11:1 or 12.5:1

[honda729]

what would be the power difference between 11:1 and 12.5:1 on a 416.

[togup]

I have 11:1 and i wished i would have went 12.5:1

[trx400EXtreme]

idk about power but i think 11:1 is the highest you can go with running pump gas.

[f150mann]

yes it is, but i put a 12.5 in mine havent run it yet, but plan on running half race half pump

[bens250ex]

im runin 12 and i run on 93 and have even run on the lowest grade fuel to get back to the truck. it runs perfect on 93. i have also run 112 and it really wasnt to much of a diff besides it smelled good

[flauge]

^^^Dang man, thats a first for me. What piston are you runnin? Wiseco??

[bens250ex]

yea. im runin stock cam right now but it runs fine on 93

[flauge]

Hmm, I wonder how far off the 12:1 wiseco's are in compression ratio? I've heard that the 11:1's are really like 10.5:1 or something like that. Anybody know about the 12's?

[bens250ex]

i dont know, i have never heard of that before. it sucks if its true

[ride_red666]

i ran an 11:1 wiseco piston in my old ex. it had 25hrs on it and i slod it too my boss. the piston blew up and it wasnt rode hard at all and a respected shop did all the work... i dont recommend getting a wiseco try je or ross.

[01440ex]

ive been running 87 in my 12.5 and it is smoking a little...u think bumping it up to 93 or 112 would help it any....i just recently rebuilt the entire top end and only have 2 hours on it

[drew416ex]

Originally posted by 01440ex
ive been running 87 in my 12.5 and it is smoking a little...u think bumping it up to 93 or 112 would help it any....i just recently rebuilt the entire top end and only have 2 hours on it

How bad is it smoking? Did you replace valve stem seals, hone the cylinder, etc. ? What brand piston are you running? Some rings take a little longer to seat than others.

[drew416ex]

Originally posted by honda729
what would be the power difference between 11:1 and 12.5:1 on a 416.

There is a small noticable low end difference on the 12.5. I have run both and I perfere the more lowend of the 12.5 I wouldnt run any lower than 110 octane though.

[drew416ex]

Originally posted by flauge
Hmm, I wonder how far off the 12:1 wiseco's are in compression ratio? I've heard that the 11:1's are really like 10.5:1 or something like that. Anybody know about the 12's?

The 11:1 wisecos arnt a true 11:1. You can fix this by removing the base gasket though. Just check your piston to valve clearance first. If you have a hotcam stage2 (old style) or smaller cam it should be fine.

[01440ex]

i replaced all gaskets and valve seals and guides...still smoking...didnt mess with the rings yet...winter project but ive only put 2 hrs on it since i replaced the seals...and will i notice a better performance running 112 octane...would u run it straight or mix it with 87 octane

[drew416ex]

I would definitely run it on strait 110 or above. Ask any engine builder and they will tell you the same thing. It wont make it stop smoking but it should run much better. I know it costs more but it is cheaper than a new piston. When does it smoke? Startup, During acceleration. If it does it most during accelleration it is most likely the rings.

[boosted3g]

When i built my engine i used a 11.0:1 wiseco piston and after cc'ing everything it came out to 11.0:1. If you guys go to the wiseco website they list the same part numbers for the xr400 and the 400ex but notice the compression ration is slightly different. Ill have to look at my notes but i think the 11.0:1 wiseco piston was a 8.2 or 8.6 cc dome for anyone calculating. This is for a stock bore also.

[drew416ex]

I dont know about the stock bore, but mine is 87mm and it wasnt a true 11:1.