80 Bobber

[jwhughes3]

Dave you got em riled now...

It is looking closer to what you envisioned in the mockup...its all yours now...

Now to swap the standard tank for a special...

Hope its running well for you.

John

[ShootersHoliday]

Notice that I specified without either a fender or fork brace, that the combo of the reduced trail (I've read fredintoon's description of the swap to standard trees with special forks enough to remember which way the hack guys go) AND no bracing of the forks as being dangerous. And the primary problem to me is the lack of any bracing. So, I spoke specifically of the COMBO of the two, and feel, fix either one and you only have a bit of a twitchy bike, rather than potential hazard, but I have PERSONALLY had the forks on mine start with the twisting because of things not being just right, and it gets scary, I could imagine it with less trail AND nothing to brace the two fork tubes together.

I'm ok with you guys thinking its ugly. But I'm wondering what your thoughts are on why its unsafe. I've ridden it pretty hard so far and she handles well.

My knowledge from the PO (and as I've said, I've been fighting gremlins since the beginning) was that it was original. I didn't care if it was or not, but there you have it.

I still have the front fender. Would you all then recommend I either put it back on or build a brace? I'll measure the forks to find the diameter as well.

It was a hack job for sure. The tank said 79 on the bottom, the seat 76 I believe. The side covers seemed to fit ok, but not sure if they were stock. They were the same color as the seats plastic. Possibly same bike.

[ShootersHoliday]

By the way, that fork/tree combo isn't safe, as it reduces your trail and makes the handling twitchy. Works fine if you're running a sidehack, but otherwise, not so good...

explain please... I figured I'd rile up the purists, but I value the wisdom from this site. So, if something that was done/is being done is unsafe, i won't keep with that method.

Keep in mind I"m in it for a great running bike, and after all of the modifications I believe I have about $700 total invested.

[ShootersHoliday]

Quote:
Originally Posted by crazy steve
By the way, that fork/tree combo isn't safe, as it reduces your trail and makes the handling twitchy. Works fine if you're running a sidehack, but otherwise, not so good...

explain please... I figured I'd rile up the purists, but I value the wisdom from this site. So, if something that was done/is being done is unsafe, i won't keep with that method.

I admit I have no idea what you all are talking about when you mention the "trail" of the combo. I know vehicle suspension, but this is my first dive into motorcycles.

Also, this "bobber" isn't permanently like this either. I built the hardtail so that I could swap back if I ever have the need/desire.

[BA80]

Do you understand alignment angles on a car? The "trail" on a motorcycle is the equivelent of the caster on a car.

It affects the ability and nimbleness of the steering. Bot he standard and the special have approximately the same "caster" in the front wheel but the wheel is mounted in a different location on thier respective fork configurations.

The difference is made up in the the angle the steering head is mounted on the respective frames.

If you put special forks on a standard frame it makes the caster more positive and will make the bike want to hold a straight line more readily but will make the steering more heavy to the touch and harder to corner quickly.

Vise versa with putting the standard forks on a special. It will make it too EASY to turn and "twichy". Unstable.

[ShootersHoliday]

Do you understand alignment angles on a car? The "trail" on a motorcycle is the equivelent of the caster on a car.

It affects the ability and nimbleness of the steering. Bot he standard and the special have approximately the same "caster" in the front wheel but the wheel is mounted in a different location on thier respective fork configurations.

The difference is made up in the the angle the steering head is mounted on the respective frames.

If you put special forks on a standard frame it makes the caster more positive and will make the bike want to hold a straight line more readily but will make the steering more heavy to the touch and harder to corner quickly.

Vise versa with putting the standard forks on a special. It will make it too EASY to turn and "twichy". Unstable.

Yah, I am quite familiar with caster. We extended the frontend of my Dodge and had to align the caster to keep it from hopping around. I've worked specifically on suspension on cars & trucks for many years.

Granted, I've not been on a stock XS, but it feels pretty nimble moving around. Pretty easy to maneuver. My brother is an engineer, we'll throw together some measurements and angles for ya'll.

Also, as it appears I have a frankensten (so the name Frank is perfect... ) , how do I decipher if it is truly a special or a standard?

[crazy steve]

explain please... I figured I'd rile up the purists, but I value the wisdom from this site. So, if something that was done/is being done is unsafe, i won't keep with that method..

To fully explain rake/trail geometry and the reasoning behind it would be a full book chapter, so here's the short version...

Each manufacturer decides what suspension geometry to have on a given bike. Factors taken into consideration are spring rates, shock damping, center of gravity, and overall bike weight among others. They're looking for the 'best balance' in handling, ease of riding, and safety; there's always tradeoffs involved. The 'type' of bike it is makes a difference too. But generally speaking, you'll see trail numbers of between 4" and 6" as the norm, with numbers under 5" usually being confined to sportbikes with their lighter weight and better suspensions. Larger, heavier bikes will run numbers in the 5 to 6 range. There are exceptions to this (you'll see pro-built choppers with lower trail numbers, but these have frames that are stretched in the downtubes/backbone), but these are general rules.

The effects of trail are these; less trail will give lighter steering effort, faster steering, but the bike will be prone to 'head shake' (violent oscillation of the bars back-and-forth) if 'upset', also known as a 'tank slapper'. The really bad part of this is the bike probably won't give any warning before it happens. The bike will also be less stable 'at speed' (needing more attention to keep it going straight). Many sportbikes with low trail numbers are fitted with steering dampers to help with this.

Too much trail has the opposite effect; heavy, slow steering, and the bike wants to go straight, resisting fast manuevering. No chance of a tank slapper.

As an anology, the effects are somewhat similar to oversteering/understeering in a car; the best 'balance' is neutral steering, but if you miss that, understeering (too much trail) is more easily controlled.

What makes this particularly bad on a XS is with the stock suspension geometry, they're prone to head shake already if you push the bike. Fork braces can help with this, but with your non-stock combo you may not be able to find anything to fit. You've got two strikes against you; you've reduced the trail with the fork/tree combo, plus by hardtailing the bike you've put added stress on the front suspension. Not at all good. The easy fix? Swap the 'standard' triple trees you have for 'Special' trees, you'll at least remove one strike. I'll also point out that those smaller-than-stock front brakes are another bad thing; the OEM brakes are only 'adequate' for a bike of this power/speed capabilities, you may find you have way more 'go' than 'whoa' with those smaller brakes.

I'm not trying to bust your chops, but if you end up as a greasy smear it won't be because you weren't warned....

For a rake/trail calculator which might help explain it better, look here: http://www.rbracing-rsr.com/rakeandtrail.html

As to 'what' bike you have, check your frame number against this: http://www.xs11.com/faqs/153-serial-...ry-colors.html. The frame controls pretty much what you can swap around.

[BA80]

how do I decipher if it is truly a special or a standard?

http://www.xs11.com/forum/showthread.php?t=396 or

http://xs11.46.forumer.com/viewtopic.php?f=9&t=127

[ShootersHoliday]

To fully explain rake/trail geometry and the reasoning behind it would be a full book chapter, so here's the short version...

Each manufacturer decides what suspension geometry to have on a given bike. Factors taken into consideration are spring rates, shock damping, center of gravity, and overall bike weight among others. They're looking for the 'best balance' in handling, ease of riding, and safety; there's always tradeoffs involved. The 'type' of bike it is makes a difference too. But generally speaking, you'll see trail numbers of between 4" and 6" as the norm, with numbers under 5" usually being confined to sportbikes with their lighter weight and better suspensions. Larger, heavier bikes will run numbers in the 5 to 6 range. There are exceptions to this (you'll see pro-built choppers with lower trail numbers, but these have frames that are stretched in the downtubes/backbone), but these are general rules.

The effects of trail are these; less trail will give lighter steering effort, faster steering, but the bike will be prone to 'head shake' (violent oscillation of the bars back-and-forth) if 'upset', also known as a 'tank slapper'. The really bad part of this is the bike probably won't give any warning before it happens. The bike will also be less stable 'at speed' (needing more attention to keep it going straight). Many sportbikes with low trail numbers are fitted with steering dampers to help with this.

Too much trail has the opposite effect; heavy, slow steering, and the bike wants to go straight, resisting fast manuevering. No chance of a tank slapper.

As an anology, the effects are somewhat similar to oversteering/understeering in a car; the best 'balance' is neutral steering, but if you miss that, understeering (too much trail) is more easily controlled.

What makes this particularly bad on a XS is with the stock suspension geometry, they're prone to head shake already if you push the bike. Fork braces can help with this, but with your non-stock combo you may not be able to find anything to fit. You've got two strikes against you; you've reduced the trail with the fork/tree combo, plus by hardtailing the bike you've put added stress on the front suspension. Not at all good. The easy fix? Swap the 'standard' triple trees you have for 'Special' trees, you'll at least remove one strike. I'll also point out that those smaller-than-stock front brakes are another bad thing; the OEM brakes are only 'adequate' for a bike of this power/speed capabilities, you may find you have way more 'go' than 'whoa' with those smaller brakes.

I'm not trying to bust your chops, but if you end up as a greasy smear it won't be because you weren't warned....

For a rake/trail calculator which might help explain it better, look here: http://www.rbracing-rsr.com/rakeandtrail.html

As to 'what' bike you have, check your frame number against this: http://www.xs11.com/faqs/153-serial-...ry-colors.html. The frame controls pretty much what you can swap around.

I don't think you're busting my chops at all. I appreciate the advice and knowledge. This bike was apparently quite the frankenstein before I got it, so I had no way of knowing that.

It was a one owner, and perhaps he did things without thinking. That is exactly opposite of what I intend to do. If its wrong or unsafe, I'm not going to keep it that way. I don't want to kill myself or anyone else if something is not correct.

As for the tank slapper syndrome, nothing yet, but I'm very familiar with death wobble on linked suspensions, so there is no way I'm gonna mess with it on a bike.

The brakes seem to stop ok, but then again, I don't drive the bike fast either. It was really just to putz around. But, I'll see about getting bigger brakes (safety is always a good excuse to modify)

I will build a fork brace for it if I can't find anything. Welding/building isn't a problem, just needed to know what to do!

Any suggestions on where/what to get bigger brakes from? What would I need for the swap?

[BA80]

To put the correct/larger brake rotors you'll need to change the forks because the calipers will mount further up on the lower.

Have you looked up the VIN to see if it's a standard or special yet?

[crazy steve]

...Any suggestions on where/what to get bigger brakes from? What would I need for the swap?

You've got several options; the easiest one would be to just get a complete XS 'standard' fork set-up (including the front wheel) and install that in place of the swapped-on one you have now. This would correct the trail issue as well as bringing bigger brakes. Second option would be replace the triple trees with 'standard' trees, then look at a brake caliper swap. This may prove to be rather complicated, as there isn't any 'bolt-on' solutions that I'm aware of. The fork design you have will allow a caliper swap with a fabricated bracket, but you'll have to see if the front wheel will accept a larger rotor. Here's one swap to give you ideas.... http://www.xs11.com/forum/showthread.php?t=27820. This would need a redesign to fit what you have, but would be similar...

Another option is a swap to a completely different set of forks/trees; here's this one: http://www.xs11.com/forum/showthread...ight=fork+swap. BikerPhil came up with this one, and of interest to you would be the fact that this can lower the front of the bike about 1.5" if you go with Phil's method of installation. One thing nice about this one is if you get tired of that hardtail and convert back, this offers better handling over any of the stock forks.

Your biggest problem will be figuring out just what parts were used on yours; you've got (as far as I can tell) stock trees, Virago forks/brakes, and I'm not sure what the front wheel is off of; it may be a virago piece, but could also be a XJ650/750 too.

Anyway, good luck...

[cywelchjr]

I wonder how those virago brakes work as far as capacity compared to stock? I know the disks are smaller, but what is the pad size? There are several ways to increase braking power, one of them is a bigger disk, but dual or 4 pot calipers also do that, and larger pads also do that.

[crazy steve]

Cy, you're right as to pad size; that has more to do with how well the brakes work as anything else. But the disadvantage to smaller rotors is they 'heat soak' quicker, so if you're really using the brakes they'll heat up faster and cool slower. Bigger rotors per se won't help braking performance until you start seeing some heat....

[ShootersHoliday]

To put the correct/larger brake rotors you'll need to change the forks because the calipers will mount further up on the lower.

Have you looked up the VIN to see if it's a standard or special yet?

Yes, it is a standard I guess... My vin starts with the 3H5...

1980 XS1100G 3H5-000101 Diamond Silver, New Ruby Red

[ShootersHoliday]

You've got several options; the easiest one would be to just get a complete XS 'standard' fork set-up (including the front wheel) and install that in place of the swapped-on one you have now. This would correct the trail issue as well as bringing bigger brakes. Second option would be replace the triple trees with 'standard' trees, then look at a brake caliper swap. This may prove to be rather complicated, as there isn't any 'bolt-on' solutions that I'm aware of. The fork design you have will allow a caliper swap with a fabricated bracket, but you'll have to see if the front wheel will accept a larger rotor. Here's one swap to give you ideas.... http://www.xs11.com/forum/showthread.php?t=27820. This would need a redesign to fit what you have, but would be similar...

Another option is a swap to a completely different set of forks/trees; here's this one: http://www.xs11.com/forum/showthread...ight=fork+swap. BikerPhil came up with this one, and of interest to you would be the fact that this can lower the front of the bike about 1.5" if you go with Phil's method of installation. One thing nice about this one is if you get tired of that hardtail and convert back, this offers better handling over any of the stock forks.

Your biggest problem will be figuring out just what parts were used on yours; you've got (as far as I can tell) stock trees, Virago forks/brakes, and I'm not sure what the front wheel is off of; it may be a virago piece, but could also be a XJ650/750 too.

Anyway, good luck...

thanks for the links. looks like I've got some reading ahead of me... Regardless of it, the wheel will get replaced ASAP. I hate the fact that it doesn't match, and want laced wheels front and rear anyways.

But, bigger brakes/ better stopping is priority number two after making sure its safe. So I'll keep ya'll posted on that journey...

I wonder how those virago brakes work as far as capacity compared to stock? I know the disks are smaller, but what is the pad size? There are several ways to increase braking power, one of them is a bigger disk, but dual or 4 pot calipers also do that, and larger pads also do that.

Cy, you're right as to pad size; that has more to do with how well the brakes work as anything else. But the disadvantage to smaller rotors is they 'heat soak' quicker, so if you're really using the brakes they'll heat up faster and cool slower. Bigger rotors per se won't help braking performance until you start seeing some heat....

As both have said, bigger disks don't do me any good if the pads and calipers aren't up to snuff. This thing stops ok, but for the weight of it, feels it could definitely stop quicker. I like the look and cooling advantage of big rotors, but may be limited as I plan to go down to a 16" wheel at some point.

I'll take very detailed measurements when I get home tonight, and pictures of the trees/forks to see if this puzzle can be identified. Any spots in particular to take pictures of for those who could identify the parts?