Fork stabilizer

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29 Aug 2019 23:55 #810081 by gordone
Fork stabilizer was created by gordone
Will installing fork stabilizer be a upgrade to my bike?

Is it improve the handling on all classic bikes?

1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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30 Aug 2019 06:19 #810093 by 650ed
Replied by 650ed on topic Fork stabilizer
If your bike's fork has a bit of a wobble there is a problem. Using a fork stabilizer will only mask the problem, but will not fix it. The KZ650 front forks should have zero wobble at any speed. Ed

1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

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30 Aug 2019 06:23 #810094 by gordone
Replied by gordone on topic Fork stabilizer
Thank you :)

Only reason for adding it is if somebody like the look then :)

1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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30 Aug 2019 06:57 #810095 by 650ed
Replied by 650ed on topic Fork stabilizer
They tend to be useful on race bikes, especially those that might become air-borne at high speeds when passing over hills. In those circumstances a wobble at very high speeds could be dangerous. Ed

1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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30 Aug 2019 09:07 #810097 by baldy110
Replied by baldy110 on topic Fork stabilizer
The stock front forks and swingarm are good until you start pushing the bike hard in the twisties. The forks will flex along with the swingarm which leads to a very unstable and uneasy feeling when your riding it fast. The fork brace does help along with a stiffer swingarm. But under normal riding it's a waste of money..
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30 Aug 2019 12:06 #810104 by zed1015
Replied by zed1015 on topic Fork stabilizer
A fork brace does help on the skinny stock forks and reduces "Walking" in fast turns and hard braking .
That's the reason why they were a popular aftermarket accessory back in the day and on race machines.
The effect is less obvious the larger the stanction diameter which is why you don't see them much on newer machine and USD's.

AIR CORRECTOR JETS FOR VM CARBS AND ETHANOL RESISTANT VITON CHOKE PLUNGER SEAL REPLACMENT FOR ALL CLASSIC AND MODERN MOTORCYCLE CARBURETTORS
kzrider.com/forum/23-for-sale/611992-air-corrector-jets-





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30 Aug 2019 12:17 #810105 by Dr. Gamma
Replied by Dr. Gamma on topic Fork stabilizer
A fork stabilizer, do you mean a fork brace?? Never used a fork brace on any of the bikes I owned or built over the years. One thing that is a must have for me is a adjustable steering damper. I would not ride any motorcycle at high speeds without one!!!! End of question!!!

I don't think its much fun when your big inline four Japanese bike hits some rough pavement at 120MPH or so and goes into a massive fork shake or what some folks call a speed wobble!!! Been there Done that!!! I had a '79 MK. II demo from the dealership I worked at back then that went into a speed wobble at high speed. It was so bad that my knee broke off the spark plug cap on the #1 cylinder!!! I did manage to save it without crashing that day. That was the very last time I rode any bike without a steering damper. What I used to do after I put a bike together was go out on a nice piece of straightaway. Get up to near redline in top gear and purposely shake the bars back and forth. If I did everything right, the bars would stop going from side to side almost instantly. If not it was back to the shop and find out what I did wrong in setting up the bike!!!!


1972 H2 750 Cafe Racer built in 1974.
1976 KH400 Production Road Racer.
1979 Kz1000 MK. II Old AMA/WERA Superbike.
1986 RG500G 2 stroke terror.
1986 GSXR750RG The one with the clutch that rattles!

Up in the hills near Prescott, Az.
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30 Aug 2019 12:28 #810106 by gordone
Replied by gordone on topic Fork stabilizer
Example of what I’m thinking about:


1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine
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30 Aug 2019 14:12 - 30 Aug 2019 14:12 #810109 by TexasKZ
Replied by TexasKZ on topic Fork stabilizer
The term for that in the US is fork brace.

1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
Last edit: 30 Aug 2019 14:12 by TexasKZ.
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30 Aug 2019 19:27 #810121 by urankjj
Replied by urankjj on topic Fork stabilizer
I know that back in the day that a set of steering dampeners-stabilizers were a must for high speed applications on almost all double down tube framed in-line fours. Especially in drag racing. Many riders also coupled them with a one-piece fork brace that joined the two fork tubes together, (as pic in your example) . Are they necessary or be an up-grade ? Motorcycles are like relationships, so anything that you can do to add stability is probably a good thing .:blink:

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31 Aug 2019 02:05 - 01 Sep 2019 01:33 #810132 by 577nitro
Replied by 577nitro on topic Fork stabilizer
I use fork braces, and have since 1985 on all of my race bikes...the ancient ones, along with a steering dampener. These, IMHO, are a must and make a huge difference on the old bikes at the limit. Now, you must define the limit, which in my opinion is that 1% of the time you NEED the bike to perform in an emergency situation on the street and when racing these old girls. The old forks with the smaller diameter tubes were not stiff enough the prevent both independent fork action(actually a function of axel strength) , and side to side twisting (walking) and bending under load (front to back) . The brace helped all of the this. Now, the down side, that load is now shifted into the frame , tires, and springs....at the limit, normal riding you can't really tell. A well balanced bike will have both the front and back re-enforced. Properly done and these old bikes can can handle extremely well. To me nothing feels so neutral and sweet as a smoothly setup Gpz550/KZ550 twin shocker. They just got it right. And as proof to me in 1985 was the article in Motorcyclist about the master Keith Code using KZ550's/Gpz550 in his super bike race school.

Get a set of decent rear shocks like the ones off a Zephyr or ZRX and add a set of the Cartridge emulators with decent oil and the right springs; you'll be amazed. And it's easier than swapping front ends...to me anyhow....and cheaper.

577-
Last edit: 01 Sep 2019 01:33 by 577nitro. Reason: spelling

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31 Aug 2019 08:09 #810138 by 650ed
Replied by 650ed on topic Fork stabilizer
Regarding fork braces one thing to consider is that many folks remove the stock front fender without realizing that i provides at least some fork brace function to the forks. This is because along with the fender itself there is a rather stiff metal support riveted to the fender that during normal riding keeps the distance between the two fork tubes constant. A stout fork brace will provide a stiffer support and may be worthwhile for use on the racetrack, but I doubt there are many, if any, situations in normal street use where distance between the two fork tubes will vary with the stock fender in place. At least I can say I haven't found it to be a problem on my KZ650-C1 for more than 42 years, 62,000+ miles, of riding, some of which were quite spirited. Ed


1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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