can i rebuild it or not??

[250rforlife]

well i dont have the money for labor so im chossing to do it myself. iv rebuild a 250r, and it runs mean. ill have a clyimer maual to do it. but i was wondering if i can put a topend rebuild in myself. i also would like to no if i have a 416 with a stg2hc ,stock valves, and stock valve springs if ill need to upgrade my valvetrain at all?? i have a fmf full exhaust too.

[CJM]

416 will require boring and new piston. Dont need new valves of valve springs. You want to take it apart and regrind the valves you can but not needed. Stg 2 hotcam will work well for this build for awesome to mid range power. Do an 11:1 piston for even better gains.

You can rebuild the topend yourself, not really hard imho, I had some experience working on 2 strokes and cars before and did my friends and then mine with no issues.

So yea its doable, take your time, make sure you got all the parts and the right tools too.

Also look online, they have free factory manuals online for the Ex.

[3400ben]

A good tip for your first top end. Take alot of pictures as you take it apart . Then you can allwAys study them
if you think your missing a step or a part.

[eprovenzano]

I too have worked on many 2 stroke engines. Over the past winter, I did the top end on our 400ex. It’s not difficult. I had the cylinder bored 2 over and new valve seals installed. Since I don’t have the equipment to do the valves I had to take them to a local machinist. You'd be surprised as to the re-gained power from the new top-end. My 400ex was 11 years old on the original top end. It smoked and used oil. Now no smoke, uses no oil, and the power is much more than before the rebuild.

[honda400ex2003]

if you put your mind to it, you can def do it. take some pics, draw diagrams, label a tackle box while taking bolts out. make cardboard sheets so you can drop the covers and such right on them with the bolts in them. you wont even have to seperate them and remember where they go in. that is how i did it. seemed to work, it went back together. with the manual it is pretty tough to miss something since it shows all of the dowel pins and such also. steve