Suspension Questions

[timdaugherty]

I have a question for all you riders out there. My '73 CB450 project is progressing quite well. It's a long-term project and nothing I'm attempting to complete any time soon. It's my commuter bike, so my attempt is to keep the projects short so I can actually ride the thing. So far, so good.

My question resides, now, within the suspension realm. I have two:

1. Front suspension related...when I ride, sometimes the front pulses a bit. Sort of hard to explain. Almost feels like I'm riding on a road that has a lot of dips. Nothing sudden, just an irritating bump bump bump sort of thing. I don't get this all the time and it's actually fairly smooth at high speeds (~70-80mph) though I wouldn't say it's speed related. Anyway, I'm suspecting the front forks need attention. They aren't doing the pogo stick sort of thing, but may not be dampening the bumps like they should be. I've not replaced the fork oil or inspected them yet...so I guess I'm looking for things to check from anyone who has experienced anything similar or can diagnose my symptoms. FYI...new rubber and balance within 50 miles so I don't suspect the actual rims.

2. Rear suspension related...I'm bottoming out just a little. The original shocks are on there still and I've not gone below the original frame with my seat pan. Looks like when I hit a bump, it rubs a little. Any suggestions on proper replacement shocks and/or is there a bump stop I need to install at some point along with replacement shocks? I know they'll need replaced...just haven't gotten to that part of the build yet.

Many thanks, as always!

Tim

 

[crazypj]

1.Have wheels balanced, you probably have a heavy spot, balancing may not have been done right?
Check steering bearings are properly adjusted.
Are wheels true?
Could need spokes tightened or they have been tightened in wrong places
2. What setting do you have shocks?
They have some adjustment for spring preload.
I generally use shocks off next heaviest bike, CB500/550 or CB750.
'Universal' shocks very rarely have even close to correct spring rate

 

[AlphaDogChoppers]

In addition to what crazypj suggested, make sure the tire bead is fully seated all around the rim. Put the front wheel in the air, spin it, and see if you can see any wobbling.

 

[Nebr_Rex]

Service your forks with a heavier fork oil.
Pulses are feedback.
I like feedback at speed so I use heavier springs different valving and lighter oil.
For shocks I use longer travel with less compression and more rebound dampning.
Rear springs are 90/130 lb. with almost no pre load.
This setup keeps the rubber on the road and only bottoms out on rough R/R tracks at speed on my KZ1000st.