Dirt Wheels - Yamaha Grizzly Special

HOW TO:

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.

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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 Grizzly’s airbox, replace the lid and reinstall the hold-down strap, heat shield, tank, tank straps, petcock, tank cover, bodywork and 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.

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8. Remove the backing on the K&N gasket and press the glued side onto the filter.

Slide the Outerwear onto the K&N.

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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.