Author Topic: best fork oil weight?  (Read 460 times)

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Offline jacksdad

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best fork oil weight?
« on: February 12, 2020, 02:06:04 pm »
Hi, I'm just rebuilding my A9 front forks, new bushes, seals etc.
With the kits I got a free litre of oil, its Fuchs Silkolene RSF 7.5, but I'm concerned this may be lighter than I need  :o
I'm a svelte 175lbs and usually ride alone, and sometimes with all the camping gear you would expect for a weekend away. If I need heavier oil, can I mix engine oils to make the correct weight? Seems a shame to not use the free bottle! :great:

Offline connie_rider

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Re: best fork oil weight?
« Reply #1 on: February 12, 2020, 02:38:11 pm »
jacksdad, the COGgers that seem to know the most about fork oil weight should be along soon to correct me, but I think you'll need at least 15 wt fork oil.
Reason is; the orifices in the C-10 are so big that heavier oil is needed to give you damping control.

If you haven't already rebuilt the forks, I have a suggestion.
While your inside them, do a simple mod and install an emulator in the forks.
This would cost you approx. $50 or so, and you can do mechanical adjustments easily.

Here is a discussion about installing the emulator.
http://forum.cog-online.org/tiressuspension-c10/fork-oil-replacement-level/msg680511/#msg680511

Ride safe, Ted
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Offline Lee

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Re: best fork oil weight?
« Reply #2 on: February 12, 2020, 03:37:24 pm »
I weigh in at 295 lbs. I have tried 15 through 50 weight over last summer. I skipped 40 weight. I now run a blend to 37 weight. So 40 weight would have done it for me probably.

Note I have emulators as Ted recommends and also cut stock springs. The C10 forks are very tunable to your preferences if you take the time to experiment.

Note also, I am still experimenting with oil levels above stock. The jury is still out there for me on that. Good luck again.

Offline jacksdad

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Re: best fork oil weight?
« Reply #3 on: February 12, 2020, 07:25:09 pm »
I've looked at fitting emulators but here in the UK they are too expensive, cost about £100 pair. I'm looking at cutting the stock springs by 100mm and fitting alloy tubes in place, but I'm still unsure as to what weight oil to add. I've been reading all the posts on here, and am still lost!

Offline Daytona_Mike

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Re: best fork oil weight?
« Reply #4 on: February 13, 2020, 03:26:44 am »
There are inexpensive  Gold Emulator clones out there.  You want those. They really help. Cuttings the coils is a really good idea...
Hopefully someone will chime in with who  has those emulators.  Ebay maybe? 
Right now I run 50 weight fork oil with emulators... that may sound really thick but it just about stops over re-bounding... extra holes have to be drilled into the emulsion tubes to accommodate emulators.
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Offline Daytona_Mike

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Normally aspirated engines have perpetual turbo lag
2000 Red C10 1052 kit 100+HP  + way more torque.
2008  C14 Silver Dammit Full AreaP- Flies are put back in SISF_Flash
2011  KLR650   688 piston ported and polished
2011  KTM 530    This thing is FUN!!

Offline jacksdad

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Re: best fork oil weight?
« Reply #6 on: February 13, 2020, 12:12:47 pm »
Hi, my problem is that the cheap emulators are sold in the USA, shipping and then impost duty and Vat treble the price!
This takes me back to another post of mine: I need someone in the US to buy a pair, unwrap them and send to me from a private address, as a used item and a gift! I'd still have to pay the ridiculous shipping though  :(
California Motorcycles have a e-store based in Spain, I'm hoping they can supply me vis this Spanish base, as its in the EU (for now) I won't pay fees.
I've read the posts on here, now understand whats involved in drilling the tubes, so now I need to find the best oil, 50 weight seems a massive number!

Offline jacksdad

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Re: best fork oil weight?
« Reply #7 on: February 21, 2020, 12:00:44 pm »
I've decided to go for cutting the springs by 4", the originals have zero wear/shrinkage so should be good.
Starting with 15W...please see my new post about mixing oil!  :great:

Offline connie_rider

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Re: best fork oil weight?
« Reply #8 on: February 21, 2020, 03:07:50 pm »
Haven't seen your post yet, but want to post this quickly.
Your planning to remove the same amount I removed to set the suspension for me and my nephew to use.
  I'm about 210 and he's over 250.

I feel that 4" is to much for your weight. I'd start by removing 3"...
EZ to remove more later, but not adjustable if you remove too much...

Ride safe, Ted
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Gone but not forgotten; 87 and 00 Connies..

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Offline jacksdad

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Re: best fork oil weight?
« Reply #9 on: February 21, 2020, 06:29:05 pm »
Thanks Ted! I will indeed try 3" cut and spacers and see how things go  :great: