Vintage Dirt Bike Q & A

hello everyone i have a problem i hope someone can help me with.I just got a 1980 cr250r that wasnt running when a friend gave it to me,it needed a piston and rings.I put it back togther and now it leaks oil pretty heavly from the exhaust port on the cylinder.I was told it could be a seal leaking oil from the tranny into the crankcase.It also bogs and leaks fuel out of the carb.I seen the fuel leaking post and that is what mine is doing also.Im running it at 32:1 and it smokes like crazy.so please if anyone could tell me if they think the oil is unburned from possibly running to rich from all the fuel or if they think it might be a seal it would help me out alot.I forgot to mention the bike sat for about three years. Thanks

Yes a seal is bad! ...Bad seal! ...? There is a main bearing seal that keeps gear oil from entering the crank. It might be leaking? Or the center case gasket could have failed. That is why it smokes so much. As for the fuel, the floats might be sticking. Just take the carb and lightly tap the float bowl with a screw driver if the leak stops then the floats are sticking. you,ll then need to clean the carb.

thank you for the help i'll have to start tearing it apart this weekend.

What color is the smoke? The smoke from transmission oil is white and the bike will absolutely not run. If you've got black drool from the header and/or the silencer and blue smoke, your carb may need a rebuild and the jetting is rich.

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

the smoke is white, but the drool from the exhaust is black (i think its been a few weeks since i ran it) and it didn't run very well. it ran like crazy when i started it up but lost power over the 15 or 20 min. it ran.

If air is getting in through the crank seal on the rotor side it will rev like crazy. On the other side, the white smoke does suggest that transmission oil is getting past the crank seal behind the primary drive gear. I am pretty sure you can get both seals in and out without splitting the cases, but you would need a puller for the rotor. I have seen posted that you can get these from Motion Pro. I got a Honda tool from the dealer. While you have the seals out check for ANY up/down play in the crank as the bearings and/or journals might be worn. I found play in my crank that was flexing the seal and letting air in. If you need a manual on CD-ROM email your address...

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

i pulled out the main seal behind the primary drive gear yesterday and it seemed worn and was hard as a rock from sitting for that long. I couldn't see any play in the bearings but i haven't pulled off the rotor yet (i need to get the tool).I ordered a seal kit from vintage elsinores, so now i just have to wait for the parts and try to scrounge up the tool somewhere. Hopefully just the seals will fix it cause the weather is finally starting to get nice and i want to ride it.

If you grab hold of the rotor (in place) and pull it up and down you'll be able to detect play in the main bearings. It shouldn't move at all. There may be some in and out play, but not much.

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Good news, bad news. The Honda tool is part # 07933-430-000. It is currently available from http://www.cmsnl.com for EUR 27.00 (about $55 I guess ). If we can work out some "escrow" agreement I would loan you mine

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF