Altitude change on 82 Seca

Hi, I just moved from Albuquerque, N.M. to New York City. I brought my 1982 Seca with me. It's still running like a champ but it just sounds a tiny bit noisier to me, and the rpms seem a bit high after the bike warms up.

I've tried adjusting the idle manually, but am wondering if the change in altitude might necessitate an inspection by someone who knows more than me about bikes.

Albuquerque is 5,000 feet above sea level, NYC is 6

 

I'm not claiming to be an expert, but as a commercial pilot I see everyday the effect of altitude on an engine. Atmospheric pressure changes are more drastic in lower elevations than in higher (ie. going from 5000' to sea level will have more of an effect than going from 10 000' to 5000', even though you have still only changed 5000'). So in short, yes that would have a significant effect on your bike's performance. I worked on the west coast of Canada (approx. 3000') last year and tuned the carbs at that elevation, and then moved home to Ontario (600') and did no adjustments and I know my bike is running a little lean. Should be as simple as another colortune and having to dial your idle screws out a couple 1/4 turns.

If anyone has more to add or to correct feel free, but that's what I've found in my experience.

Cheers!

 

Thanks XJpilot. How was living on Canada's west coast? I would like to visit there. I took my bike out for a decent ride today, probably 2 hrs or so. Adjusted the idle again, so now it stays pretty much where I like it, but, it sounds different still. It doesn't sound noisier in a bad way necessarily, I'm
kinda thinking. I almost wanna say it sounds throatier.

Don't know if you've ever been to NYC but on my ride today I drove by the USS Intrepid, which is docked here and which appeared to have an SR-71 and several other fighter jets on display.

 

Hi JC, you have what are known as "constant velocity carbs", they have diaphagms inside that compensate for altitude changes. It's the other type of carb, the "slide type" that need to be adjusted when changing altitude.

 

Correct me if I'm wrong, but aren't the CV carbs only good for minor altitude adjustments? I didn't think they could counteract a 5000' change...

Jc, the west coast is amazing! I spent 2 weeks on my maxim touring through the mountains last summer after I was done work and it was absolutely phenomenal! Got a ride report here if you're interested. http://xjbikes.com/Forums/viewtopic/t=34905.html

 

LVSteve2011, thanks, I'll check that out too. And XJPilot, I checked that trip post, great pix and story! Definitely inspiring.

 

If you think about it, XJPilot, the diaphragms are operated by atmospheric pressure, the diaphragm doesn't care what the elevation is as long as there are balancing forces above and below the diaphragm.