Xr650l problems with carb, jetting? Exhaust pops, rev limiter.

[Jeremy Evans]

I just bought a 2012 xr650l and it starts and runs great until about 4000 rpm give or take (I’m guessing) it feels like it spits and pukes. Also when releasing the throttle the exhaust pops and hiccups. I am calling the dealership to ask if they are willing to fix the problem as I just purchased from them yesterday but I am curious as to what the problem could be in case they do not offer to help for my “as is” purchase. I have read a couple other topics on here that talk about the vacuum lines being hooked up to an air cut diaphram but I don’t know what that is. The smog delete has been done on this bike as well as a slip on dg exhaust and the side cover has a bunch of holes drilled in it exposing the air filter. The battery has also been relocated. My question is what jetting should I have at 2000 feet? I am planning on opening up the carb to see what the idle jet and main jet are and if they were even changed from stock. Also if someone knows about the air cut being hooked up to vacuum and can supply pictures that would be very helpful. I know that the smog block off kits just plug the vacuum holes and the air cut usually gets disconnected. Thanks. 

[ScottRNelson]

If you open up the carburetor, just replace the jets so that you'll know for sure what is in there.  They don't cost all that much at JetsRUs.com

Off the top of my head, I would say a 155 main and a 55 pilot, but I'm sure someone will jump in here with the right answer if that is wrong.  You could consider a 158 main to make it slightly richer.

As for the popping, my bike runs great, I mean really well everywhere, and pops like crazy under deceleration at higher rpms.  I just live with it.

You haven't mentioned the air filter.  A foam Uni Filter works very well with these bikes.

[drewbug]

Sounds like it's running lean.  Mine had similar symptoms when I installed a new carb and exhaust system, even though I went with the jets recommended online.  Only way I solved it was to get a few larger jets and try them.  In the end, it was perfect.  Good luck!

Nice looking pig, by the way.

[Jeremy Evans]

3 hours ago, ScottRNelson said:

You haven't mentioned the air filter.  A foam Uni Filter works very well with these bikes.

It does have a foam uni style filter. I was not sure of what the stock filter was so did not comment on the filter. 

[ricardoguitars]

I have the same problem, it pops an bangs when decelerating, I managed to get rid of the problem rising the nidle to it higher position, but it drank fuel like crazy and stank fuel at idle, it was running too rich; I placed the nidle back on the middle, 55 and 160 jets, 2 turns on the AF screw, and it runs fine, but still popping and banging, I will let it be if that's how she likes it.

[Prairie Rider]

If you're happy with your jetting or re-jetting doesn't improve the condition, there are a few easy things you can try:  1.  Turn the mixture screw out a little at a time to see if the condition improves.  These bikes are usually good at 2 turns out like Scott says. 2. Cover some of the air holes in the side plate with tape, a row at a time, if you find the sweet spot where your bike runs optimally with no popping, you can tape those holes off from the inside of the side panel.   3.  If you have a free flowing exhaust installed and the spark arrester is removed, this may cause the condition you describe as well.  I couldn't get rid of the popping on decel with the spark arrester removed on my Yoshi RS2.  I re-installed the spark arrester and the popping ceased. I also had to close off some air holes to achieve optimal performance.  My bike runs perfectly all the way around...and is a little quieter too.  You may find that a combination of these things will be required - trial and error test rides.  Good luck.

[Prairie Rider]

BTW - Nice bike Jeremy

[Jeremy Evans]

Great info prairie. I will give that a go. I ran the bike today and I think I’m being a little anal. The bike has a ton of torque. It really runs great. I will play a little to try and get the popping to go away but I think you’re right on about the arrester. 

[Prairie Rider]

Ya - if your bike is running great then perhaps the spark arrester will be your fix.  All my Hondas have been like that - XR400, CRF450X and now the XRL.  All these bikes popped on decel with entirely free flowing exhaust - they seem to like a little back pressure.  By the look of your bike I would think that the fella or gal who had it before you had it running as well as it is outfitted and looks.  As Scott said, some just put up with the popping.  At first I thought the spark arrester robbed power but overall the bike just runs a little differently - I notice that it takes a LITTLE away from the low end grunt but allows the bike to rev out better at the high end.  I likey.

[ScottRNelson]

I don't know what sort of spark arrester Prairie Rider uses, but mine is just a fine screen and makes no contribution to back pressure in any way.

It's back pressure that will reduce the popping.  A quiet muffler doesn't make pops that you can hear.  The exhaust on my KTM 990 Adv is totally stock and there is no popping.  But I can hear something on deceleration that might be popping if the sound could get out.  But it's so slight that nobody notices it.

[Prairie Rider]

Stock Yoshimura RS2 screen type spark arrester. Came with pipe.  Definitely the right amount of back pressure to prevent popping.  Living proof.

[Jeremy Evans]

5 hours ago, Prairie Rider said:

 By the look of your bike I would think that the fella or gal who had it before you had it running as well as it is outfitted and looks.

Pretty much exactly what my mechanic said. He is not a bike mechanic but he rides. I had him take this for a spin and he said “leave it alone, whoever set this bike up knew what they were doing” 

[Prairie Rider]

Good stuff.  I'm not familiar with DG exhaust but all the pipes i have owned either came equipped or the manufacturer offers a quiet insert or spark arrester.  Good luck - Jealous you are riding - I lye in wait, steering a snowblower.  I am however in the process of installing a high compression piston and hotcam in my bike - anxious to try it out.

[JoeRC51]

1 hour ago, Prairie Rider said:

Good stuff.  I'm not familiar with DG exhaust but all the pipes i have owned either came equipped or the manufacturer offers a quiet insert or spark arrester.  Good luck - Jealous you are riding - I lye in wait, steering a snowblower.  I am however in the process of installing a high compression piston and hotcam in my bike - anxious to try it out.

While you're in there , slot the cam sprocket holes and retard the cam 6*.

[Prairie Rider]

Interesting. Forgive my ignorance but what will that refinement achieve?

 

[JoeRC51]

More top end and it will rev out a little better.

[Prairie Rider]

I'm all for that!  Once again, thanks for the advice Joe, on it.

[Jeremy Evans]

Thanks for all the help guys. This is my first post in here and the best feedback I have ever received in any forum. It’s true what they say about dual sport riders. You are a bunch of cool ass MF’ers. I just started riding less than a year ago and you guys help keep the sport fun. ??

[Prairie Rider]

Ha! Ride Red!! Well I guess in your case...white.