Rebulding Engine

[hjsmith00843]

I have a used ATV I recently purchased as a project. It runs aweseome and does not smoke and starts up very easily.

I am going to tear it completley down to the frame and get it PC and replace all bushings and bearings this winter and put alot of aftermart parts on it this winter. I have already ordered some stuff for this rebuild.

When it comes to the motor I want to make sure it is fresh as well. I was told it was a 440 but I am unsure. When I go through it should I replace the crank/rod, timing chain, guides, valve springs, lap valves, going to get a aftermarket cam, and maybe out a new kit in it for the bore. Might not go so big. And a full exhaust set.

Maybe a larger oil cooler with a fan install.

What else should I replace with this rebuild. I am in the process of buying new parts to make this a heck of a quad.

Hopefully it is going to go from fugly to pretty decent.

Not looking for stupid HP but a decent amount but with relabillity in mind. Not racing other quads just trail riding...

[honda400ex2003]

Originally posted by hjsmith00843
[B
When it comes to the motor I want to make sure it is fresh as well. I was told it was a 440 but I am unsure. When I go through it should I replace the crank/rod, timing chain, guides, valve springs, lap valves, going to get a aftermarket cam, and maybe out a new kit in it for the bore. Might not go so big. And a full exhaust set.

Maybe a larger oil cooler with a fan install.

What else should I replace with this rebuild. I am in the process of buying new parts to make this a heck of a quad.

Hopefully it is going to go from fugly to pretty decent.

Not looking for stupid HP but a decent amount but with relabillity in mind. Not racing other quads just trail riding... [/B]

You should not need to do a complete engine tear down and put a new crank and such in it. you would be looking at quite a bit of $$ to do that. If you want to make sure everything is new, you can do valve seals, rings and hone, and an hd cam chain. you could also get some new guides for the cam chain while in there since the grooves will be different with a hd chain as they are wider. you can do a valve lap pretty easy if you have the compound or you can have it done with a port and polish or something while the seals are replaced if you dont want to do that yourself. get a cam if it does not have one already, you will be amazed at the increase in performance from a cam with your 440. doing some nice arms, shocks, axle, and tires really makes a machine a different animal also. New fenders may be in order if they are really rough. it sounds like you will have a fun time with it, keep up the good craftsman ship with it and it will treat you good for a long time. steve

[hjsmith00843]

Originally posted by honda400ex2003
You should not need to do a complete engine tear down and put a new crank and such in it. you would be looking at quite a bit of $$ to do that. If you want to make sure everything is new, you can do valve seals, rings and hone, and an hd cam chain. you could also get some new guides for the cam chain while in there since the grooves will be different with a hd chain as they are wider. you can do a valve lap pretty easy if you have the compound or you can have it done with a port and polish or something while the seals are replaced if you dont want to do that yourself. get a cam if it does not have one already, you will be amazed at the increase in performance from a cam with your 440. doing some nice arms, shocks, axle, and tires really makes a machine a different animal also. New fenders may be in order if they are really rough. it sounds like you will have a fun time with it, keep up the good craftsman ship with it and it will treat you good for a long time. steve

Thanks for the very informative post. The engine itself is already pretty strong but then again this is my first ATV. I come from a kart racing background and this has already become more enjoyable. The racing was too much like a full time job. Prepping ties and getting it ready every week.

The motor right now runs perfect. So instead of spending the $$ on the motor I might allot it to put some better suspension componets in it.

I figure I will go with the 450 shocks.

[honda400ex2003]

sounds like a plan on the 450 shocks. they are great for jumping and such, i was hitting a 40 fter last week that would bottom the fronts a bit and it was so smooth with these it was rediculous. they are a bit stiff on the smaller chopper bumps though with stock arms. I am planning to do a bit of experimenting with them when i am home for the summer to see if i can get them dialed a bit softer. I plan to reduce the compression a bit more and see how it does. I would suggest getting +2 arms with them, then you wont even have to do anything with them really. If the motor runs good there is no real reason to take it apart at all. the more it comes apart the more issues that are possible lol. steve