Old Dog, on 23 August 2012 - 10:31 PM, said:
I've had the same problems in the past on other bikes, and it was usually an air/vacum leak somewhere that was causing it. Have you checked the carb boots (from engine to carb and carb to airbox) to see if they're cracked/split/leaking/loose? Even a tiny leak/crack can cause BIG problems that all the jetting adjustments in the world won't fix.
elsalvadorklr, on 24 August 2012 - 08:12 AM, said:
well jet down till you feel lean means just that...till you start surging at a certain rpm then jet back up...
but befor you do any of this like old dog says you have other issues
1. you shouldnt have excess backfiring or close to none when letting off the throttle especially with your jetting
2. HANGING IDLE is a huge indication that you have an air leak
make sure the boots on your carb are sealed, check with some carb cleaner sprayed around the intake boot sealing area and airbox...
I beleive the xr650r is 17 or 18mm from flat part of bow to flat part of float
on the xr600 its 15mm
in reality unless the floats are installed upside down it really is hard to bedn them out of shape
for example if you park the bike on the stand are you getting fuel spilling out the vents? thats a sign you need to readjust your float
hanging idle can also be caused by a dirty pilot jet...
fix this before you start jetting
like mentioned before its really hard to start jetting if all of your systems arent 100 percent
no point in jetting for example if your stator is acting up or you have weak spark or a muffler full of holes or an airbox with a torn boot. etc..etc...
scalejockey, on 24 August 2012 - 12:11 PM, said:
I noted that the "intake valves were at zero"? Might check them again,they might be sucking into the head.They can be good for a short while then go out again once they start moving(or cupping),, Then problems show up when the bike is hot. Had mine do this last year.
Also the float level is picky on these..
Mikie1, on 24 August 2012 - 12:52 PM, said:
Do you use one of those one-way valves on your vent line? If so, try just a straight vent tube. Seen this problem several times.
So after reading all your posts I went out and really tore into the carb. I adjusted the float, took out the main jet, pilot jet, air fuel screw, and the main emmusification (spelling, sorry) tube that holds the main jet. And to my surprise the little needle guide that is held in by the emmusification tube was backwards!!!! So I flipped that around. Put the jetting to 65, 3rd clip, and 168. Buttoned it up and messed with the air/fuel screw while at a low idle, set it about half way through the range. Bike is running a lot better, even at high temp, still pulses a bit, but I am going to take your guys advice and keep jetting down until I feel a difference. I also checked the plug and it was black but burnt black not like oil black so I checked the manual
and it called it a carbonated plug and that the mixture was to rich so I am going to keep going down in size. The bike already responds much much better. To be very honest I think I put the needle guide in backwards the other day which obviously is causing a huge hanging idle, my bad. BUT, now that it is the right way I am still having the same problem pulsing. I am really starting to be convinced I am jetted to rich.
So I tried spraying carb cleaner around the boots on the carb and the engine no change. I will re check the valves. What do you mean by the one way valves on the vent line, I am not sure which of the 4 tubes coming of the carb is the vent line. Thanks for all your help, I think I am getting close.