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Tommy 17
09-06-2001, 01:29 PM
I was wonder if this story i heard is true. can u put a xr 400 cam on a 400ex. if i do this to my quad what will it do to it power wise. how much will it cost and will i have to do any rejettin or gearing. thanks.

09-06-2001, 02:41 PM
Well if you put it on a 400ex it won't do much,, you'll need to put it inside the motor..LOL

OK all joking aside,,,yes it's possible,,I've got one sitting at home right now to put in mine. What the best thing to do when putting a cam in a 4 stroke is to also get a higher compression piston to go with it,,they work hand in hand and the benifit of doing both will give you a much much better power gain than just doin the cam by itself,,Now You can just put the cam in but hell if ya got the motor tore apart ya might as well throw in a new piston, and like me get the head ported ,there are quite a few guys on this message board that have an XR400 cam and love what it's done for their bikes,,but they didn't just drop a cam in and be done with it, they also did other mods to go with it. You will need to rejet, and the cost of a XR400 cam is 120 bucks from Marcums ATV,,,:D

Tommy 17
09-06-2001, 04:18 PM
Rico thanks i am plannin on puttin a 416 kit and a wiseco piston or sumtin of that sort into it too but i was goin to buy it piece at a time when i get the extra money and put it all in at once. when ur 16 moneys hard to find when u have to pay for gas and car insurance wit no job except workin for u dad at his own company. I think i may order that cam this week and the piston and stuff next month or so...

09-06-2001, 05:31 PM
Rico,


Can't wait to hear the outcome of your new cam & piston, that is what I'm thinkin about doing. You are keepin stock bore right? Keep us updated!

trx400ex
09-06-2001, 06:57 PM
i think hes doin a 416

Tommy 17
09-06-2001, 07:37 PM
rico u seem like u know ur **** so where can i buy the 416 from and how much will it cost for me to get them to do it. i want a high compression piston the highest u can go b4 u have to run over 94 octane fuel. what should i buy. i dunno bc none else here has the kits and we all clueless on what to buy.

max400EX
09-06-2001, 11:04 PM
Where does the XR400 give you power(top mid low)? What other cams do you all recomend?

09-07-2001, 09:06 AM
Well WJW77 I've decided that if I want to be more competitive racing I might as well go with a 416 10.8:1 JE piston (cuz JE pistons are lighter than wiseco) and I'm gonna send my head to Marcums and have Terry Port and polish it, with a nice exriders discount,,,he emailed me today and said that he's working on a special 416 kit just for exriders members so everyone needs to hold off to see what kind of deal he's gonna have for us..

400ex21 you need to get your cams and pistons from marcums ATV nobody else will be cheaper,,I garauntee it..link to his webpage is at the top of this forum..

And from what I've read the XR400 cam works best in the mid ta top area,,which is just perfect for MX racing..and it's a simple drop in part,,no extry bells and whistles to make it work..

And a 10.8:1 piston is about as close as your gonna get to running on 93 octane,,,I'll be using some Klotz octane booster with mine just to kick it up a little. To be completely safe you could get a 10:1 or maybe a 10.5:1,,but you'll need to use an XR400 head gasket to keep the same compression ratio..due to the different sizes of the gaskets between an XR motor and a 400ex motor..

MJNOVA
09-07-2001, 09:49 AM
I have a spare Curtis Sparks Cam---Brand new---Full race----It requires the hardened rockers and the shorter valve guides though. I have a used CC----Torque cam also.....

max400EX
09-08-2001, 12:15 AM
Whats the best cam that you dont need to hardface and/or get a new valve setup for?
Thanks in advance

FlyinRed
09-09-2001, 04:53 PM
Hey 400ex21,
Go ahead and do it. I've noticed a good gain. Not too impressive, but good. It should come alive when I get my 416. Everyone says wate untill you have everything. I say do it 1 part at a time, for budget and you can tell what was a good investment and what wasn't. Also I think it took me 1.5 hrs to get it in. and you only have to take the plastic, gas tank and valve cover off. Let me know before you start. I have a few pointers from my screw up. I had to guess at which way it went in. I was right, but it was scary.

Red Rooster
09-10-2001, 11:17 AM
Rico,
does marcums have cams for the 300ex too??? Free shipping is a definite plus:D

09-10-2001, 11:42 AM
According to Terry @ Marcums they will have a page dedicated to the 300ex up sometime this week. :)

Hopefully that will show all the available goodies he has! :devil

Red Rooster
09-10-2001, 11:46 AM
sweet!!!!! last time i was on his site it seemed kinda confusing:huh

ccole400EX
09-10-2001, 12:40 PM
I just did the 416 with a HRC cam it seems to work really well and you don't need anything extra. It is more $$ than the stock XR cam ($120=$277 but it is the hop-up for the XR bike over the stocker. XR's only makes a copy for $179 wich will work with your stock parts. It seems to work really well from mid to top and i didn't lose anything on the lower end.

86atc250r
09-10-2001, 01:42 PM
FlyinRed -
I say do it 1 part at a time, for budget and you can tell what was a good investment and what wasn't.

The problem with that statement is that items like camshafts, carbs, etc... may work poorly when used by themselves, but when used in conjunction with higher compression, and exhaust and a carb can make a huge improvement.

Making an engine run well is all about complimenting modifications, using stuff that works well together.

You're almost always better off planning your buildup, saving, and building it all at once, than trying to piecemeal it together. You'll also only have to tear your engine down once instead of many times.

max400EX -
Whats the best cam that you dont need to hardface and/or get a new valve setup for?

There is no such thing as a "best cam" - if there were, no other cams would exist.

You need to decide what you're looking for. If you want top end and to be the fastest in a drag race, the XR likely won't be the cam for you. However, if you ride mostly trails and you want lots of stump pulling bottom end and mid, a "full race" style cam will not be in your best interests.

Rico -
And from what I've read the XR400 cam works best in the mid ta top area

Well, that's not entirely true. The XR cam works best in the mid. The rest of your mods will dictate how the rest of the powerband works.

Currently with my setup I've got unbelieveable bottom end right off idle, a very strong mid, and a respectable top end. Mine doesn't pull past 9000 RPM unless the tires are unhooked though.

On the other hand, we have an identically setup bike with a GT thunder cam here too. It has a usable bottom, a nice mid, and a great upper mid and top. It will pull a little ways past the stock rev limiter and loves to rev. It doesn't like to be short shifted (mine loves it), and has a noticible powerband (although not as noticible as a Cannondale).

For mostly MX or duning, I'd probably be more inclined to go with the GT Thunder cam. For woods racing, I really like my XR cam. Neither cam requires hardfacing or different valve springs. Cost on the GTT cam is approx $160

rhandw69
09-10-2001, 04:28 PM
So Gabe,
I could be wrong in this statement,
but it sounds like to me if you were to do 200-300 ft sand drags, then you may want to XR cam so you CAN grab gears? Or do I have that backwards.

I take it that the GT cam is a Mid to Top end increase than huh, and the XR is a mainly Mid increase.
But,,

What I rely on is alot of low end torque for hill climbing and a good pull to increase speed. What i found after putting in my 416, although it may just have had something to do with my jetting, was that i had great bottom end torque, but my mid to top was very dull and nonexistent. I think we have fixed that problem by increasing the main jet, but still i like the low end torque to get going, and I want that Mid power for a good powerband hit.
So am I safe to say that the XR cam, or perhaps the Webcam, should be the way to go???
Rhan

max400EX
09-10-2001, 11:31 PM
Oops, thanks for bringing a typo up, i meant best as in best brand, like white brothers, web, and others. I know some companys put more time and quality behind their products.

What cams are recomended for all around? I just want good gains in the mid and low w/o hardface and valve work.
Thanks in advance

86atc250r
09-11-2001, 12:27 AM
rhandw69 -
Expect the XR to give you some additional mid and a little top if you are still running the stock cam. I haven't ridden an HRC cam, so I can't really comment on them.

I've ridden a few Web cams, but didn't really spend enough time on them to be able to make a recommendation. If a person could obtain cam specifications, that would help the decision making process out a bunch.

I'm not very experienced in the sand drags, but I'd assume you'd want lots of top end power since more HP can be made in the upper RPMs. Tire speed is also your friend in the sand.

max400EX -
I believe White Bros, just repackages Web cams, so they are one in the same.

I know that Lazarus at GT Thunder put a lot of time and testing into his cam. It has a lot more high lift duration than the stock or XR cam and the difference is very visible when looking at the two.

It really depends on what you want, the GT Thunder cam still puts out an acceptable amount of bottom, but my XR setup kills it as far as grunt goes. On the other hand, the GT Thunder setup pulls quite a bit stronger thru the upper mid than my XR setup does.

Either can be used without hard facing the rockers. Also keep in mind that to run a fairly wild cam in a 400EX a free flowing exhaust and intake setup are a must. You will never get it tuned otherwise. Also big cams take more work to get the jetting nailed down.

I have the jetting on my engine nailed down to perfection. We're still fine tuning the GT Thunder setup (granted we desperately need a better pipe on that bike).

09-11-2001, 08:35 AM
I'M INSTALLING A GT THUNDER 12.5 PISTON AND CAM IN MINE LATTER THIS WEEK AND I'M WONDERING ABOUT MY CURRENT SETTUP IF IT IS GONNA FLOW ENOUGH. PLEASE TELL ME WHAT YOU THINK: E SERIES SLIP-ON, K&N, 155 MAIN 42 PIOLT AND NO AIR BOX LID. I TALKED WITH A GUY FROM GT THUNDER AND HE SAID AFTER I INSTALL THE PISTON AND CAM THAT MY EXHAUST WILL BE HOLDING ME BACK. DO YOU THINK I SHOULD GET A POWERBOMB HEADPIPE WITH THE E SERIES OR BUY A COMPLETE SETTUP FROM GT THUNDER OR LRD.
THANKS IN ADVANCE!!:devil

FlyinRed
09-11-2001, 08:41 AM
I know that the power numbers are bigger with a full exhaust over a slipon. I like the PowerBong because it liiks like a better engineered piece. If you don't like it with the E I would sell the E and get an FMF to go with it. I remember hearing that the E flows a lot better than most exhausts though (I think it was GT Thunders web site). I hope that helps.

max400EX
09-13-2001, 10:08 PM
Thanks for all the help Gabe,
The free flowing exhaust will be no problem as i will be getting a WB Pro Meg (only if the sparks X series were quieter) System.

2002-400EX
Let me know how everything on the new bike is

rhino99
09-13-2001, 10:54 PM
So this is what I understand from all this, if you want a mid-top powerband and make your 4-stroke more like a 2-stroke, you would go with the GT thunder cam, a better filter and a full exhaust? Do you also suggest high comp, or stock, or something in between, I dont know if that will make a difference in your powerband or not. I am thinkin about trading my R for a 400ex but wanted to build it to have a better powerband more in the high end, but still usable low end of course.