I have just bought a 04 DS650 Baja X, I bought it knowing the compression was low. I am looking for any and all information on my options as far as getting a good solid lasting repair the first time. I am looking for reliability and longevity over performance or speed. I am supposed to get some extra parts for it soon to start my port,polish etc. on. but for noe my 15yr old son wants to play with it and see if his tuned 400ex is comparable to it. I will surprise him with the power later. I guess what I am asking is can I go back stock on the valves with dbl springs and get longet life oorrr...what combination gets me the most bang for the buck. By the way I live in the Appalachain mts. so the riding is slower and hilly.

 

if you are going to rebuild the head. IMO a +1mm on both valves and some minr porting & polish would be good. i think a +1mm on the valves does not require new seats. and run the bigger springs. this would help performance & still be VERY reliable. while its open maybe concider higher compression piston. 11:1 or12:1 would be good & still run on pump gas. any more radical porting and valving would require race gas. my last build had this setup & worked very good on trails at low RPMs and did not run hot. this is pretty mild but will increase hp and performance. don't go crazy on the porting, just open a little and polish as needed. there are motor builders on here who know more of the details than i do. i sent my stuff out to be done and i assembled the pieces.

 

Thanks, I am considering some slight mods. Right now I am going to get the thing running and then look into the most bang for the buck, without getting away from Pump gas. I am going to do a little port work and hone and polish the intake, port work will only be a gasket match on both ends. I also think I will clean up the head area around valve seats. I am considering going 11.5 to 1 but how does the starter do with this?. How thick is the head in the top of the intake between inside the port and where the bucket sits? how much can u take out? What about exaust ports? How much to take out?