exhaust

[blown331]

2003 EX 400 Bone stock motor wise.. what is my best option.. I wouldn't mind losing some bottom end power for now since I will be doing internal work in the very near future. What is my best option?

I really dig the HMF Carbon fiber piece.. anyone?

ive done searches but most people are already modified

[krt400ex]

HMF is good. yoshi is good. sparks is good. with the sparks u will gain more mid to top, and lose a little off the bottom. the HMF is pretty even throught the powerspread, and the yoshi will give u more bottom to mid, and some more top...but the yoshi is more of a bottom to mid focussed pipe

[blown331]

well considering i'm running down my buddys CRF450 dirtbike and a raptor for the most part I think i'll go with the HMF.. Plus they look sweet!

thanks

[Kaleigh]

i found this.. dont know if it helps..

[blown331]

hmm... nice graph wish i could see the graph for each unit... :) that works though

[krt400ex]

remember though, those r only for s/o's

[Kaleigh]

yes.. these are all on stock quads.. all they did was jet/filter/exhaust..

[Kaleigh]

sorry guys but this is all I got.. if I find anymore ill post them up for you..

[Kaleigh]

Originally posted by krt400ex
remember though, those r only for s/o's

I dont understand what you mean by s/o's ? :huh please explain.. you're good at explaining things.. :D :macho

[Mechanixx]

He means Slip-on not a full system :)

[Kaleigh]

:D OH.... hehehe.. cool thanks..

[krt400ex]

Originally posted by Mechanixx
He means Slip-on not a full system :)

yupp, that was a dirtwheels test, and they only tested slip ons in that shootout.

[Kaleigh]

yuppers.. Dirtwheels.. I remember buying the magazine that it came in ^_^..

[blown331]

I see HMF dealers advertising 9hp gain with a SLIP ON exhaust... That seems way out of control..

Wouldn't 9hp still be almost out of the question with a full system + jet?

[CHEVYZ]

9HP would still be WAY out of the question with a full system exhaust, airfilter and a properly tuned carb,

[blown331]

that's what I figured... damn propaganda...


I'll still be doing it here next week (=

[krt400ex]

Originally posted by blown331
I see HMF dealers advertising 9hp gain with a SLIP ON exhaust... That seems way out of control..

Wouldn't 9hp still be almost out of the question with a full system + jet?

with the 450s that is not completely out of the question. but that is still alot out of just a slip on. with a full system on a 450, some of them will ive u 10-11hp...but ya, u might get 7 hp out of a s/o on a 450, but in the ex u will be looking at around 2 hp out of a s/o

[Eviltanker]

On mine the HMF S/O(w/quietcore in), K&N and jetting tunned with the Boysen powerwing I picked up 5 H.P.

[CHEVYZ]

Originally posted by krt400ex
with the 450s that is not completely out of the question. but that is still alot out of just a slip on. with a full system on a 450, some of them will ive u 10-11hp...but ya, u might get 7 hp out of a s/o on a 450, but in the ex u will be looking at around 2 hp out of a s/o Not quite. Depending on the dyno you are using, I have seen bikes go from completely stock to full exhaust, airfilter, and jetted with the airlid removed and only pick up around 5 HP.

Here is a dyno of a stock, uncorked YFZ and the same bike with the above stated mods that was posted in the dyno forum.

http://www.exriders.com/vbb/attachment.php?s=&postid=2304848

[CHEVYZ]

As another idea on the numbers used with a 400EX, a stock 400EX puts out around 27 HP. A fully modified EX will push the 40 HP mark. That is a 13 HP gain from stock to a high(er) compression big bore engine, cammed, port and polished head, carb, full exhaust, airfilter, air lid removed, ect.

9 HP from just exhaust, and a slip-on at that.... not likely.

Here are more realistic numbers of a stock EX to an EX with:
HMF Slipon-Yellow
K&N Filter
Airbox Lid OFF
K165 Long 6mm Hex

http://www.exriders.com/vbb/attachment.php?s=&postid=2400580

[krt400ex]

Originally posted by CHEVYZ
Not quite. Depending on the dyno you are using, I have seen bikes go from completely stock to full exhaust, airfilter, and jetted with the airlid removed and only pick up around 5 HP.

Here is a dyno of a stock, uncorked YFZ and the same bike with the above stated mods that was posted in the dyno forum.

http://www.exriders.com/vbb/attachment.php?s=&postid=2304848

what kind of pipe were they using?

cuz i have seen better out of a pipe, filter, jest, and no lid.

but with a bad pipe, ya, u won't get all that much

[troutman561]

Originally posted by blown331
well considering i'm running down my buddys CRF450 dirtbike and a raptor for the most part I think i'll go with the HMF.. Plus they look sweet!

thanks

Your running down a CRF450? does it have no tired, this seems highly unlikely since a CRF250 kills 400ex's? plz explain...

[krt400ex]

Originally posted by troutman561
Your running down a CRF450? does it have no tired, this seems highly unlikely since a CRF250 kills 400ex's? plz explain...

umm, i rode with a crf 250 a couple of weeks agao, and he didn't "kill" me. he would have beat me in a drag race, but no by that much

[CHEVYZ]

Originally posted by krt400ex
what kind of pipe were they using?

cuz i have seen better out of a pipe, filter, jest, and no lid.

but with a bad pipe, ya, u won't get all that much Rossier

[krt400ex]

Originally posted by CHEVYZ
Rossier


really??? did mobile dyno do that test? cuz the last time i saw one of his tests, i knew either there is something wrong with his dyno, or his jetting is WAAYY off...cuz the ### were way too low. the rossier should make more than that

[CHEVYZ]

Looks fine to me. His numbers seem to be pretty legit.

[krt400ex]

i saw one where he had a WB full system for the 400ex matched up against a HMF s/o, and the WB made .5 hp over stock..and he was running a d/j 165 main...way too rich. the HMF made, i think, 1-1.5 over stock and he was running slightly leaner, but still way too rich. i wouldn't trust his dyno results. thats all i am saying

[2004exrider]

Just curious as to why your running 110 in your stock motor?

Jimmy