Jetting question 650R - starting issue


8 replies to this topic
  • resslera

Posted October 29, 2006 - 10:32 AM

#1

Question here. First off, bike is uncorked but I'm at approx 6,500 alt and jetted for it. When starting, sometimes the bike starts on first or second kick when full choke. Other times it sputters on the first kick and then I know I am going to have to work a little. Some times when this happens I immediately drop to half choke and it will fire right up. If it still doesn't start, could take several more kicks.

I found out today that if I crack the throttle a little, it starts easier cold. Does this mean I am lean on the pilot? Could adjusting the fuel screw help with this situation?

  • RhedF350

Posted October 29, 2006 - 05:24 PM

#2

Are you talking about a 650r? I'm at 5000' and went with the 68s pilot. It starts much easier than when it had the stock 65.

  • snaggleXR650

Posted October 29, 2006 - 06:48 PM

#3

The 68s pilot is plenty rich at sea level, it would be really rich at altitude. If the bike doesn't like full choke it's because the pilot is too rich. It will start better on half choke because there is more air coming in through the butterfly valve, which if fully closed during full choke. Cracking the throttle is a no-no. Another way to tell is how quickly the motor will run after a cold start. If you only choke it for 5 seconds and then the bike seems like it's ready to rip immediately, then the pilot jet is rich. At the same time, when the bike is hot, and get's to be a pain to start, this is also due to a rich pilot.

I've found that a bit leaner pilot jet is better during hot starts and keeps the bike from flooding out so easy if you kill it in the woods or dump it. Cold starts will require full choke and a bit of warm up until the motor idles smoothly. This is a good thing though, as it's better to let the oil warm up before you take off.

  • RhedF350

Posted October 29, 2006 - 07:31 PM

#4

I settled on the 68s after jetting the main with a 162. I tried the 65 at first, but it was definitely harder to start. With the 68s on a 100f day, the full choke is about 15-30 seconds, and on the 30f days, the full choke time is a full minute. It seems like the right setup for the bike, however the hot flooded starting is hard. I never gave much thought to the 65 being easier to start after flooding. Maybe I'll retry the 65 next time it's apart...:mad:

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  • resslera

Posted October 29, 2006 - 08:01 PM

#5

Yep, 650R I'm talking about. Mine sometimes will fire on full choke but if it sputters and quits, I have to go to half. I still have the stock 65 which is what was recommended at my altitude by other 650R pilots. As far as choke goes, I drop it off full immediately, half just about 15 seconds, then no choke for a warm up. I always thought you didn't want choke on too long.

Also don't want to go too rich on the bottom because I end up riding to elevations as high as 10,000 and don't want the bottom ridiculous rich at those alts.

  • doc8m

Posted October 29, 2006 - 10:31 PM

#6

I settled on the 68s after jetting the main with a 162. I tried the 65 at first, but it was definitely harder to start. With the 68s on a 100f day, the full choke is about 15-30 seconds, and on the 30f days, the full choke time is a full minute. It seems like the right setup for the bike, however the hot flooded starting is hard. I never gave much thought to the 65 being easier to start after flooding. Maybe I'll retry the 65 next time it's apart...:mad:


If i flood mine, and it doesn't start on first or second kick my proceedure is 1)turn off the gas2) while pulling decompression lever and holding throttle wide open, kick at least ten times usually resulting in a backfire, then repeat, usually resulting in a second backfire,3) try to start the bike, gas still off. it will almost always start at this time. not fast but very reliable.. My riding is pretty much all done in the desert at about sea level. I don't remember the jetting but it was as recomended for the basic proceedure of opening exhaust and intake. otherwise the bike is stock 2003 xr650r

  • RhedF350

Posted October 30, 2006 - 06:45 AM

#7

Well, I'm goin out this am for a ride. Start here at 5000 and ride to about 9000 and back. I'll try the flooded thing with the 68s that's in the bike, then When I ride the same loop later this week, I'll have the 65 in it. It's about 30f now with a max of 58 today.

  • RhedF350

Posted October 31, 2006 - 09:12 AM

#8

Went for a 55 mile mostly single track ride yesterday. The first stall and dump on a rocky uphill resulted in 20 minutes of trying to restart the pig. I'll switch to the 65 pilot soon. Then I boiled all of the coolant from the overflow tank after another slow uphill...but ran it for another 20 miles with no trouble. I checked the radiator level after it cooled and could still see antifreeze over the fins. Also ordered a 13 for the front sprocket.:mad:

  • doc8m

Posted October 31, 2006 - 03:45 PM

#9

bummer..I thought i had the magic formula for ya. It crosses my mind that i also do much better starting in neutral than in gear. didn't mention it but pretty much a given. also most guys start with no throttle, the same as the 600, but for mine I actually barely tease the throttle when i kick it. good luck with the jetting





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