just because there are barely enough threads exposed on the cable to fasten the lower nut.

 

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