Kortbroek
Race Dog
So I had an interesting new issue on the XR650R the past weekend. At speed (120kmh+) and around 6000rpm the bike sometimes bogs down and starts losing revs. This only happens when I am accelerating with the throttle wide open, if I back off the throttle a bit it recovers right away. If I roll it on more gently it pulls fine to 160kmh+ and will keep going . Now I was able to get this to happen multiple times and the common denominator was being on a rough surface. I tried the same on tar and it didn't happen.
My suspicion:
1) Choke plate might be closing at high revs over a rough surface. Likely the spring holding it open is tired so high revs combined with the bike running over a rough surface could see this getting sucked closed? Might explain the quick
recovery as soon as I roll off the throttle a bit? :dontknow:
2) Another possible culprit could be a blocked breather causing crap at higher revs (not sure if this would actually cause this symptom)?
Then another issue I have picked up over the last few months is a hanging idle. I would set the idle at 1400rpm when the bike is warm, after riding a few km it would idle at 2200-2300rpm and only settle down after a few blips on the throttle.
Now I'm thinking there are a few possible culprits here:
1) Pilot jet mixture screw setting has gone awry.
2) Carb needs a good clean maybe. It is overdue for one anyhow.
3) Leaking carb boots? Also not unlikely. What is the easiest way to diagnose this?
What say the XR brains trust?
My suspicion:
1) Choke plate might be closing at high revs over a rough surface. Likely the spring holding it open is tired so high revs combined with the bike running over a rough surface could see this getting sucked closed? Might explain the quick
recovery as soon as I roll off the throttle a bit? :dontknow:
2) Another possible culprit could be a blocked breather causing crap at higher revs (not sure if this would actually cause this symptom)?
Then another issue I have picked up over the last few months is a hanging idle. I would set the idle at 1400rpm when the bike is warm, after riding a few km it would idle at 2200-2300rpm and only settle down after a few blips on the throttle.
Now I'm thinking there are a few possible culprits here:
1) Pilot jet mixture screw setting has gone awry.
2) Carb needs a good clean maybe. It is overdue for one anyhow.
3) Leaking carb boots? Also not unlikely. What is the easiest way to diagnose this?
What say the XR brains trust?
