xr650r surging

5 replies to this topic
  • aussiexr

Posted May 02, 2003 - 12:11 PM


Had my xr650r for a month now.
Has been uncorked with,
172 main
68s pilot
competion needle centre position
Bike surges at 80-90 k/hr
Any one had the same problem?
Bike is used for riding to work and fun on days off :)

  • needsprayer

Posted May 02, 2003 - 02:14 PM



What's your altitude? The jetting may be off a little.
Have you checked the foam air filter? An over oiled air filter can cause problems.
Have you checked the carb clamps (front and rear) to make sure of a good fitting?
Any sign of gas overflowing out of the carb when sitting with the petcock open?
Does this always occur at the speed indicated regardless of which gear you are in? Trying to determine throttle position when this occurs.

It may be possible that the main jet is not seated properly (not snug).

There are other possibilites but this may help you in troubleshooting.

  • Guest_XRANDY_*

Posted May 02, 2003 - 09:51 PM


Try running the stock pilot jet. I found mine ran better with it vs. the 68S.

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  • PeterJ

Posted May 06, 2003 - 04:58 PM


I've got only a few hundred miles on mine and have noticed the same thing. It usually occurs at partial throttle during the last ten miles of running with the petcock in the "on" position, before switching to reserve. Try running on reserve and see if the condition goes away.

  • Burren_Rider

Posted May 11, 2003 - 03:10 PM



One thing you might try is going to a 165 MJ. At 80-90km/hr it would be working on the main and it is likely that the 172 is too rich for Australian conditions (especially at any kind of altitiude). I run a 165 Main and a 65 Pilot and find the bike runs really well in that trim. As far as I know the Safari bikes run by the Honda team also ran that jetting prior to using the HRC kit so I guess that is a fair indication that a 165 is rich enough.

Another thing to watch out for is the spring loaded flap on the choke butterfly. This won't cause surging but can do a lot worse if it fatigues and gets sucked thru to the combustion chamber as they had a habit of doing on the 600's. It is easily removed and might be worth looking at if you intend to to a fair few miles.

  • aussiexr

Posted May 14, 2003 - 11:55 PM


Just an update. With many trips to the dyno :D,jet changes a new exhaust,the problem was fairly simple last resort a sugestion was to check the tappets on doing so we found that the inlet we couldn`t get a feeler gauge in and on getting them adjusted found the locknuts were loose on them.So returned back to spec .Who said pig don`t fly! :)
Thank You

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