Any way to firm up the front supsension?

I just set up the rear shock on a firmer setting and noticed quiet the difference in the ride. I was wondering if there's any settings up front to adjust to compliant the stiffer rear? I've yet to do a full rebuild on the front and I'm sure the springs are quiet worn by now, but was hoping for a few quick tricks to stiffin up the front for a litter firmer of a ride.

 

Since there is no rebound adjustment knob like the rear shocks have there are two options. Change fork oil to a thicker oil. Before you do that make sure that you have oil in the forks now. No oil in the forks makes for a weak front end. You can also change the springs to a stiffer one. I did both on my XS11 and it made a huge improvement.

 

Okay in regards to changing the fork oil, do I have to remove the forks to get the old oil out? Will any seals NEED to be replaced? I know it's best that all seals should be replaced, but as of now my forks are not weaping/wet of any sort. Plus I already dumped my budget into the bike for the season. So I'd like to get by with a simple drain refill, but if theres a seal that will be possibly damaged in the drain/refill I have no choice but to replace that.

I plan to do a full rebuild in the future but I'm pretty sure the oil that's in there now needs to be changed. Plus if I change the oil now and rebuild it in the off season the second oil change should be much cleaner. This oil change is more to free up/thin out any mud junk that may be in there so when the rebuild happens I'm dealing with a cleaner medium.

I did a quick search of fork oil change and didn't see much, my clymer says to completely remove the forks and invert to drain the oil, but doesn't mention if any seals NEED to be replaced.

 

I run Hydraulic Jack Oil instead of Fork Oil.
You can get Stainless Allen Cap Screws and correct Metric Viton O-rings for the Drains at TruValue Hdwe.

My '79 XS-650 Special had 3-Way Adjustable Preload Front Fork Tube Caps.
There is a chance you could find a set to fit your bike in the aftermarket.

Another option is to insert a "Non-adjustable" Preload beneath your Stock Tube-end Cap.

I made a pair of Preloads for my 900 from the Solid Acrylic Rod that was once a Snow Shovel Handle.

You need to be sure that you don't add too much Preload.
The Springs might Bind.

https://www.google.com/search?client=fi ... B600%3B469

 

Any specs on oring needed on the drain or you take the old ones in and match up the pieces. Do the c rings need yo be replaced on the top end under the rubber dust cover or are the reuse able. Any sort of oring/gasket up there?

 

Best thing is to take them apart and clean all the grit out of them. I spray carb cleaner down the outer tube to get all the nasty out. Call Race Tech or Sonic Springs to find out if they can help you to find a straight wound spring for your bike. Tests indicate straight wound are better than progressive wound springs.

When setting up the spring forces in a bike you want a setup that is progressive enough yet not too progressive. A setup that is not progressive enough will have a tendency to feel too harsh yet when a big hit is encountered bottoming occurs. A setup that is too progressive will either drop through the travel feeling mushy and then feel as though it hits a wall or can feel good until it hits that wall. On front forks there are two forces we consider to be "spring" forces. First is the coil (mechanical) spring and second is the force due to air pressure and oil level. Even if you run zero air pressure the oil level causes the pressure to increase as the forks are compressed. By its very nature this increase in pressure is very progressive. We have found that in combination with a straight wound spring we have a good level of progressiveness. If we want more progressiveness we simply raise the oil level.

Another subtle benefit of straight wound springs is that they are easy to understand. In order to make sense of progressively wound springs you really have to map out the force as you compress the spring. For example a spring marked 20/40 lb/in (excuse me for the Imperial units but this will work with metric units as well) may start out at 20 lbs/in in the first inch but where does the 40 refer to? It might be referring to the rate in the 4th inch or it could be referring to the rate in the 6th inch. This would cause a huge difference in ride.

 

bump up to 15 or 20 wt fork oil makes a difference

 

Thanks thrasher, as stated in my previous post I'm not looking for a rebuild just yet. More of a quick fix for now. Like an oil and and maybe I preloaded spacer. The front isn't horrible, I'm just looking for a slight improvement for now. Plus if I do the oil change now, then again this off season it will the forks a chance to rinse out.

 

Start by changing the fork oil for sure.

Remove the rubber cap, and press the plug down further just far enough to remove the internal wire circlip in the top of the tube, then let the cap come back up and out. The cap/plug has an o-ring on it you'll want to replace.

IF you can get the plugs free.

DO NOT drain the fork oil until you're sure you can get the plugs out of the tops of the forks first. They're often rusted in and getting them out may indeed require removing the forks. Oncee you're sure you can get into the tops of the forks, then drain them. You'll want new "gaskets" (tiny nylon rings) for the drain screws. Do one side at a time and you don't have to do anything special as far as supporting the front of the bike.

Then go to 15W and you should be fine unless the seals start leaking once the forks have oil in them.

 

Wow, this is a lot harder then on the 750. I had little screws at the bottom of the forks. Take that out and the oil just comes out. Unscrew the top and pore in the oil.
When I made my forks harder to push down, I just added air and it stiffed them right up.

Chris.

 

You have the anti dive forks. 550s didn't get them. So its a bit more involved for us

 

Only getting the caps out. And only the 750 Seca had anti-dive; while quite a few Maxims had air-assisted forks. The 550s are easy once you get the caps out.

 

On the 650 with air-assist, can you remove the air fitting instead of the whole cap to replace the fork oil?