variance?

haha I love the line "if somebody knows what happening please let me know" 
but yea it's probably variance, infact i'm pretty sure of it

Please post your stats from 4 mans, as well as 2 mans, separated by buyin level and we can give you a much more accurate idea of what is going on.
 
Edit: By stats I mean, games played, buyin level and ROI.  You can just copy paste from Sharkscope if you have a subscription.

That's not a big sample so it's propably just variance. The only psychological effect I can think of is that when you win the first round in a 4mans you play the final with much more focuss and that makes you a better player.

You're running hot in the higher stakes 4 man games (or running bad in the lower stakes 4 man games), looking at your profit per game and ROI, when your ROI is lower than profit per game that means you're doing better in higher level games than lower level games.
With such small sample sizes nothing is conclusive, but I'd guess some combination of the following is what is happening here:
- Like I just mentioned, running bad in lower stakes 4 mans
- Running good in higher stakes 4 mans
- Running bad in 2 mans
- Running good in 4 mans
- Avg stake in 2 mans is higher, so on avg you should be facing tougher competition and your results should be weaker than in 4 mans.
Yes, there is a pretty big gap between your 2 man and 4 man stats, but your sample sizes are so small and the gap can be legitimately explained by variance.  If this gap continues for another 500-1k games at each game, then I'd start to dissect the results further and look for different explanations.
 

Oh, and I forgot to say, ROI in 4 mans is likely going to be higher per game  than 2 man games as it is.
It's the same thing with regular speed games vs turbo speed games.  If the regular speed games finished as quickly as turbo speeds, everybody would be playing regular speeds.  But regular speed husngs take longer to complete (as do 4 mans).  So playing a turbo speed with 6% ROI and getting 2 games finished in the same time it takes to get one 4 man with a 10% ROI finished, you would be more profitable playing the 2 turbo games with your time.
So... what does this mean?
It means you shouldn't expect 13% ROI in the 2 man games, like with the 4 man games.  Say you're really a 10% winner in 4 man games, but since you've ran well or improved your game in the higher games, your ROI shows 13% ROI now.  You would then be roughly 5% or so in 2 man games and your -12% could easily be explained by bad variance for 200 or so games coupled with added pressure/tougher players since your avg stake is higher for 2 mans.

It also means your sample of 426 4 man games is something like 600-800 2 man games as far as time invested means.
If you have holdem manager, tourney manager, poker tracker or some other form of tracking software, you can get much more precise numbers than I am giving.  I am generalizing in these examples, two turbo games are usually faster than 1 turbo 4 man, but it's probably close on average (wait time between first and second game is the difference, it dwarfs waiting time for a new 2 man game at most stakes).

Heh, I'll let Primo explain that one.

4man tag teams ;)