85 slabby k3 front end speed wobble, help!

[cams666]

http://www.streetfighters.com.au/forum/upload/998670064130262.JPG

gudday, iam a new lad to this forum, [& find it a bit hard to navergate]so please bare with me, never the less i need some help with me bike. ive got an 85 slabby, 1127 donk, k3 750 front end, 04r1 shock in the rear plus the usual fighter trimmings [see pic]. problem is this setup has a nasty speed wobble from 160 ks up. i just wanted to know if any one else had this setup or had the same problem & had managed to fix it. any commets would be welcome. cheers cams666.

[alfiestorm]

Are the tyre pressures ok and the steering damper working
are the swing arm bearings and rear supension and linkages ok
are the wheel bearings ok
are the steering head bearings ok
is the front suspension ok smooth operation
Is the wheel alignment ok

Oh and welcome aboard

[WATEVR]

as above and the only other one might be wheels correctly balanced.

welcome to the madness

[MDM]

Weave or wobble?
Or tankslapper?
On power or steady throttle?
Road conditions?
Gripping bars or light touch?
Tough man or scaredy cat?

[Stocky]

Get yourself 2 bathroom scales.

Put 1 under each wheel and tell us what it reads.

Then get on it and get someone to read them with you in a semi normal riding position.

Post back the results please.

[Booster]

Welcome
All of the above and can you post a pic from side on so we can see the rear height and headstem angles.

[cams666]

http://www.streetfighters.com.au/forum/upload/13410372571916.jpg


thanks for the replys, i wil answer your questions as best i can.
all wheel, steering, swinger bearings are in good nick,wheels are in line, tyre pressures are @ 38 psi front & rear[ this seems to prduce the lest amount of trouble.]
its a wobble that moves to a tank slap as speed increases[ i asume death would be acieved @ 200+ ks.] this happens in any conditions regardless of grip to the bars[ altough a tighter grip @ higher speeds seems a good idea].i wouldnt call myself a tough man but iam not a fucking poof either.
i will try the bath scales & get back to you.
some more info on the problem. k3 forks are 25mm shorter than the slabby jobs, i also have a friend who has a 7/11 [ not fightered ] which had a;; the same mods as mine exept for the fork & it was rock solid. he then fitted k41000 forks & develope to same problem only not as bad. we think the loss of fork lenght [& hense steeper steering angle] maybe the culprit. but any other thoughts, comments would be very welcome. thanks cams666.

p.s. i have a nother frame iam putting a k3 750 rearend in to hopfully help the problem.

[Deano]

if the forks are 25mm shorter then try dropping them through the top triple instead of having them flush with the top edge.

you wont get your 25mm back and i wouldn't recommend going to far through but if the speed wobble isn't as bad you could be onto something.

then it would be a matter of getting some for extensions for those forks.

the later model gixxers ran with a 32mm stem/fork offset where as the earlier (unsure about slabby) ran a 35mm offset.

that been the case with the steeper headstem and less offset this could be something to think about.

i put a k4 750 on my 7/11w it had the different offset but the forks were the exact same length as the ones removed had no issues what so ever solid as a rock at all speeds. since putting the new front end on i have raised the rear end about 10mm so that would have steepened up the head stem angle to.

just had a thourght. Are your forks in line?

best way to check is to get a 6 or 8mm piece of glass that is wider than the forks and lay it against the chromed legs resting on the stauntions. if you get some wobble in the glass then the forks are twisted in the triples and that will be making the front wheel point slightly the wrong wat when the bars are straight.

worth checking any way.

[HueyonaBlade]

quote:Originally posted by cams666

http://www.streetfighters.com.au/forum/upload/13410372571916.jpg


thanks for the replys, i wil answer your questions as best i can.
all wheel, steering, swinger bearings are in good nick,wheels are in line, tyre pressures are @ 38 psi front & rear[ this seems to prduce the lest amount of trouble.]
its a wobble that moves to a tank slap as speed increases[ i asume death would be acieved @ 200+ ks.] this happens in any conditions regardless of grip to the bars[ altough a tighter grip @ higher speeds seems a good idea].i wouldnt call myself a tough man but iam not a fucking poof either.
i will try the bath scales & get back to you.
some more info on the problem. k3 forks are 25mm shorter than the slabby jobs, i also have a friend who has a 7/11 [ not fightered ] which had a;; the same mods as mine exept for the fork & it was rock solid. he then fitted k41000 forks & develope to same problem only not as bad. we think the loss of fork lenght [& hense steeper steering angle] maybe the culprit. but any other thoughts, comments would be very welcome. thanks cams666.

p.s. i have a nother frame iam putting a k3 750 rearend in to hopfully help the problem.

It would be a shame to waste them beautiful forks cam they obviously arnt suited to the slabby so I best have a look at them ..........:D

[HueyonaBlade]

M8 can you post a list of your mods ?I see a few interesting part on her , Front guard and rotors

[cams666]

thanks for the info. ill try slipping the forks throw as far as i can & get it a try. just one thing i have been playing with, instead of fork extenions, wot about making up a top clamp stepped down to take up said short coming of the fork legs? just a thought thanks again. cams666

[cams666]

to hueyonablade. mods are as follows. k3 750 forks , wheel, lower triple clamp, abm top triple clamp, k3 1000 brakes, 1127 lump,36mm b12 carbs, 04 r1 rear shock, 91 gsxr 1100 rear wheel, home made rear sub frame extenion thingy, k3 duck tail, battery moved to under the tank, total wet wheight 188 kgs, sphinter pucking speed wobble.........free!!!

[cams666]

p.s. keep ya greesy mexican eyes offa me forks m8!!!!!

[Stocky]

As stated above, push the forks through as far as you can and see how it goes.

If it's better you can buy different caps for them that make them longer.

I'll try to find them for you.

[Benz]

My old GPz1100a2 had this same thing,[yes that was a while ago now..] the faster you went , the more violent the wobble would get, until at 180 or so it was impossible to hang onto. Turned out to be the rear wheel was slightly misasligned in the swingarm, the notchmarks were not exactly correct. Once realigned the bike was solid to 230.
Did you put the standard fork-brace under the front guard???

[cams666]

to benz, ah..... wot standard fork brace????????????? & i just got a thingo to check the rear wheel ,swingarm alignment, so i will check that to. i might be able to set the bike up & go for a spin thisarvo. see how i go for time.
And to stocky, the cap sound gr8. would all the comp, peload adjuster still work etc ?

[Benz]

Sorry cams, there may be no brace on the later forks...'91 model usd's have a steel guard mount/fork brace fitted under the guard. If you have removed this I could see the front possibly being less stable......but if it aint there in the first place disregard previous bollocks!

[cams666]

said bollocks disregarded.....:D

[Slain]

nothing wrong with a stepped triple clamp, my 954 has one stock however you have to be more carfl when mounting moto bars as the angle of the steps means you need stronger risers

[Booster]

You could drop the rear a little,25mm there would have a large effect on the steering angles ,

[cams666]

to booster, when i put the k3 rearend in i was going to add a ride hight adjuster to do just that. only problem with that [all be it small] is ground clearance. the roads that i ride here where i live are the best in the state, but there bloody rough at times...

[Stocky]

If raising the front back up helps then you can make the forks longer.

I found the things I was thinking of.....

http://www.traxxion.com/store/detail.asp?product_id=ESFC

http://www.gpsuspension.com/products/newproducts.php

[Watto]

G'day Cams

saw you put the late model front on the slabby frame - how'd you go with the top steering stem bearings when converting - did you manage to find a suitable bearing that allows the for the fatter late model steering stem to fit into the frame or did press the original steering stem into the late model triples

Reason for asking is I'm about to undertake fitting an 04 1000 front end onto a slingshot frame but understand may have trouble getting the right bearing for the top due to the fatter steering stem on the k4 triples and the smaller neck on the slingy frame

[cams666]

to stocky, thanks for the info. just one question,dont spose you know if the caps in 06 600/750 gsxrs are the same as 03 gsxr 750.?
to watto, you have to press the 85 slabby stem into the k series bottom triple clamp. this is spose to a straight job but if is not . the stem is a loose fit in the clamp so you have to get a bush fitted to the clamp. as far as the top bearing goes, i just bought one with the correct dimenions. hope this helps.

[Stocky]

I'd say they'll fit but I'd flick an email to one or both of the suppliers to check first mate.