Author: Nick Stolten

While the shock is off and the bike is sidelined, it was a good time to send the ECU off to Flash Tune. These guys are experts when it comes to Yamaha ECU’s, so there shouldn’t be any issues hacking into it. This will give us, and customers, a nice way to make adjustments directly to the ECU without the need for a piggyback controller. Tuning YCCT parameters, speedo adjustments to compensate for gearing changes, mode modification, and of course fuel/spark changes will all be within reach. Looking forward to seeing what’s inside!

But first, gotta get to the ECU, which is located on top of the airbox, under the fuel tank. Someone PM’d with a few questions on doing this, so here are some photos for those unsure how it all comes apart. Pretty straight-forward, but it’s highly recommended to run the bike as low on fuel as possible to lighten the tank. Don’t run it dry, though…Stoltec’s towing fees are through the roof!

1. Remove both side scoops. These hide a tank mount on each side. Remove one screw and two pop rivets per side. To remove these pop rivets, depress the center button and then evenly pry around the outside ring/base. New rivets free of dirt should easily pop right out. Here is a view looking down at the insides of the scoops (tank removed). Note the frame bosses where the tank mount.

And here is the mount on the tank (one on each side). No need to remove the upper two bolts, just remove the bottom.

2. Remove the plastic trim panel at the front of the tank. The rubber trim peels off and the panel is secured with four pop rivets – same as on scoops. Here are the parts off the tank:

3. Remove the two side bolts followed by the two bolts at the back of the tank after the seat is removed.
4. Time to disconnect the harness, fuel line, and vents from under the tank. This is easily done if you lift the tank up and slide back a couple inches. You can rest the tank directly on the rear mount casting (silver). From the side, you can see the connections you’ll need to disconnect.

As always, it’s recommended to remove the fuel line with no residual line pressure. Let it bleed down if the bike was running or the pump was primed. The longer you let it sit, the better. Still have a rag handy for the little bit of fuel remaining in the hose. That’s pretty much it.

Now that the tank is off, you can see the front shock mount alluded to in a previous post. Will definitely be easiest to reinstall the shock with the tank removed!

So with the tank off, this is what we were after:

Hopefully have it back within the next two weeks…

While under the tank, figured it was a good time to have look into the airbox and see how fancy Yamaha got. Pretty impressive!

Pretty amazed at how many leaves this thing sucked up in only 350 miles…

Here’s a better look at those staggered velocity stacks we’ve all been reading about. Pretty neat.

Looking at the underside of the lid, you can see two resonators…one on each side of the filter. The clean side is fed by a breather, but the dirty side is not. At this time, no one outside of Yamaha likely knows if the Helmholtz chamber is there for sound suppression or resonance tuning for power. If/when the laundry list of projects on this bike dies down, it would be interesting to see if removing the clean chamber has a noticeable effect on either. Gains are likely to be minimal (if any!), but curiosity has killed this cat before…

First real order of business is to start disassembling the bike before any changes are made. With the large number of changes planned, there is no sense in throwing things on just yet when the very basis of the bike is going to change.

Missing something?

Oh yeah!

The good news is that the shock comes off in a few minutes without rotating the subframe. The tank didn’t even need to be removed, though it looks like reassembly will be much easier with the tank off.

So what you see is what you get with this shock (not much). Ramped preload collar and rebound adjustment (made through frame access). This shock is atypical in the sense that most shocks have the preload adjustment on the top of the shock. This, of course, was done for the sake of packaging on Yamaha’s behalf. No worry, though. Kawasaki used a similar approach on a few of their shocks, so Penske already has access to the bottom preload collar setup.

The plan moving forward will be to develop all three of Penske’s shocks for this bike:

• 8975 – Low speed rebound, low speed compression, and spring preload adjustments. No reservoir – but keep in mind this is NOT an emulsion shock like of the competitors!
• 8983 – ‘Double Clicker’. Same functionality as the 8975, but adds a reservoir (remote or piggyback depending on what we can fit) and ride height adjustment.
• 8987 – ‘Triple Clicker’. Same as 8983, but adds high speed compression adjustment. Penske makes fancier shocks for the race guys, but this is top of the food chain for street and most racers.

I hope to have a dry shock in hand soon, but we’re waiting on Penske now. With the final dirt track race of the season this weekend and the Orlando show this week, resources are thin. Still, the sooner the better. Anxiously awaiting the dry shock to check fit/interferences and determine the shock linkage rate.