exhaust issue

Hey guys,

I recently modded my 09 250x for the altitude. I ride mostly around 7,000 ft. I opened the airbox (removed the snorkel, cut the top of the box off) and removed the screen, added a No Toil filter and frame, rejetted the carb (JD Jetting kit.....42pilot, 165 main, red needle with clip in third slot from top), replaced the fuel screw. I also threw on an exhaust tip from 2R Racing. It gets rid of the stock tip and baffle. The exhaust opening is now 1.650 inches. I have seen some mention of this tip here and how much people like them. In my application, the exhaust pops now on deceleration (a pretty decent backfire sound). Is this normal, or do I have to adjust something? Any help would be appreciated!!!

Thanks,

Brian

Your bike had a muffler (which quenched pops), you have opened it up and it can no longer quiet it.

You should ensure you have no exhaust leaks and I assume you properly reset the fuel screw and did not just set iot to'some position' without proper testing.

Also, looking at your jetting for 7,000', you look way rich on the main and needle.

Mine pops a bit, too. I kinda like it. :thumbsup:

It would pop on decel because there is too much unburned fuel in the exhaust. What grade of fuel are you running, and have you thought about running a tad leaner? Also check for an exhaust leak where the header meats the muffler.

Hey guys,

Thanks for the input! I was wondering if I was running too rich. All I did was follow the instructions included with the JD Jetting kit for use above 6,000 ft. Maybe I need to experiment with the jets. I was told the advantage of this kit was that it took the guess work out of the jets to use. Oh well, back to the drawing board. I dont think I have a leak at the header junction. The bike is brand new, but I guess stranger this have happened. This is so frustrating.....I'm no mechanic, but I am learning!

Thanks,

Brian

Also if your running too high of an octane the fuel won't completely burn off. You might try lowering your octane to mid grade.

I'm just using 91 octane. I suppose I could try 89. Anyhow, I will see what leaning out the jetting will do. Sounds like I will be in for some trial and error. I was trying to avoid that. Oh well. Thanks for the input everyone.

Brian

You are way rich for that alttiude. Does your bike have the air pump? The Cali bikes that have the air pump have a decel pop. It is annoying but normal.

Hey guys,

I recently modded my 09 250x for the altitude. I ride mostly around 7,000 ft. I opened the airbox (removed the snorkel, cut the top of the box off) and removed the screen, added a No Toil filter and frame, rejetted the carb (JD Jetting kit.....42pilot, 165 main, red needle with clip in third slot from top), replaced the fuel screw. I also threw on an exhaust tip from 2R Racing. It gets rid of the stock tip and baffle. The exhaust opening is now 1.650 inches. I have seen some mention of this tip here and how much people like them. In my application, the exhaust pops now on deceleration (a pretty decent backfire sound). Is this normal, or do I have to adjust something? Any help would be appreciated!!!

Thanks,

Brian

you might want to lean out the clip a little more. i normally ride 3500ft and did a race at 9500ft elevation. we jetted it according to JD specs. when we got up there, it had such a bad bog. it was on the 3rd clip and then changed it to the 4th (maybe 5th, which is what we normally run at 3500ft) it worked perfect.

and for the poping..do you have that smog pump thing on your bike? I have one on my bike. all it does is add oxygen to the exhaust for a cleaner exhuast output. so if you still have it on your bike, that probably explains the popping.

hopfully this helps.

you might want to lean out the clip a little more. i normally ride 3500ft and did a race at 9500ft elevation. we jetted it according to JD specs. when we got up there, it had such a bad bog. it was on the 3rd clip and then changed it to the 4th (maybe 5th, which is what we normally run at 3500ft) it worked perfect.

and for the poping..do you have that smog pump thing on your bike? QUOTE]

Lets see....thats 2 posts in this thread that say the same thing I've experienced....the JD kit is not a magical solution. I've tried about 20 different jetting settings and am back to my stock needle now. Unfortunately, my o-ring on the AP broke somewhere along the line, so likely would have been golden before now....I've wired it so that won't recur! Bottom line though was I did exactly what he said and it bogged.

+3 on the CA version bike with a smog pump. Mine too backfired with it, but it did it with the stock muffler. If it didn't backfire before, then likely thats not it.

Dave

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