GL1500 High Altitude Jets?

[PagosaRider]

Hello everyone. I just moved by 1998 GL1500 to 7500 ft from sea level. It ran fine at sea level. The bike only has 35,000 miles on it. The bike is running very rough and hesitates alot below 3000 RPM. I was told by someone that I may need to get high altitude jets for it. Does anyone have an idea on where to get high altitude jets, or if they are even offered on the GL1500?

Thanks much and let me know!

[Rambozo]

I bet DenverWinger can answer that.

[DenverWinger]

I changed jets on some older cars imported from low altitude and most of my bikes previous to the 1500, but I've found the 1500 altitude compensation to be very good. And the high altitude jets correct an overly "Rich" condition, you sound like you are running "Lean". Symptoms of needing High Altitude jets are the engine idles fine, but black exhaust and poor power at high RPM/Heavy throttle because the engine is drowning in fuel.

I've also found additional timing advance helps many older engines without the fancy compensation, again the 1500 hasn't needed that at 5280 ft, nor have I noticed any "bad" performance at even higher altitudes like 10,000 ft. If the majority of your driving will be at high altitude you may benefit from a 4 degree advance ignition trigger wheel - available from Cyclemax. But I don't think that's your problem, either.

Your lower RPM issues indicate fuel/carburetion problems, I'd be investigating a vacuum leak somewhere, especially in the vacuum hoses known to be fail points (under the rubber heat mat). In the thin high altitude air the 1500 will never have the same power it does at sea level (neither does anything else), but without any mods should still run admirably and to perfection at lower RPM without any roughness or stumbling.

[Rednaxs60]

Agree with DenverWinger, the 1500 should perform as well at higher elevations as it does at sea level. The 1500 engine system may use carbs, but the system design is to emulate a fuel injection system with its 5 components systems. There is a thread on this forum, maybe on others, that explains the 5 component systems. Not fuel injection, but Honda did a good job with this engine. Went looking, but could not find it, maybe someone else remembers the article.

Some good reading:

viewtopic.php?t=37739

Edit: Was concerned about the 1500 carb issue when I bought mine, since sold - prefer FI. No issues with the carbs in the two years I owned it riding in British Columbia. Carbs get a bad rap whenever anything happens, when the issue can be something else. Agree with the vacuum hoses, lots of forum threads regarding 1500 vacuum system. 25 year old bike engines that have never been apart for system parts/components replacement may need closer inspection - nothing lasts forever.

Good Luck.

[PagosaRider]

Thank you so much guys! I really appreciate it. I'll start looking into the vacuum issue. I sure appreciate all your expertise!