phat head racing heads

[killerbeez 75]

I have an 02 cr250 with an fmf fatty and v-force reedsand what I was wondering is will putting this head on make a huge differencein the power of the bike or is it just a waste of money.I think they look pretty cool so if they work as good as they look than I'll buy one,also if you bump up the compression by one, does that mean you also have to run race gas. :think:

 

[Dragmeistr]

I tried the VHM head on my 03 CR and did not like it. It made the top end run flat with very little increase down low. Obviously these are not the same heads, but I would imagine that they are pretty close. Eric re-worked the dome for me and it is much better now. I am sure that you would have to run race gas, it seems the newer CR's with stock jetting and carbs are detonation prone anyway. Good luck.

 

[marcusgunby]

You wont see a big gain if any at all.

 

[john3_16]

I've heard of some guys having huge gains with the phat heads.... I guess we need a real test with some dyno charts...

 

[marcusgunby]

On a 125 ive seen 1hp from a head setup-thats going from a really bad design to the best one for our fuel, i doubt you would see much of a gain from a cr250 but i cant say for sure.

 

[elf]

I have a phathead on my 00 yz125. It made very impressive power gains throughout the rpm range. And it still revs out good on top.And yes you need to use race gas or at least 50/50 race pump. It also has better cooling capacity than stock. But like the others said it might not help on your bike.

 

[killerbeez 75]

Thanx for the info and i'll keep my money :cool:

 

[Studboy]

It is only ~$35 for a mod to your stock head which will do the same thing.

 

[elf]

It is only ~$35 for a mod to your stock head which will do the same thing.

That is true. but with the phat head you get 2 domes with different comp. ratios. so you can switch back to a pump gas setup if you want. you can also get additional domes with even higher comp, or with less than stock. Then you can find the one that suits your engine the best.Not saying this is the best or cheapest way to go, but it does give you a way to fine tune your engine.

 

[Studboy]

Ha ha I have a nice shiny VHM head with two different inserts sitting on my bench. I've tried them both...and the stock setup is just plain better IMO on the YZ. Both of the inserts make the bike feel much flatter than stock with a little bit of lowend added.
I would probably find a cheap stock head somewhere and get it modded for race gas and keep the stocker for pump.

The quality is top notch on the aftermarket heads but they aren't worth the money. I'm glad that mine came unused with the bike.