Pipe Oil Discharge

[Walt Hollis]

I recently changed out the carb set up to the recommended set up from the popular mx magazines. The magazines had a different needle / jet set up than stock after their test. I felt pretty comfortable doing it since they tested my bike at the same track I ride at. I have a 03 CR 250 and after making the changes it runs a ton better. The only thing that has changed is that I am getting oil discharge out of joint between the pipe and silencer (the lowest point on the exhaust system). I am very happy with the way the bike runs now that I made tha changes. Should I be worried about the oil discharge? If so what is it indicative of?

Thanks, Walt

 

[Senior KX Rider]

It would be indicative of a rich condition ;)

 

[Buzz Bomb]

It's nothing to be worried about. Are you running pump fuel or race fuel? Its very hard to get your bike spot on with pump fuel due to the inconsistency, so sealing the bike with silicone is the best idea. I would simply pull off the silencer and seal the pipe/silencer joint with silicone sealant. Also, I don't know if the 03s come with one, but they should have a rubber tube to go over this joint to seal it better.

 

[bclapham]

Walt, just out of interest, i sometimes ride those tracks and my settings are massively leaner accross the board than what the mags say. i friend had the similar bike, he is in the same boat.

as far as the mags go, treat them as they are, simply advertising brochures, DRN will have all you need to learn to jet for yourself rather than take handouts. hopefully okie will have the search function fixed soon and then you can find out all you need. we need to meet for a ride soon, have you been to the new track near Temecula yet? a very good place to test that suspension!:)

 

[jmics19067]

that goo is from incomplete burning of either the oil or gas that you are using. Most likely good that you won't seize the engine from being too lean, most likely bad that you are not getting complete combustion costing you horsepower and yes definately ugly. I say most likely because one circuit of your carb could be rich while the other is lean, causing spooge and yet running dangerous in two different throttle settings.

Definately agree in the type of gas you are using you may not be able to jet cleanly, and I definately agree that you would be much better off learning how to jet for your own than to be following someone else's settings. Every engine is going to be slightly different and every rider can be vastly different easily changing what could be best for you.

 

[Walt Hollis]

The bike is box stock at this point. The factory settings were a 420 main / 3873 needle / clip position #2 / 30 pilot / 1.5 turns on the air screw. I changed it to a 400 main / 3870 needle / clip position #1 / 40 pilot / 1.5 turns on the air screw per the recommendations of both Motocross Action and Dirt Bike. The bike runs better but now I have the goop. I run pump gas at 40:1. The track I ride at is at about 1500 feet above sea level. Based on the threads even though I am running better I am still not running at peak power based on the goop discharge.

Should I make another change in the carb? Race gas? Fuel / gas ratio?

Appreciate the help - Walt

 

[bedell99]

Did you know they used a "leaner" slide which will dramatically change your low end circuit. That is what is causing your goop. The slide they used is 4.25 mm slide that came stock in last year's (2002 CR250) bike. Your bike has a 4.00mm slide. In order to use that jetting I would imagine you would have to get a the slide off the 2002 bike. Make sure it is 2002 and they go for about 40 dollars


Erik

 

[bclapham]

Walt: race gas will help, but the jetting will be much different from pump gas, the bike might even run much richer for example. using reccomended settings can be very dangerous, since so many things can change it. i would leave the mags alone when it comes to "technical reccomendations"!:)