upside down forks on front end

i have purchased a suzuki rgv 125 to break but i gather from the regs that upside down forks are a no no! pity cos i was after the extra stiffness that my honda nsr 125 forks weren´t giving me. how strict is this rule and is it VMCC generated or bantam? don´t want an unfair advantage but rather avoiding unnecessary and expensive solutions to existing set up. any comments?

ray

Hi Ray shame but the forks are a no no as you put it? RG125 pre 89 are fine and cheap about £20-£30 on ebay. Mick potter uses nsr forks with no problem? are yours worn? Various rules were tightened up by 'us' years ago to fit in with our new home.Things like bantam back hub, normal forks, no wavy or carbon discs.... Mike

cheers mike

i think the nsr forks are adequate .. a bit of experimenting with oil capacity and maybe an extra top yoke placed below the bottom yoke may help in the way that robbie has an extra brace on his. a change of riding position i think is going to be the most significant improvement i plan to make (contemplating a monoshock rear to free up space for exhaust etc) .. got to keep myself amused because i sticking with the same engine next year!

ray

Hi Ray.
With referance to Honda NSR 125 Forks. I am saprised to read that you are having trouble with the stifness of your forks. The NSR 125 is about twice the weight of a racing Bantam. Therfore the preload on the spring is far to high. Ted & I have shortend the spacer on top of the spring & played about with air gap & oil vicosity. We now have what I belive to be a front end set up as good if not beter than any outher Bantam.
If you (or anyone else) would like a bit more information let me know.

Mick

PS If you didnt know, I cant spel for toffie.

He can't spell toffee either - Sue

Dunn matter a toss do it -- as long as ee says suffink!
Go well and keep well Mick & Sue, and all you uvver Bantam racers too,
Poetic -- ennitt!
Aye! John-Boy.

yeh could well be my imagination!

i actually had the fork stanctions (if that´s right spelling!) shortened 3 inches so i took the spacer out all together. at cadwell i had 250ml of oil .. 10 rating i think .. wanted 15 but couldn´t get any in time , in each leg. anyway the viscosity i think has minimal effect as when i took 50ml of each leg they went from being far too stiff to far too spongy. i think the reduced volume inside the legs has tightened up the parameters. anyway was happy enough with experiment with up and down susp. i was starting to wonder under heavy breaking if weaving was due to twist in the yokes etc. anyway could be something else. something i needed to investigate was the length of spring. one seemed to have dropped lower than the other when i was last tinkering with the other. have you ever heard of fork springs tiring in this way!? all speculation at the moment cos i am in spain and the bike in UK. hope to get a look at it soon.

anyway rambling now

cheers ray

Ray!
When I was at Simms we made a special rig for "scragging" scores of torsion springs at a time, which were used in our mechanically governed diesel pumps.
Each spring was subjected to 50 hours of `Scragging´ (twisting forth & back) thro´the working angle, before installation... They definitely relaxed or work-hardened ... take your pick- -- we never found out, just applied the paliative. Can´t imagine the same applies to long helical springs.
Have you taken a serious look at your steering geometry: the rake angle, trail, `Centre-Point location...´ and wheel Centre of Gravity. That is, how far ahead of the steering axis is the CofG of the front wheel ?

I experimented with many of these factors on Icarus 2 -- my second home-made Bantam -- and a fast 250 which is much too long for here...
Yet frightening experiments indeed!
Aye! JayBee.

JB

i am learning spanish at the moment. don´t know if i have got the time or energy to learn another new language!

ray

Hi Ray!
It is in English -- book with title, "Motorcycle Chassis Design -- the theory & practice," by Tony Foale & Vic Willougby. Even I could understand it! Was why I experimented -- and nearly broke my neck at Brands on a practice day.
...On the other hand -- if I were in Spain I´d probably do the same as you -- get a lovely Spanish lady to teach me Spanish by her singing to me -- whilst supping her wine!
All the best! JayBee.