Black "soot" dropping out of silencer?

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#1
The bottom of the silencer on my 97' CR125 is dripping black soot onto the swingarm and brake caliper of my bike. I've only had the bike a few weeks and it had its first hard ride today. Is this normal? The bike runs great and does not foul the plug. The stuff looks like black syrup.
 

BEEF706

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#2
Probably running a little rich on your jetting, probably in the lower rev ranges, you might try turning the airscrew counter clockwise a little at a time (1/4 turn or so). If you ask em at a shop you are likely to be told to gas it more :confused: Other things to check into, is the air filter clean? How much and what kind of oil are you using in your premix?
 
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#3
Originally posted by BEEF706
Probably running a little rich on your jetting, probably in the lower rev ranges, you might try turning the airscrew counter clockwise a little at a time (1/4 turn or so). If you ask em at a shop you are likely to be told to gas it more :confused: Other things to check into, is the air filter clean? How much and what kind of oil are you using in your premix?
I'll check the air filter. Im using Maxima Castor 927 premix oil, 4oz per gallon with 109 race gas. My elevation here in Lubbock, TX is around 3,000 feet and the guy I bought the bike from is at sea level.
 

CaptainObvious

Formally known as RV6Junkie
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#4
Adjusting the air screw isn't going to cure a spooge problem. The airscrew really affects throttle response below 1/4 throttle.

More than likely your pilot jet is too rich, a very common problem. If you are happy with the throttle response above 1/4 throttle you needn't worry about the needle, however, if the bike seems a little fat in the mid range you might want to raise the clip by one position.

But before you go changing jets and needle positions, make sure that your air filter is clean and that you repack your silencer. Both of these items can lead to jetting that is too rich.
 
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#5
Originally posted by RV6junkie


But before you go changing jets and needle positions, make sure that your air filter is clean and that you repack your silencer. Both of these items can lead to jetting that is too rich.
I'll do those things. Thanks for the help guys.
 
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#6
Originally posted by BEEF706
If you ask em at a shop you are likely to be told to gas it more :confused:
I think Beef got that one right. Mine did the same thing when I 1st started riding, you have to ride 125's like 125's were meant to be ridden...revved out tight. :aj:
I thought I had been doing that untill I let a guy that raced ride mine, when he brought it back, the silencer was practicaly on fire from the oil and splooge in the packing burning out. Every since I started racing I've never had a splooging problem.
 
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#7
You have an elevation problem too. I'm at a lower altitude than you (1900') but when I came from sea level to the Georgia mountains, I ended up having to lean out 1 main jet size to get it to run half way decent. I've played with the needle to no end and the bike is a spooge monster. I switched overe to Motul synthetic to see how it worked in comparo to the 927 or Super M and it ran much cleaner - but the bike still spooges. I'm sure if I were running race fuel it might clear the problem up a great deal, but we're in hillbillyville here so no race fuel to be found.

You probably should check with someone like www.BillsPipes.com and their jetting specs. Compare them to www.Boyesen.com and their jetting specs. I think www.FMFRacing.com might have jetting - then realize these are all probably sea level specs or close to it. If they are already going leaner on your bike by one for sea level, you might find yourself going 2 jets leaner? Maybe more?

How does the race fuel affect your bike? While others disagree, I've yet to run race fuel (not including Ultimate 2) that didn't require that I go at least 1 leaner on the mainjet. So you might find you are too rich because of the altitude, and too rich because of the race fuel...

Start reading those jetting charts - find out some elevation info for your bike. Better yet, find a fast rider at your track on the same basic bike running race fuel and talk to him to see what his approx jetting is on his bike. It might save you a ton of time.

Just a few thoughts for you - hope it helps.
MP