Jumping in feet first.

[mmbintn]

I bought a brand new 2007 400ex about 3 months ago and since then I have put a slip-on hmf and an Edelbrock carb along with other non motor stuff. While I am happy with the power I anted more (but not crazy more).

I came into some money and went ahead and bought an 11:1 standard bore wiseco/cometic piston kit and a stage 2 hotcam. What can I expect from this setup?

also I run a 440 edelbrock carb and was wondering if I will have to adjust the carb when I am done as it's still the stock bore. Will seating the rings be the same as it was when I bought the quad new?

Thanks, Micah.

[250x_kyle]

your going to see a power increase from the set up but it would go alot nicer with a port and polish. any time you mess with your engine you have to adjust your fule. the 440 carb is probably un needed but if you can tune it to work go for it.

[honda400ex2003]

you will like that setup. it will give you plenty of power for any situation. i would make sure you get the cylinder honed with a new cross hatch pattern so your rings will seat correctly and you should be set. Otherwise ride it however you like to break them in and you will be set. i personally like the 3 rides for 15 minutes with varied situations and rpms. then let it cool between rides. i guess it works for me and you will hear many ways but do it how you want to so you have the peice of mind. steve

[mmbintn]

Originally posted by 250x_kyle
your going to see a power increase from the set up but it would go alot nicer with a port and polish. any time you mess with your engine you have to adjust your fule. the 440 carb is probably un needed but if you can tune it to work go for it.

I have the carb tuned perfectly now. Just didn't know if I would have to adjust it.

[F-16Guy]

That should be a pretty good improvement in power. I agree with getting a light honing done. You could buy a small engine hone and do it yourself with a drill and some lightweight oil if you wanted to, or pay someone. For break-in, richen the carb before you fire it up the first time. You don't want a tight engine to run any hotter than it has to. When you start it up the first time, you need to break in the cam by getting the RPMs up above 2K as quickly as possible and keeping them there for about 20 minutes. I usually start it up, check for major leaks or other problems, and then take it for an easy half hour ride. Just remember to keeps the RPMs up above about 2K (no idling) and don't lug or rev too much. Once the cam is broke in (20-30 minutes), you can ride it normally to break in the rings, but again, no hard lugging and no hard revving. After a tank or two you can dial the carb back in and ride normally.

[tri5ron]

since it has not been mentioned yet,...
400EX's are known for stretching, and stripping studs, and blowing head gaskets,...
directly due to high compression piston upgrades.

it is HIGHLY adviseable that you have HD studs installed along with the higher compressin piston.

you say your quad is brand new, that's a good thing, and you will want it to run strong and reliably for a long time.

do a search here on the forum, on the HD studs, and read, Read, READ.
Learn everything that you can about it, BEFORE doing it.

The last thing you want to have happen is for your studs to stretch, (or worse), strip out of your new engine, due to that higher compression.


on Edit...
here's yet another perfect example...
http://www.exriders.com/vbb/showthread.php?s=&threadid=405692

your thread title say's your jumping in feet first.
make sure that when you make the jump,
you do it Right the first time,...
or you WILL be doing it again, and at greater expense.

[F-16Guy]

Definitely do studs if you can afford it. Just to add to that: The problem isn't with the studs themselves. The hole in the cylinder for the forward stud is located right next to the exhaust ports. The aluminum there gets very hot (especially when you have a high compression big bore) and can weaken, which allows the forward stud to pull out of the weakened aluminum threads. That usually results in a blown head gasket.

[mmbintn]

Yeah I have been trying to get ahold of GT Thunder for the past week with no luck. I'm in the Army and I dont get off till they are closed every day. Is there another way or place to get them?

[F-16Guy]

I'm pretty sure C&D Racing does them too. I recommend having them professionally installed. You only get one chance with something like that, and you don't want to have to buy a new cylinder if you mess it up. Not a good place to skimp.