1. The differences between the kits listed is minimal. Your only talking about an 8% difference in motor size from a 406 to a 440.

2. Refer to question 1

3. (this is for a 440 kit)You need to pull the valve cover off, pull the head off, pull the cylinder off and take the piston off the rod. Then take the cylinder, new sleeve, 440 piston, and rings to a shop who is experienced in doing this kit. They will machine the cylinder to fit the bore and bore/hone the sleeve for the piston. Don't expect to pay more than $150 for this to be done, or if you just go with a 426 or less kit, dont pay more then $40 for a bore/hone to that size.

4. Refer to #3, and I did all the work besides this machine work myself also. It was easy, just follow the book and make sure to install the rings correctly!

5. I got the IMS kit and it wasn't very detailed but did help.

6. I upgraded my cam to a XR 400 cam. You dont have to do this but it did change the powerband (which i liked). You will probably need to bump up your jetting a bit.
7. You only need race fuel if your going above 10.1-10.5:1. I am running 11:1 and run a 110-92 mix ( = 100 octane ).

 

What did the XR cam do to your powerband?? More low, mid or top end performance???

 

I am currently running a TC National MX cam, 10.5:1 Piston (JE), TC pipe, K&N filter w/outerwears and a little bit of porting from Mp racing....

I will be running a 12:1 piston by this springtime, hard finding one for a STOCK bore, that and most likely an FCR Alchohol carb for the dunage trips[img]i/expressions/face-icon-small-smile.gif[/img]

 

I gave it a nice mid range hit and more power up top. Took a little away from the extreme bottom end but the midrange/topend gain is worth it.

BTW... i just raced a kid the same weight as me, on the road. He had the 440 kit, with the 11:1 CR piston, XR cam, polished & ported head, Pro circuit T-4 pipe, filter, and valve job. I just have the 440 kit 11:1, XR cam, and filter. I pulled away from him each time pretty easily. So either the shop that ported his head did more damage than good, the rings didn't get to seat completely, or my motor is really strong / his is really weak. Both of your motors have the about the same amount of time on them after the rebuild.
This just goes to show, that just because you have more mods, doens't mean your is faster. It takes more than that. I was quite surprised, seeing as I expected him to pull away from me pretty easy.

 

It's possible that his 440 is NOT jetted properly. This can make all the difference in the world... also- shifting at the right time in the powerband can make a BIG difference.- you could be the better rider. Did you guys switch bikes?- and then do the drag?

 

RotGutBottom,

I live in Utah as well, and if you need help building up your motor call Dewey at Mountain High Motorsports ( the old QuadFever ). He has built many 400ex motors and has a lot of experience with them. By the way what mx tracks do you ride on? We raced Delta and Tooele and it was great. In Delta we had a twenty three rider gate. Delta is probably the best quad track in Utah.

 

(Budda)

I ride the track in Ogden. It's a private track. It's 400 bucks a year to join- or $150 if you get a working membership (work races, attend meetings, etc).
That track was built for dirtbikes- but ATV's are allowed on it. They say it's the hardest track to race in the state if you're on a quad.

2 laps- and I'm dead tired. The jumps are HUGE- and there are only a couple doubles that I'll dare to take. I need MORE POWER to get out of the turn and get enough speed to clear most of the doubles. Also- I need some longer a-arms and suspension before I attempt the big one's.

I've only done recreation riding on that track- no racing (yet).

Thanks for that machine shop. Do you have a phone number for them? What town are they located? What mods have you done on your quad?

 

RotGut,

The shop is located in West Jordan and the phone # is (801)565-1300. The Ogden track is big and it definitely takes endurance to complete a solid race. We rode four laps at Delta and I was whipped. At 35 yrs. old I wasn't to disappointed. I don't have a 400ex, I own an '88 250r with a CT 350 motor (for sale). I just sold my raptor which I raced and it was a fast machine. I have a new Suzuki on order from Vesco's and I will get it in April. We should hook up sometime and go down to the dunes, if the weather would just clear up. Email me at buddahburrito@aol.com.

 

RotGut, it is possible that his bike isn't correctly jetted, thus robbing hp. We didn't try switching bikes but we did a few runs where we just started in 2nd gear and pinned it. It was quite evident that I was making more power. Of course there is A LOT of variables that could of restricted him, like overtight chain, jetting, bad bearings, etc.

But the point is, just doing mods to a motor doesn't make it fast. All the mods have to work together and be done right. And many machine shops are doing work that they aren't educated in, such as head work.

 

buddah-

We should head out to knolls- have you ever been there? It's got dunes... mountains, and sand flats. And it's only an hour away. We go camping there alot. We'd love to have you join us... especially with you new bike. I can't wait to see the new suzuki.

Email me when you get it- and we'll plan a trip! (cbrian3@qwest.net)

I'm suprized you sold the raptor... why did you sell it? Was there something you didn't like about it?

Hopefully I'll have my 426 by then. I'm ordering it now from (adams44) see above...

-Brian