swopping CB500 yokes for NSR125 ones

[Ewan 500 K1]

so...in building my cafe racer I increased the rear forks by 46mm (nearly 2 inches) ... On a test ride today I was getting a front end side to side twitch at 90mph, despite having a steering damper on and with it set at full damping. So, I need Triple T set with less offset to compensaet for the reduced trail caused by raising the rear end. I understand that the NSR125 triple T would do the the job ... can anyone offer any advice on what is involved in this modification ?
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[Bitsa (Ralph Wright - RIP)]

Ewan
Love the exhausts apart from the blueing.Not keen on cafes but I like the look of yours
Well done
Bitsa

[Ewan 500 K1]

Ewan
Love the exhausts apart from the blueing.Not keen on cafes but I like the look of yours
Well done
Bitsa

Thanks Bitsa... now if it didnt have a twitchy front end, didn't chuck oil out and rune lean as twiggy the doin would match the lookin ... i can see another 12 months of refinment at this rate.

[Trigger]

Ewan, because you have jacked the back end up you need to stiffen the front end. You could try a couple of washers in the forks to tighten up the springs a bit. This is the cheapest option. Do you still have the old springs in?

[Ewan 500 K1]

Ewan, because you have jacked the back end up you need to stiffen the front end. You could try a couple of washers in the forks to tighten up the springs a bit. This is the cheapest option. Do you still have the old springs in?

Hi Trig, yep its still the old springs that are in. I was warned that raising the back end that much would give it front end tank slapping tendancies .. which is why I fitted the damper,. I suppose if I hadnt fitted the damper and run it on max damping, this mornings twitchy front end might have been a bit more violent.

Do you reckon that stiffening the front foks would help get rid of twitching tendancies ?

Looks like the NSR yokes might be a far from simple solution. I'll maybe have a  look into billet yokes with a 10mm reduction in offset to 35mm, which should bring my trail back up to about 4 inches.

[matthewmosse]

I have an ns125r in the shed - wonder how close this would be? I know phisically a cb250 or 400 front end of the superdream era slot streight in too.

[Ewan 500 K1]

I have an ns125r in the shed - wonder how close this would be? I know phisically a cb250 or 400 front end of the superdream era slot streight in too.

Got this on the US site: " I'm in the process of organizing a set of these for another forum member. Because the NSR top clamp is flat & not "dropped" like the original the forks need to slide through the lower clamp enough to sit flush with the top of the upper. This ultimately brings the top of the fork leg closer to the bottom of the lower clamp reducing available travel. I need to play some more but may mean longer tubes or else the front of the frame will be lower. This might be ok except if there is already a change to an 18" wheel as well as longer rear shocks. If this is the case longer forks or tubes may be the answer, otherwise too great a change in rake & loss of trail will result even with 10mm less offset.

The OD of the steering stem where the lower bearing sits is smaller than the original so in order to use tapered roller bearings for a Honda it will be necessary to machine a sleeve for that lower brg".

I've just started looking at this so I have no final advice yet. Otherwise the fork spacing & diameter of these triples is correct.looks a lot more complicated that a straight swop or simple mod of steering stem ! Cb250/400 solutoion probs not an option given the £'s alreay laid out on wheel and brake refurbs. Now think a one off CNC billet job might need to be the answer ... though that would take a fair bit of saving for

[Trigger]

Ewan, i think Norniron jacked up his back end on this 400, give him a shout. I know hes a shy boy but, he knows this cafe stuff. Washers is always worth a try and cheap. You never know until you try.