Author Topic: YZ250D fork top out springs - advice required please  (Read 4850 times)

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Offline JohnnyO

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #15 on: October 27, 2013, 09:14:02 AM »
I went for Nathens "CRAP" option. Removed the long top out spring, shortened and modified dampener rod. Now they operate look like forks that are one everyone's  VMX bike. Crap option for me.
That's the best way to do it and the way I've done my RM250 & 370 forks last year. You may have to alter the length of the preload spacer for the main spring to suit.
You also need to check that the new spacer doesn't block the rebound holes in the top of the damper rod.
We used to remove the long preload spring from suzuki forks back in 77 to obtain more travel..

Offline Slakewell

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #16 on: October 27, 2013, 10:07:36 AM »
Hmm this works for me. 50mm top out springs that I made myself from cutting up springs plus spacer. Some cut up old YZ 465 springs and double valve springs on top under the caps very little pre load. Gives just under 9 inch. ATF 140mm from the top springs out.
« Last Edit: October 27, 2013, 10:09:18 AM by Slakewell »
Current bikes. KTM MC 250 77 Husky CR 360 77, Husky 82 420 Auto Bitsa XR 200 project.
Kawasaki A4 125 78 for sale

Simo63

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #17 on: October 27, 2013, 10:18:03 AM »
You guys are awesome .. thanks for the info

When I have more time I'm definitely doing a similar thing to the shorter dampner rod pictured

Just one thing .. where was all this wonderful advice when I had the bloody forks apart BEFORE I reassembled it back into the bike   ;D  ;D  ;D
« Last Edit: October 27, 2013, 11:06:56 AM by Simo63 »

Offline JohnnyO

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #18 on: October 27, 2013, 10:18:48 AM »
Hmm this works for me. 50mm top out springs that I made myself from cutting up springs plus spacer. Some cut up old YZ 465 springs and double valve springs on top under the caps very little pre load. Gives just under 9 inch. ATF 140mm from the top springs out.
I have done it similar to that in the past also using a car valve spring cut to length instead of a solid spacer with the short top out spring. I use PVC pipe cut to length for the fork preload spacer for firmer fork action.

Offline Iain Cameron

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #19 on: October 27, 2013, 11:45:57 AM »
I'll keep mine standard and play at club level only . It was made with the best at the time why go backwards . Iain
Yamaha tragic ; dt1, rt1, dt2, rt2, dt2mx , rt2mx , mx250, mx360,sc500, 74dt125, yzx125, yzc250, yzc400, yzd250, yzd400, yzh250, yzh80 , dt100 , xr75 ko xr80 03 , it175 82 . Not a member of any club

Offline Husky500evo

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #20 on: October 27, 2013, 12:37:02 PM »
I'll keep mine standard and play at club level only . It was made with the best at the time why go backwards . Iain
My sentiments as well. Yamaha always seemed to be at the forefront when it came to front suspension and brakes. That is why I am going to use '77 YZ front ends on my '77 Huskys and VB Montesas and 43mm '81 YZ front ends on some of my Evo bike projects. But I will probably only ride the pre '78 bikes at club days, because I don't feel like complying to stupid rules. 

Offline Slakewell

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #21 on: October 27, 2013, 12:46:49 PM »
Dont start me on the pre 78 suspension rules I have just been shortening up my Husky rear end all week trying to get the balance correct. The bike looks funny now but does fit on a milk create.  >:( 
Current bikes. KTM MC 250 77 Husky CR 360 77, Husky 82 420 Auto Bitsa XR 200 project.
Kawasaki A4 125 78 for sale

Simo63

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #22 on: October 27, 2013, 01:55:48 PM »
I'll keep mine standard and play at club level only . It was made with the best at the time why go backwards . Iain

Iain I completely understand what you are saying and I also have an issue with having to lower it to meet the mom's.   Remember the thread from 12 months ago where I won no friends with the 2012 Nats organisers and scrutinisers?  But at the end of the day, if you don't do it, you are technically not complying with the rules.

And the fact is, we all need to comply otherwise it's not fair.

Offline JohnnyO

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #23 on: October 27, 2013, 02:26:19 PM »
None of us agree with the pre 78 rule but you guys are the ones short changing yourselves by staying home while we ride the big meetings...
I personally think the rule should be set at 10" so all std bikes and aftermarket fork kits and shocks comply without modification.

Simo63

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #24 on: October 27, 2013, 02:31:45 PM »
None of us agree with the pre 78 rule but you guys are the ones short changing yourselves by staying home while we ride the big meetings...

Agree entirely JO

Offline Iain Cameron

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #25 on: October 27, 2013, 02:42:37 PM »
I do go by the rules my pre 70 and 75 bikes are within the rules and I ride them at the nats . Simo I felt for you at 2012 I would have had no probs with your bike as Im of the idea that the better rider can win on any bike within reason . I just don't want to change my bike backwards and as Im usually fighting for last place whats the point .
Yamaha tragic ; dt1, rt1, dt2, rt2, dt2mx , rt2mx , mx250, mx360,sc500, 74dt125, yzx125, yzc250, yzc400, yzd250, yzd400, yzh250, yzh80 , dt100 , xr75 ko xr80 03 , it175 82 . Not a member of any club

Simo63

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #26 on: October 27, 2013, 02:51:20 PM »
All good Iain  :)

I might ask to lock this now as I have the info I needed and don't want to risk it turning into a rule based thread  ;)

Thanks for everyone's input, it's greatly appreciated.

Cheers

Offline JohnnyO

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #27 on: October 27, 2013, 03:01:08 PM »
Slakewell or Husky500Evo can you tell me what the standard shock length should be on a 77 390 Husky?
Mine has 14.25 YSS shocks with only 4" shaft travel giving 7.25" rear wheel travel. Obviously not the correct shocks for the job..

Offline Husky500evo

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #28 on: October 27, 2013, 04:29:28 PM »
Standard shock length for a '77 CR390 is 380mm, with around 140mm of shaft travel. They came out with Gas Girlings with dual rate springs, with the smaller springs being a bit strange because they were wound with square section material , rather than the usual round section material. I run remote reservoir Ohlins on my '77 CR 390, which are 383mm long and have around 140mm shaft travel. I think that these Ohlins came out standard on '79 WR Huskys.
« Last Edit: October 27, 2013, 06:34:39 PM by Husky500evo »

Offline Slakewell

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Re: YZ250D fork top out springs - urgent advice required please
« Reply #29 on: October 27, 2013, 05:32:20 PM »
I have 340mm shocks on the Husky now and slide the forks pass the bars. It does steer a little bit better being lower. It does comply with the rules. I will submit to MA that the suspension limits in Pre 78 are not necessary and no limits should apply. Please start a new discussion if you want to bash the rules thou. Hope you got your forks fixed. 
Current bikes. KTM MC 250 77 Husky CR 360 77, Husky 82 420 Auto Bitsa XR 200 project.
Kawasaki A4 125 78 for sale