cr125 spitting out oil after silencer

[SmogNazi]

My buddy and I went riding yesterday. He has an 04 cr125, about 8 hours on the bike, very easy riding, we are just cruisers doing some trail riding.

Bike was running good other than the oil dripping out good of the brand new silencer (fmf turbinecore2 SA). Then the bike out of no where would not start, new ngk plau and it was fine. Same thing happened today, new spark plug and it started finally.

The oil looks pretty gnarly, i thinking bad jetting. It is stock other than the silencer. Any ideas? what is the stock jetting on a 125 and what should he go to instead for jetting with that pipe?

Thanks
erik

 

[xr100ider]

its running too rich due to the new pipe. just rejet. nothing else to look to here....

 

[hammy56]

if you guys are doing "easy" trail riding, try to rev the bike now and then to clear the thing out, or it'll foul the plug....if it has the stock jetting chances are its a little on the rich side, most bikes come that way. Every new 125 Ive ever had I instantly dropped one size on the main, one position,leaner(raise the clip) on the needle, and one size smaller on the pilot...but it also depends on your location(elevation) and weather....but you should be safe to do this considering that kind of riding.

 

[DIRT-RIDER]

Yeah my bike was doing the same, until i fixed the float heigth adjustment, It had strangely gone off by a whole lot. So fixed it,But it is still running a little rich. But no more bridged gap plugs. And yeah it happens if you are riding the bike too low in the RPM range. And oil always comes out of my silencer even if it is running rich or normal,though i run a 40:1 mixture. Im also thinking it is rich jetting. Ive only had the bike 4 months. So i have no idea what jet sizes it has, or how long it has been on the same top end. It also has a Turbine Core 2, and a PC pipe. So im am guessing it has stock jetting. Any ideas about this oil comming out of the pipe, is it normal? Cause my plug seems to be running a charcol color.

 

[motometal]

even if a bike is jetted spot on, if you ride it below the power band in trails, it could spew a little oil. You're just not creating enough heat in the combustion chamber to burn off the oil. If you are running it hard and it's spewing oil, then it's rich.

I do a variety of riding, and I jet based on how the bike runs, not based on whether or not it spews oil. Different oils will behave differently as well.

 

[jp2396]

I bought an '05 YZ-250 this year and it was running rich and spewing oil out the silencer. It ran fine during the colder months (Jan thru March). I also put on an FMF TC2 and it made no difference to the spooge. When the weather warmed up though, I couldn't get it to start, when it finally did it would foul the plug. I dropped the pilot jet down 1 size and that cured the non-start issue. It is still running a little rich and has oil on the silencer but nowhere near the amount before. Try changing the pilot first and see how that goes.

 

[CspineRider]

Speaking of oil on the silencer, what do you guys consider alot. I am assuming if it is dripping, thats alot. How about just a ring around the silencer hole. No matter how I jet, I still have a ring of oil but no dribbles or drips. What do you think about the ring, still rich?

 

[jp2396]

I still have a small trail going about 1/4 of the way down my silencer.

 

[CspineRider]

I still have a small trail going about 1/4 of the way down my silencer.

You still have a trail of that size after you went down one size on the pilot? What type of riding do you do? MX or free ride and if your always at full throttle then one size down on the main as well. How many turns is your air screw at? If your at 3 turns out and it's still rich, then you know for sure you need to go down one more on the pilot.

 

[motometal]

good advice on the pilot, but that's a bit of an assumption on the main. I'd hate to see you seize it. It's really tough to make that close of a judgement on jetting just based on the end of the silencer. Even different brands of fuel and oil will affect this...not just the jetting. If you did/do lean out the jetting, there is a lot of residue still in the pipe and silencer that could still be making it's mark on the silencer exit.

One thing is for sure. If you lean the main and DON'T notice an increase in top end or over-rev, put the richer one in right away, because this means you were already plenty lean.

 

[hammy56]

try looking in your manual first to see what the stock jetting is and compare it to yours. A lot of manuals also have troubleshooting graphs for the jetting that show altitude, temp, etc....if you jet it by the chart it might not be perfect but it may at least put you in the ballpark....

 

[CspineRider]

Your right Motometal. But do you think there is that much residue in the pipe and silencer to spit out that much oil? I didnt think about that, but it makes scence.

 

[motometal]

what doesn't burn must come out somewhere, either in droplet/vapor form right out into the air, or coating the insides of your exhaust. A pint to five gallons or whatver you are mixing, when you think about it that's a lot of oil. Very few bikes out there are tuned to efficiently burn up all the oil at various throtle positions and rpms.

For most people, that kind of jetting isn't practical anyway, because if the temp changes 20 degrees (not to mention the humidity), you'd be rejetting.

 

[jp2396]

You still have a trail of that size after you went down one size on the pilot? What type of riding do you do? MX or free ride and if your always at full throttle then one size down on the main as well. How many turns is your air screw at? If your at 3 turns out and it's still rich, then you know for sure you need to go down one more on the pilot.

Before the pilot change, after a couple of hours it would normally be the length of the pipe! I had to drop the pilot 'cause the bike refused to start in the hot weather here. I did not touch the main jet, bike didn't seem to need it so it's still stock. By using the correction chart, I can drop at least one more size on the pilot and be okay, but it's fine for me at this point. I free ride the bike so I only go full throttle on straight-aways (scarry enough doing that) and my air screw is between 1/2 and 1 turn out. Remember though, I'm at 4,700' ASL. I do know that I'm still rich, but I'd rather be a little safe than sorry. If I was racing then I would definitely be dialing it in more precisely and include the main and needle.

 

[motometal]

generally you won't hurt a bike even if you end up with the pilot lean. The bike will talk to you, bogging when you come out of corners or surging. Turn the air screw out, see what effect that has. If it likes to be 2.5 turns (or further) out, then you could use a smaller (leaner) pilot jet.

 

[i_955]

Try taking the carb cap off and raising the clip one notch...

My YZ likes this when the temps go up.

 

[CspineRider]

generally you won't hurt a bike even if you end up with the pilot lean. The bike will talk to you, bogging when you come out of corners or surging. Turn the air screw out, see what effect that has. If it likes to be 2.5 turns (or further) out, then you could use a smaller (leaner) pilot jet.

Exactly :cool:

 

[CspineRider]

Try taking the carb cap off and raising the clip one notch...

My YZ likes this when the temps go up.

I was thinking about trying that on my CR, my book says 2nd or 3rd position, for the temp and alt I ride in, but I kept it in the 3rd which is stock. I think I will try it.