'86 vfr750 front suspension

Hello all, I would like to rebuild the front end of my '86 vfr750f. Ideally, I would like to keep things cosmetically as original as possible. Given that, does anyone have some suggestions on springs, fork oil weights, etc? Please bear in mind that I'm not planning on racing this machine but I would like it to handle better. Any input would be appreciated and my apologies if this is an old topic. If so, please send me in the right direction. Thanks.

 

The correct spring for your weight. Race Tech or Sonic. Stay away from "progressive" springs in my opinion. Plus you can't upgrade to Emulators later if you go with progressive (see below).
Set the oil level per Race Tech info, don't just add the "Capacity" amount listed in Service Manual.
With stock damping rods, go for 10wt fork oil. Stock is approximately 7-ish. 15 is usually too harsh with stock internals.
Consider upgrading to some Race Tech Cartridge Emulators for a vastly improved front end with the original forks.

 

Thanks Captain. I appreciate the info.

 

Capt. Replying to old thread.

RT recommends Oil level to 180mm do you happen to know what the level measures out to on a stock set up for a 500? Kind of a weird question but the Service Manual only provides a volume of Right: 320 cc (10.8 oz), Left: 335 cc (11.3 oz) Without experience with this fork I am not sure how that equates to level? I will have to put the bike back together this time with stock springs, unless they are progressives then I may be forced to look for money to at least get some RT 85 kg springs. Eventually I would like to go with he emulators. I have RT springs in my KLR. They are magic. I have 10 and 15 wt oil on hand for this build. My plan is to get the bike road safe do some riding then work out a plan for what I discover after the testing.

WD

 

Listed fluid capacity shouldn't translate into anything close to a proper fluid level. You can verify that as you add fluid if you want.

If the RT recommendation is 180mm for the 500, use that. Especially if you are not upgrading the springs right now. I would use the 10 wt. Maybe, just maybe, mix them 50/50 for a ~12.5.

180mm measurement is forks vertical, no springs, forks fully compressed after cycling them a few times to remove air bubbles, top of the tube to the oil level. You can use just about anything as your measurement device, just mark 180mm and wipe off the oil between check dips. You can remove extra oil if you go over by dipping some tubing, putting your thumb on the end and lifting the tube out to drain. Like a straw.

Do not run any additional air pressure, you are already going to be reducing the air space by using a proper oil level.

 

Dude, I hope I can be of some help to you some day! If you have need for a process vacuum engineer I am the one! So just ordered a set of .85kg RT Springs. I like the idea of custom mixing the 15 w and 10 wt to come up with a 12.5 ish! I have the perfect instrument to make a 180mm measuring rod also. I think I made one for the KLR out of the same stuff.

I will let you know how it goes.

Wavey

 

I am waiting for my RT fork springs to arrive and am reading through the install detail at RaceTech website. If I am just replacing stock springs with RT springs am I just doing a direct replacement. Not sure if I need to acquire any spacers for preload adjustment? I am just going to replace the springs and install the RT recommended amount of oil to begin with. Depending on outcome later I may go with the Emulators. Just taking things as they come for now, but still want to be prepared when the springs arrive.

Thanks

Wavey

 

You absolutely need to apply the right preload and you will very likely need to make new spacers. They often supply a length of material. Sometimes the original spacers can be shortened. PVC pipe is 100% acceptable to use and easier to cut if wanted.

Cuts need to be square, deburred and cleaned. Be sure to separate springs and spacers with washers, regardless of material. If the spacers are steel I will put a washer between the spacer and aluminum cap too.

Often the recommended preload amount (I see that it is 20mm) is about the same as the length of the threads on the fork cap.

 

I was wondering about whether the springs will be shipped with any material? From what I am hearing around is that the existing preload spacers arre usually too long? If so I can chop them down to fit. We will see. I hope that I can find the right diameter washers her locally. Ace Hardware is my only resource here in the desert. I miss Fastenal, and Windustrial!

 

Wonder No More. Per Mike at RaceTech : "There is a 12" piece of spacer material included. If you need more, we use 3/4'' PVC.

 

Often, there is 4 washers included in the kit too. You should have 4 out of your forks anyway.

 

Good to know. Thanks.