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Discussion Starter #1
Hi all thanks for reading.

Recently my bike has developed a wobble under deceleration from ~48-41mph. If I keep my hands on the handlebars (which is always a good thing ;) ) my arms dampen the wobble out but if I take a hand off I can feel the wobble. I'm just scared it will progress to a tank-slapping deal and would rather be safe and fix it ASAP.

My tires are inflated to about 35psi f/r and I've messed around with the pressures (28-35psi) to see if it helped any which it hasn't. I havn't flatspotted my front wheel nor hit anything that I think could bend it. Perhaps it has slowly squared up. From what I've read, this sounds just like my front tire is getting worn down. I'm not sure how many miles are on it since I bought it with the current tires from PO, but tread depth seems good and I see no flat spots. Normally I do all my automotive work myself, but will probably have to take it to a shop due to my crazy school schedule (about to graduate with a doctorate ;D ;D).

Besides tires, I didn't know if this could be related to the forks/shocks/bearings. I have also searched and haven't been able to find how much freeplay and bound/compression is acceptable in the front shocks. Although I have never seen any fluid leaking from them, the bike seems to have a lot of dive under braking and when I sit my 170lb self on it. Reading from another motorcycle forum, and applying my bicycling knowledge, I also didn't know if the front end wobble could be related to the bearing and if this is readily serviceable.

Does this seem like a reasonable train of thought, or am I missing something obvious? Next step will likely be to call a shop.

Again thank you all for reading and helping me out.
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Discussion Starter #4
Ray W,

It is most apparent under engine braking, I get some appreciation of it under front/rear braking too however. Forgot to mention this!
 

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Discussion Starter #6
It seems to be less severe when I'm braking harder and loading the front fork - but then I normally have both hands on the handlebar when I'm loading it too. However, it doesn't seem to do it while accelerating (again though, I have at least one hand on the throttle).
 

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My advice would be listen to the advice given but maybe use elimination first and start by doing the no cost actions first.

String thing, fork rocking, tyre pressures front & back.
 

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Be sure to check for play in the steering/stem bearing. A worn bearing will cause wobble. There should be no play in this. Lift the front end and grab the front wheel and yank in different directions, any lateral play, even a fraction of a cm means you need a new bearing, normal after 20,000+ miles.
 

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Last time I had my bike in for new tires, the shop techs let me know that there was a similar-sounding wobble, though pretty minute, and said it was almost certainly the steering stem bearing. They are cheap ($35), but the labor for swapping them seems pretty intensive. Have any of you guys had to replace the steering head bearing? Thoughts on the process? The Clymber manual make sit seems like you have to take the whole damn front enough apart. If that's the case, I might as well change the fork seals and replace the oil (just hit 18k miles, so I'm probably due).
 

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This is going to sound ridiculous but i had the same problem. Have you recently changed your air/fuel mixture somehow? After i added a K&N i had a bad wobble then adjusted the pilots and bammm! Wobble gone. Sounds crazy right? Go with me here, if you have an engine thats not running properly, the vibration has to transfer somewhere.
 

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No man, its in the alignment not the engine. sometimes its in the steering head, but not the pilot screws, i assure you it was a co incidence tricking you.
 

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rayycc1 said:
sounds like steering head bearings to me...I just bought these to replace mine...http://www.allballsracing.com/22-1014.html
this is a way better design. IIRC it cost less than $50 shipped
+1. The fact that it's most prominent under engine braking (forks unloaded) would cause me to suspect them first. They're easy to check. Put the bike on the centerstand. From straight ahead position with the front wheel off the ground, a gentle nudge should cause the forks to turn all the way to full lock (although the cables sometines restrict this a bit). If not they're too tight, . Now straddle the front fender, grab the lower fork legs and gently try to rock the entire fork forward and back. Any perceptible movement means they're too loose. If they're too loose they could possibly be adjusted but more likely they're worn. The stock steering head bearings/ seal is a common failure on these bikes and the All Balls ball bearing replacements are serious improvement over the stock loose ball-in race type. I love them. And yes, you do have to disassemble the front end.
 

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Im sticking to my story. That way if im right, I look like a genius. If not, i was....just..kidding..maybe? Anyways, ive been riding for only a few months and one thing ive learned is that these guys on here truly know their stuff. Take THEIR advice, not mine lol, and run with it. They havent led me astray yet!
 

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Discussion Starter #16
Thanks everyone!

I'm pretty mechanically astute, but I'll probably take it to a shop on account of my business. I'll throw it up on the centerstand tomorrow when I have some time off and see if I can detect any freeplay in said bearing.
 

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Hi all thanks for reading.

Recently my bike has developed a wobble under deceleration from ~48-41mph. If I keep my hands on the handlebars (which is always a good thing ;) ) my arms dampen the wobble out but if I take a hand off I can feel the wobble. I'm just scared it will progress to a tank-slapping deal and would rather be safe and fix it ASAP.

My tires are inflated to about 35psi f/r and I've messed around with the pressures (28-35psi) to see if it helped any which it hasn't. I havn't flatspotted my front wheel nor hit anything that I think could bend it. Perhaps it has slowly squared up. From what I've read, this sounds just like my front tire is getting worn down. I'm not sure how many miles are on it since I bought it with the current tires from PO, but tread depth seems good and I see no flat spots. Normally I do all my automotive work myself, but will probably have to take it to a shop due to my crazy school schedule (about to graduate with a doctorate ;D ;D).

Besides tires, I didn't know if this could be related to the forks/shocks/bearings. I have also searched and haven't been able to find how much freeplay and bound/compression is acceptable in the front shocks. Although I have never seen any fluid leaking from them, the bike seems to have a lot of dive under braking and when I sit my 170lb self on it. Reading from another motorcycle forum, and applying my bicycling knowledge, I also didn't know if the front end wobble could be related to the bearing and if this is readily serviceable.

Does this seem like a reasonable train of thought, or am I missing something obvious? Next step will likely be to call a shop.

Again thank you all for reading and helping me out.
Read
I have just bought an 88 GPZ500 and I discovered I have exactly the same issue. I was trying to close my jacket with my left hand and suddenly this crazy fast wobble.
The exhausts are noisy (baffles removed) and it’s lumpy as hell if I try to go more than 100kph. It won’t go any faster. Idle is very high too (3000rpm) and the wobble probably was as I eased off a little. Then it went away. Both hands on the bars, no problem.
It’s taken me more than 4hrs to get home. And I’m in Sweden. And it’s cold. It was horrible!🥶
So yes, I want to know what this wobble is. I saw maybe head bearings? Tyres are worn out as well. But pressures are ok (2.2bar)
I also want to know why it won’t go more than 100kph. It just gets lumpy and won’t go faster.
 

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hi it's better to start a new thread than tag onto one that is 10 years old. if you do you may get the answer you seek quicker many members like myself do not usually reply to old threads as the participants may have long since departed.

note to mods. if you move this to a new topic please delete this post.
 

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We all know newer posts added into older threads are bumped to the top....clearly visible for all to see. Its fully OP's decision to start fresh or add on to older thread, there are no rules prohibiting his choice.

To address the wobble....with a "new to you" EX" .....has OP first examined trueness of rim and tire fully seated? No preexisting damages or tire install errors? Also checked steering head bearing adjustment?
 

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Possible rear wheel out of alignment.
As far as the 100kph top speed. Hard to say, maybe a defective carburetor diaphragm. It's to my understanding that some of the bikes in Europe have governor restrictors that keep the bike below a certain speed.
 
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