Upside Down Forks Part II

[andyoutandabout]

I recognize that shed. Full of good stuff.
Great build.
Hey, giantkiller, if you're in need of extra cash, you could always give me that FZ750. It's a long term idea whereby you don't actually get any money up front, but you save later by not having to insure it, buy consumables, fill it with ever rising priced gas. It's been going on in the world of big business for ages. Trust me, we all win.
Andy

[giantkiller]

Don't have an Fz750 anymore. Have the wife's Vance n Hines fzr600 for sale. I have the Human race team's world endurance championship fzr750. But going to keep that.

[racerrad8]

When the machinist opened the bore of the lower triple, he left a 1/8" tall band that the stem seats against, making it nearly impossible for the stem to press through the bottom of the triple.

Add in the extremely tight press fit. The steering stem sat in Liquid Nitrogen for 30 minutes before it was pressed into the lower.

Then I added the set screw. Also, remember the steering stem goes through the upper triple and has the acorn nut. With everything bolted together, I would think it would take a catastrophic front end hit for the steering stem to move at all.

Fred

Unfortunately the step the machinist put onto the lower triple is opposite of what Yamaha did with the snap ring. The stem pressed in from bottom at the factory. If he put a lip in the bore of the triple then you had to press the stem in from the top. If that is the case you are relying solely on the press fit and the set screw.

I understand he might have chilled the stem, but what was the PSI required to press the stem into the triple?

Dan, your wheelies and hard landings (compression) are more a concern than the deer in the chest (extension). I also understand the fork adapters are good and beefy, which I why I have a set of those as well.

But the fact still remains, the lower FJ triple is steel compared to the USD conversions being done. The newer lowers are thicker and have more surface area on the stem because they are made of the softer, malleable aluminum. The R1 lower is 1.600" thick compared to the stock FJ at 1.145" or right around a half an inch.

The stock stem, by just setting it in the R1 lower is around .400" if an inch which is not contacting the lower triple. If you added the distance from the bottom of the stem to the snap ring, that would put right around the 1/2" distance (.500").

I have attached several photos of the stock FJ stems sitting in the R1 lower I am using. You can see the distance the stock stem is missing in the bore.

There is also a couple of photos of the R1 stems, the stock FJ stem and the modified FJ stem I had completed. If notice on the bottom of the modified stem, the shoulder is on the stem just like the snap ring is located on the stock stem. The modified FJ stem will press into the bottom of the R1 lower triple from the bottom just like Yamaha designed.

One more thing, the wall thicknoess of the R1 stem is much more significant that the wall thickness of the FJ stem as you can see in the photo.

At the end of the day, it boils down to what you are comfortable putting on and riding with on your bike. Since I am building this bike from someone from all the way across the US, I am going to make sure I do not venture too far away from the original Yamaha design principle. I am only bringing this up because I do not want to see anyone get hurt doing these modifications to their FJ's.

Riding a FJ is dangerous enough without inducing other dangers when modifying.

Randy - RPM

[aviationfred]

Randy, I agree with you 100%. Making sure that it will be impossible for anything bad to happen is paramount.

The light in the shop showed the wheel stripe as not close to matching with the stripes on the bike. In the daylight, I think it is much closer. The Carbon Fiber looks amazing.

Fred

[aviationfred]

At the moment, I have no working speedometer. I have one on order. It should arrive this coming week.
This is a fuzzy photo of what I ordered.

Fred

[FJ_Hooligan]

Fred,
If you want to clean up that residual ABS wiring, it all unplugs from the stock wire harness.

Follow it far enough back and it will all pull off with a few connectors.

[aviationfred]

Fred,
If you want to clean up that residual ABS wiring, it all unplugs from the stock wire harness.

Follow it far enough back and it will all pull off with a few connectors.

Good to know, thank you Dave. At the moment, I have been sealing the un-used connectors with Marine grade shrink tubing.


Fred