More power for your Grizzly 660 or other 4x4
INSTALL A QUAD WORKS JET KIT
ATV manufacturers have to abide by a lot of rules and regulations when producing machines, and noise and emissions laws require ridiculously lean
jetting. This leads to hard-starting problems in extreme
conditions, and a loss in power. Also, when enthusiasts
want to modify their ATVs for mud-bog or closed-course
competition, like the Stock and Modified Utility classes in
GNCC, the non-adjustable jetting is so lean it can lead to
engine damage. Quad Works has the remedy in its ATV
Power Kit, which includes a Dynojet jet kit, K&N airfilter
and Outerwear prefilter. What’s cool about the Quad Works
kit is that it includes jets and instructions for the K&N only,
for the filter and airbox mods (like removing the lid) and for
going to an aftermarket pipe. For this how-to, we decided
to install the Quad Works kit on a brand-new Yamaha
Grizzly 660 4x4. It retails for $152.95.
1. Here’s the Quad Works ATV Power Kit for
the Yamaha Grizzly 660.
2. On the Grizzly, you have to remove the
front rack, engine shrouds and tank cover
bodywork to get to the fuel tank. Unplug
the fuel-level sensor wire, unscrew the petcock extension and remove the gas tank.
This is all much easier on a clean machine.
Remove the heat protector so you can get
at the carb. Also, remove the battery hold-down strap to get at the airbox lid.
4. The stock needle isn’t adjustable, but the
richer Dynojet needle is (numbers vary per
kit). Remove the OEM needle and pay
attention to how the spacers come off. For
the Grizzly 660 airfilter-only mod, the clip
goes in the fourth groove (this’ll vary per
kit). Place the spacers on the new needle
and place it in the slide.
6. Stuff rags in both sides of the carb to protect it from debris. Drill out the brass cap covering the air/fuel mixture screw. Russ uses a
left-hand, 5/32-inch drill bit and goes very
slowly to prevent damaging the screw. The
left-hand bit will bite and back out the brass
cap. Adjust needle to 2. 5 turns out (or per
instructions) and reinstall the carb and airbox.
7. Remove the foam airfilter and clean the
airbox. Use contact cleaner to clean the air-box/filter mating area and the end of the
K&N pre-oiled filter.
9. Push the K&N
down into the
replace the lid
and reinstall the
heat shield, tank,
tank straps, petcock, tank cover,
rack. Now enjoy
the added power.
Also, with the
Outerwears prefilter, water beads
up and slides off
of the filter for
less splash-foul-ing. ❏
5. For the Stage 1 mod on the 660, replace
the stock 135 mainjet with the Dynojet 150
(or bigger if you’re going with a new pipe)
and replace the float bowl. Replace the
slide, rubber diaphram and cover, spring,
and tighten the screws. The Dynojet slide
spring is softer for better throttle response.
8. Remove the backing on the K&N gasket
and press the glued side onto the filter.
Slide the Outerwear onto the K&N.
3. With your long screwdriver, loosen the
airboot clamp. Remove the airbox mounting bolts and slide the airbox rearward,
then loosen the carb/manifold clamp and
slide the carb out of the manifold. Float-bowl screws are notoriously soft, so use an
impact driver with the proper-sized
phillips bit (#2) to loosen the float fasteners. It helps to use a block of wood and
rag, as shown by Russell the Ragin’ Cajun.
Now flip the carb over and use the
impact on the CV-carb’s slide cover
screws. Remove the diaphragm and slide.