Archive for the ‘Frame – Forks’ Category

XS650: Fork Lowering   Leave a comment

Some time ago I posted ‘How to lower those Forks‘. Have always had misgivings about this method – it reduces the ammount of fork travel. OK if you dont push your bike.

It is true that our XS650s do suffer from posture. Front is a bit high/rear a bit low.

My blue rat runs an SR500 front drum brake. One of my SR500s runs with an XS650 fork.

Comparing the XS650 and SR500 upper yokes you can see marked differences. And similarities. Fork width and tube diameters are the same. Yoke height isnt. SR500 front sits lower as the yoke is flat.

unpainted SR500 upper yoke – painted XS650 one … (SR500 yoke has been a little modified-handlebar has been solid mounted and instrument cluster mounts have been removed) – apart from that the geometry matches

.

you can see that the XS650 yoke mounts higher than the SR500 – translates to the fork tubes sitting lower and the front higher

.

here you can see the same – the difference is about 27mm or so

Can definitely gain over an inch (ca 27mm) height change very easily without compromising fork travel.

Advertisements

Posted July 15, 2015 by xscafe in Frame - Forks

Tagged with , , ,

XS650: Pedestrian Slicer   Leave a comment

Don’t get confused with a ‘Cheese Cutter’. That nefarious device constructed by Road Engineers to facilitate our safety as road users.

No. I’m old enough to remember when motorcycles had front number plates. Cool things. Can’t imagine why they were removed. Probably something stupid to do with safety.

 

fine condiment … from denver, co.

 

Registration was either stamped into the plate or painted on. Some nigggly voice in my head tells me that ‘Trials’ and ‘Street’ applications required different sized font … 1.75″ and 2.5″ respectively.

Shape. Size. Colour. Material. Design. Painted. Stamped. Engraved. Embossed. Perforated. Simply style. ‘Form n Function’.

2 basic types …

  • cast … look good … watch those modern Indian and Chinese knock-offs. Poorer quality. Brittle.

 

polished or chromed cast aluminium

 

Britcycle.com

 

painted on numbers etc

 

cool oldie

 

nice

 

contrasting black

 

brass … ready for shaping

 

  • blade, flat plate  … you’re only limited by your own lack of imagination here.

 

weld-on lugs

 

BCR. Benjie’s Cafe Racer.

 

from benjis cafe racer

 

nice fttings

 

in brass too

 

fitting

 

clamps

 

blade type

 

British Customs

Domiracer

 

blade

 

Bellacorse.com

 

triumph … no drill

 

no drill … stronger, not so vibration prone

 

NewBonneville No Drill.

 

looks so

 

blade type … stamped numbers

 

… check out Tippers Vintage Plates.

 

more stamped plates

 

old japanese bicycle … mt fuji … brass  …  check out the bottle dynamo ”GE Tachometer” apparently ex Fei Ji

 

nice styling

 

steampunk’d

 

Paradox Cycles.

 

paradox cycles

 

Need to match the curve to the guard. From draggin @ triumphrat. net

 

use curve finder to get the guard profile

 

make a pattern … transfer to the slicer

 

add or remove material to fit

 

sweet

 

and to finish off … skaere

 

Hard case link.

Hunt around. Ebay. Swap meets. Junk shops. Make your own.

 

cheese cutter … dont fuck with them … NSW petition banner

Imagine looking up to see that strung across your flight-path.

XS650: Sag   Leave a comment

Your body can and will tell you all about this. In time. Some parts more than others. Size. Weight. Time. Wear. All, factors.

The harder they come the harder they’ll fall, one and all

 

Amount of change in your motorcycle’s suspension travel with the rider on board-varies around 30% of your total suspension travel. Helps you choose correct spring rates. And correct spring pre-load.

Because suspension works under both compression and dampening a certain amount of preload prevents topping or bottoming out.

First check your springs. Correct rate. Not too progressive. Fork oil. Seals. Bearings. Set your gearing. Half tank of gas. Load when touring.

Have a look at this. For help choosing springs. From here. May need separate springs for touring or carrying a passenger. Or riding conditions.

Static Sag.

Best with a couple of mates. 1 to help you hold the bike up. The other to measure.

Paul Thede from Racetech advises to allow for stiction. Friction and inertia. Both serve to complicate correct measurement but can be compensated for.

Mark 2 points front and rear. Axle centres..2. Frame..2. One each above and below the spring. Front-lower triple clamp. Rear-as close to perpendicular as possible.

  • L1. Set the bike on it’s centrestand. Or racestand not interferring with the swingarm. So both wheels are at full suspension extension.

Measure and record.

Set the bike on the ground. Sit the rider on the bike. In riding position. With full gear.

  • L2. Push down on the suspension. 25-30mm. Slowly release. Measure.
  • L3. Liftbike and rider. 25-30mm. Slowly lower to rest. Measure. Average. This is Static Sag.

Static Sag … L1- L2 + L3/2

Free Sag

Sag from bike alone. Only makes sense after Static Sag is set. Push down. Slowly release. Measure. Lift. Slowly lower. Measure. Split the difference. This is Free Sag. Used mostly setting up rear suspension.

Don’t ignore your stiction result L2-L3. This shows suspension condition. Front should be 10-20mm. Rear, 2-3mm. More or less than these? Time to start getting intimate with your bouncies.

Recommended Sag Measurements: mm …from Racetech

Road Race Street Dirt-full size Dirt-mini
Front
Sag 25-35 30-35 60-75 55-65
Preload 5-25 10-35 3-15 3-10
Stiction 5-15 5-15 10-25 10-20
Rear
Sag 25-35 30-35 90-100 80-85
Free Sag, Top-out bumper 2-8 2-8 15-40 10-25
Free Sag, negative spring 10-15 10-15
Stiction 2-5 2-5 2-5 2-5

Correct Sag numbers are personal. Will vary depending on the type of bike you ride, your individual riding style, your weight of the day, surface conditions….. This may help you get a baseline. Fine tuning is up to you.

Posted February 15, 2011 by xscafe in Frame - Forks, Frame - Handling

Tagged with , , , ,

XS650: Fork Rake Adjustor   Leave a comment

From Cheney Engineering:

 

rake adjustors…top, bottom or both

 

These give you the ability to quickly change your rake.

  • Insert one adjustor in the top of your fork head: -can position this for a +0.50 or -0.50 degrees over 30″
  • Add an adjustor in the bottom of your fork head: -gives an adjustment of ~ +1 or -1 degree over the 30″

Each Adjustor comes with Adjusting Offset, Race and Bearing.

You need to supply the diameter, thickness and length of your fork head.

Your stem probably requires machining to fit the bearing. Or buy one of theirs and press it into your bottom yoke.

They also have some nice trick stuff to adjust your offset-

  • Offsets provide the ability to make incremental adjustments to move your forks closer or away from your fork steering stem. Offsetting forks farther from the steering stem transfers more of the engine weight to the rear wheel…provides better hook-up. By modifying your offsets, you can improve your rear wheel hook-up. The trick is getting the right amount of offset for each style of track.

…and for dealing with shorter inverted forks.

XS650: Caster/Rake and Trail   1 comment

Motorcycle manouverability and stability is a product of many factors: …eg…

  • Front wheel alignment
  • Wheelbase
  • Weight distribution
  • Centre of gravity
  • Position, type and performance of the suspension
  • Size and performance of tyres
  • Riding position

2 of the most critical are Caster or Rake and Trail.

 

Caster/Rake

 

Caster/Rake:

The angle created by the vertical through the front wheel centre and the line through the centre of the steering head tube.

 

changing caster/rake

 

trail

 

Trail:

Take that vertical line through the centre of the front wheel. And follow the Caster/Rake through to the ground. This distance is the trail – how far the wheel trails the rake geometry.

Large Caster/Rake and Trail give better high speed stability-tracking-longer wheel base and poorer low speed handling. Great for straights.

Small Caster/Rake and Trail has the opposite effect. Reducing wheel base. Allowing you to carve through the corners.

In practcal terms it means you can optimise your riding by understanding where you are going to ride. 2 or 3 triple trees drilled to different Casters/Rakes allow you a certain flexibility.

Understand your frame and steering geometry. Know your suspension dynamics. And how to change them for a desired effect..

However. When we talk wheel base, it makes sense to me that not all wheel base is the same. I see 3 types:

  • before the steering head..trail
  • between the steering head and the centre of gravity..rake and stretch
  • after the centre of gravity..traction..probably be able to divide into pre and post suspension points

Easy variables:

  • Fork Length
  • Fork preload
  • Fork Spring Rate
  • Caster/Rake
  • Swingarm Length
  • Rear Shock Length
  • Rear Shock Preload
  • Rear Sock Angle
  • Rear Shock Length
  • Wheel Size and Weight Distribution
  • Tyre Characteristics

And don’t forget the Fork Brace.

It’s simple physics at low cost. And a lot of feeling.

Large return on investment.

 

XS650: Frame Dimensions

 

Early:256, 306
Mid:447, except 78-9 french
Late:specials
Rake 27° 27° 27°
Length: Steeringhead bottom to swing arm pivot 685 688.7 688.7
Swingarm pivot to upper shock mount, rear 302 311.5 300
Height Steeringhead  bottom to Swingarm pivot 434.6 409.5 409.5
Steeringhead top to frame bottom 816 811.1
Swing arm pivot to upper shock mount, rear 311 311.5 291.5
Swingarm length: To centre of adjuster
Rear-shock length: On bench, spring fitted
On bike,at rest:
On bike, with rider:
Sag: rear
Rear shock: Spring rating
Angle
Front Forks: Rake
Trail
Fork length: At rest
With rider
Sag: front
Wheel and tyre height: Front
Rear
Weight: Frame
Bike, dry
Bike, wet
Rider and gear

 

 

 

Somewhere in the back of my mind comes a voice telling me that european models after ’75 had a reduced rake, 26.5°. Trail being reduced from 115mm to 108mm. Is this correct? I don’t know.

What I do know is that frame modifications meant drastic weight gains. Ride improved.

XS650: Fork Brace   3 comments

I have a wife and kids. A home. Some toys. And my bikes. We live ok, are not well-off. Cash is always tight. Whatever I buy for my bikes is a compromise. That cash could, simply put, be used for other things.

So. Bang for my buck?

Good question.

I have an answer. It’s not a single item however.

There is a list. Needs prioritising according to your pocket and your bike.

If it’s not broken don’t fix it.

My basic list includes:

  • tapered roller steering head bearings…if needed
  • new fork oil, and seals when needed
  • swing arm roller bearings or bushes…always needed
  • rear shocks…anything is an improvement
  • check wheel bearings
  • look at the tyres
  • fork brace

Note that none of these are related to the motor. All affect handling. Directly.

I always keep my eye out for cheap fork braces. You hardly ever buy a bike with one on it.

Basic pattern is:

  • 35 x 55 x 185…’77-on
  • 35 x 55-58 x 185…’76
  • 34 x …………………….up to ’75 -i don’t have one here to measure

The later 35 x 55 x 185 version is shared with several other models. Some are:

  • SR500
  • XS750
  • XS1100
  • XJ550..80
  • XZ550S..82
  • XJ400..82
  • XZ400..82

’76 models are also found in ’80 Suzuki CM400L

The 35mm models produced that I know of are:

Daytona..japan..i have these…i like the foil shape, although i turn it around, to push down as i go forward

 

motoline … 35 x 55 x 182-185 … forged .. 500g

 

Motoline – certified for:

Yamaha XS 500 650 750 SR 500 XJ 550 XJ 650  XS 400 TR1

Kawasaki KZ650B KZ750E KZ750B Z1F KZT00A KZ550B KZ440A

Suzuki GS400 GS1000 GS850 GS450

Honda CB400T CX500 CB1 CB750F CB750G

Tarozzi…can fit the boot or gaitors over these

 

Telefix…also boot and gaitor friendly

 

AME…simple, clean

 

and the old standby .. hooped

 

Any of these will strengthen up the front. Remove the fork flex. The results are immediately noticeable. Careful, it will uncover other problems.

Where do you stop?

Posted January 19, 2011 by xscafe in Frame - Forks, Frame - Handling

Tagged with , , , ,

XS650: Clip-on   Leave a comment

I feel sick.

My younger brother and I came over to the mainland one school holidays. Xmas. 10 weeks. Stayed with my aunt. Direct on Takapuna Beach. Think we were 9 and 10. One day we smoked cigars with our older cousin. Right of passage thing. Cool. So cool I have never liked the colour green since. We were both thankful the house held 2 flush toilets.

Last night I had a green flashback. There was a distinct difference though. Green is also the colour of envy. Negative I know. Yet not. I found these on Ebay.

i’m in lust…Telefix Type 111A 35-42mm 4 piece adjustable

And I’m in lust. I’ve never seen these before. It wont happen unfortunately. She who stands in the way says NO. She likes lists. I do to. Mine. I have several. One is hers and I don’t prioritise quite how she wishes. The hot water radiator in the spare room isn’t working. Nor is the dishwasher. And the car heater bearing is complaining.

Telefix

  • Type 111A
  • 35-42 mm
  • 22mm grip
  • 4 Pieces
  • Adjustable
  • Certified by TÜV Bayern.

Fortunately it is all over. Would have made a good set-up tool.

I wish someone happiness.

Posted January 18, 2011 by xscafe in Frame - Forks

Tagged with , , ,