[SirFoxx]

Hello--

Just wanted to get some input on an issue I'm having. While riding my '78 cx500 at highway speeds (~70-80mph) if I hit a bump or the wind shoves me from the side, the front of the bike will start wobbling / snaking down the highway until it stabilizes again. I am strongly leaning towards it being a tire issue (and maybe a mix of a front shock issue) due to the fact that my rear tire is so squared off it looks like a car tire with a bulging sidewall 😂. While yes, I am due for tires, I would assume this would cause stability issues?

Also, I have to drop the motor out of the frame again to replace the rear cover gasket due to a persistent oil leak from the rear left corner (not the shifter seal) and to have my carbs checked over by murray. Anything I should check while the bike is off the road? The frame has ~60k miles on it, and I keep telling myself it prolly due for some crazy service soon...

 

[D-Fresh]

Check your swing arm bearings i would think?

 

[DouginEasternWashington]

Check the head bearings too. In my opinion it is worth upgrading to tapered head bearings anyway.

 

[murrayf]

1st check tire pressure

 

[Sidecar Bob]

All of what they said^^^

And while the engine is out & apart have a look at the stator and the camchain & guides.

 

[bahn88]

yes all of the above....but you did state that the tyres are squared off....that'll often do it.....and at 90mph...things get exaggerated/magnified.....

 

[SirFoxx]

All of what they said^^^

And while the engine is out & apart have a look at the stator and the camchain & guides.

how would i go about checking the bearings?

the engine was swapped from a 500 to a 650. i just did the swap, so i know the chain and stator is good

yes all of the above....but you did state that the tyres are squared off....that'll often do it.....and at 90mph...things get exaggerated/magnified.....

hey now, i said 70-80, not 90 lol. the bike feels too sketchy at those speeds.

 

[bahn88]

tail wind😀

 

[Paul.slough.uk]

I had a BSA 650 spitfire which had been raced and was fitted with a steering damper, made it feel very stable at speed - thinking of putting one on the CX - fork rake angle plays a big part - less rake = easier to manoeuvre, more rake = more stable - it's a trade off.
Just a thought - defo go through all the other suggestions first.

 

[SirFoxx]

how do i go about checking the swing arm bearings?

 

[D-Fresh]

how do i go about checking the swing arm bearings?

There are more capable people on here to answer that question but i'll take a stab at it. With the shocks disconnected, move the swingarm up/down through it's range of motion and listen for any unusual noise and/or a rough or binding feeling. If your prop shaft is still connected make sure any anomalies are from swingarm and not the U-joint. Hopefully others will chime in.

 

[reclinedrelic]

There may be some useful information here? https://coodie.com/cx/CX500 Service Manual - Ch14 - Rear Wheel, Brake, Final Drive, Suspension.pdf

 

[D-Fresh]

There may be some useful information here? https://coodie.com/cx/CX500 Service Manual - Ch14 - Rear Wheel, Brake, Final Drive, Suspension.pdf

Oops, i did omit trying to move the swingarm side to side to test for any play/excess movement. The FSM is always a good "go to" for service. 🤪