Project Suzuki LTZ400: Air Filter and Yoshimura Exhaust

Apr. 29, 2009 By Ricky Sosebee

Sometimes the greatest things in life are free but for the most part you better prepare the bank account. Luckily we have some secrets to help you save the dough for gas and snacks.

Building the new 2009 LTZ400 into a basic budgeted woods machine has been good for us so far. The shock modifications came with a price tag ($750) but one much less than a complete aftermarket shock set-up. After getting the suspension dialed in and literally “ironing” out the frame we thought is would be good to put a few more ponies under the plastics. The quickest way to get more power from any ATV is through adding air and removing the restrictive exhaust with a finely tuned larger one. So this was our next move.

Calling the biggest name in Air Filtration for this project meant we had great filtration and less restriction than a stock filter. Twin Air filters have been in our industry for many years and I personally have learned to trust them with all of my engines breathing needs. The filters now come pre-oiled with the power of Bio Oil from Twin Air and these are Dual stage filters, which gives twice the protection. The Bio oil is biodegradable, works in all riding conditions and will clean up easily.

We found the ready to install filter really nice and it meant I didn’t have to break out the gloves and oil pan to get the filter prepped myself. Before installing the filter I always like to rub on some water-proof grease on the lip of the filter that will actually be making contact with the air-box. Some may say this isn’t nesecary but I have had stock filter cages collapse and without this grease in place it could allow dusty dirty air into the engine. It’s a safety/peace of mind thing for me. Just rub in a good liberal layer of waterproof bearing grease and stick that dual stage Twin Air in place.

After the new Twin Air is loaded and ready to hunt, the package that the new filter came in can be used to hold the dirty stock filter until you get around to cleaning it. It has a recloseable zip-lock top and that’s why I love Twin Air. They think of everything.

Page 2 - Yoshimura Exhaust


So we have plenty of air coming into the new fuel injected Z400 and the next step is to make sure that the added air gets out. Putting added volume down the throat of our beast we wanted to make sure that the same air could escape with little restriction and maybe intern add a bit of a punch on its way out. The last thing we want is a super loud pipe because here in Georgia the trails get closed by the loud unrestricted exhausts. Besides no one really wants to hear that rapping noise on a long day of riding.

Turning to another king in the ATV world and a virtual expert in Suzuki power adders we rang up Yoshimura RD for a quick question, answer session on which exhaust would work best on this machine. Of course the engineers here had already built what hey claim would give our Fuel Injected rocket a bit more pep. The only thing we had to do was remove the air-box lid.

The Yoshimura RS2 performance exhaust pipe came with all the little specialtys that made our install a cinch. They even send out a spring tool and exhaust plug for the wash down after the ride. The stock system is removed really easily and with a few adaptor pieces the new Yoshi pipe was ready, The new exhaust gasket was installed and the pipe slipped into place with no trouble. Sometimes we get exhausts that have to be “modified”, and you all know what I mean, but this one fit awesome the first time.

The bike is starting to take on an awesome look and as I grew more impatient, I decided to start this puppy up and gloat in the excitement. The3-sound was not defining but it was different. The 400cc single stroker pounded away and I couldn’t wait to rip open the throttle to see where the changes were.

Our ride time was spent in the deep North Georgia woods and I can attest to the additional power the Twin Air filter and Yoshimura exhaust put into our ride. The power on the throttle was moved into mid range with plenty of bottom still hanging around for the quick blasts through the tight stuff. The tone of the pipe grew on us as we drilled the trail time and time again. The biggest test of both of these add-ons will be very evident with a fuel-mapping device but we will have to wait for Yoshimura to get those perfected.

So with part two under our belt we move on to the next addition for the Z400. Next round we will add some excellent treads and new rims. Stay tuned for the next installment of the sleeping giant.

Sosebee Out


Twin-Air Pre-Oiled filter

PT# TA153908X : $32.95


Yoshimura RS2 Performance Exhaust

PT# 2176703: $375 for the slip-on as tested

PT#2176503: $595 for the full system Newsletter
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