Katana 1100 with bandit 1200 front and back ends

[katanamak]

Looking for ideas/opinions.
i have fitted bandit rear adapted with twin koni shocks spaced etc as required and complete front end. I originally used fork extenders of 110 mm (including internal damper extensions etc). All functions well but dislike the look of the front end as sits too high. Dropping forks in yokes results in too much poking thro ,I intend to get machined once correct length established. The trouble is the bike is very stable in a straight line but tends o dive into any sort of corner if leaned at all. Feels uncomfortable with the extensions but when removed feels downright dangerous and have to inch round corners. I know this is to do with rake,trail etc but any  advice is welcome before I start buggering around again. Here are some measurements:
 original katana: forks 81cm, yoke offset 5cm, front tyre radius 33cm, rear tyre radius 33cm
bandit 1200 as fitted without extensions: forks 77cm, yoke offset 3cm, front tyre radius 29cm, rear tyre radius 31cm
the rake angle of katana is 28*50"
the ride height seems similar to before.
thanks
mark

[busaash]

you may be better of with a stepped top yoke as this has been done before , some one will post a picture I am sure as lots of katana owners on here

[katanamak]

Thanks for the quick reply.
I had thought of this, but wish to retain clipons as I do not like the look of straight bars and these make the bars way too low. Anyway this would make no difference to the problem I am encountering as I would still be replicating the same set up I have now with respect to trail angle etc. If anyone has used a Bandit 1200 front and rear it would be good to hear what length extension (or step down on the yoke)they used, to make up for the change in dimensions. I suspect by using the standard fat back tire from the bandit that the bike would hesitiate to corner on the back whilst wanting to speed up on the front with the smaller diameter wheel. When measured the Katana tyre diameter was actually even front to back even with the 19 front wheel.It is now different. I convetred the bike a number of years ago MOT,d it and rode for a year or so with the extensions and a slightly "tippy feel" . I have recently resurected it ,removing the extensions and either I am more nervous as older or the bike feels unrideable. Others must have come across a similar problem surely or am I being a wuss.

[katanamak]

Really confused after looking at RB Racing "trail Calculator". Converted everything to inches and I get an increase in trail compared to the original Kat one which should give more stability and slow down cornering not make it more tippy.Comes out at around 4.9"

[neilw]

gsxr1100k forks fit the bandit yokes and are shorter.

On my kat I run a gsxr110k front end, jmc swinging arm with 365mm rear shocks, 5.5 rear gsx wheel and 170/60 tyre and i've tried it with the gsxr1100k 17 " front wheel and 120 tyre but was never happy with the handling as it can best be described as being floppy.

I ended up using a matching 18" three spoke gsxr1100j front wheel and 110/80 radial tyre on the front and the handling is totally neutral .

[pedda]

Got a B12 running gear in this Kat:






No fork extensions though. I always felt absolutely comfy on it, last year I noticed something similar what you describes, falling into turns something like that, traced it down to the headstock bearing being a wee bit loose. Tightened it again - all fine.

In addition I'd check oil measurements in the stanchions as well as all the other relevant bearings like swingarm and wheels.

Should be fine by then.

[katanamak]

Thanks or the above replies. It does look like Neil had come across the same problem.
I have just spent out on powder coating the bandit wheels and replacing tyres as we're 9 years, all in all £300+ so don't really want to change wheel size. I do wonder if a narrower rear tyre may help ( which would be a relatively cheap option) as 180 now.
All the levels are correct, Hagon progressive springs, bearings are all new and everything torqued up to spec.
Still looking for anyone else who has dealt with the same
Ta
Mark

[pedda]

I would not bother 'bout the rear tyre. You'd be the first to have trouble with that.

What tyres are you using? At what pressure? Pumped up too stiff can also cause funny experiences...

[katanamak]

Pilot road 34 psi front and rear

[pedda]

Not too bad, me thinks. I'm using 36 psi rear. Not a big difference.

Did you give your bike to someone with a good arse-o-meter for a testride?

[katanamak]

Bit of a dilemma test riding - no mot,tax,insurance yet so any ride involves complete assembly each time as easily spotted if minus fairing etc so a right pain in the arse adjusting for each run . to get mot et al needs to be sorted/stable so a bit chicken and egg situation. Be great if anyone is near me in Cambridge and could pop round for a looksee

[dodgygs750]

Easiest solution fit an 18" wheel should solve it I experimented now don't laugh too much with a 16" wheel , 17" wheel and a 21" wheel on a harley night train a few years ago after fitting longer forks and increasing rake by 6 degrees, the 21" didn't want to turn in ,the 16" was great for cornering thing just fell on its side with slightest movement and the 17" was totally neutral even if you could scrounge an 18" wheel from someone just to give it a try.

[katanamak]

I find it difficult to understand when so many people have done These conversions that only the above have had any issues with changing wheels and forks on gsx's
I don't really want to change my wheels and really do appreciate the guys above trying to give me ideas, but surely someone has done virtually the same transplant and can give me some idea to base a starting point on regarding fork length or step down on yokes they used.
I am still trying to register on the acs site as devised but have yet to be approved by the admin.
Thanks
Mark

[coombehouse]

Just a thought but have you considered the wheelbase of the bike. I have tried 19, 18, 17 & 16 inch wheels over the years with varying results. I have run 17 inch front & rear since about 1992. It does seem that changing where the rear wheel sits combined with the ride height makes a big difference to how the bike steers. Pulling the rear wheel forwards to shorten the bike improves that feeling of being too stable & then falling off the edge of the tyre when you turn. Raising the rear ride height can also improve things too & make the bike feel more normal whilst also reducing trail & head angle. 36f & r tyre pressures always work for me on most bikes these days.
Nick

[katanamak]

Thanks for reply. The actual measured trail is now 125mm which is an increase of 7mm over the original kat. This is due to the reduction of offset to 35mm with the bandit yokes.
This is what has got me really confused as I should have actually slowed down the steering. Tried f or an answer on acs as well and am still surprised no one has done the same swap and dealt with similar probs. stripping down again currently and welcome any more suggestions/thoughts.