Just picked up an update for this site on alt.atv. Has pics of a-arms and exhaust. Also a Z400 dyno chart at 40.9 hp. Don't know anything about this company but they sure work fast!

http://www.gtthunder.com/400z.html

 

GT Thunder is a well known company on the east coast. They do very good work. Laz is the guy behind the little Cobra mini-motocrossers. He builds the engines for them.

 

dang...FMF exhaust? 40HP....yeehaw!!

 

to get that 40....cams, intake kit, and full exhaust.

 

when was the last time you saw a 400EX with 40hp from cams intake and exhaust...

 

Im not trying to argue but its VERY common these days to see a 400ex with JUST a cam and piston and pipe achieving OVER 40HP. I have one and just sold my other one to buy my Raptor. I love all quads but just offering my perspective on the Honda statement you made. I just bought a 02 Raptor and its jetted and piped. It outruns Banshees and Cannondales in drag races but my 400ex has more power and pulls it barely top end. But its not a trail rider or reliable. I guess I better mention the 13/1 JE piston . Risky but powerful and becoming more and more common. ANY TIME you build a quads engine you decrease the reliablity and design that the factory designed and intended it for. It just depends in what you are after in a quad. If you are looking for the fastest and most upgradable HP,(like drag racing) you spend the same amount of money on any two quads and the 650ds or 660 Raptor (reliable torque and power)will get you due to the starting cc's. Like I said, I like them all and have nothing bad to say about any make. I own a brand of almost all of them and will probably have a Suzuki next too. But when I build this Raptor with a 13/1 and port the head and install a cam,it will take another Built Raptor or DS or Heavily built Banshee to catch it. It would be neat to see the cr450 in a 400ex frame! from Honda.

 

Guido- LS is a great resource for you LTZ guys.

He's a very honest, hard working guy. He did a lot of the preliminary work that we all take for granted for what works on the 400EX. It's good that he's enthused about the LTZ, you guys will get a lot of good info from him.

 

Hey Shockwave,

I think you're overstating your case when you say 40+ hp 400EX's are VERY common. You are talking about a RACE engine. The GT Thunder EX didn't crack 40hp and it was built-to-the-hilt. In effect, you are saying that your 400EX, with an inferior cylinder head and pedestrian carburetor made more power than a Cannondale?

 

Actually, lateapex-

GT Thunder built a lot of 400EX's well in excess of 40HP. One such dyno run was posted shortly after the 400EX came out.

http://www.geocities.com/gtthunder.geo/400s.jpg - (43hp) may have to open in a new window.

Their old catalog had a kit that developed around 40HP out of a 440 kit, intake mods, a cam and an exhaust.

The 400's problem is not an inferior head, but it's overall design which limits it's peak output (but makes for an engine with a nice spread, although more limited to the lower RPMs). Further, the 400EX's "pedestrian" carb is actually a better carb than what comes on the LTZ stock.

I will agree though that the LTZ has more potential for top end output than a 400EX and will be a big hit with the aftermarket since it's so detuned from the factory.

 

I'm certain that places like GT Thunder routinely build 400EX's with 40+ hp, but that's not the same as getting 40 with compression, cams and pipe, which is what Shockwave was claiming. The fact that GT Thunder had a radical EX that couldn't make 40 proves my point: big numbers aren't guaranteed.

I wasn't making a comparison to the LTZ. My point was Shockwave was claiming to be making as much or more hp than the Cannondale and, from what I've seen and read, the Honda head is good (and well-integrated into the overall engine design), but is not up to the Cannondale, stock-for-stock. And compared to F.I. (and the 41mm carb the GT Thunder machine was sporting), the OEM 400E carb is very pedestrian.

Maybe Shockwave is a whiz of a tuner? If so, more power to him (literally ;-)). But, his experience is not common.