225 efi cc's

**rcb99team** · 09-09-2021, 08:38 PM

i've searched and searched, and none can give me a for sure cc number for stock 225 efi heads and 300 promax heads, it blows my mind. PLEASE can someone tell me what the ccs are and where i should be to upgrade my 225 efi to 300 promax spec?

**Chaz** · 09-09-2021, 10:23 PM

Early model porting (ex notch sleeves) was all the same for 225 , 250 and 300 . So changing heads between any of the three won't get you in trouble .

Heads :

225 = 73cc
250 = some (most) were 73cc but later ones and xb's were 68cc
300 pm = 63 - 64cc

Late model (large thermostat)

225 = 73cc

250 = either 73 or 68 , what ever they had in stock .

To be fair , there was a few years where they changed port height on 250's every year , so i rekon they tried to keep compression low . Best to measure exhaust port ht. and cc your heads to see where your at if you own a late 250 .

300x = 61cc

**rcb99team** · 09-10-2021, 06:07 AM

thank you mine is a 2001 225efi. it has the 4 butterflys. comp is around 115 to 120. the company that is gonna tune my boxs says the heads dont need to be smaller than 67cc's. whats your take on this sir?

**Chaz** · 09-10-2021, 10:42 AM

Heads :

225 = 73cc
250 = some (most) were 73cc but later ones and xb's were 68cc
300 pm = 63 - 64cc

I have no idea what you are putting the motor on or how you plan to use it. Too many cooks spoil the recipe .. as my mom would say .

Your guy is following the factory numbers . If it worked for them , it should work for you ..

**Mangrumssfe** · 10-06-2021, 02:38 PM

Originally Posted by rcb99team

thank you mine is a 2001 225efi. it has the 4 butterflys. comp is around 115 to 120. the company that is gonna tune my boxs says the heads dont need to be smaller than 67cc's. whats your take on this sir?

Do you mind sharing who is re programming your ecm boxes?