85 500XC jetting

[Dave Mills]

Can someone give me some baseline jetting specs for this bike, it is stock aside from boyesen reeds. I only ride SoCal deserts in Johnson and Lucerne valley. It has a Mikuni carb, the throat measured 40-41mm. It currently has a 410 main and a 50 pilot and is way too rich. I would like to know if there is some magic needle/jet/slide combo that you guys run. I almost forgot, I run maxima 927 at 32:1 with premium pump gas (octane booster always added)

 

[Dave Mills]

Come on, I know some one has jetting specs. How about stock jetting?

 

[Bryll]

This for -83 and -84 CR/XC 500

Mikuni VM40
Main Jet 340
Needle Jet AA5
Idle Jet 45
Clip Pos #3
Air Jet 0,7
Needle 7DH3
Air screw 1,5 Turn
Throttle 2,0

 

[Bryll]

This for the -85 CR/XC 500 (Factory Settings)

Mikuni VM40
Main Jet 350
Needle Jet AA5
Idle Jet 55
Clip Pos #3
Air Jet 0,7
Needle 7DH3
Air screw 1,5 Turn
Throttle 2,5​

 

[wrenchinremo]

Hey Dave, I'd love to help but my lowest elevation is 4300ft. So my settings are way off the mark. Bryll will get you close. You didn't mention your exhaust system? I also have a 82.5 CR500 with a 44mm Mikuni, Midrange? forget it. the Power delivery is like a light switch! I'm greatful it'll even idle!!! Mess around with the needle and nozzle (needle) jets, different tapers provide different power delivery. I can't see changing a slide. Mikuni carbs are the most tunable of any of them, if you put the in time and a little money it will reward you.

 

[Northern Husky]

Can someone give me some baseline jetting specs for this bike, it is stock aside from boyesen reeds. I only ride SoCal deserts in Johnson and Lucerne valley. It has a Mikuni carb, the throat measured 40-41mm. It currently has a 410 main and a 50 pilot and is way too rich. I would like to know if there is some magic needle/jet/slide combo that you guys run. I almost forgot, I run maxima 927 at 32:1 with premium pump gas (octane booster always added)

...............................l have tried octane boosters, l have found that they make the plug difficult to read correctly on the porclien. They can also change the true smell of the motor which coupled with a hard to read plug......................................can lead to pain in the pocket.

 

[scoott]

When I was desert racing my 85 500xc, the Factory Husky combo was a B-B-O needle jet with a 7F7 needle. Drill a 1/16 inch hole in the needle jet shroud. Main and pilot were dependent on alttitude/temperature. In central Oregon Millican valley desert races at 4,000' and up, I would run a 390-400 main and a 48-50 pilot. Slide cutout was a 3.0. This was for wide open 6th gear desert runs for miles on end. Didn't blubber, never stuck a piston.

 

[Dave Mills]

thanks scoott. is the BBO/7F7 combo richer? I doubt I will be riding 6th gear flat out. I don't want it to load up if i'm just cruising

 

[scoott]

The BBO is richer than stock AA5, but the 7F7 needle is leaner than the stock7DH3. It was supposed to give a more linear response. Leaner on the bottom, but richer on top.The jetting was developed for the Mojave. Qregon's Millican valley starts at 4,000 and goes up into the trees. 100mph in the desert valley, 30mph in the high desert forest. Never had a problem with loading up, blubbering, or fouling plugs.

Or seizing. Raced my 85 500xc till replaced with a 430cr in 88. Can't remember fouling a plug and never seized it. It was still on standard bore. 1st open am in 85, 9th 30x in 86, 2nd 30x in 87.

 

[Dave Mills]

Thanks again scoott! I'll give it a try. What kind of fork setup did you run? I'm about 235 less gear, so I'm sure it was different. Just want an idea of what worked. I' am looking to get the emulator system, but I gotta get the warden aka wife to sign off on it

 

[scoott]

Thanks again scoott! I'll give it a try. What kind of fork setup did you run? I'm about 235 less gear, so I'm sure it was different. Just want an idea of what worked. I' am looking to get the emulator system, but I gotta get the warden aka wife to sign off on it

Back in 85-88, I ran the Simon's anti-cavitation kit with the self-bleeding fork caps to hold down pressure buid-up. Oil was 10wt at 5 inches with 24lb springs. I weighed around 200 sans gear, but stand 6'3", which always caused leverage issues.

Nowadays I'm around 220 sans gear, can't find any of the old bits, so I run the 87-88 conventional forks with emulators with the stiffest orange? spring, 15w oil at 5 1/2" and the stiffest fork springs out of my collection cut 5" for a stiffer rate.

The 87-88 conventional forks are much better than the earlier forks. They have a teflon bushing like modern forks to address stiction, a bottoming cone set-up to help control end of stroke action, and rudimentary valving. The emulators work without ANY damping rod modification.

For off-road/ desert, the 87-88 Husky conventionals were better than the WP upside down forks. The WP were stiffer and turned without deflection, but the action on chop and rocks was terrible.