Muzzy's Full Exhaust System Review – Yamaha Grizzly 700

[GRIZZLYWIZARD]

A few months back we were given the chance to review the Muzzy Pro exhaust for the KFX-700. We were very impressed with that system, so when we were asked to review the new system for the Yamaha Grizzly 700 we were very excited. The Muzzy exhaust for the Grizzly 700 is a stainless steel exhaust system from the head pipe back to the muffler. This system utilizes a combination of stainless and aluminum components. By utilizing a stainless steel exhaust system, Muzzy’s is able to not only to eliminate corrosion, but they also increase horsepower and torque. The combination of components and exhaust engineering set a new standard in exhaust performance for the Grizzly 700. In order maximize horsepower and torque, you must maintain a high level of exhaust velocity and increase the scavenging effect by using a heat wrap or ceramic coatings. Stainless steel has a much lower coefficient for thermal conductivity which allows for the head pipe to keep more heat inside and will do very much the same thing without all of the ad-on components. So, the excellent heat retention characteristics, fatigue retention, and cosmetic qualities make stainless an ideal choice for this system.

First Impression

Once the Muzzy system arrived, a close inspection was in order to determine if this setup would work for the 2007 Grizzly. Muzzy’s only listed the system for 2008 – 2009 model years. A few quick measurements and it was determined that it will fit just fine. It appears that the 2007 Grizzly has an OEM exhaust can with three tabs welded on the top in order for the heat shield to attach. The 2008 – 2009 models had a change with the absence of the 3 tabs. The heat shields on the newer models were attached with 3 worm gear radiator type clamps making the differentiation between the Grizzly models insignificant as far as this installation was concerned. Muzzy’s does a very good job in the packing of their exhaust system. All parts are individually wrapped in plastic and separated with foam padding to prevent any damage during transit. The muffler is an oval brushed aluminum can with polished end caps and stainless steel hardware. I first noticed that the muffler was heavier when compared to many of the systems we have tested to date. This is clearly indicative to quality engineering and construction. The system comes with the spark arrestor installed. If you prefer to remove the spark arrestor, shims are provided to allow for proper spacing of the end cap. When looking over the head pipe sections I noticed that Muzzy’s took great care in the final appearance of this exhaust system. They also increased the overall size of the head pipe diameter as well as the tail pipe section of the system. This wider pipe diameter allows for better flow over the OEM system.

Installation

Muzzy’s provided clear step by step instructions for installation of their exhaust system. The hardest chore I found was removal of the stock system. With a 3 year old machine I found that the head pipe clamp nuts had rusted themselves to their mated bolts. Not only that, the confined space made for a more difficult time in getting the OEM head pipe off. The words “Patience is a virtue”, play a big role here. So, I sprayed the flange nuts with some penetrating oil, sat back for an hour enjoying the awe-inspiring workmanship of the Muzzy exhaust system and waited for the penetrate to do it’s magic. With the OEM system removed, it was time to install the new Muzzy’s system. We recommend that you go to your local dealer and purchase some new exhaust gaskets (part number # 3YF-14613-01-00) as Muzzy’s does not provide them with the parts kit. These can be acquired through your local Yamaha dealer and are usually under $10. Another thing to note, we highly recommend the use of anti-seize compound on all fasteners. We also applied a bit to all of the fitted part of the exhaust system where the head pipes meet the exhaust collector to allow it to slide together during the final assembly.

The system utilizes the mid section heat shield. Originally we didn’t think we would need to use this, and had planned to wrap the system with heat wrap to eliminate excessive heat. However, we noticed how hot the exhaust got and decided we better use the shield. The shield not only keeps the heat off your legs and plastic, but it also acts as a stiffener and provides another level of rigidity to the entire setup. Installation time took approximately 2 hours from start to finish. We loose fit the entire assembly to make sure everything was properly aligned. Once confident that everything was in place and aligned we tightened everything down to the proper torque specs which are illustrated in the service manual. Muzzy’s also provides a welded bung and plug which allows the user to incorporate an oxygen sensor, which when used in combination with certain test devices such as the Innovate Motorsports LM-2 or other wideband AFR gauges gives the end user the ability to monitor their air to fuel ratio. Having that information you can optimally tune your engine for the most efficient use of fuel and maximum horsepower.

Muzzy’s also provides a welded bung and plug which allows the user to incorporate an oxygen sensor...

Rider Report

With the vehicle started, we noticed how docile the muffler sounded. Idle noise is very minimal; it is louder that the stock setup but it is not an obnoxious level. While cruising along with steady throttle, the exhaust is quieter that I had expected. Only when I rolled into full throttle could you tell that you were running an aftermarket system. I noticed a snappier throttle response when compared to the OEM setup. As with other Muzzy exhaust system, it has a very distinctive sound. While many associate loud exhausts with horsepower, this isn’t always the case. The following test bed of our test included a stock air box lid, a UNI air filter and the stock fuel map. On startup we noticed the Innovate LM-2 monitoring 13.5:1 AFR (air fuel ratio). When revving the motor the AFR would bump up to 15.2:1 and then spike to 19.1:1 when the throttle body slammed shut.

Our next step would be to begin ride testing and monitoring the AFR while under a load. From a dead stop to wide open throttle we were monitoring the AFR in a lean condition up to about 40 mph. This condition was unacceptable and we knew we were robbing ourselves of horsepower and could possibly lead to potential engine damage if left in this condition. The lean condition required the use of an EFI controller; Muzzy’s makes a fuel controller for the Grizzly 700. Since we already had a fuel controller from EHS Racing installed on the machine, we chose to use it. Tuning was very quick with the EHS Racing tuner. We strived for 13.5:1 AFR across the complete power band; this seemed to give us the best low end response, mid range acceleration and top end speeds. Once we completed our tuning, we quickly noticed an increase in low and mid range horsepower. To summarize our final test setup, we used the EHS Racing Bullet Box fuel controller, a stock air box with UNI filter, and the Muzzy’s system with the spark arrestor installed. We are certain that some more horsepower can be achieved with some component tweaking to allow better airflow for the exhaust.

Our next part of our evaluation was to record some sound results with the use of an analog decibel meter. Since we only recommend riding with an approved spark arrestor, we only tested the system with the spark arrestor screen intact. The idle levels we recorded were at 95 db at 3,750 RPM’s this is slightly higher than the stock exhaust readings we recorded at 87 dbm. These recordings were done at the standard 45 degree 20 inch manner for off road sound testing.

Conclusion

The Muzzy full exhaust system for the Grizzly 700 has answered the question that few exhaust manufacturers have been able to do and that is offer system geared towards total performance. The stainless steel construction is paramount to those who demand the best qualities in materials and workmanship. The fit and finish are perfect; we could not find any areas for improvement with this system.

For more information or to purchase the Muzzy’s exhaust system for the Grizzly 700, you can contact them at:

Muzzys Inc. – http://www.muzzys.com
62910 Peerless Ct.
Bend, OR 97701
541-385-0706