TL125 /Koni rear shock spring rate?

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Jools
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TL125 /Koni rear shock spring rate?

Postby Jools » Thu Dec 17, 2015 9:18 pm

I'm right at the end of my resto of my K0 Tl125. It has a set of Konis on the back, (they were originally fitted to a little roadracer). Damping is still very good, but the spring rate has always been way too heavy . So I'm trying Ikon to get lighter springs. I want something VERY supple. Anyone have any ideas re: the spring rate I should be looking at? I'm pretty light, around 65-70 kilos.
-Jools



David Lahey
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Re: TL125 /Koni rear shock spring rate?

Postby David Lahey » Thu Dec 17, 2015 9:51 pm

It's hard to say for sure because KONIs have much heavier damping both ways than modern trials twin shocks.
If they were modern trials shocks I would have no hesitation saying 40 pounds/inch springs, and the compression stroke action would be livable, but the rebound speed would be quite slow.
Last time I checked IKON didn't make springs that light. Maybe there is better availability now
I suspect that OEM TY250 springs would be about the right spring rate, and from memory might fit on KONI special D shocks. If you want to go that way I can see if they fit on the weekend
No matter how light you make the springs, the action with KONIs will never be even remotely supple unless you redo the internal valving (which would probably cost more than buying some modern shocks if you have to pay someone to do it).


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Jon V8
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Re: TL125 /Koni rear shock spring rate?

Postby Jon V8 » Fri Dec 18, 2015 9:16 am

If you want something that actually works it might be worth considering some Falcons or Rockshocks from the UK. Both are very popular here, and for good reason - they actually work. both companies will ask questions relating to rider weight etc,and will supply rebuildable shocks to fit your bike.
http://www.falconshockabsorbers.co.uk/
http://www.rockshocks.co.uk/



Jools
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Re: TL125 /Koni rear shock spring rate?

Postby Jools » Fri Dec 18, 2015 10:27 am

Thanks for your input lads.
I'm not flush enough to buy new shocks, so I'll try to optimise the Konis I have. Take your point David that with lighter springs they'll be overdamped, but maybe I'll have to live with that. Hopefully with a lighter spring rate I'll get an improvement over A: My stock TL125 shocks which are absolutely totally stuffed (and were from new!), and B: the Konis which are oversprung. Be great if you could check the Koni / TY spring fit David, that might be an option.
My Konis are 76F-1312. 380mm eye to eye, 110 damper stroke, spring free length 260mm. Outer dia of spring 52mm, (can't be more because it needs to clear the muffler) Inner dia of spring min 38mm. (15 turns of 6.5mm wire).
Cheers,
Jools



mrgor
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Re: TL125 /Koni rear shock spring rate?

Postby mrgor » Fri Dec 18, 2015 4:09 pm

Hello, We have been using NJB Shocks from the UK on TLR200 Honda's.
Been very happy with them.
Have seen a number of Twin Shock Bikes fitted with these units.
They will build a shock to suit your bike, weight of rider etc.
Very reasonable prices and fast delivery.
The company is very responsive to emails and queries.
Check our their site at http://www.njbshocks.co.uk. Norman Blackmore has always been most helpful.
Best Regards and Seasons Greetings,
Ron S



David Lahey
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Re: TL125 /Koni rear shock spring rate?

Postby David Lahey » Sat Dec 19, 2015 11:17 am

Jools wrote:Thanks for your input lads.
I'm not flush enough to buy new shocks, so I'll try to optimise the Konis I have. Take your point David that with lighter springs they'll be overdamped, but maybe I'll have to live with that. Hopefully with a lighter spring rate I'll get an improvement over A: My stock TL125 shocks which are absolutely totally stuffed (and were from new!), and B: the Konis which are oversprung. Be great if you could check the Koni / TY spring fit David, that might be an option.
My Konis are 76F-1312. 380mm eye to eye, 110 damper stroke, spring free length 260mm. Outer dia of spring 52mm, (can't be more because it needs to clear the muffler) Inner dia of spring min 38mm. (15 turns of 6.5mm wire).
Cheers,
Jools

I just found an original TY175 shockie spring and tried it for fit on an (early 1970s) KONI 76F-1326.
The TY spring is a very nice fit on the KONI body and the bottom spring seat, but the spigot on the top KONI retainer is too big in diameter for the TY175 spring, because the TY spring has reduced diameter coils on each end. There looks to be enough metal in the KONI retainer to allow for the spigot to be machined down to fit into the end of the TY spring
Details of TY175 spring:
225mm free length
15 turns of 5.5mm
main spring coils are 38mm ID (outer diameter 49mm)
end coils (one on each end) are 36.5mm ID

I just worked out the spring rates: KONI spring 72 pounds/inch and the TY175 spring 42 pounds/inch
I measured the KONI body at 36mm OD


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David Lahey
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Re: TL125 /Koni rear shock spring rate?

Postby David Lahey » Sat Dec 19, 2015 11:20 am

If you didn't want to machine the KONI spring retainer, the TY175 top spring retainer will fit on the KONI if the slot in the retainer is slightly widened (TY shockie shaft is smaller diameter)


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Jools
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Re: TL125 /Koni rear shock spring rate?

Postby Jools » Sat Dec 19, 2015 11:34 am

David, TY springs sound like a very viable proposition. (Thanks very much for helping).
I can make up a 25mm packer if I want to retain the 250mm spring length, and the slightly smaller outer diameter will give better clearance to the triangular muffler -the Koni spring does rub a little. (Ikon haven't got back to me yet to let me know if they can supply a light spring, but I'm not hopeful as there's nothing like that listed on their site).
I wonder where I can get a pair of TY springs (and possibly the top collar) from. I wonder if TY250 and TY175 are the same?
Hmmm...
Cheers.



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Re: TL125 /Koni rear shock spring rate?

Postby David Lahey » Sat Dec 19, 2015 11:38 am

I remember in 1995 wanting some new shocks for my TY250A for the Aussie titles and the only ones I could find available then was the chromed body KONI (same as current IKON) and the lightest springs I could get to fit them were KONI multi-rate springs 50-72 lb/inch. They had very heavy rebound damping even on the lightest damping setting and the springs were way too stiff for trials competition.
I later tried some lighter (non-KONI) springs on them (after machining the top spring retainer spigot) and they were still crap.
Today I looked at the IKON web page and the lightest springs they list are those same 50-72 lb springs, and straight-wound 62 lb springs.


relax, nothing is under control

David Lahey
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Re: TL125 /Koni rear shock spring rate?

Postby David Lahey » Sat Dec 19, 2015 11:52 am

Sorry Jools I didn't see your last posting until after I posted mine
From memory, TY250 shocks do have a slightly higher spring rate than TY175, but I couldn't find any that I was certain were TY250 to measure up.
I'm sure there are lots of old TY shocks lying around. The shock shafts bend very easily in a fall and are not worth fixing so are usually taken off early in the life of a competition bike.
I only have the one set of TY175 springs and want to keep them.


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