Author Topic: High (very) Altitude Engine Issues ('74 TX500)  (Read 296 times)

0 Members and 1 Guest are viewing this topic.

Offline Zeph

  • Newbie
  • *
  • Posts: 3
  • Karma: 0
    • Fraser, Colorado
High (very) Altitude Engine Issues ('74 TX500)
« on: August 03, 2018, 01:35:28 PM »
Hey guys,
I tend to ride between 9,000 and 12,000ft. My bike runs mostly OK down at 9000, but when I get up towards to top of a pass at around 12k I run into issues with the oxygen content in the air and dies as if it's being choked out. Has anyone else had an issue with this? A few local guys suggested dropping a smaller needle in to the carb but I can't seem to find anything that actually exists as far as parts for it. Anyone have any insight?

Offline guylr

  • Administrator
  • Hero Member
  • *****
  • Posts: 1126
  • Karma: 17
    • ATL in the USA
Re: High (very) Altitude Engine Issues ('74 TX500)
« Reply #1 on: August 04, 2018, 05:29:47 AM »
The old rule of thumb is to drop one main jet size per 5,000 feet of altitude but I'd only go one size for your 9 to 12k riding because of the ethanol in fuel now. Your Keihin needles should have adjustable clips. If so, then drop the needles (lower them) one clip position and it should be about right. Remember you'll be running lean if you drop down closer to sea level.

Guy
« Last Edit: August 04, 2018, 05:34:51 AM by guylr »
Now Retired Yamaha guy. Cut me and I bleed "Cinquasia Red"

Offline Zeph

  • Newbie
  • *
  • Posts: 3
  • Karma: 0
    • Fraser, Colorado
Re: High (very) Altitude Engine Issues ('74 TX500)
« Reply #2 on: August 04, 2018, 10:44:39 PM »
Hey thanks a bunch! I'll tear into it a little bit this weekend and we'll see how she does up the pass!