head Milling 1997 YZ 250

[Rcannon]

I was at the local machinists the other day. He was talking about engine performance. He mentioned that due to our high altitude, 4500 ft, that the bikes benefit greatly from head milling.

My question is this. If a person did this, how much should you take? Second, would this make the bike useless in a low altitude application. I would like to continue to use pump gas just because it is easy.

Thanks!!!!

 

[bclapham]

Roland:

I did mine when swapping to race gas- it turned into a complete nightmare since the guy took way too much off.

it might be worth just trying a thinner base gasket, or if you are paying for the head mod, just send the whole lot to Eric and have him set the cylinder up bang on the money for your altitude.
but remember, you will need to run better gas if you get to sea level!

 

[Enduro_Nut]

I agree with bclapham, if the machinest is not very knowledgable you can ruin the head. I milled all of my heads on my jet skii's with great response, but the guy was knowlegable and he only milled enought to change jetting and still run pump gas. The second part of the sory is about a year later due to smog restrictions they changed the formula of the gas and in turn I was forced to run race fuel because of burnt up motors(ran lean!)

 

[Rcannon]

I think you guys are probably right. I should just let Eric take care of the whole thing. I would not mind running race gas when I take that trip to California to ride...oh wait, that trip never happens!

I just need to make that committment to myself. Having a bike that would run well at sea level "just in case" does not make a great deal of sence, for me!

 

[Rich Rohrich]

Rcannon - Cylinder heads are super cheap, so it would be really easy to have one setup for your normal altitude and one for those sea level adventures. It's probably cheaper than race gas over the long haul.

Getting the cylinder pressure and squish properly matched to the conditions makes a huge difference in the rideability. The fun factor goes way up too. :)

 

[Studboy]

Yes, just generally milling heads is a bad idea, it could be good or bad but it isn't easily reversable.
I am still running the stock untouched head on my 02 YZ250, and it has a lot of overrev. Would it have less overrev at sea level?

 

[bclapham]

i think Rich has yamaha mixed up with honda :) - i looked up a spare head for my YZ- $170, yet you can get one for a honda for $50!!!!!!

 

[Rcannon]

I agree that cylinder heads are cheap, except when I want one.

The cheapest I can fins one for is 165.00. Maybe that would be worth it. It is better than wondering about it all the time!

Cheap to Rich is different than Cheap to me. I dont know if you all know this or not, but Rich hosts a show every Thursday night. It is called "The Apprentice"

 

[Studboy]

Are you serious? On what channel?

 

[Rcannon]

I think it is on NBC. He is much nicer to the girls than the guys. That much I know.