Are aftermarket carbs a worthwhile upgrade on a 400ex?

[RNL]

I was curious if anyone has any experience with aftermarket carbs on 400exs? I have read a little on the 450r carb swap, but I seen that a few companies sell carbs for the ex. Ct racing has a Keihin 39mm FCR Carburetor Kit, are these worth investing in?

[tri5ron]

That would greatly depend on 2 things.

1- what your engine mods are.

2- how deep your pockets are.

[RNL]

Originally posted by tri5ron
That would greatly depend on 2 things.

1- what your engine mods are.

2- how deep your pockets are.


1.Was looking at a Sparks x1 cam, full exhaust, Sparks timing key.

2. Shallow, lol.

[RNL]

I should say this to, I'm not the most mechanical guy in the world....... so if I'm off base on mods, feel free to steer me in the right direction. I'm basically looking for a good mostly bolt on modded trail and woods thumper. Something with some kick thats still reliable.

[tri5ron]

Lets see if we can help to save you about $700.

A full exhaust, ($500 - $600),...
with your listed mods,....
will deliver NO MORE than,...
1.0 to 1.5 HP,...
And that is ONLY,...
when combined with airbox mods, aftermarket air filters, and rejetting.

http://www.ctracing.com/PD_ct%20photos/dirt_wheels_march_2001.htm


Stock Header weld grind is free,...

A decent NEW slip-on aftermarket muffler, can be had for $150 - $250 any day of the week,... (and often much cheaper if you buy a used one, and just repack it),...
and will provide the same measurable gains.


CT's 39mm carb is listed at $577,
(and I'm assuming,... + shipping?)

'04 - '05 450r carbs, (42mm), can be had on ebay for around $120 - $150 all day long.
often, including the hot start valve, and the throttle cable, (you DO need the h/s valve, and the 450r throttle cable,...
( the 400ex cable will not work on the 450r carb.)
or,
purchased new for about $230 (I THINK that's accurate, but someone here can correct me if I am wrong).

Here's a couple of threads you might find interesting....

http://www.exriders.com/vbb/showthread.php?s=&threadid=314423&perpage=10&highlight=42mm%20450r%20carb&pagenumber=1

http://www.exriders.com/vbb/showthread.php?s=&threadid=409169

http://www.exriders.com/vbb/showthread.php?s=&threadid=445008&perpage=10&highlight=header%20grind%20welds&pagenumber=1

For Shallow pockets, (like mine),
it's pretty simple math if you ask me. :D

Hope this helps

[400exrip]

I got one on mine it's a FCR Curtis Sparks 39mm carb. But like stated you better have some deep pockets to buy it!

Makes a world of difference on the 400ex.

But depends what you got in the motor I have a 440 Curtis Sparks National motor in my bike. with full race port, Titanium valves, Custom grind race profile cam, Hardface rocker arms, Its a National built motor and it does great on the bike.

I would probably do good with a regular ol setup like bigbore kit, pipe, and a cam.

[RNL]

Thanks guys for the help. One thing for sure, this stuff sure isnt cheap to do!!! I have another question on the full exhaust. If you could get a full system for only $20 more than a slip on, then is it worth it? The reason I ask is my buddy has a like new ct full exhaust he's willing to sell me with the jet kit it came with for $200. He got rid of his 2005 400ex in favor of a 450r. The pipes in beautiful shape, maybe like 10-20 hours on it.

[400exrip]

Yes it is worth it cause the full exhaust comes with the header and that aftermarket header is going to be bigger than the stock one, which = better exhaust flow which = more power!

Now it is going to be a little bit louder than the slip on though. but it is going to sound a lot better too.

Now when you get this exhaust system you need to take care of it, if you want it to last a long time, If you are going to be racing this bike you are going to need to repack the muffler (slip on part of the pipe) every month but if you are just going to ride it repack it every 3 months

Repacking a muffler is pretty simple just take the bolts out that hold the canister in, slide it out take out the old packing put new in and re-install then you are ready to ride.

Their should be a video on youtube or something that shows you how to do this, or a forum on this site

[tri5ron]

Originally posted by RNL
Thanks guys for the help. One thing for sure, this stuff sure isnt cheap to do!!! I have another question on the full exhaust. If you could get a full system for only $20 more than a slip on, then is it worth it? The reason I ask is my buddy has a like new ct full exhaust he's willing to sell me with the jet kit it came with for $200. He got rid of his 2005 400ex in favor of a 450r. The pipes in beautiful shape, maybe like 10-20 hours on it.
IF,...
you currently have the stock 400EX exhaust , (and stock muffler),....
and,...
you fully intend to be upgrading the exhaust anyway,...

Then yeah,.... I'd say your buddies full system for $200 bucks, is a no-brainer.

Buy it.
(if you dont, there are PLENTY of guys on here who would be thrilled to get it for even more cash)