06 stock exhaust questions

[roundsy]

i have a stock engine and i was inspecting my spark arrester and inerds of my stock exhaust and i discovered that on my 06 you can take out either the whole spark arrester/restrictor inerds, or just the restrictor thing...my questions are if take my exhaust apart and put just the spark arrestor back in, will i have to rejet, and if i dont wil i do anything harmful to my engine?\

thanks

[trick250r]

i tried it on mine but i backfires a lot and it just wont rin right... same with the airbox lid off, only it runs fine untill you hit high rpms. i wouldnt run it for too long w/o rejetting it.

[tltcracing]

you can do it but dont do it for over a month or so. over time the motor will have accelerated wear. get some jets and tune her so she gets even more power.

[trx400exxracer]

you need to rejet it and get a UNI air filter on there to go along with it

[roundsy]

alright with that said, im only going to do that on occasion like when i go to tracks....but i do have another question, with the HRC kit, what is the exhaust piece they include and what does it sound like?

thanks

[roundsy]

trx400exxracer, i have always been a fan of uni filters, so i would get one of those but i got a quick question first, whats the difference between a uni and stock on the 06?...i couldnt imagine a bigger filter fitting in my airbox thats all...lol

thanks

[ryann mx68]

twin air, uni = better flow rate

twin air makes a nice filter for the 06, thats what i run. eliminates the cage, has special backfire foam inside filter so it wont catch fire. dual stage filter. like $30 bucks or so

[roundsy]

are twin air or uni filter built different, sizewise or w/e, like how do they have better air flow?

[trx400exxracer]

Originally posted by roundsy
are twin air or uni filter built different, sizewise or w/e, like how do they have better air flow?

ehh
there about the same but i am a fan of UNI i think they are a bit biggers than stock and the back part of the stock that is rubber is foam on the UNI and the uni is 2 stage like said above you will deff. feel a difference after rejetting and all

[HAVOK]

Uni's are better then twinair.They are the same as for filtering goes, they are both 2 stage. UNI has a new cage, and twinair you have to use your stock cage, and is real hard to get in and out. I broke my stock cage twice and jb weld it back together useing twinair.Also uni is bigger then twinair.

[roundsy]

Originally posted by trx400exxracer
ehh
there about the same but i am a fan of UNI i think they are a bit biggers than stock and the back part of the stock that is rubber is foam on the UNI and the uni is 2 stage like said above you will deff. feel a difference after rejetting and all

yea about the rubber on the backside, on my 400ex it was like that and that was one of the main reasons i got a new filter for it, but on my 06 r it is foam on the backside, and that was why i was wondering how you could get any better flow but ill probably just get a uni, i like having two filters anyways, when ones on, clean the other so theres always one ready to go

[ryann mx68]

Originally posted by HAVOK
Uni's are better then twinair.They are the same as for filtering goes, they are both 2 stage. UNI has a new cage, and twinair you have to use your stock cage, and is real hard to get in and out. I broke my stock cage twice and jb weld it back together useing twinair.Also uni is bigger then twinair.

twin air- for the 06 does not use the stock cage, it clamps directly to the air boot. thats why it has the anti-backfire foam on the inside= it doesnt need a cage or screen.

size of the air filter [aftermarket] doesnt really matter compared to stock, the filter materials are diff. a same or smaller size aftermarket filter will flow more air than a larger stock filter

[atvridernc]

what jets would you guys suggest if you got a uni and took out the baffle? I am wanting to do this but dont know what size jets to get.

What is the stock size main jet?

[roundsy]

Originally posted by atvridernc
what jets would you guys suggest if you got a uni and took out the baffle? I am wanting to do this but dont know what size jets to get.

What is the stock size main jet?

that was my next question :p

[trx400exxracer]

These are a few suggestions that you might want to try:

1. Remove the baffle but leave the spark arrestor in the exhaust. It opens up the exhaust enough without making it too loud. Loud is not good!

2. Get a Uni or Twin Air filter. The UNI comes with a high flow cage and has much more air flow.

3. Do Not remove the air box lid! You need to open up the air box lid by drilling approximately 10 1 inch holes in it or you can get the HRC air box lid. You could also fabricate one similar to the HRC lid using your stock one. You also need to remove the snorkle. The lid needs to be opened up but you will find that the quad will not run right if you remove it completely.

4. With these changes you will have to rejet the quad. You need to consider your elevation and things like air temp and humidity, but here are a few suggestions that work for us, keep in mind that we approximately 300 to 600 feet above sea level. It also changes some from winter to summer:

Main Jet = 180 - 185
Pilot Jet = 45
Leak Jet = 55
Needle = JD Jet Kit Red (for summer) (blue for winter)

We use the JD Jet Kits for the quads, they use the same jets as stock. The jet numbers are the same as Honda.

We have two '06 models running the mods and have found this to be the best setup for these bikes and the areas that we race. We race cross country in the southeast. One quad has the stock exhaust and the other has a full Yosh system. On the Yosh, we fabricated an insert to tune the exhaust. The jetting is the same for both. We run a 50/50 mixture of premium pump fuel and Sunoco Race fuel. These are only suggestions, you will have to experiment according to your conditions.


Hope this helps.

[Dale Szydlowski]

I took out the inner of two screens in side the stock plus completly removed the end screen and had to rejet the sceens in air filter. left the outer screen 4 suport. I belive I used a 152 main and raised needle 1 click boy what a diferance I cant wait to get a pipe

[roundsy]

thanks trx400exxracer for al lthe help, that was the reply i was looking for

[trx400exxracer]

My pleasure.

We use the JD Jet Kits, since they use the same Keihin jets and the jet sizes are the same. It is easier to keep up with. They supply a wide range of jets, I think from a 170 through a 190. Plus they include two needles. The instructions they include are very detailed and give you a good starting point.

It's my opinion that other than weight and excessive noise, there is no sizable difference in stock versus aftermarket exhaust systems. The noise issue is a serious issue. If the aftermarket companies do not start producing quiet exhaust systems, we are going to find ourselves with no places to ride. The tree hugging radicals can use the noise issue to get everyone to jump on their bandwagon and start forcing the government to close land that we now ride on. The $$$ that one spends on aftermarket exhaust could be better spent on suspension or an IMS tank, expecially when competing in cross country and/or GNCC. The 450 has gobs of power, the trick is getting that power to the ground and having the quad handling correctly.


Another thing you might consider is ordering a "T handle" ajduster or something similar for the fuel screw adjustment. On the '06 model, the fuel screw is a D shaped adjustment. When you have the carb apart, you can remove the fuel screw, take a Dremel and careful cut a slot in it so you can make adjustments, or you can order the aftermarket adjusters. We ordered the Scotts fuel screw. They (Scotts) said that it wouldn't work in a TRX 450, but James Dean told me that they do work. After we installed it, we put some silicone around the adjustment to insure that it would not back out or move. You will probably have to adjust the fuel screw to aleviate the slight hesitation in the throttle that varies due to temp and humidity.



Let us know your results.

[DanW]

Originally posted by trx400exxracer
My pleasure.

We use the JD Jet Kits, since they use the same Keihin jets and the jet sizes are the same. It is easier to keep up with. They supply a wide range of jets, I think from a 170 through a 190. Plus they include two needles. The instructions they include are very detailed and give you a good starting point.

It's my opinion that other than weight and excessive noise, there is no sizable difference in stock versus aftermarket exhaust systems. The noise issue is a serious issue. If the aftermarket companies do not start producing quiet exhaust systems, we are going to find ourselves with no places to ride. The tree hugging radicals can use the noise issue to get everyone to jump on their bandwagon and start forcing the government to close land that we now ride on. The $$$ that one spends on aftermarket exhaust could be better spent on suspension or an IMS tank, expecially when competing in cross country and/or GNCC. The 450 has gobs of power, the trick is getting that power to the ground and having the quad handling correctly.


Another thing you might consider is ordering a "T handle" ajduster or something similar for the fuel screw adjustment. On the '06 model, the fuel screw is a D shaped adjustment. When you have the carb apart, you can remove the fuel screw, take a Dremel and careful cut a slot in it so you can make adjustments, or you can order the aftermarket adjusters. We ordered the Scotts fuel screw. They (Scotts) said that it wouldn't work in a TRX 450, but James Dean told me that they do work. After we installed it, we put some silicone around the adjustment to insure that it would not back out or move. You will probably have to adjust the fuel screw to aleviate the slight hesitation in the throttle that varies due to temp and humidity.

Yep, that's all good info.

If you can't get the JD jet kit, the HMF needle works pretty well too (it's $10).

I run with no air box lid (racing XC), but I do have an Outerwear cover on my filter.

175 main for me (with HRC needle). I was running the 162 that the HRC kit recommends, but that just seems too lean!





Let us know your results.