I was planning on head machining my trailblazer 250 but now im kinda second guessing myself. My main fear is, will i risk blowing the engine if i have porting and i take off .020. And does it help the acceleration noticeably and does it help out the top end the most. I really want to but my dad thinks maybe because the fuel nowdays is so bad with all the additives in it might not be good for it. Would it better to run premium. But yet again, my main fear is blowing the engine. Your opinions and knowledge mean alot to me.

 

No you won't blow up your motor. It just helps when you have porting done. Heck it even helps when you don't have porting done. All I have ever used is premium pump gas. It will be fine to shave your head .020. Don't sweat it. It will help more with bottom end power I think. And the TB really needs more bottom end since it doesn't have reeds. It should help it acclerate better as well.

 

Thats what i was trying to tell him. Well thankgod for this website. Your message pretty much sealed the deal. Thanx. And duneaholic, what kinda nerf bars is that on your wifes quad and yours, those look really nice, and was it alot of work to mount them.

 

tblazer,

You dont have to worry about blowing your motor. The 250 is pretty tough and does not have some of the problemd the 400's do when moded. Machining the head .020 will give you better compression, gives you slightly better throttle response and slightly more power. You will have to run premium to help with pre detonation. Porting will make a huge difference expecially with a good pipe. Are you going to change the piston?

 

I dont plan on changing the piston. I know i should because it will give you a couple more horses but it probably wont happen unless i really have to. When i took off the cylinder to port it i put new rings on and the piston was in great shape so ill just see how it holds up.

 

Mine are banshee nerfs and my wifes are Raptor nerfs. Hers are AC Pro Peg and mine are AC nerfs. Mine went on really easy. My wifes required quite a bit of welding and cutting.

 

i'm not positive of this but i believe your not supposed to run a stock piston on a ported cylinder. your supposed to use a forged piston such as wiseco. i don't think it cost any more to bore the cylinder if your having it ported. somebody corect me if i'm wrong here.

 

It would probably cost 150 bucks with the cost of the piston and labor. Cheap when considering how expensive it will cost if you break a piston. With the higher RPMs of the pipe and porting it will really be a good thing to have a Wiseco piston.

 

Really, i suppose i will have to get one then. It doesn't cost me anything to get it ported, bored, or head machined which i have already got the porting done and i had ran it quite a bit with the porting and the stock piston, even ran it wide open alot at high rpm's - no harm. My dads got a really good friend who is a very highly trained machinest who works in minneapolis and he does these things for me for free as good as if you were to send it to a performance specialist.

If i were to get a forged piston would it be alright to just replace it with the stock size. And what website would be the best to get them cheap.

 

Hey if it doesn't cost you anything I think I would just have him check the bore to see how good of shape it's in. If it needs to be bored then go as little as possible to get it back to a straight bore. Like .010 or .020.