Fork oils / grades

Ok, just dismantled forks and renewed seals on xj750.

I now require 312cc SAE 20 fork oil for each leg.

However, SAE 20 takes 5-7 days to order + delivery add 2 more days!

SAE 10 and SAE 15 available off the shelf, also Automatic Transmission Fluid (ATF).

Do I wait and refill with SAE 20 or can I use any of the alternatives that are readily available? Will these alter handling on the anti dive, air ect?

all thoughts and comments much appreciated,

Thanks. :lol:

 

Oil weight and type is a personal preference for riding style. I'm a big guy and I prefer AFT( Mobil 1 synthetic) I have tried 10, 15 and 20W. I still like the ATF.

 

You must have a 750 Maxim as I just rebuilt mine and the 750 Seca takes 309cc of 20W. I first tried a Triumph dealer (because it was closer) and they couldn't think of why a bike would need such a weight of fork oil. Maybe it is a British thing. :lol: Next went to the Kawasaki/Suzuki/Ducati dealer and they had 20W right on the shelf with the other weights. Get fork oil (I know others use ATF) of the correct weight because the fork oil is more consistent for this purpose than ATF and you don't need a whole lot of it. If you start messing with the weight then you will probably need to start messing with the internal valving too.

One extra thing - I also put Progressive Suspension springs in (with PVC spacers) to improve front end action and I may not use any additional air pressure (tends to blow out seals anyway). Since you have the forks apart...

 

ATF is generally 5W or 10W.

Going to a lower viscosity oil will reduce damping, making the suspension more bouncy but less harsh. You might like it that way, or not.

The viscosity needed will be effected by fork travel, fork diameter and the size of the damping rod orifices. Just because most forks don't require 20W isn't a reason do discount what Yamaha recommends for your particular fork.

 

Ok, thanks for all advice, having spent the last 18months repairing and learning about the bike i'm itching to get it taxed and tested and back on he road for the summer season!

If all works well I may strip and powder coat the frame next winter so will probably use ATF for now and replace again later.

 

How much should the forks move in and out when they are set up properly?

 

Not to sure about measured movement, I will check and let you know.

I refilled fork legs with SAE15 for now, all air seals are holding so i've repressurised the air circuits, but have not bothered with dismantling anti dive units, I will run for the summer and see how the bike handles!

I have now had the bike since march 09 and undertaken so much work on it to get it back on the road that paint and running repairs can wait until the sun goes in!

However, I would not have been able to complete as much as I have with just a haynes manual, this site has been a great source of information and advice, thanks to all contributors with their "how to's" and photographs.

Capn' Redbeard - Us Gingers are not a dying breed ! :lol:

 

Your right about that CapnRedbeard.

"However, I would not have been able to complete as much as I have with just a haynes manual, this site has been a great source of information and advice, thanks to all contributors with their "how to's" and photographs."

If it were not for this site and chacal I would have given up long ago. In fact I think thats why there are such good buys on XJ's out there. People just don't know where to get the right help or the parts. And they get frustrated and sell the bikes cheap as the dealers want nothing to do with keeping them going.

 

Think of setting up your bike like going to a shoe store if 5 of us go into a shoe store and we all buy the same size shoe some us us wont be happy with the fit to loose to tight just right almost perfect but not quite there, right. While we will all probably be able to at least walk in the shoes some of us wont be able to run a marathon or hike up a mountain trail. Your bike weighs around 500 pounds without a rider if you weigh 200 pounds your almost 30% of the bikes weight when your riding. Check out this video on setting sag:http://www.youtube.com/watch?playnext=1&index=4&feature=PlayList&v=bBlqVx4mWUw&list=PL066D54DA23BCBF1B

 

Ground Hugger,

I've just taxed and tested the bike and driven 16 miles, Measuring the dirt mark s on the forks from the top of the dust seal 115 - 125mm.

This is based on SAE 15 oil grade, air and standard as manufactured 1982 front springs.

As I do not use the bike for daily commute only as a leisure activity I intend to monitor future performance and adjust if I have any problems.

Waldo, when I get the chance I will view the youtube files.

thanks

Capn' Redbeard