I have a '88 250r it has a 310 kit in it. I just recently rebuilt and bored it out. The reason for the rebuild was that it overheated and scufted because of a blown hose. But after the rebuild water was coming out of the weep hole under the pump. So I replaced all the bearings and seals in the pump. Then it started leaking out of the over flow, and I just thought it was too full but thought I would check anyways. So while I was riding back it ran out of power and blew white smoke and now has no compression. It does'nt even have 5 minutes of riding since I did the work. This has me very confused so any help would be great. Thanks , Chad E-mail chado2@earthlink.com

 

Could be a blown head gasket or o-ring.Did you forget to install one of the 2 o-rings on the head?

 

sounds like you blew the o rings in the head

 

Chris, It still has the stock style head gasget not o rings, but I did replace them with exactley what was on there befor, when it ran fine. Do you know why it would constantly leak out of the radatior over flow aswell? I think this could be the cause of my problems. When the cap is off it seems to be flowing fine. I am in the process of tearing the cylinder down and will see the extent of the damage. Thanks for your help. Chad

 

A blown head gasket will do the same thing that is happening to you. I would buy a new gasket and try Permatex copper spray-a-gasket on it before installing it