For those of you wanting to upgrade your XJ, I'll tell you what I read from the April 91' Cycle World article about this very subject. They used an editor's 1982 Seca 650 for their article, but these tips should apply for almost all the XJ's and even most older Japanese bikes.
It has a weak midrange so they tackled the restrictive airbox. The purpose
of the restrictive air path was to silence the honk of wide open throttle
operation . They removed the rubber airbox snorkel and also installed a K&N
Air Filter, but did not alter the airbox itself. Nor did they touch the stock
exhaust system. Their reason: "the XJ650 doesn't need one. Aftermarket
exhaust manufacturers have known for some time that it is very difficult
to make more power than stock Japanese exhausts without letting their systems
get outrageously loud". The K&N filter only makes a little more noise
than stock, yet is so less restrictive than stock that they had to go up
three main-jet sizes to correct their XJ's full- throttle mixture." The
filter , though, made the part-throttle mixture even more lean than it already
was". They removed the soft aluminum plugs covering the idle mixture
screws on top of the carbs and opened the the screws 7/8 of a turn each.
The result was crisp carburetion and more punch in the midrange.Still, keep
in mind that these settings are for a 1982 Seca 650 and are more of a guideline
than anything.
If you'd like to update the XJ's suspension it is still possible to get aftermarket shocks for your bike. Front suspension is noticeably soft, so they replaced the fork springs and oil. Fortunately Progressive Suspension still makes springs designed for these bikes, though it is the only company which Cycle World is aware of that still makes them. They used the #1106 spring set in their XJ650 with 1 inch preload spacers made from 1 inch diameter PVC water pipe as recommended in the instructions. After testing they decided to cut the spacers down to a 1/2 inch. They used 10W Kal Gard Smooth Stroke fork oil and filled to a level of 6 inches below the top of each fork tube (with the fork springs out and the fork completely compressed).
Because their Seca 650 already had Ohlins shocks installed on the
rear they did not change the rear suspension. But the Ohlins are pricey
. Can you say around $383. For the budget minded Progressive Suspension
and Works Performance make more economical setups which are certainly
better than your old stock setup.
Front Brakes- I've heard about a lot of problems with the XJ's brakes specifically the Seca's. Anyway, if you don't want to make any big changes to your braking system then you should probably just give it an overhaul. Change the brake fluid (should be changed every 2 years) and get some better brake pads like Ferodo's or some other good quality brand. Consider disassembling the calipers and checking all the seals to make sure everything is in order also. What Cycle World did was more drastic. Apparently the discs are made from too soft steel and have a tendency for galling and forming grooves. They found a company called Spec II that drills holes in the the front discs to keep this from happening which in turn causes the brakes to work better. Spec II drilled 96 holes which were sharp edged in the Seca 650 rotors. They then added Ferodo soft-compound (#2453) brake pads. "The Ferodo's, when combined with the drilled discs, will smooth and flatten an already-galled disc. They last a long time, and require less lever effort than stock pads and continue to work well when wet." One additional problem with the XJ's brakes is rather limp brake hose which expands under pressure, thus reducing the feel of the brakes. So they added Russell rigid brake lines which, unlike stock lines, will not expand enough to notice.
I'll elaborate a little later on this subject, but for now I will get to the point. If you still have stock steering head bearings then you should replace them with tapered roller bearings, which are stock on almost all new bikes, because they are better and last alot longer. Cycle World had trouble finding the correct size because of the odd sized bearings, but was able to get some from K&L Supply.
Keep in mind that the article was written in 1991, prices have probably changed, maybe even the addresses or the companies are out of date.
| Suppliers | |
|---|---|
|
Kal Gard 16616 Schoenborn Blvd. Sepulveda, CA 91343 818/894-3615 Fork Oil: ~$4.15/pint |
Performance Research Organization 1194 Shetland Way El Dorado Hills, CA 95630 916/933-4166 Ferodo brake pads: ~$23/pair |
|
K&L Supply 1040 Richard Ave. Santa Clara, CA 95050 408/727-6767 (dealers only) Steering-head bearings: ~$47.50 |
Progressive Suspension 11129 G Ave. Hesperia, CA 92345 619/948-4012 Fork Springs: ~$56 |
|
K&N Engineering 561 Iowa Ave. Riverside, CA 92502 714/684-9762 Air Filter: ~$26 |
Spec II 9812 Glenoaks Blvd. Sun Valley, CA 91352 818/504-6364 Disc Drilling: ~$40/disc |
|
Russell Performance Products 6301 E. Alondra Blvd. Paramount, Ca 90723 213/602-1202 Brake lines: ~$97 |
Noleen Racing 2141 E. Philadelphia Unit T Ontario, CA 91761 714/947-5773 Ohlins shocks: ~$385/pair |