Word from the wise - ride height and rake and trail etc on a Katana build.

[Solcambs]

So - anyone add some pearls of wisdom on what would be a good set of measurements for a Katana 1100 (750 import frame)  - I've ohlin shocks on a bandit swingarm, TL1000S front forks, 17 inch wheels obviously. I'm looking for some ballpark measurements that would give a good stable starting point. I'll assume you have a bike with a similar set up and that you've got it handling just so!

Shock length, position of swingarm shock attachment, rake, trail, sag front and rear, front fork spring weight, oil weight etc etc? Have no reference points to know how far off I am. I will do the obvious and assume I will be in the ball park, but hoping to short circuit the guessing game when the bike is up and running. 

Any help appreciated.

[Gammaboy]

Measured mine up the other night - compared to stock I'm running an 18" rear vs factory 17", 18" front vs factory 19", my swingarm is almost 1" deeper, and my shocks are near on 40mm longer, forks are dropped 1" as well - gives me 26* head angle and 98mm of trail (vs OEM 30 degrees and ~118mm) - works pretty well, no steering damper needed. 0.95 springs in the front, rear is the springs as per whatever my XJR1300SP Ohlins came with, damping set up to suit.

Someone will probably be along with something with modern forks for comparison.

Can also probably sneak some measurements to compare for you. Mate of mine has a stock framed kat, stock swinger, same XJR1300SP ohlins, stock K1/2 GSXR1000 forks that he's eeked another 5mm of effective length out of by skimming the bottom of the top triple, 17" BSTs, no steering damper, works magic.

[R1guy]

7 hours ago, Gammaboy said:

 he's eeked another 5mm of effective length out of by skimming the bottom of the top triple

I can't picture this?

[gsx]

Gsxr 11 forks and started with hagons at 335 mm , hard as fuck . Set soft enough to be usable it ran wide on corners , funnily though with them on hardest setting with missis on board was fine.

Set swingarm mounts on b12 arm same distance from frame as original.

My advice for what it's worth is to jack it up as far as you can.

Mono shocked now and running a jockey wheel to take up the slack in the chain 

 

 

[KATANAMANGLER]

I built 50mm extentions for my Kong dial- a- rides to raise the back end and pitch it so that it turned in little quicker at the front.  I fitted 17" wheels. I made 50mm slugs for the SV front forks to match the ride height of the original 19" wheel and standard forks.

I don't have any measurements but it handles well.

 

[Gammaboy]

15 hours ago, R1guy said:

I can't picture this?

There's a boss on the bottom of the GSXR triple that sits against the upper bearing nuts - he skimmed it flush with the rest of the triple.- I think he knocked a mm off of each nut too - he was chasing every possible mm without going to blade triples or fork extenders.

These things have so much friggin rake that if you've got modern triples you can really get them nose down without getting into trouble with headshakes... just use a bubble level app on yer iphone to check the steering head angle.

fer example - current stance of mine - cranked round to 26* head angle, contemplating going further.

(oh yeah, I'm running a jockey wheel on the bottom chain run as well - just tidys the chain up a bit when the bike is at rest and unloaded, and controls the flap a bit on the move - works great)

[Solcambs]

Thanks all .... I've got this ... I know I need to rebuild the TL forks anyhow so we'll stick some heavier springs in (.78kg at the mo- which is soft for the TL never mind the Kat) - probably go .95 or 1 kg? Looking at the stand elf the bike now it could definitely do with being lifted a bit front and rear. I'm thinking heavier springs and preload will sort front sag ou and lift the front a tad. The rear will just have to wait. No idea what the Ohlins are from ... but now I have the stock measurements I can see how much difference they are. 

[Gammaboy]

.95 springs work nicely for me - 90ish kg, bike is relatively light at ~205kg dry give or take.

[Solcambs]

On ‎08‎/‎03‎/‎2016 at 3:01 AM, Gammaboy said:

.95 springs work nicely for me - 90ish kg, bike is relatively light at ~205kg dry give or take.

Now there's something to do ... bike is pretty much no oil and fuel at the mo. Get scales and  weigh front, then back. I guess within a few pounds the two added together will give the bike weight. I can then get an idea for F/R ratio also. That may come in useful if I need it for spring calculations later.

[Gammaboy]

If you put the end of the bike that isn't on the scales on a block of wood the same thickness as the scales you'll get a very accurate measurement of the weight.

[Nickydodds]

1 hour ago, Gammaboy said:

If you put the end of the bike that isn't on the scales on a block of wood the same thickness as the scales you'll get a very accurate measurement of the weight.

Feel free to jump on me if I'm wrong but is that not just taking a downforce measurement at a given point?

eg. Two bikes both weigh 500lbs, one with a wheelbase of 6 feet and the other 8 feet...pretty sure the two readings would differ.

something to do with an equation involving fulcrum(wheel on block), moment(downwards force on scales), and lever(actual bike wheelbase taken as a measurement of distance between the previous two)

Nearly 40 years since school so can't remember exactly how it pans out...

[Gammaboy]

Ok, picture replacing the wooden block with another scale. The sum of the reading on the two scales is the total mass. Replace one scale with the block of wood - the remaining scale would not change. repeat with the block of wood and the scale swapped around - you get the weight of the other half of the bike.

If you leave the block of wood out, The height of the centre of mass of the bike will change the weight split  as the bike it tilted - less weight will be registered on the scale.

Depending on the type of paddock stand, weighing the front of the bike with the back supported by a paddock stand will change things significantly - if it's a shaft through a hollow rear axle stand, and the tyre is the same height off the ground as the scales, it'll be spot on. If its lifting off a set of bobbins mounted forward of the axle, it'll register less weight on the front wheel. Lifting by swingarm hooks behind the axle, and it'll put more weight on the scales (matches the effect of stuffing with swingarm lengths).

[Solcambs]

What @Gammaboy said. For the record I did it in the past with the RG570 project I previously had -I was working out F/R distribution, but the weight was only 1/2 kg out when I got it to a weight bridge some months later.