Hello,
I am new here and I have just purchased a used DRZ400SM.  The mods are as follows:

Athena big bore kit
FCR39 carb
MRD/SSW exhaust without quiet insert
Aftermarket cams (previous owner could not remember which cams because they were installed by the owner before him)
E model CDI

The bike runs well but there is excessive popping during deceleration.  I have searched and realize that some decel popping is normal but this is excessive.  I have checked the valve adjustment, performed a cylinder leak-down test, checked for vacuum and exhaust leaks, everything seems OK, oh and the bike does not have a 'Pair' Valve.  So with that being said I was hoping some of the many experts here could verify my jetting specs.
The current carb jetting specs are as follows:


Altitude: 3740 ft
Avg Temp: 53 deg F
Fuel: 93 octane pump gas
Main Jet: 155
Pilot Jet: 48
Main Air Jet: 200
Pilot Air Jet removed
Needle: EMP position 6
Air Screw: 1 3/4 turns out
O-Ring mod has be done

You help is greatly appreciated!

Clint

Edited by Clint E., 21 February 2012 - 07:27 AM.

Clint E., on 21 February 2012 - 06:19 AM, said:

So are these the specs that the bike currently has or what you think you will need to change to?

In my experience having the pilot air jet removed causes excessive popping. On the track it wouldnt matter so much but on the street that much popping is obnoxious. I would rather run a slightly rich pilot circuit and have much less popping.

I run a 45 pilot jet with the 100 pilot air jet installed and have minimal decel popping.

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These are the current specs

where did the fcr come from?

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Eddie,
Not sure where the fcr came from.  The guy that I bought the bike from only had it a short while, he bought the bike from the original owner who did all of the modifications.

Clint

this is very important info and relevant to any jetting advice you take.

you should start by taking a pic of the carb from the left side and posting it here.

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Thanks Eddie, pic below as you requested.

the needle needs to be on clip 3 from the flat end. replace the o-ring with wire.

does the carb have the pilot air jet removed?

Eddie,
Yes the pilot air jet is removed.  I will make the adjustment on the needle, unfortunately the weather here has taken a turn for the worse and I may not be able to try it right away.