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DRZ blowing black smoke

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So this comes after another problem I've been hunting down.  There has been gas in my oil and I plan on replacing the petcock with a Yamaha one, but decided to check the float needle in my FCR 39 in the mean time.  I removed the carb and only opened the bowl to inspect/clean the needle.  Looked fine so I put everything back together (I think correctly?) and changed the oil.  My bike now whistles under acceleration (very rich?), blows black smoke when revving, and back fires like crazy when letting off the gas.  Before it just burped.  I checked all the electrical connections and everything seems in place, but something is obviously very wrong.  The FCR has a 165 main jet as well.  Any ideas on why there is suddenly so much fuel being dumped into the engine?

 

Also, on the FCR I noticed a wire tie almost like a paper clip was wound around something (used bike).  What is it and why?  Photos attached.

 

My understanding of carburetors is very limited.  I have more photos or can take some if requested.

 

 

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Edited by Shaz

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That wrapped paper clip is safety wire. Commonly used in the aerospace industry to make sure a nut doesn't back off it's bolt, like a locking cotter pin

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safety wire is a common mod and holds the AP arm to the screw, this helps with throttle response. 

 

Did you check the float height when replacing them? did you bend the tang on the float assembly at all?

 

You may have an air leak around the carb boots, check them as well.

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That bell adapter looks homemade. Since you have the removable type you should get the appropriate adapter from Sudco. While it's off, replace the O-ring with the stock E model part, make sure you have a 200 main air jet and a 100 pilot air jet installed. Some people mistakenly removed the pilot air jet(left one) due to some outdated information on the web.

Float level should be 9mm. What pilot and needle do you have? What is your location?

Google FCR o-ring Mod, it will explain everything about your wired accelerator pump arm.

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Ok, so an update.  I took the carb out again and tore open the bowl.  Everything looked fine, but this time I checked and set the bowl level to 8mm.  All I could find online said 8mm before the comments in here, although I think it will be fine.

Here's where I found my error.  In adjusting my fuel/air screw, I turned it all in and backed it off until I got a decent idle.  Although I was able to achieve a good idle, the black smoke problem appeared.  I assumed this was cause by a too rich mixture, because it was exhausting gas into the MRD.  In fact it's a too lean mixture, the opposite of what I thought.  So now I have it somewhere around 3.5-4 turns out, a quarter turn from where it will backfire.  She's now running like a champ with barely any visible smoke, but I might give her another quarter turn to be safe.

I don't know my jet or needle sizes, but will remove them next time I take out the carb.  I am around 300ft elevation with very hot summers, so maybe the jetting is good enough?  I do believe I need a new rubber boot between the engine and carb, as the one now is cracked and doesn't fit well.  I'll also look into the bell issue mentioned.

Another issue I'm now looking into is the bike dying after giving it a quick blip of the throttle.  I equate this to the accelerator pump squirting in too much gas.  Is there a fine tune adjustment on the carb where I can decrease the amount of fuel being added?  Is it the green striped phillips screw?

Thanks!

Edited by Shaz

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