glennpm
Another Old Biker Nut!
thanks guys!
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Zombie thread revival! Are the kids in bed? We need to talk. I like to ride the backroads, county and township roads where the curves are frequent enough that 60-65 in the straights is usually for short periods. it's farm, deer country (I) can't get too crazy on the street, but.
I think I'm at a crossroads. I have been working hard "upgrading" the resto-mod. And I think I hit a roadblock.
View attachment 64288
This still has a stock engine with a bit better air filters in the stock housings, commando type mufflers on stock headers, jetted well, Pamco ignition, running super. Typical maintenance-upgrades are done; tapered, bronze, a mikes front rotor MMM vesrah pads 10mm MC, ss line Mikes cart emulators, just in, sportster springs. some decent progressive shocks/springs on the back The biggest change this year is 3x18 rims front and rear with 110/80/18 PP3 tires. Wow the thing is now capable of cornering beyond what is sane (for me) on the street. Yes I could use a stiffer fork brace yet, and it's in the works, for now I may swipe a fork brace living on madness. and there is a reinforced fender getting ready to go on. I have "upgrade" stiffer swing arms that could go on. The front tire has moved me beyond what I think can get out of one rotor/ caliper. That tire is well capable of handling "stoppie level" braking without skidding. I am deciding on what fork brake combo will get me there, but...
While running "too hard" with some sport bikes I got into some fairly good head shakes at the brake/turn transition. I was able to damp them and then separated the braking from the turn in just a bit more, to keep them at bay. But now have been doing some studies of what that shake is. I think I have it narrowed down. While at speed if I really force the bars back and forth I can see the top of the frame steering head flexing side to side. I did this repeatedly over several days, thought at first it may have been an optical illusion since the forks/trees are moving in that area, but I put fingers on the gas tank and frame at the gap and can actually feel the flex as the top of the frame goes left right. Don't think too hard about me at speed, one hand on the bars forcing them rapidly back and forth, the other down in the frame tank junction while I'm looking in there and not at the road... So I guess that's the place I'm at, I think it may be time to take the resto mod back one step, put the 2.15 19 front 2.5 18 back rims with pilot active tires on it and call it done. And start in a on a different XS with the aim of street racerish power and handling while keeping a generally "ancient" look. My snarky goal is an old poop's; shame the "kids on sport bikes that don't know much" ride. I just love watching some whipper snapper say WTF how can he do that? The big question is going to be the frame. I think top of the head bracing will be in order and have just a couple ideas to explore, shy of a ground up frame build!!! This is dumb, I admit it, I can go buy better performance for 3K and just go riding but where's the fun in that? Any one else see what I 'm seeing or have I been drinking the kool/aid a bit much?
I think I'm at a crossroads. I have been working hard "upgrading" the resto-mod. And I think I hit a roadblock.
View attachment 64288
This still has a stock engine with a bit better air filters in the stock housings, commando type mufflers on stock headers, jetted well, Pamco ignition, running super. Typical maintenance-upgrades are done; tapered, bronze, a mikes front rotor MMM vesrah pads 10mm MC, ss line Mikes cart emulators, just in, sportster springs. some decent progressive shocks/springs on the back The biggest change this year is 3x18 rims front and rear with 110/80/18 PP3 tires. Wow the thing is now capable of cornering beyond what is sane (for me) on the street. Yes I could use a stiffer fork brace yet, and it's in the works, for now I may swipe a fork brace living on madness. and there is a reinforced fender getting ready to go on. I have "upgrade" stiffer swing arms that could go on. The front tire has moved me beyond what I think can get out of one rotor/ caliper. That tire is well capable of handling "stoppie level" braking without skidding. I am deciding on what fork brake combo will get me there, but...
While running "too hard" with some sport bikes I got into some fairly good head shakes at the brake/turn transition. I was able to damp them and then separated the braking from the turn in just a bit more, to keep them at bay. But now have been doing some studies of what that shake is. I think I have it narrowed down. While at speed if I really force the bars back and forth I can see the top of the frame steering head flexing side to side. I did this repeatedly over several days, thought at first it may have been an optical illusion since the forks/trees are moving in that area, but I put fingers on the gas tank and frame at the gap and can actually feel the flex as the top of the frame goes left right. Don't think too hard about me at speed, one hand on the bars forcing them rapidly back and forth, the other down in the frame tank junction while I'm looking in there and not at the road... So I guess that's the place I'm at, I think it may be time to take the resto mod back one step, put the 2.15 19 front 2.5 18 back rims with pilot active tires on it and call it done. And start in a on a different XS with the aim of street racerish power and handling while keeping a generally "ancient" look. My snarky goal is an old poop's; shame the "kids on sport bikes that don't know much" ride. I just love watching some whipper snapper say WTF how can he do that? The big question is going to be the frame. I think top of the head bracing will be in order and have just a couple ideas to explore, shy of a ground up frame build!!! This is dumb, I admit it, I can go buy better performance for 3K and just go riding but where's the fun in that? Any one else see what I 'm seeing or have I been drinking the kool/aid a bit much?
Gary,
Tell us about the Sportster springs. Are they progressive wound? If so, I have never met anyone who has had success tuning emulators with progressive springs. I have known several who tried it and said emulators aren't worth the trouble. If that's the case, it's a good place to start. Get someone from RaceTech or Traxxion Dynamics on the horn. Custom straight rate springs should set you back $100. I think TKAT can make you a fork brace low on unsprung weight.
tkat.com
I have an XS1100 set up with this stuff and the front end works great, even with the 20 lbs of brakes on it! Yours should be way better.
Let's stick Growl's "frame stiffening mod" in here:
http://www.xs650.com/forum/showthread.php?p=436850#post436850
http://www.xs650.com/forum/showthread.php?p=436850#post436850
JM I have a brace similar to that I just have to move over to the restomod.
The sporty springs ARE straight wound, the wire is a bit thicker, and they are 3/4" longer. I did some weight vs. compression testing against a stock spring and came up with 13% stiffer. I could prolly put a bit more preload on them. thinking about adding threaded preload adjusters to a pair of 77 caps. It's such a pain to the change the spring preload in the cart emulator that I haven't messed with it yet. Got some ideas there too. I found a set of handlebar clamps with a bit of offset, so I don't have to keep removing the bars to pull the caps... that's up next.
2M You burned my eyes damn it! I can be crude but.... and they stop short of the neck area...... Seems to work for Growl though.
The sporty springs ARE straight wound, the wire is a bit thicker, and they are 3/4" longer. I did some weight vs. compression testing against a stock spring and came up with 13% stiffer. I could prolly put a bit more preload on them. thinking about adding threaded preload adjusters to a pair of 77 caps. It's such a pain to the change the spring preload in the cart emulator that I haven't messed with it yet. Got some ideas there too. I found a set of handlebar clamps with a bit of offset, so I don't have to keep removing the bars to pull the caps... that's up next.
2M You burned my eyes damn it! I can be crude but.... and they stop short of the neck area...... Seems to work for Growl though.
Haha, pretty serious application of angle iron.
This is one of those situations where I'd advocate building a frame cage, clamp everything down tight, and do strain analysis (deflection vs force), to find the weak spots, and to quantitize any mods...
Dwayne Burge's solution to flex in the swingarm pivot region on his full-race machines (the only flex prone area that would be significantly stiffened by all that angle iron) was adding a single piece of bar stock across the top of the pivot area, behind the engine. Gary, re. steering head flex, you might think about welding in a brace across the front downtubes; that's the most flex prone area of the assembly. And congrats on the results so far! If you have that scoot holding the line while you pitch it over that hard, you've done a whole lot of righteous work on the suspension!
eman13261
XS650 Enthusiast
Didn't read over every post so I might be repeating some stuff but start off simple.
1) Replace fork oil-just did mine today and it was black. Replaced with 7oz of 10w30 oil and wow is there a huge difference
2) Tires-nothing can replace a good set of tires. If you update your suspension/frame for handling you will out-ride your tires if they are old. Its simple but make sure they are also filled up properly
3) Bronze swing arm bushings and new gaskets
On a similar note make sure the swing arm is well greased
4) Fork brace-some front fenders also act as fork braces
5) Take some riding lessons. You can't get your bike to perform at its peak if you cannot
Once the simple stuff has been maintained then start replacing shock absorbers and fork springs
1) Replace fork oil-just did mine today and it was black. Replaced with 7oz of 10w30 oil and wow is there a huge difference
2) Tires-nothing can replace a good set of tires. If you update your suspension/frame for handling you will out-ride your tires if they are old. Its simple but make sure they are also filled up properly
3) Bronze swing arm bushings and new gaskets
On a similar note make sure the swing arm is well greased
4) Fork brace-some front fenders also act as fork braces
5) Take some riding lessons. You can't get your bike to perform at its peak if you cannot
Once the simple stuff has been maintained then start replacing shock absorbers and fork springs
"The front tire has moved me beyond what I think can get out of one rotor/ caliper." Maybe so for the stock front caliper, but consider a 4-pot Brembo and 1/2" bore m/c before going the twin-rotor route.
DrewMartin
Old fashioned new guy
I actually plan to in the not too distant future model the stock frame in solidworks in order to be able to do FEA strain analysis in pursuit of performance. I'm sure it'll be some interesting results and there's no doubt going to be plenty of discussion around my results on here.
This actually isn't the first time I've heard of sportster springs in our bikes. Straight wound springs and cartridges are where I believe serious performance lies. MMM's racing tales on 650 central dive a bit into this, I wish I had more information on it...
"I still have a 70 lb. rear weight bias (laden), and this won't work the front tire hard enough to get to an optimum, grippy temperature, even with 25 lbs air pressure. The rear tire temps, however, continue to climb, in spite of 41 psi. The 2" + swing arm should make it come right in, and allow me to use the 44 lb. straight-wound front springs, and get rid of the Progressive 35/50s. As rigid as the chassis is now, and with balance, I think I'll be ready to "Banzai!" Turn 9 more consistently and comfortably."
*sigh* I need to build a fork dyno...
There's also been a lot of swingarm swaps and mods, but no quantitative comparisons of torsional rigidity...
DrewMartin
Old fashioned new guy
I'll make sure to include stock, braced stock, tx750 and radian swingarms in my tests. In addition to basic strain I'll try post a bit on the resonance of the frame/swingarm combo. I'm still learning quite a bit on that but I'm willing to bet a few key placed braces can tune the oscillations of head shake out without adding lbs to the bike.
Can anyone confirm that the XS1/1b/2 frames are the same as the standards? I have a special frame to reference dimensions from and blueprints of both. If I'm confident in the specials' blueprints I'll go ahead and do the standard as well.
The early frames also had a shorter headtube, 2-piece front motor mount, a slightly different bottom mount, and narrower seat rails. The bottom/rear motor mount went thru some subtle strengthening iterations.
DrewMartin
Old fashioned new guy
Thanks gentlemen. I'll get to work and post my results here when they're ready. I only have a special frame at my disposal so I'll have to make the assumption that all 3 share the same wall thicknesses in the same sections.
DrewMartin
Old fashioned new guy
So it turns out I did have some blueprints for the early frames as well. I may still need a couple measurements from someone here but that link you provided 2M should fill in the gaps.
pcombe, you say you run 30 psi both front and rear? I don't think that's right. The 30 in the rear sound ok but the 30 in front seems a bit much.
On my Harley I run 30 in the front and 35 rear. Works well but it weighs 762 lbs. On my xs650's I run 28 rear and 23 front.
To find this pressure set your tires to what ever you feel is right then ride it for at least 15 minutes to warm the tires well. Don't just poke along but ride it hard at highway speeds.
Then stop and check hot tire pressures. they should be about 10% more than cold.
If they don't come up that much your cold pressure is too high. If it comes up too much your cold pressure is too low.
Leo
On my Harley I run 30 in the front and 35 rear. Works well but it weighs 762 lbs. On my xs650's I run 28 rear and 23 front.
To find this pressure set your tires to what ever you feel is right then ride it for at least 15 minutes to warm the tires well. Don't just poke along but ride it hard at highway speeds.
Then stop and check hot tire pressures. they should be about 10% more than cold.
If they don't come up that much your cold pressure is too high. If it comes up too much your cold pressure is too low.
Leo
DrewMartin
Old fashioned new guy
Minor update on the CAD/analysis for any interested parties. I've unfortunately been stupid busy with work and missed my personal deadline for this. In addition to this I just got a promotion and am moving back across the country. Hopefully I'll have a chance to get this finished up by the end of August. I'll be starting up a new thread once this is complete with my results.
"end of August. I'll be starting up a new thread once this is complete with my results."
please post up a link to that thread here....
"The front tire has moved me beyond what I think can get out of one rotor/ caliper." Maybe so for the stock front caliper, but consider a 4-pot Brembo and 1/2" bore m/c before going the twin-rotor route.
Still the stock caliper, but a 10 mm MC, IMHO torquing those long thin fork tubes with one brake is part of the issue.
please post up a link to that thread here....
"The front tire has moved me beyond what I think can get out of one rotor/ caliper." Maybe so for the stock front caliper, but consider a 4-pot Brembo and 1/2" bore m/c before going the twin-rotor route.
Still the stock caliper, but a 10 mm MC, IMHO torquing those long thin fork tubes with one brake is part of the issue.
