How much oily stuff to expect in exhaust

[curtis73]

I've been dirting now for about a year. I always borrowed bikes from the group I rode with but I finally bought my own. Its a Yamaha WR250... (I forget the year right now... late 90s)

Anyway, that bike always had an oily drip from the front of the can. I pulled the bolt out of the bottom and got probably a couple teaspoons of black gunk out of it. Most of my experience with 2-strokes is in marine applications and i'm not used to seeing any of that oily stuff. Is it an obvious indicator of anything, or perfectly normal? It doesn't go through plugs any faster than anybody else's bike. Thoughts?

By the way, the bike can be seen by clicking the link in my signature and then clicking on the appropriate page... or just click here http://www.curtisandkim.com/yamaha250.htm

[BNaylor]

I've owned a lot of two stroke dirt bikes and some drooling or spooge is normal. Basically it is just unburned oil from combustion. Some people have minimized it by experimenting with mixture ratios. Like going from 32:1 to 40:1 or rejetting the carb. Also, you are more likely to get spooge if you are running full synthetic premix oil. Even how you ride can cause it. Going too slow or lugging it while out riding and not keeping it on the pipe because it doesn't allow for consistent exhaust pipe temperature where the stuff will be burned off. In a worse case you could have worn out piston rings.

I used to have the problem with my Honda CR250. I experimented with jetting and was able to minimize it. Then I found out that Honda had a bad design on the exhaust flange so I replaced it with a CNC machined one from Boyesen. That helped the leak at the pipe header but eventually I could still see drooling at the tail pipe at the silencer. Even with a new Wiseco piston and rings I still had it.

Later I decided to mod by adding VForce3 reeds and a Pro Circuit Platinum pipe. Did some minor jetting changes like the pilot, needle and main jet due to the mods. I haven't had any problems with spooge ever since. The spark plug looks perfect after taking a reading.

BTW - The Yamaha WR250 and Honda CR250 are notorious for jetting problems. Normally too rich.

Also, I had experimented with spark plug heat ranges and it didn't help much.

[curtis73]

Great, thanks for the reply. I've known the bike for about a year, but just bought it this week. I know that it has four rides on a complete new top end. I know that the exhaust was ported and I think aftermarket reeds were used. The way he described it to me was that he rejetted it for the porting mods, but kept the stock exhaust for the sake of low end. He said if you want more power out of it, just rejet it and get a better exhaust.

It has always puked that black stuff, so my guess is that its just rich. I'll play around with jets and see what happens. Thanks so much.

[BNaylor]

You're welcome Curtis. Good luck and let us know how it turns out.

[RoostRider]

You're on the right track with the jetting... you can find a jetting guide at pingertalk.com if you need. I think it's called Spanky's Jetting Guide. It should get you straight, but remember, a little rich is better than a little lean.

[curtis73]

Excellent.

I am now engrossed in modifying my trailer for use as a bike hauler. It was a tiny little converted jet-ski trailer and I decided to make it big enough for a couple bikes.... well, every step I take I see a need to modify something else about it. I've missed two days of riding because I don't have a trailer

I'll look into some jetting... Thanks guys.

[VR43000GT]

^^ Best of luck. We went through the same thing except our trailor was meant to haul golf carts. Its worth it in the end though.

[curtis73]

Well, the trailer turned out great. Its been too darned hot to really hit the trails, but I'll get into it later. There is more to be had here since its a ported engine with aftermarket reeds on a stock exhaust. I think I'll upgrade the exhuast, re-pack the silencer, and take it from there. I'd hate to re-jet it only to change the exhaust later and have to jet it a second time.

Here's the trailer... Not quite finished yet. The bed will get a coating of spray-on bedliner and I have to weld on a couple stake pockets and front tire holders, but its ready for duty. Not bad for free steel

[BNaylor]

Originally Posted by curtis73

Here's the trailer... Not quite finished yet. The bed will get a coating of spray-on bedliner and I have to weld on a couple stake pockets and front tire holders, but its ready for duty. Not bad for free steel

Looks good Curtis.

Here is a pic of the one I got about 4 years ago. It cost around $225 and took me about 4 hours to put it together. It came in kit form with the single rail. All the lighting works and I have an adapter to mate it up to a GM "W" body car or a Ford F150 pickup. I was able to register it with the State Of Texas with no problems.