To Port or Not To Port.......

This is the question....


I'm rebuilding my 08 YZ250.  So far, I've got a new Hotrods crank, replaced every bearing and seal in the engine, need a new shift shaft, clutch kit..... the list goes on.  I also need to have my cylinder plated and, of course, new piston and rings, but I'm not sure if I should get the cylinder ported with matching head work while it's getting done.  Money is an issue, but I have another bike, so if I can't afford it today, I can tomorrow, if you know what I mean.  I suspect this bike won't be ready till mid-season.


A little about me: I'm 6-5, 240ish, race a little MX (40+ C), but mostly hare scrambles in senior B.  I usually finish mid-pack, but I occasionally shine and run with the top 5 for a while.  I never thought the bike lacked power except for maybe mid/top where I've been pulled before on the MX track coming out of a turn into a long straight or similar off road, opening it up on a long straight.  I've run the stock pipe and an FMF Fatty and wasn't able to notice much difference between the two.  I have a TMV flywheel weight, but I'm not sure which one since it came on the bike when I bought it.


I've read a little about porting the YZ250's.  It's been suggested that the stock porting is already very good and any changes just move the powerband, but the head has room for improvement with the squish.  I'm going to get the head done and bump compression a bit.  I already run 50/50 race gas, so I'm not worried. 


Should I get the cylinder ported also?  My friend with a 2000 CR250 said his ported cylinder was the biggest improvement of any mod he did, by far.  Maybe it just works well for the CR?  Would you say porting is the best power improvement for the YZ?


If so, who should I send it to?  I know there's the guy up north who plated my 02 cylinder and worked the head.  Or there's the guy down south that many swear by.  I'm sure there's more than one shop in the Northeast that can get it done, too.


Any suggestions, comments or help would be greatly appreciated :worthy:

So far I heard porting is really the best.

Low to mid port was the best thing I did to my YZ250 other than suspension.

You can't go wrong with good quality port work. I had the head ported/polished on my YZ250, TM400, and 450R.


It's important to have a professional shop do the work like Ron Hamp or Eddie Sisneros. Make sure whoever you use has a solid reputation for porting/polishing mx heads. You don't want to send it to someone that will ruin your head.


Ron Hamp is probably the best porter/tuner/engine builder within the mx community. 


Hope this helps.

Yes, porting is the single biggest thing you can do to improve the characteristics of your engine. Especially, two strokes!! Pipes just move power around, whereas porting done by the proper individual, can improve everything.

Port, give Derek a call at HP....

One of Derek's jobs, Stage 1


Nearly 5hp for just porting? or is there more involved in Derek's stage 1?

Nearly 5hp for just porting? or is there more involved in Derek's stage 1?

Just porting....

Nearly 5hp for just porting? or is there more involved in Derek's stage 1?

I have heard/seen bikes that respond to modifications in completely different manners. I knew 2 guys that virtually same cbr600's. One put a stage 1 jet kit, k&n and full exhaust on his the other put a slip on pipe and k&n filter on his nothing else and they picked up within 1 hp of each other on the dyno. Now 1 played with jetting a little but only gained like 2 more hp. For a difference of 3 to the plus on bike 2. But bike 1 spent nearly twice the coin.

Port, give Derek a call at HP....

Monk do you gave Derek's contact info?

1 210-882-0330

I have Derek's stage two package. It is a monster.

Keep in mind, added hp is USELESS if you can't 100% efficiently use what you alrerady have.... Added hp in many cases actually results in SLOWER lap times resulting from excessive wheelspin, and elevated rider fatigue. Adding  5 hp to a MX 2 stroke with poring alone is impressive on paper, but putting the added 5hp to efficient use into the dirt is another...  In my experiences sometimes replacing a worn out rear tire is equivilant to adding 5hp.... ;)

Edited by Polar_Bus

yeah I wouldn't get it done personally because my yz250 is fine in the way it is.  Just impressed with the numbers they made by porting.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now