B400 Fork Adjustments?

[canyonbreeze]

I put a shock from a 2006 GSX-R in my '91 B400.  The seating is a bit higher (an inch or two), the rear suspension feels much firmer and is tracking those bumps much better so I'm not feeling them.  But the front suspension feels noticeably worse now.  Probably due to change in geometry and weight loading.  It's not really bad just has a bit more 'squish' feeling and a slight wobble at high speed.  I don't want to change front ends as some do, easier to get another bike.  What tips can all you pros give for doing some adjustments to improve this using the existing parts or minor changes? 

[Unique]

Hi canyonbreeze

I put a shock from a 2006 GSX-R in my '91 B400.  The seating is a bit higher (an inch or two), the rear suspension feels much firmer and is tracking those bumps much better so I'm not feeling them.  But the front suspension feels noticeably worse now.  Probably due to change in geometry and weight loading.  It's not really bad just has a bit more 'squish' feeling and a slight wobble at high speed.  I don't want to change front ends as some do, easier to get another bike.  What tips can all you pros give for doing some adjustments to improve this using the existing parts or minor changes? 

i've changed my rear shock and got front end 'squish' too, BUT really bad... That’s why am doing 94 gsxr750 change, and as am not just putting front end straight in the b4, its taking time to do and working long hours at the moment doesn't help the b4 get back on the road, will post when finished.

you could just upgrade the front springs and oil but i hear that these who do usually change the front end or bike in the end.

just changing to a better oil and make sure the right amount of oil is in each fork.... and on my.. one of the seals were leaking a bit so lowing the oil in one of the forks.

dek

[tomacGTi]

Said this a thousand times...

The most cost-effective, simple way to get the front to match the upgraded rear are straight-rate springs, 15-20wt oil and gold valves.

Barring a full on swap, this is as simple and straightforward as it gets. I've been down the same road that all of you have with the shit damper rod front end and nothing you can do to it will make it work better than it does with the gold valves. You don't even need to pull the uppers to do the swap.

[canyonbreeze]

Any suggestions on sources, part numbers, etc, for the springs and valves?  Or other models they can be salvaged from?  Thanks for the feedback.

[tomacGTi]

Just go on racetech's website and go from there.

All the info you'll need.

[canyonbreeze]

Uff, not a big enough issue to warrant ~$300 in parts for valves and springs.  Will just use some heavier oil when I get around to a change and leave it as-is.  Thanks.

[tomacGTi]

http://forum.svrider.com/showthread.php?t=130507

An alternative.

Something to think about: the problem is in the valving of the stock forks, not the oil.

Thicker oil will mean it has less tendency to blow through the travel when braking but will pack up like hell when you hit higher frequency stuff.

It'll work, but it isn't ideal if you're looking to match up the rear.

[canyonbreeze]

The high speed wheel wobble was the part I was mainly concerned with.  That turned out to be an overinflated front tire.  (I got new tires the day before I put the shock on).  When I get a chance to change the fork oil I'll see what springs it has in it.  The bike was 20 years old when I got it so who knows? 

[canyonbreeze]

Argh, one of the fork seals just started leaking so this issue has more urgency.  It may have just been the seal time to die but it probably was hurried along by the extra front end loading caused by the stiffer rear shock.  I'd like to do some stiffening up at the same time I change the seals.  As I don't have a good place to do this myself I'll have to take it to a shop.  The ones around hear will charge way too much for anything extra.  Will changing the springs give sufficient stiffening if the valves aren't added?  Assuming the springs are stock, should I get straight rate or progressive?  I've gotten recommendations both ways.

With my tax return I may be getting a bigger bike.  There's a 2001 Bandit 1200S here in Craigslist right now that is very tempting.  My main concern with the 400 is to keep it in good shape for the next 5 years so I can pass it to my daughter.