Mohawk

I can’t recall the cfm, but when I did work it out 2x140mm + 2x 120mm fans had more cfm than the stock fan. 140’s mounted to outside front of each rad & 120’s at the outside rear. I only used different sizes because they fit on the rad cores & clear the fairing all bar a few small inlets to the outlet holes to clear the fan frames.

Make sure you balance the starter valves correctly, it will vibrate much less when they are sync’d correctly. The difference is night & day. But there will always be a little vibration.

Just to qualify this particular wheel After investigation was discovered to be a hand me down from a sponsored team to the team where it broke, it was IIRC a magnesium Race wheel & had been crashed a few times & NEVER x-ray/dye checked. That’s why cheap secondhand race wheels should be avoided & magnesium ones never used on the road as there are prone Stress fractures. And on broken spoke on a marginally strong wheel is all it takes to overload the rest !

The F4 has compression damper adjusters at the bottom on the sliders, so if you use the VFR cartridge you will need a means to seal that extra hole. I fitted Honda cartridges to a Kawasaki lower, that had a much large bottom bolt. I turned the Kawa bolt down & cut a new thread to suit the Honda cartridge. You might be able to do the same, or use a sleeve to centre the VFR bolt in the CBR hole !

If you’d do a little research then you would know that F4/F4i have fully adjustable forks, 1.Preload, 2.Rebound,3.Compression. The 6th gen only has Preload & Rebound adjustment, the reason for swapping to F4 lowers is to gain Compression damping & for Brake delinking with much better front brakes. The only consideration here is the damper rod length at full extension, if with the forks fully extended you have the damper rod out of the fork top just high enough to attach to the preload adjuster then they are good to go. So swapping lowers with their associated cartridge means using the same bolt/washer designed for it. The one thing that has always Pee’d me off about Japanese manufactured bikes is they keep changing parts like damper rod bolt for no apparent reason, it would be much cheaper for all concerned if they’d pick a standard & stick to it. And don’t get me started on part numbers 😞

Looking good, enjoy & summer is nearly here 🙂

A tip for those clamp springs, get some heat shrink colour of your choice & slide over the springs. It keeps the exhaust free of marks & rust from the springs, they will rust.

Good info there. Write it in a file & stuff it in the VFRD library downloads section.

Call me cautious but might I mention, new user, stolen bike, girls name & what appears to be a male hand in the picture. Can anyone vouch for this user, before sharing info on how to steal & or fix stolen US model VFR’s. Euro versions from Y2K have anti-theft HISS technology.

Most people just update the whole front end, with CBR600F4/i or VTR1000 if sticking with RWU forks, or many other USD forks. But if you search for 5th gen delink you will find complete how to info. Should give you plenty of ideas.

Aha, small cock up on my part. most rear calipers are single piston or two very small ones. Your ratio is correct due to two large pistons. As you have worked out the 14mm has nearly halved the effective effort ! Less brake piston area, means big changes in ratio for small changes in MC diameter. IIRC the stock VFR rear MC is 1/2" or 12.7mm (check that I'm sufferring brain fade ATM) which would give 14/1 ratio, which is the same as 7/1 for a single piston caliper.

So the simple answer is work out your ratios, its pretty simple. Area of ALL brake pistons in a caliper / devided by area of master cylinder = brake ratio. So if a 4pot caliper had 4 equal sized 32mm pistons, then 32/2=16x16=256x3.14 (pye)=804mm PER piston, so x4 = 3216mm2 is the area of the pistons. These would normally have a 16-19mm MC piston diameter, so we will use 16/2=8x8=64x3.14=201mm2. So devide the 3216 from the caliper pistons by the 201 from the MC. 3216/201=16/1 ratio. I hear you say thats not right & you are correct ! That 16mm MC usually works on 2x4pot calipers, so 3216x2=6432/20=32 or 32/1 ratio. Now do the same for your rear brake. They normally run around 7-9/1 ratios (for a single piston, or two small piston rear caliper), because your foot has a big leg attached & can push much harder than your tiddly fingers can pull 🙂 For fronts the preferred range is 25-35/1 where 25/1 gives a very stiff lever but instant if wooden bite, and 35/1 gives a soft lever with travel that allows for very fine modulation. I find 32 or 33/1 is best for me but that's my preference. As always YMMV.

On normal roads, the bike always until about 110mph, then I'm usually happier in the car. But bike on track at any speed. There was a test done a few years ago, with a sports car & bike, even on a continuous circle test the bike was just a little quicker. But in most performance car V bike race track tests the cars are always significantly quicker in the corners, but lose out on acceleration, so the bike usually wins, by a nose, having slowed the cars in the corners by using its acceleration to get to every next corner first. But the cars are true super cars & 10K for a bike comapred to 150-200K+ for the car, on that basis alone the bike wins.

If not the wax unit, it will most likely be an air leak. Check the throttle butterflies are closing all the way. They are NOT used for the idle cycle, which is what causes the sudden lurch from idle to initial throttle! If you can get something to block all four air intakes, then block one at a time first whilst bike idles & see if the idle drops on any particular one. You could try some grease to seal the butterflies or squirt some quick start into each intake in turn & check the result. You can also squirt it at the intake boots & vacuum tubes under the throttle bodies & see if the engine picks up. Check that the flapper valve vacuum tube is connected &/or blocked off correctly, same the the MAP sensor hose at rear right of lower airbox half. I assume you have adjusted the idle screw ? It's on the right side of the throttle body next to the starter valves, accessed via a small hole in the right frame rail covered with a rubber bung if it there. Also the starter valves can leak, squirt some quick start or WD40 around them, as the O-rings n=may have perished without use, they are 20 years old. If you want to check the injectors, just disconnect one at a time & the result should be the same for all four. Let us know how you get on.

Well I guess your memory is better than mine John 🙂