Jon's FZR Page

Tires:
what's the biggest size?
what kind of tires should I run?

Best Mods for the $$:
14 tooth sprocket
110 main jets I don't need no stinkin' jet kit!
Adjusting your mixture(pilot) screws THE most important modification(an adjustment really). Properly adjusting your pilot screws cures 90% of hard starting problems.
YZF600 mirrors
Fork Oil and Springs

Biggest Tires

Stock tire size for a 90'-99' FZR600 is 110/70 R-17 front, 140/60 R-18.
The biggest tires you can physically squeeze on is a 120/70R-17 for the front and a 160/60R-18 for the rear. Different tires have different profiles, but these are the BIGGEST you can put on w/o major modifications or handling consequences. Before you run out and buy these, let me warn you about the drawbacks.

First the front tire:
- I highly recommend running the stock size 110/70 R-17 instead of the 120/70 or 120/60 because it doesn't fit right on the 3" rim. The 3" rim slightly pinches the tire and causes it to bow. It doesn't let you use the whole tire like the 110 and the 110 steers quicker/faster.
It's not easy finding a 110 that is sticky because most of the newest tires are made for the 3 1/2" rims. This said, many people use a 120 because of the limited selection(including myself at this point in time). It really doesn't feel that much different. You can compensate for the taller tire by dropping your forks through the triple clamp 19mm. Doing this will restore your quick steering, since the taller tire slows it down a bit.

The rear tire:
- The perfect size for the rear is a 150/60 R-18. It's one size bigger than stock and it fits nicely. It also happens to be the one size that anyone seems to make. Hardly anybody but Bridgestone makes a 140/60 that's any good.
Do yourself a favor and stay away from a 160 size rear. You are asking for trouble. You might have to shim the front and rear sprockets out to clear the tire from the chain and you will have to shim the brake arm out to clear the tire. Getting the tire to fit is not the biggest problem. The biggest problem is the way the bike handles with that oversized tire. You start leaning on that tire and it will flex too much. If you don't ride hard, then don't worry about it. Maybe you'll gain a few poseur points.
Top

What Kind of Tires

First of all, don't mix radials with bias plys. I don't recommend bias ply tires anyway, but some people do use them. Since I don't recommend bias ply, I won't list any. Hey, it's my site and I like radials dammit! Let me break this into front and rear tires.

Front : For the stock size(110/70), you have a few choices.

Bridgestone BT56ss - dual compound tire, harder center for mileage, soft sides for twisties. I've heard it gives excellent feedback, very predictable.

Bridgestone BT50 - street and hard to find race compound. One guy I ride with uses the race compound and really likes it, pretty sticky. The street compound is a bit hard for my taste, but makes a good tire for mileage/commuter/weekend semi-aggressive riders.

Metzeler MEZ1 - street and race compounds available

Pirelli Dragon(Corsa) - street and race(Corsa) compounds available. The Pirelli and Metzeler are one in the same. Only difference is the tread pattern.

For one size up from stock(120/70 or 120/60) , you have unlimited selection. All modern rubber is made in either or both sizes.

I use a Dunlop 207ZR(street compound) right now and it sticks like snot. It's also predictable when it does slide, being very progressive. Definitely confidence inspiring. You can push and push that front end pretty hard and know just where you stand and how far you might be able to push it.
Another nice thing about the tire is that it's very triangular. The center is pointy and gives you very quick turn in. The tire just wants to lay over. The street compound is excellent, I can only imagine what the race compound is like once it gets really hot!
The problem I have with this tire is that they don't make it in a 110/70!!!! The tire is pinched and I will never wear the last 5-10mm of tread on the sides because of this.
The other problem is that it's cupping pretty fast and I only have 2k miles on it. I've talked to a few others who run it and they have the same problem. I've heard that it's just a property of Dunlop tires.

Rear:

Guess what, you have the same choices as the front tires listed above. There are a couple that are made in 160 like the Micheline Macadam and Avon Azzaro......
Top

14 tooth sprocket

Spend $20 and get one. Lets the motor work at a higher rpm range by spinning the motor faster at lower speeds. For example, you're in 6th gear doing 70mph at 6k rpms. Drop one tooth from the front sprocket and the revs will increase to 6,500 rpms.
This increases your torque and acceleration, but lowers your top speed.
Top

110 main jets

For $12, buy 4 Mikuni large round main jets in size 110. All you are doing is increasing your stock main jet size(107.5) by one. This will add a bigger kick above 7k rpm. This will work properly with stock or aftermarket pipes/air filters, except individual filters.
Top

Mixture Screws

This doesn't cost a dime! All you need is a drill with a small drill bit, a wood screw, pliers and a small screw driver. There are 4 brass plugs on the back of the carbs, bottom middle side of the float bowls. All you do is drill a small hole, tap the screw in there and yank the plugs out. You will find a slotted screw underneath. Turn them in clockwise until they bottom out and turn them back out 2 full turns.

In order to set them properly, you need to let your bike warm up to normal operating temperature.
- Set your idle speed under 1k rpms
- Blip the throttle several times, watching the needle and how it drops.
- If the needle hangs and then drops to where you set the idle, it's too lean. Turn the mixture screws OUT an additional 1/2 turn and retry.
- If the needle drops back down and dips a lot lower than where you set the idle and slowly comes back up, it's set too rich. Turn the mixture screws IN a 1/2 turn and retry.
- You have them set right when you blip the throttle and the needle smoothly drops right where you set it.

Like I said, this will cure most hard starting problems. My bike starts first/second try every time, no matter how long it has sat.
Properly adjusted pilots prevents plugs from being fouled. Also make sure you set your spark plug gaps as close as you can to 0.030".
Top

YZF600 Mirrors

Replace your stock, round mirrors for square, YZF600 mirrors. They are a direct bolt on. Find the EMGO replacement mirrors, they should be around $30 a set. You can see a little better and they are much better looking.
Top

Fork Oil and Springs

$20 for 2 bottles of fork oil and $90 for Race Tech springs. Make your front end come alive and change your fork oil to heavier weight to increase your rebound dampening. Stock weight oil is 10w, go to 15w or 20w. When you fill the forks, do it w/o the springs in place and measure down 120mm from the top for the correct oil level.

Make sure you pick the best spring rate for your size. There is a chart on Race Tech's web site. Don't worry about getting the emulators if you are a street rider, these 2 mods should be enough for 99% of you canyon carvers. Save your money for a used Fox shock.
Top