Modifying The Stock Exhaust Tip / Spark Arrester

[triple b]

Has anybody every modified the stock exhaust tip for better flow?
Right now my Father-In-Laws 05 TRX400EX is bone stock except for the AC Skid Plates & Nerf Bars.
He wants to un-cork / re-jet this thing to help start better but it is pointless with the stock exhaust. I would rater see him spend money on suspension and tires.
My plan was to remove the exhaust tip / spark arrester and take it a part, cut out the 3/4" out let and weld in a new 1 1/4" out let with a turn down. (Keeping this around 92 dbs and a functioning sparky is very important to us)
Then we can get a new air fliter, modify the air box lid and re-jet to make this Honda start better and run better. What do you guys think will it work or am I just wasting my time.
BTW He is not looking for max HP or to save 5 lbs he want a great running reliable quad. If he wanted more HP and a lighter quad he would have bought a 450R.......

[BossmanEX]

Ive met one person that ran one of these and it sounded better and even ran a bit better but nothing will substitute a full aftermarket exhaust.

CLICK HERE (http://cgi.ebay.com/ebaymotors/2-Billet-Power-Tip-Honda-400EX-400-EX-ATV-Exhaust_W0QQcmdZViewItemQQcategoryZ43978QQihZ007QQ itemZ170008140580QQrdZ1QQsspagenameZWDVW)

[-copyguy-]

I did it. I cut the silencer out where it is joined to the back of the exhaust tip (so I could JB it back together if i wanted to :D )

I then took some fine screen and wrapped it over the backside of the exhaust cap, it is held in place by the cap itself when it is screwed into place

Sound is not that bad, take the exhaust tip off and run the quad, it'll be a little quieter than that...still not as loud as a lot of aftermarket ones.

i didn't touch any of the baffles in the can though. If you took one of them out, I imagine it would get louder pretty quick.

I plan on modding the air box lid as well and rejetting...got the stuff, just haven't had a chance yet. It seemed to gain a little bit with just opening up the exhaust tip, but I hope to see some more gain once I vent the airbox and do the rejet.

Let me know how it works out for you if you do it. I would have gotten an HMF slip on if I had the cash, but other things gotta get done first...

[Wheelie]

Modifying the stock tip was one of the first mods I did. I simply took out the small core/restrictor and re-attached the spark arrestor. At the same time I also opened up the airbox, removed the choke and removed the mesh around the core of the stock filter.

All said and done it made a very noticable difference for very little investment. I spent about 2 hours on the mods and $10 on jets.

[-copyguy-]

Originally posted by Wheelie
Modifying the stock tip was one of the first mods I did. I simply took out the small core/restrictor and re-attached the spark arrestor. At the same time I also opened up the airbox, removed the choke and removed the mesh around the core of the stock filter.

All said and done it made a very noticable difference for very little investment. I spent about 2 hours on the mods and $10 on jets.

What jet size did you end up putting in?

[Wheelie]

40 Pilot, 152 Main.

[triple b]

Thanks Copy and Wheelie.
This is going to be one of our summer projects for the 400. I will take pics as we are working on it and after it cools down I will let you know how it works. (it is going to be 112 deg this weekend)

Bossman Thanks but the e-bay ad has expired..........

[-copyguy-]

for the ebay thing, just search for "400ex exhaust tip" ...worth 50+ bucks...I don't think so...

[triple b]

Hey Guys,
I did this mod a few weeks ago and finally had a chance to ride the 400ex last weekend. I was very pleased with the results

This is what I did is......
Drill out the spot welds on the spark arrester, cut out the stock 7/8" tip re-weld a 1 1/2" stainless steel tube in its place. Re-weld the spark arrester spot welds.
New Uni Filter
Drilled four 1 1/2" holes on the air box lid
42 pilot jet and 155 main (It may be a bit rich but I needed to start some where)

For under $60.00 and a few hours of work I am very pleased it starts a lot easer and seams to pull harder through the rpm's
It is still very quite and has the stock spark arrester. You do hear more engine noise with the air box lid mod but it is not bad at all.

[jrafter]

i might have to try this.....i just got done rejetting with a 42 pilot and 150 main added K&N filter.

it was alot easier than i thought it would be....didnt even take the carb off......just rolled it over.

now it time to play with the exhaust.

Joe

[Grant Casey]

yeah my mate punched the hole in side of his exhaust out and put screen and packing in there sounds like a real exhaust now.

[jrafter]

could someone who has done this take a pic of there baffle so i can see what i have to do.

Thanks

[400ex_rider13]

me and my dad made my spark arrester out of aluminum , turn out awesome and sounds nice too !

[hondajoe05]

so what about removing the whole spark arrestor... and leaveing it off? bad idea i was thinkin about drillin some holes in the inside restrictor too.. ? even worse idea anyone know anything about any of this? will it mess the back pressure the exhaust is suppose to have oh ya i wasn't planning on jetting it too soon either to that adjustment

[triple b]

Hondajoe
Re-moving the spark arrester is not a good idea. I know here in California it is up to an $800.00 ticket for not having a sparkey on public lands. With that said I do not know of anybody getting that ticket they just got a warning and the Ranger told them about the $800.00 fine.
I thought about drilling 2 or 3 ¼” holes in the internal baffle but then I started looking at the spot welds on the side of the muffler and it looks like there is another baffle towards the front of the muffler.
If you do any exhaust or intake mods you have to re-jet accordingly.

[Grant Casey]

yeah there is a big baffle in side me and a mate cut the exhaust up and punched it out them, we put packing and some mesh stuff in there. sounds good. but i plan to get a aftermarket one though.

ill try to get photos uploaded later on