[Yorik]

I have to rebuild my 749 forks because of a seal leak. It's nothing major, but it's a good excuse to service them. I have no idea when and if they have ever been done before.

I have new seals, dust wipers, and bushings on order. I'll be using Maxima 5wt fork oil which I've been using in the ST to good results.

I'd like to verify the correct oil level. The bike is a 2003 and the factory manual I have is from 2005 which says 104 mm. The Race Tech website says 110 mm for the 2003. But, if you look at 2004-2006 Race Tech says 90 mm. To the best of my knowledge, the forks are basically the same throughout the years other than if they're TiN coated or not. I'm not sure which measurement I should be using. Does anyone have their experience to share?

Thanks.

Edit: I should also note that the factory level looks like it's without the spring in and the Race Tech level doesn't say.

 

[Strega]

105 mm is correct before the STOCK spring is inserted. Perhaps the 90 mm and 105 mm is correct when installing Race Tech springs that won't necessarily give the same fluid displacement as the stock springs. Race Tech sometimes uses spacers and shorter-than stock-springs to achieve the desired spring stiffness levels. Talk to Race Tech.

 

[Namor]

I did 90mm on my 996,etc. showas with the springs in. More fluid = harsher base from which to adjust. Less fluid = more mushy base from which to adjust.

Get the spring tool if you have not. It can be a 1 man job, but using wife or friend for 3 minutes on the assembly helps a good amount.

 

[SS904]

Race Tech gives its value with the spring and spacer in. I prefer that as it takes in to account oil displacement for different spring and spacer combos. Every RT spring I've used is shorter than the originals, so if you used the oil level listed in the manual, which assumes springs and spacers out AND you're using OEM springs, you'd a bit low once the shorter RT springs were added.

If you like how the forks are working now, try to measure the oil level of the fork leg that's not leaking with the springs and spacers in. Restore that value upon reassembly and adjust from there in 5MM increments if you feel the need to.

 

[Yorik]

I plan on reusing the springs. But come to think of it, I don't know if the springs are OEM. I guess I'll find out when I take them apart and measure the length.

 

[Chuckracer]

You may want to consider softer springs while you're there. These bikes come with very stiff fork springs...and soft shock springs.

I've always preferred lower, rather than higher oil levels in my forks.

 

[Yorik]

Budget is a little tight right now and there are competing priorities. If the spring is OEM, that makes it a .90 and not that different than a replacement. I'll have to make do for the season and see how I feel about it later.

 

[Strega]

Keep in mind that if your spring is too soft for your bodyweight, this will increase the amount of rider sag in the front-end — so the amount of fork travel is reduced before encountering air-spring effect stiffness increases .

 

[bradblack]

i'd run them around 135 - 140mm without springs. the only thing oil height effects is the air spring effect.

 

[Chuckracer]

If the spring is OEM, that makes it a .90 and not that different than a replacement.

You can buy springs in whatever rate you want. Free length and wire diameter is all there is to it. Steer clear of the Racetech charts - they always recommend stiff as hell. I went 8.5's in mine and it was wonderful.