Maybe Travis Pastrana's bike.
I think I read somewhere recently that the fastest Supercross Pros are using oil that heavy in their modern works forks, but us mortals should be ok with 5,7 or 10 wt.
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| How much oil and air in front forks? https://vintagedirtbikeforums.alp-sys.com/viewtopic.php?f=21&t=203 |
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| Author: | 78cr250r [ Thu Apr 15, 2004 9:28 am ] |
| Post subject: | How much oil and air in front forks? |
Hello I was wondering if anyone would beable to tell me how much fork oil to put in my 78 cr250? The guy at the store I bought the oil from (30w by the way) said about 4 ounces in each? Thought I would check here first to doublecheck. And after that what should I set the air pressure at in them. Any help would be appreciated! Thanks! |
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| Author: | redrocket190 [ Thu Apr 15, 2004 9:42 am ] |
| Post subject: | |
If you drain the forks then re-fill with 205 c.c. (6.9 oz) If you completely dis-assemble them then re-build with 275 c.c. (9.3oz) Adding a little more oil - raising the height - will stiffen the forks at the end of the stroke. Less oil will have the opposite effect. The manual recommends 5 weight oil but I have heard of 2 weight oil being used. There are suspension people who will drill an extra hole in the damping rod to make the forks more supple. I recommend you start with 5 weight at the stock height and work from there. Normally the air cap is used to bleed out air pressure created when the forks get warmed up. However you can use a little air pressure - say 5 lbs - to again make a stiffer air spring that will resist bottoming (if you have after-market air caps). Don't use air pressure to over-come sacked out springs. The springs should be at least 41mm and 517.5mm respectively. |
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| Author: | 78cr250r [ Thu Apr 15, 2004 1:16 pm ] |
| Post subject: | |
So this 30w oil he sold me wont work then? There is a big difference between 5w and 30w. What bikes would use a 30w fork oil? just curious thanks for the help! |
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| Author: | J [ Thu Apr 15, 2004 2:58 pm ] |
| Post subject: | |
Maybe Travis Pastrana's bike.
I think I read somewhere recently that the fastest Supercross Pros are using oil that heavy in their modern works forks, but us mortals should be ok with 5,7 or 10 wt. |
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| Author: | 78cr250r [ Thu Apr 15, 2004 6:41 pm ] |
| Post subject: | |
Ok when I go back into the city I am gona trade the 30w in for a bottle of 5w or maybe 10w what do you think? How much stiffer would 10w be over 5w? And I was wondering if in the meantime until I get to the city (I live quite aways away) if using 5w30 engine oil would work in the forks just for about 4 days or is that just a stupid idea? thanks! |
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| Author: | J [ Fri Apr 16, 2004 10:27 am ] |
| Post subject: | |
Bad Idea! Totally different type of fluid. I remember reading in old Dirt Bike mags that they often used GM transmission fuild (ATF) in there forks, so maybe that would be an alternative until you can get back into town. |
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| Author: | redrocket190 [ Mon Apr 19, 2004 1:21 am ] |
| Post subject: | |
I think ATF is about 10 weight and it would get you by.... |
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