Best combo for ride quality?

[KFunk740]

I've got ~9 mile commute on a fairly curvy 2-lane road (only one passing zone on whole road), and a 55mph limit. It's highly frequented by bikers on road trips because its challenging and very scenic. However, it is now very lumpy and potholed, and it won't be re-paved anytime soon.
The problem is the XS400 just doesn't feel that confident at speed on the road. It's fairly shakey (so much I can barely ever get a good solid view in the mirrors), and the bumps throw me all over. I usually run 55 to 60mph, but I still end up with cars waiting behind me much of the time (the locals often run way too fast on the road, there's never any law enforcement on it). If I went much faster, I feel like it would be too risky with the way bumps throw me around.

So, what kind of combo of fork oil/shock setting you think would help this, or any other way to improve it?
It's pretty much a bone stock '81 XS-400 SH, with 7200 miles (but beat to hell and rusty, not stored well). It has OK used stock rear shocks that I got off ebay (originals were rusted so bad I couldn't adjust them), and they're currently at the 3rd setting down from the firmest they'll go. I think I've just got the stock recommended fork oil in it. Any rubber bushings are probably not great, and original. I've got Duro tires at the stock air pressure. I've got a little windscreen that helps some. I weigh around 155 lbs.
Any room for improvement, without giving up and buying a bigger and newer bike?

 

[Wolfe_11B]

Fork swap.
Hagon shocks

 

[KFunk740]

any ideas for a good source/spec on those parts? My googling isn't helping much. I'm not that familiar with bike vendors, or the specs necessary for the xs400.

 

[Wolfe_11B]

For hagon shocks, you call them up and give them the length you want, along with rider weight, and they will set you up with the proper springs and shocks. I think they run about $200 a set for the low end model.

As for a fork upgrade, the possibilities are almost endless as long as you can fab stuff up

 

[billday]

Is your fork oil fresh?

How old are your tires? (I mean the manufacture date not how much tread do they have.)

 

[xschris]

Swing arm bushings? Neck/wheel bearings?

 

[KFunk740]

I replaced the fork oil a couple years ago, so I presume it should be OK. The inner fork tubes were rusty/pitted and leaking lots of oil, so I replaced them with a decent set from ebay, and put the proper fork oil in it. I measured spring length to be within spec.
I did whatever procedures the manual said for checking neck/wheel bearings, and all seemed OK. No idea about swing arm bushing. That's a good idea, I should look into it. Does that have a grease nipple? If so, I know I've greased it at some point before, but haven't inspected anything.
The tires are around 4 to 5 years old I think.

I'm not looking to spend much at all if possible, and just tweak cheap stuff at first. I only paid $150 for the bike, and have lots of other projects that need attention as well.
What about a set of XS650 shocks? I've found cheap ones on ebay, and my googling tells me that might be an upgrade.
Thanks for the help, guys. If I can get this thing more comfortable, I'll be riding it almost everyday for many years to come.

 

[16VGTIDave]

Tires first. They are THE most important thing on a bike. If the tires are not doing their job, everything else is irrelevant. Duro tires are crap when new, and you say yours are 4 or 5 years old. This time of year, you should be able to get a deal on new tires.

Fork oil is supposed to be changed every 8k mi. Probably time to change it again. Worn swing arm bushings/bearings can create wild handling issues. You should check them sooner rather than later.

The only thing cheap on a bike is the rider. Everything else will cost, one way or another. What would a ride in an ambulance cost you? (for me it's around $45) If you budget that amount for every day you ride and spend it on maintenance and gear, you will have money left over for gas, insurance, and beer (once you are home!), and what you don't spend can be saved for the next bike!

 

[XSLeo]

yes, new tires are always a good thing. The tire maker recommend not using tire over 6 years old. If you don't know for sure or know how to read the DOT number for the manufacturers date replace them.
Old tire are dangerous tires.
On the tire is a DOT number. The last few digits are in an oval. This digits are the week and year they were made. If there are 3 digits they were made before the year 2000. 2000 and later have 4 digits. The first two are the week, the rest are the year, on three digits as in 348 is the 34th week of 1998. On a 4 digit as in 2712 is the 27th week of 2012. Any three digit tires should be scrapped.
On the fork oil the best way I have found to set oil height is the 6 inch down method. Drain the old oil, remove the caps and springs, fully collapse the forks. pour in about 8 ounces of oil. I have a Miti Vac tool. Put a loing hose on the tool. Put a zip tie on this hose, 6 inches from the end. Now put this end down into the fork. Hold the zip tie at the top of the fork. use the tool to draw out the extra oil. Now reassemble the spring and caps.
Try different weights of oil. 10w, 15w or 20w. use what feels best to you.
On rear shocks contact MMM at 650central. He sells Progressive shocks. He will talk to you about you, your bike and riding style. He will assemble shocks with the right springs to match what you need.
Around $200 last I checked.
Steering stem bearings, stock are loose balls, these are ok if not worn out. Not hard to replace. Kits can be found for tapered roller bearings.
On the swing arm lift the rear tire off the ground, remove the wheel and unhook the shocks, try to move the swing arm left/right.
Lift the swing arm so it's straight back, release it. Does it drop quickly? I like it to hold where it is but move easily by hand.
If it moves left/right or drops then try checking the torque on the pivot bolt. If loose it will do these things.
If with the pivot bolt tight the bushings are worn. Kits are available.
With these changes it should improve the ride and handling.
On Mike's XS there is link to the "Minton Mods" These if done properly are easy to do and help the forks a lot.
I did this on my 75 XS650, replaced the springs, Adjusted the oil as recommended. Works very well.
Leo

 

[KFunk740]

OK guys, an update here. Most of these things you mentioned were in fine shape, and little tweaks to them aren't going to make the major difference that would be necessary. I decided to go the cheap and easy way, and followed the lead of someone else I saw posting on the forum (forget who).
I just got a cheap set of stock XS650 shocks on ebay, for like $20. I also bought a front sprocket from bike bandit that is one tooth larger, and I think that was in the $15 range. I just finally got around to putting them on a week ago.
For the XS650 shocks, I just had to swap the rubber bushings from my stock shocks and put them in the 650 shocks. Just a little time with the vise and some sockets, and all done. Front sprocket was easy.
I wish there was a way to swap the chrome cap/red reflector to the 650 shocks for safety, but it's not quite obvious without having to compress the springs (not sure how to safely do that with bike shocks).

Altogether, it feels much more stable at speed on my bumpy road. I was going 65 to 70mph pretty drama free this morning, with no cars waiting behind me. The bigger front sprocket didn't too noticeably decrease bottom end power. It might make it a bit less likely to lose grip when I'm taking off/turning at stop signs in slippery intersections, so that could be good. Over bumps it feels much more firm and planted.
Some prerty great upgrades for ~$40, I think. We'll see how comfortable it is in the long run.