oily exhaust 2004 cr85

[bif]

Hi, looking for some ideas on how to correct a problem w my sons cr85 expert. It's a 2004 that I just picked up for him used, he's moving up from a XR100 that had some mods. So anyway there is a good amout of oil leaking from the exhaust pipe at the connection to the cylinder, it's pretty messy, gets on his left boot. I thought the fuel in the tank might be old and too rich so I drained the tank and repl w fresh using honda premix at 32:1, also air filter was pretty dirty so repl w new, and repl the sparkplug w a BR9EG, had a 10 in it which I heard were prone to fouling unless your racing. Now I still have same problem with the oil, I see his friends KX65 that he rides with does leak oil there. Is this common with these bikes, should I just live with it or can I chg the premix ratio or chg to a diff premix? Is there a gasket there that may be worn or missing? Anyone had or has the same problem with their bike?
Any help appreciated please!!

[crazyrydermx]

Yes, it is an extremely common problem and one of the most posted problems there are. Anything you do apart from rejetting is just avoiding the problem. You need to jet your bike. Right now it is running to rich. There is too much fuel that is not being burnt and it's escaping and causing this problem. When a two stroke dirt bike "fires", there is always a small amount of time on the combustion stroke in which fuel basically goes straight past the piston and out of the exhaust. This is because the piston acts as valves in a two stroke engine, and the piston is not always covering up the reeds. In that small amount of time where the reeds aren't covered up and nor is the exhaust, fuel is obviously going to get past. Now fuel HAS to get past because without fuel, the bike will not run...but because there is some fuel not being burned, you don't need that fuel. So what you want to do is rejet. We have some experts on here about jetting and if you need help jetting we can help, but that is your problem and everything else is just avoiding the problem and correcting it in the incorrect way.
Welcome to Hope you enjoy your stay with us

[Just George]

My friend tooks his pipe off of a 2002 cr125 and put it back with something that filled in where the black goo was comming out from good luck

[crazyrydermx]

Oh yeah, no more thing. You have to make sure all the o-rings and springs are good....bad o-rings can lead to leaking and bad springs can lead to head warping...

[Just George]

Good call he did get new springs too

[crazyrydermx]

Originally Posted by bif

Is there a gasket there that may be worn or missing?

Yeah it isn't a gasket it is an o-ring Like I said, you should replace those they are cheap and it is a pretty good idea to replace them whenever you take the exhaust off because they slowly get worn.

[AKColby]

I use something called Permatex, like a high-temp silicone, it's good stuff The gaskets they sell for the exhaust are crap.

[Henry]

i had this problem on my bike and when i took off the exhaust there was SUPPOSED to be a metal washer and a squared off o-ring, but nothing. so i replaced those and it still leaked, then i took some high sperature silicone sealer(got it from the hardware store) and put a bead of that around the exhaust port, and it hasn't leaked since.

the exhaust also got my bike all oily and dirt stuck to that, so it was pretty annoying.

[Faded]

Throw the o-ring away and use Permatex Ultra Copper high temp RTV silicone sealant, this will cure your problem. Don't try to rejet until the leak is fixed, if your getting oil spooge from the header area it's obvious you have a leak...but the problem is that fresh air can be drawn in during the exhaust reversion and lean out the intake charge.

[crazyrydermx]

Originally Posted by Faded

Throw the o-ring away and use Permatex Ultra Copper high temp RTV silicone sealant, this will cure your problem. Don't try to rejet until the leak is fixed, if your getting oil spooge from the header area it's obvious you have a leak...but the problem is that fresh air can be drawn in during the exhaust reversion and lean out the intake charge.

But, after doing this, you may have leakage out of the silencer. The oil needs to go somewhere, and this may be the place if it isn't all used. Then you will need to rejet.
I suggest rejetting anyway though. You could be robbing your bike of potential power if you refuse to rejet.