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Old 10-12-18, 07:54 PM   #11
Adam Ef
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Default Re: Spring weight for bike weight.

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have you welded up the top rebound holes in the damper rods?
Not yet. I wanted to try just changing the springs and new oil first so I don't change too much at once and not know what helped / worked.



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what brand of fork oil did you use?
One recommended by your good self in another thread somewhere . Silkolene 10wt



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how much oil did you put in each fork leg and was the springs in or out when you measured the oil height?
Springs out, 94mm air gap as recommended in the Haynes Manual for K3 onwards.


Will a bit more or less air gap help at all?
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Old 10-12-18, 10:44 PM   #12
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Default Re: Spring weight for bike weight.

weld the rebound holes up.. its the only way to get the rebound under control without going nuts with heavy oil viscosity.

to get the rebound spot on requires mixing of oil viscosity's and a lot of faffing about.

playing with the oil height only adjusts the "air spring" and has very little effect in damper rod forks unless its large adjustments. just stick to what the book says and you wont go wrong.
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Old 10-12-18, 11:22 PM   #13
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Default Re: Spring weight for bike weight.

I did the air gap by the book, but haven't taken into account any difference of volume of the K Tech spring compared to stock. Not sure how I'd work that out.. or if I need to.


One thing that has just clicked though is I've realised I've firmed up the front with the new springs which is feeling great and diving less, but obviously throwing the bike back up harder.. increasing the pogo effect!?
With nothing to counter that effect with I've made the lack of rebound damping SV fork problem worse than it would be as stock.


I've only just got the bike back together after 3 weeks of back end, swingarm, exhaust and front end being off and hadn't wanted to take it apart again, but looks like I might be to get those rebound holes welded. Just pushing on the forks in the garage I can get it to wobble up and down 3 or 4 times before it settles. It's worse on the road, so something needs doing.


Thanks for all your help on this. I'm learning loads.. again!
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Old 11-12-18, 08:36 PM   #14
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Default Re: Spring weight for bike weight.

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One thing that has just clicked though is I've realised I've firmed up the front with the new springs which is feeling great and diving less, but obviously throwing the bike back up harder.. increasing the pogo effect!?
With nothing to counter that effect with I've made the lack of rebound damping SV fork problem worse than it would be as stock.
you have sort of hit the nail on the head with the spring weight and this is why i recommend welding up the damper rod rebound holes. why do we weld the damper rod rebound bleed holes? we do this due to the check valves on the bottom of the stanchions being carp and leaking like a sieve.

i think there might be something else going on as 4 "bounces" is worse than stock. 10wt RSF Maintain (pro) is heavy for a 10 weight oil so by its self should be better than stock.

something you might have missed is pumping the stanchion up and down when you initially filled the forks with oil.
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Old 11-12-18, 09:23 PM   #15
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Default Re: Spring weight for bike weight.

I did pump the stachions and left them overnight. Checked oil level the next day and it was slightly low, so topped up and pumped them again before reassembling.


I think the back being set for decent rebound is having an effect on the front as it throws backwards and forwards a bit. I could lose the rebound on the back to match the speed of the front rise, but that would make it crap all round, although balanced. Ideally I'd like to sort the front. It's coming apart again in the next few days to have the holes welded and I'll take it from there. Next step after that will be to try mixing 10wt and 15wt if the welding doesn't do enough.


If I hadn't just done the bar conversion with the new Topyoke I'd think about doing the total front end swap instead.


It doesn't need loads of change on the front. Just a bit of decent rebound on it and then it should all be good enough for what I use it for.


The back feels ok even with the "temporary" ZX10r shock on there. If I aim at potholes and ride through hardly touching the bars the back end stays impressively smooth. If I'm holding on to the bars even lightly though I get knocked and bounced about. I noticed it a while back too when I was doing the TPS adjustment as the bounce when riding was causing issues with throttle control.


In terms of handling on decent surfaces, cornering etc it all feels so much better.
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Old 11-12-18, 09:29 PM   #16
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Default Re: Spring weight for bike weight.

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i think there might be something else going on as 4 "bounces" is worse than stock.

3 pronounced bounces.. the same as it was when stock. The oil has probably made it better and the spring has made it worse... so back the same as it was!


Much less dive though.
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Old 11-12-18, 10:49 PM   #17
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Default Re: Spring weight for bike weight.

i've done a good few SV front ends and each one of them has needed the rebound holes welded.

dont bother with 15w and get 20w or even 30w instead. you need to suck out and replace much less oil to get same effect. remember that you need to let the oil mix till the proper effect is gained. dont go mad as the heavier the oil the slower (hard) the compression will also be. work on about 30ml at a time.

TBH most front ends i have done all work out to around 10w once the rebound holes are welded.

BTW did you cut the top spacers for the new springs?
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Old 11-12-18, 10:57 PM   #18
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Default Re: Spring weight for bike weight.

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BTW did you cut the top spacers for the new springs?

No. Should I have done?
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Old 11-12-18, 11:01 PM   #19
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Default Re: Spring weight for bike weight.

if the spring lengths were different yes. if the new springs were longer and you kept the spacers the same length then you are adding preload. IIR they are pretty much the same though.

did you get linear springs or progressive?
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Old 11-12-18, 11:09 PM   #20
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Default Re: Spring weight for bike weight.

Linear springs. Preload is working out ok. Static sag is good and rider sag 'checked' against it is in the right area. Not getting all the fork travel though, still about 30mm left. Maybe as it's rebounding up so fast before it compresses again.
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