I rode my 35 year old XS650 549 miles yesterday through the gold Country of the Sierra Nevada. Long, long day, but a lot of fun and beautiful scenery. The best thing is the 650 ran perfectly the whole way, never skipped a beat. 15 hours of riding, altitude change of over 4000 ft, the perfect day!
-
Enjoy XS650.com? Consider making a donation to help support the site.
XS650.com receives a small share of sales from some links on this page, but direct donations have a much greater impact on keeping this site going.
jriehl08
XS650 Addict
Awesome. Post up some pictures if you took any.
Mikeinnh
XS650 Enthusiast
Outstanding!
tonyc
XS650 Guru
DLD regardless what opinions that you may here on this board, these bikes were meant to be ridden like you just did. Good job.
For sure Tony, that's a completely normal ride for any XS650 that has been mechanically and electrically restored properly. These bikes are a lot tougher than most riders.
When going up in the mountains, these engines (CV carbs) handle 4000 ft elevation change with no trouble at all.
DLD1...................you must have an iron butt
When going up in the mountains, these engines (CV carbs) handle 4000 ft elevation change with no trouble at all.
DLD1...................you must have an iron butt
Thanks guys,
I agree that these bikes are as tough as anything on the road. Unfortunately we did not take any photos. My cell phone doesn't take photos well, and I didn't want to carry the big camera. And as far as me having an iron butt, it was pretty damn sore by the end of the day, and I'm still tired 24 hours after we got back( I am 60 years old), but it was well worth it. It was one of the most enjoyable rides I've ever had.
Also, I agree about the carbs, they handle elevation change very well. I used to think I wanted to change carbs, but the way these handle elevation change, and the fact that there are at least six mountain passes within easy riding distance that are in the 9,000ft range, I think it's best to keep the CVs.
DLD
I agree that these bikes are as tough as anything on the road. Unfortunately we did not take any photos. My cell phone doesn't take photos well, and I didn't want to carry the big camera. And as far as me having an iron butt, it was pretty damn sore by the end of the day, and I'm still tired 24 hours after we got back( I am 60 years old), but it was well worth it. It was one of the most enjoyable rides I've ever had.
Also, I agree about the carbs, they handle elevation change very well. I used to think I wanted to change carbs, but the way these handle elevation change, and the fact that there are at least six mountain passes within easy riding distance that are in the 9,000ft range, I think it's best to keep the CVs.
DLD
When I was a youngster in my 30's I used to do 500 miles in a day. But now that I'm 66, I find that 400 kms is about right for me. I'm more into the quality of the ride than the distance these days.
One of my favourite rides is going up to Highwood Pass, which is at about 7200 ft asl, from my home at 3400 ft asl. I can't detect any difference in how the engine runs at the different elevations.
I'm thinking about taking a ride on the Icefield Parkway up to Jasper in July. Its beautiful scenery along the continental divide, complete with glaciers.
One of my favourite rides is going up to Highwood Pass, which is at about 7200 ft asl, from my home at 3400 ft asl. I can't detect any difference in how the engine runs at the different elevations.
I'm thinking about taking a ride on the Icefield Parkway up to Jasper in July. Its beautiful scenery along the continental divide, complete with glaciers.
The elevation where I live is about 65 feet ASL, and the mountain passes I can ride to in a few hours go up over 9,000 feet ASL, and so far the XS only shows signs of running a little rich at the very highest elevations.
jd750ace
Front Toward Enemy
The constant velocity carb is "self compensating" for altitude. The slide lift and intake vacuum are dependent on ambient pressure, so it will only open up and flow fuel relative to the absolute atmospheric pressure you are operating in. As the atmospheric pressure drops, the volumetric efficiency drops, but a properly jetted (metered, as the technical term goes) carb will keep the same fueling ratio as it would at a given density altitude, regardless of if you are at 8000 feet in the Rockies on a 70 degree day, or rolling around Florida on a 95 degree day with 90% humidity. Altitude reduces available oxygen for a given weight of charge, just as hotter air contains less oxygen, and humidity reduces it even farther. Either way, less power is developed for a given rate of flow through the engine, both due to the absolute pressure, and the reduction in available oxygen for the combustible mixture. We see similar power losses in the south on days with high temperatures, even near sea level, and humidity plays a role as well. It's approximately 3% HP loss per 1000 feet elevation, based on a standard day, IIRC. I have seen days calibrating aircraft turbine engines where in Dallas, at 531 feet MSL, my calculated density altitude was over 5000 feet MSL. That's why "hot and high" is the double whammy for robbing engine performance.
I hope I can get my bike reliable and go hit some of the shallow mountains here in the Northeast in the next few weeks. We'll see.
CV carbs are very good at making this work. Try the same run with a flat or round slide carb, and you'd have a hard time staying happy.
I hope I can get my bike reliable and go hit some of the shallow mountains here in the Northeast in the next few weeks. We'll see.
CV carbs are very good at making this work. Try the same run with a flat or round slide carb, and you'd have a hard time staying happy.
Last edited:
Nice explanation of the CV carb. I've actually tried it with a different motorcycle and it can be a real pain in the arse at high altitude when your engine is running so rich it doesn't want to start. Good luck on those mountain runs, ACE.
Similar threads
