Fork oil weight with sidecar?

JohnB53

XS650 Enthusiast
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I have been working on a sidecar project this fall/winter and now have the sidecar finished. I have started on a 1981 XS650 special one owner with 8200 miles on it. The trouble with it that it had a stator issue and has been parked since "08. It has been quite a job with it needing a lot of work done. It is now running good and I am happy overall . I am replacing the front seals and when I replace the fluid I am wondering if I should go with a heavier weight fluid for side car duty. I have already replaced the bearings with all Balls tapered roller bearings. I built a vw trike and used a 650 front end on it with the all Balls bearings and it works fine, but I did have to go up to a 50 weight HD oil to keep the front end from diving when breaking . I am wondering if any one has delt with this issue and what did they do. By the way the car is a Velorex 562.
 
Yes, I think you'll want thicker oil, probably 15 to 20 wt. (10 is stock), more of it (about 7 ounces per leg - this will help lots with the front end dive), and stiffer springs or at the very least, 1" spacers added to the stock springs.
 
If you want to reduce front end dive, and still keep the stock telescopic fork, I would recommend a Gold Valve emulator from Race Tech, with a harder than stock valve spring, and possibly a smaller than standard low speed damping hole (bleed hole). This to increase compression damping without increasing rebound damping at the same time. I suggest you call Racetech, and talk to them about your suspension requirements. They may well recommend new springs + emulators.
Just using thicker oil will increase both compression and rebound damping, and since rebound damping is stronger, that may lead to the fork not being able to rebound fully then hitting several bumps in a short amount of time, sort of "pumping itself down".
 
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