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cvk40 install problem

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What's up thumpertalk!  New member long time lurker.  Need help with something.  I've been reading up on cvk40 swaps on the DRZ and I've gone ahead and did it.  I got a problem maybe you guys can help me with.  Now that I did the swap I went for a test ride and jumped on the freeway.  I was up to about 65-70 and my throttle was bottomed out already.  I don't think that's normal, is something wrong?

 

3x3, yosh exhaust, k&n filter

 

I got a 150 main and 42 pilot in there, dynojet needle 4th notch, fuel screw about 1.5 turns out. 

 

I've always been able to get a lot of great info on this forum but couldn't find anything about this.  Forgive me if this is a common sense fix.  I'm a newbie to bikes let alone installing a carb in one. 

Edited by sa-botage

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Have a read through this post , by there reckoning you should have a 152 main jet and should have drilled out the slide , as you didnt mention the slide in your post , maybe it makes a difference , greg

 

 

http://www.thumpertalk.com/topic/1056323-cvk-40-carb/

Sorry, yes I did drill out the slide.  Can't remember what size but it was pretty much as big as I could without hitting the wall.  Also, I have read that post a few times.  Thats what made me decide to attempt the carb swap.  Not sure what it could be.  Could the jetting make that happen?  I was thinking maybe I need to change the throttle tube, but haven't seen anyone else mentioning changing the tube.  I know that I'm not topping out.  I have a vapor so don't know how accurate the rpm's are but it was only at about 6.5k and i've taken it higher than that with the mikuni carb.

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Before you put the carb back in you probably shouldve tested that the butterfly valve is opening all the way and the throttle cable arm on the carb itself hits the stop plate. You may be able to check this without removing the carb. Also do this full lock on the steering both ways to make sure steering input isnt pulling the cable and revving your engine. I just did this swap and had to remove and throw away the throttle return cable completely and hook my pull cable up to the return cable slot on the throttle tube. This took out the extra slack in the cable I was having problems with. Your jetting should be ok, others recommeded 150 mj for my bike so maybe your jetting is ok and your just not getting full carb valve opening. Prepare for fun times on the bike when you get it dialled. I am having a blast on my bike with this carb! Good luck. . hope it something simple

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Use the Motion Pro R1 replacement throttle tube, most bike shops have them.  There are two places to adjust cable slack, at the carb and the throttle cable adjuster.  Make sure the diaphram is seated under the cap and no leaks.  Shoe goop is a good band aid.

 

Welcome to the BSR Anonimous Club.

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Okay, I checked my throttle cable and it seems to be opening the throttle all the way to the stopper.  But I'm not sure if the butterfly on the inside is opening all the way.  I will pull the carb and check when I have time.  Assuming that it is opening all the way, what else could it be?

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the butterfly cable bracket has a horizontal tab under the return cable attach point, at idle it is aligned with the carb bore.  At WOT you should see this tab rotate clockwise a bit less than  90 degrees from the idle position.   Best place to peek is just above the oil breather on the engine left side, mind your nose if the bike's been running.

 

Slide opening depends on engine vacuum.  Diaphram cap not sealing, slide diaphram has a small puncture / tear, open vacuum line or port are the ususal suspects.

 

Diaphram slide movement in the carb should not bind nor stick.  Make sure the needle is installed in the slide with the correct parts and the needle jet does not bind the needle. 

 

 

 Mahalo

Edited by 38super
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the butterfly cable bracket has a horizontal tab under the return cable attach point, at idle it is aligned with the carb bore.  At WOT you should see this tab rotate clockwise a bit less than  90 degrees from the idle position.   Best place to peek is just above the oil breather on the engine left side, mind your nose if the bike's been running.

 

Slide opening depends on engine vacuum.  Diaphram cap not sealing, slide diaphram has a small puncture / tear, open vacuum line or port are the ususal suspects.

 

Diaphram slide movement in the carb should not bind nor stick.  Make sure the needle is installed in the slide with the correct parts and the needle jet does not bind the needle. 

 

 

 Mahalo

AWESOME INFO!!!!  :thumbsup: :thumbsup:

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Don't know if this is a dumb question but the I'm using the stock drz vacuum petcock.  I attached it to the carb vice the vacuum port nipple on the intake.  I have one installed on the intake that I capped off.  Could that be the culprit?  Should I try to attach it to the nipple on the intake instead? 

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Nevermind, I switched the vacuum line to the intake nipple and it didn't really make a difference.  I guess I'll have to pull the carb and see what's up.

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The diaphram cap can be removed in situ, may have to gently pry the carb away from the frame for screw access.  Don't drop anything.  Inspect the diaphram for any wear or perforation, stretch gently against a very bright light.  As required, repair with a thin coat of shoe goo.  Also check the  sealing bead on the diaphram outer circumference and where the diaphram attaches to the slide.  Ensure the part stack supporting the needle is correct.  Ensure the slide does not bind in the carb body.  Ensure diaphram spring is centered in the slide and slips over the spring guide in the diaphram cap. 

 

There's a good IPB at Jets R Us.

 

'Nuther good site - https://web.archive.org/web/20061207053346/http://jimrace.com/faq/CVK40.html

 

Don't give up, it's something simple.

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Auright!!!  So, I left the carb on the bike, took the carb cover off.  MADE SURE that the diaphram was sealing and tightened down the cover.  I moved around the carb and retightened the air boot and intake clamps.  I readjusted the throttle cable.  Took it for a test ride and it's awesome.  Got the weekend off so I'm going to take that baby out and see what this carb can do.  Thanks to everybody for your help especially 38super.  You were right, it was a simple fix.  Much Mahalo's!  Aloha!  FYI, take your time when installing.  I think I was so excited to put the carb on the bike I lost attention to the details.

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Auright!!!  So, I left the carb on the bike, took the carb cover off.  MADE SURE that the diaphram was sealing and tightened down the cover.  I moved around the carb and retightened the air boot and intake clamps.  I readjusted the throttle cable.  Took it for a test ride and it's awesome.  Got the weekend off so I'm going to take that baby out and see what this carb can do.  Thanks to everybody for your help especially 38super.  You were right, it was a simple fix.  Much Mahalo's!  Aloha!  FYI, take your time when installing.  I think I was so excited to put the carb on the bike I lost attention to the details.

 

38super da CVK man  :thumbsup: :thumbsup:

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Eddie O and Freewheelers are the CVK Gods.  Weren't for them I'd have a bad running bike and a pile of useless jets and needles.  They've taken these carbs to the track and beyond.

 

Sa Bo  - Ride out for SHAVE ICE, wahini pic required.

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Eddie O and Freewheelers are the CVK Gods.  Weren't for them I'd have a bad running bike and a pile of useless jets and needles.  They've taken these carbs to the track and beyond.

 

Sa Bo  - Ride out for SHAVE ICE, wahini pic required.

Hah, hah!  Rahjah dat!  It's been raining all day so I've been working on a headlight swap instead of riding.  It just never ends with the DRZ.  This is my first bike and couldn't be happier.  Will post pics when I can don't know about the wahine pic, my wife might get all nutz.  38 super you from hawaii?

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Katonk, my block is the buddha head ghetto.  

 

edit - nix the pics for your sake.

Edited by 38super

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