yz125 porting info?

[Blaner]

A friend of mine has a YZ125 he has apart and called me the other day with regard to my advice/opnion on some porting.

Now i have never had the opportunity to work on a YZ125 before and while I have done successful porting and head rechambering on blasters, i don not know any figures with regards to port timing/duration, squish and potential of these motors.

Can anyone give me some info on the timing and duration, ie, is it optimized from factory? is there any point in adjusting port height and size? is a general port clean up all thats needed?

shot!

 

[Larry's Shee]

First have to consider that 125s are wound pretty tight already. Next, not real familular with it, but does it have powervalve or plated cylinder? If so I would think it will limit what can be done vs cost. If you want to open up plated ports it's far easier to have the plating stripped first because it's hard!! However , opening up the bottom of transfers, removing flaws will help. Might be bit much work to port match cases and jug unless you have the time to split cases. Let us know what you decide and how it goes!!

Might want to cruise/join YZ forum to find more info.

 

[Blaner]

yeah he has powervalves not sure about the liner, im going to check it out for him this weekend and do some measuring etc..

the 125 pushes 33hp as it is so, like you say its pretty tweaked, hence my question, i think its pretty much optimized, but hopefully there is room for port clean ups etc.

will have to do a port map to find it all out but was hoping someone could save me the effort

 

[theblasterboy]

If I'm correct the 98-01 motors had the best porting from factory. Yea these thing pump out 33 rwh. That's more stock than what a full blOwn modded blaster could drea maybe. Besides what year is the yz of ur friends?