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Discussion Starter #1 (Edited)
Hi. I just sold my 2008 530 EXC which was in brand new condition, and purchased a 2012 500 EXC to replace it with and so far I feel I could have made a mistake, and I don't want that to be the case. I feel the EFI isn't properly tuned or something, possibly too lean on idle because it backfires upon deceleration EXTREMELY BAD, and non-stop. I understand that a main cause for backfiring upon deceleration is an exhaust leak but I can't see, hear, or feel any exhaust leak which makes me think that the EFI is just simply tuned too lean on idle or something like that.

Can anyone here please help me with this? At this point I'm really frustrated with my decision to upgrade from the perfect '08 530 to this flawed 2012 500. I also noticed that when I rode the new 500 from my home (Utah) at 4700 feet to the top of the mountain I live nearby to 9000 feet the 500 didn't want to idle. My 08 530 never had a problem up there, you would think that this EFI machine would work better than a carburetor, rather than worse. :mad:

Thanks guys,

Scott
 

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Hi. I just sold my 2008 530 EXC which was in brand new condition, and purchased a 2012 500 EXC to replace it with and so far I feel I could have made a mistake, and I don't want that to be the case. I feel the EFI isn't properly tuned or something, possibly too lean on idle because it backfires upon deceleration EXTREMELY BAD, and non-stop. I understand that a main cause for backfiring upon deceleration is an exhaust leak but I can't see, hear, or feel any exhaust leak which makes me think that the EFI is just simply tuned too lean on idle or something like that.

Can anyone here please help me with this? At this point I'm really frustrated with my decision to upgrade from the perfect '08 530 to this flawed 2012 500. I also noticed that when I rode the new 500 from my home (Utah) at 4700 feet to the top of the mountain I live nearby to 9000 feet the 500 didn't want to idle. My 08 530 never had a problem up there, you would think that this EFI machine would work better than a carburetor, rather than worse. :mad:

Thanks guys,

Scott
sounds like the fuel pressure regulater,but if its new it should be coverd
 

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I am having the same experience - coming off of a very strong running '08 530 and on to a 2012 500 with the same lean issue.

I am, however, that more information will come on this bike on how to tune it to get it running properly. When I first got my 530, it ran like an XR200, then I learned about jetting it properly, a muffler mod and it ran perfect.

I am hoping for the same kind of success on this bike as soon as more information is learned ....
 

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If you remove the cold air pump and filter from the right side of the cylinder head (and plug it with the supplied plug), the lean pop issue disappears.
 

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Same situation

After about 3 hours on my 2012 500 exc the backfire and pop on decel started and has stayed. Dont like it at all. ecavaliere you mention a "supplied" plug. Where would i find that please? I've searched my tool kit and new owners kit etc to no avail.

Thank you all!
Scott
 

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Discussion Starter #7 (Edited)
2012 EXC 500 Popping problem solved

Ok, a follow up.... On the 2012 EXC 500 "popping" or backfiring issue that I knew was caused by a lean condition at idle....

I have found by troubleshooting the issue to be 60% caused by the EVAP purge solenoid and EVAP canister system, and the other 40% caused by the SAS valve (secondary air system).
The EVAP purge solenoid system can be disabled by simply unplugging the small two wire connector from the rubber mounted solenoid just under the throttle body (EFI unit) and it will quit allowing outside air into the cylinder. I personally believe that the factory needs to reprogram the ECM/PCM so that the solenoid is NOT energized at idle, but that's my personal opinion, I think they missed the boat in the programming of "when" the EVAP purge solenoid should be open or closed.

HOWEVER, I don't care if they come out with a new program or not because I've learned that it doesn't need to be there anyway, so I've removed the solenoid, the vacuum hoses, the canister (tucked behind the right side of the gas tank) and the little brass fitting that's screwed into the right side of the intake port of the cylinder and replaced the brass fitting with a small metric screw with locktite on the threads. Also to finish up on the removal of the EVAP system you have to re-route the gas tank breather hose to the hole in the frame where it normally goes on the XC-W or other KTM models, or do what I did and purchase the little orange annodized gas cap breather check valve and hose that is way cool looking. (click on the link)
http://www.ktm-parts.com/U6951010.html
This solves 60% of the popping.

Now for the other 40% of the popping... it's caused by the SAS valve, or secondary air system valve and hose. On the right side of the cylinder you'll see an aluminum valve with about a 1/2" or 5/8" diameter black rubber hose attached and the hose runs up and between the right side of the tank and the frame. This system is also for emmissions and not needed in most states (But KTM had to put it there to sell it in the U.S. as a 50-state legal bike). Remove the hose and the valve from the cylinder and then screw in a 12mm x 1.5mm thread x "as short as you can get it" bolt into the threaded hole in the cylinder with the copper washer and locktite on the threads and you're done! I re-used the aluminum locknut that was on the SAS valve to make my bolt essentially shorter than it actually was so I didn't have to cut my bolt shorter... I spun on the aluminum nut onto my bolt then put on the copper washer, then locktite, then threaded it into the cylinder.

One more thing, when you start the bike after the EVAP removal, it won't idle, you'll have to turn the idle up with the idle knob on the left side of the throttle body. THIS IS BECAUSE the idle screw/knob is actually an air screw and since the idle was adjusted stock with all that extra air being allowed into the cylinder, the idle knob was probably like mine, almost all the way screwed in. In fact, you should be able to kill the engine by turning the idle knob all the way in but in STOCK FORM, you cannot turn the idle down far enough to kill the engine because of all the extra air the other two unnecessary systems are allowing into the cylinder at idle.

I now am finally happy with my 2012 EXC 500.
I also rode it yesterday to 9712 feet in elevation and it idled just fine up there now with the modification, where before the mod it wouldn't idle at that altitude.
Very nice bike,

Scott in Utah
 

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Ok, a follow up.... On the 2012 EXC 500 "popping" or backfiring issue that I knew was caused by a lean condition at idle....

I have found by troubleshooting the issue to be 60% caused by the EVAP purge solenoid and EVAP canister system, and the other 40% caused by the SAS valve (secondary air system).
The EVAP purge solenoid system can be disabled by simply unplugging the small two wire connector from the rubber mounted solenoid just under the throttle body (EFI unit) and it will quit allowing outside air into the cylinder. I personally believe that the factory needs to reprogram the ECM/PCM so that the solenoid is NOT energized at idle, but that's my personal opinion, I think they missed the boat in the programming of "when" the EVAP purge solenoid should be open or closed.

HOWEVER, I don't care if they come out with a new program or not because I've learned that it doesn't need to be there anyway, so I've removed the solenoid, the vacuum hoses, the canister (tucked behind the right side of the gas tank) and the little brass fitting that's screwed into the right side of the intake port of the cylinder and replaced the brass fitting with a small metric screw with locktite on the threads. Also to finish up on the removal of the EVAP system you have to re-route the gas tank breather hose to the hole in the frame where it normally goes on the XC-W or other KTM models, or do what I did and purchase the little orange annodized gas cap breather check valve and hose that is way cool looking. (click on the link)
http://www.ktm-parts.com/U6951010.html
This solves 60% of the popping.

Now for the other 40% of the popping... it's caused by the SAS valve, or secondary air system valve and hose. On the right side of the cylinder you'll see an aluminum valve with about a 1/2" or 5/8" diameter black rubber hose attached and the hose runs up and between the right side of the tank and the frame. This system is also for emmissions and not needed in most states (But KTM had to put it there to sell it in the U.S. as a 50-state legal bike). Remove the hose and the valve from the cylinder and then screw in a 12mm x 1.5mm thread x "as short as you can get it" bolt into the threaded hole in the cylinder with the copper washer and locktite on the threads and you're done! I re-used the aluminum locknut that was on the SAS valve to make my bolt essentially shorter than it actually was so I didn't have to cut my bolt shorter... I spun on the aluminum nut onto my bolt then put on the copper washer, then locktite, then threaded it into the cylinder.

One more thing, when you start the bike after the EVAP removal, it won't idle, you'll have to turn the idle up with the idle knob on the left side of the throttle body. THIS IS BECAUSE the idle screw/knob is actually an air screw and since the idle was adjusted stock with all that extra air being allowed into the cylinder, the idle knob was probably like mine, almost all the way screwed in. In fact, you should be able to kill the engine by turning the idle knob all the way in but in STOCK FORM, you cannot turn the idle down far enough to kill the engine because of all the extra air the other two unnecessary systems are allowing into the cylinder at idle.

I now am finally happy with my 2012 EXC 500.
I also rode it yesterday to 9712 feet in elevation and it idled just fine up there now with the modification, where before the mod it wouldn't idle at that altitude.
Very nice bike,

Scott in Utah
Thanks Scott!

Great info there - I have experimented a bit my 500exc with similar results. Removing the SAS system was a huge improvement, and when I removed the EVAP system my bike would not idle (as you described). I pretty much chickened out from there and re-installed the EVAP system. It sounds like I just need to turn up the idle and I'll be good to go - great news. How much time and how many miles have you put on your bike since removing all of this equipment? It sounds like you have been "trouble free" since removing all the extra equipment, and that is what I am hoping to hear.

Thanks again!
 

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After about 3 hours on my 2012 500 exc the backfire and pop on decel started and has stayed. Dont like it at all. ecavaliere you mention a "supplied" plug. Where would i find that please? I've searched my tool kit and new owners kit etc to no avail.

Thank you all!
Scott
Scott,

The plug I am describing was supplied in the PDI bag along with the mirrors, tool kit, etc. If you did not get one, you can order the plug off of the '12 500xc-w.

Good Luck!
 

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Discussion Starter #11
Trouble free?

Yes, trouble free since the modification... and I also believe it will always be trouble free because if you stop by your KTM dealer and look at a 2012 500 XC-W engine, on the right side of the cylinder, you'll see the two plugs in the two ports that I mention that I plugged on the EXC. This tells me that everything is "as it should be" now with the plugs I installed because it's now the same as the XC-W comes from the factory.

I believe that all 500 EXC owners should remove these two systems.
(unless of course you live in an area that requires emmissions testing on your street legal dirt bike)

Take care guys, KTM bikes are the Mercedes Benz of bikes I believe,

Scott
 

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Gents, what method did you use to remove the SAS from the cylinder head?

I'd sincerely appreciate your guidance on how you removed the fixture from the head as i'm a little gun shy here!

My sincerest thanks!
Scott
 

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Discussion Starter #13 (Edited)
Just go for it...

Ok, I can feel I might get long winded with this reply for you... but here goes.

(removing SAS valve)

Ok, first you remove the rubber hose from the valve's hose nipple and set the hose somewhere, then I used a 3/4" (or 19mm) "crow's foot" wrench to loosen the aluminum lock-nut (it only needs to be cracked loose, that's all) If you don't have a crow's foot wrench, you might try to reach in with a typical wrench and see if you can grab onto just enough of the locknut to crack it loose. Then I simply rotated the entire valve counter-clockwise to remove it from the engine, but you'll quickly notice that it only rotates about 90 degrees and then the nipple will hit the radiator hose/thermostat housing. I simply pushed that hose/housing away from the valve with the right hand while I rotated the valve with the left hand and it will scrape a little but it does clear and it will continue to spin out all the way after doing that about 3 times. If you don't want to do that you can simply remove the small screws that hold the valve halves together and it will then spin out easily, but really that's not necessary.
Then remember that the bolt that you need to plug the hole where the SAS was removed is a 12mmx1.5 thread. I removed the locknut from the SAS valve and took it with me to Lowes to buy a bolt and quickly found out that Lowes stocks 12mm x 1.25 thread, and 12mm x 1.75 thread, but NOT the 1.5mm thread bolts. So I had to go to a nut & bolt store to buy my bolt.

The SAS valve does the exact same job as the "air pump" does on cars in the '80's and '90's. It allows outside air to be administered into the exhaust near the engine so as the air gets mixed with the exhaust, the 21% of oxygen in the air helps to more completely burn the un-burned hydrocarbons as the air and the unburned HC's travel down the exhaust pipe so that by the time the exhaust exits the pipe there is less un-burned HC's emitted. This system on the KTM acts like an exhaust leak near the exhaust pipe/head flange and that's why it pops in the exhaust during deceleration is because of the cold air coming into the exhaust from the SAS is exactly like an exhaust leak sucking in cold air during deceleration.

The EVAP system isn't allowing cold air into the exhaust, it's allowing outside air directly into the intake port of the cylinder, leaning out the mixture substantially which is why the idle has to be adjusted after removing the EVAP system. I honestly believe that KTM is going to have longevity issues with the EXC engines if they continue to leave the ECM programming the way it presently is now in regards to this EVAP system. It's just simply bad news and not engineered properly I think. After removing both systems I feel soooooooooooooooo much better about my bike's longevity for the long run, and I am also not embarassed anymore by the extreme backfiring or popping.

Scott in Utah
 

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Scott, WOW, let me convey my sincerest gratitude for your detailed explanation. No doubt this will serve many members and 500 exc owners. I'm very grateful!

Any chance you ride much in Southern Utah? Would love to shake your hand and say "Thanks" some day!

My best,
Scott
 

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Discussion Starter #15
Orange stuff

With as cold as it is getting now in northern Utah it makes me start to consider riding in southern Utah, but it's hard to set aside the time... but I might try to make time this winter...

Here's some pics.











 

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Thanks A Bunch Wizard64

My son purchased a 2012 EXC 500 a couple of weeks ago and it had the same backfiring problem. We were waiting for someone to come out with a fix online. I found this KTM forum while searching for fix, and watched everyday for the FIX! Thanks A Bunch to Wizard64!! We followed your directions, plugs came with the owners kit, and it took less than a hour to fix. The difference is amazing! No more backfiring, seems to pull better everywhere,(maybe yes, maybe no. It could just be we're so happy no POP!!). Great bike now! Now, how do I get my son to let me ride his bike more? If he keeps it up I'm going to buy my own!! I've been waiting on Honda or Yamaha to build basicly their own EXC 500 street legal bike. But I've waited long enough, and this KTM 500
ROCKS!!!
Again Thanks a Bunch Wizard64 we owe u!

whatarush
 

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Wizard, I TOO Thank you a TON!!!! Followed your directions exactly and yes not only is the backfire gone, but I genuinely feel that bike has more "pull" now. There's certainly a difference.

Biggest challenge i had is i did not have the plugs and therefore ended up cutting a bolt to size for the SAS plug. Took some time assuring all barbs etc were clean as i didn't want to have any left over metal filings around in the cylinder.

After that, the rest was a breeze. Used locktite and had to turn my idle screw (choke) about five times to get her to idle.

Sincerest thanks!!!!

Scott
 

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I have made the same mods as Scott with similar results. It is odd that KTM tells you not to remove the smog stuff (read the Dirt Bike review that says the bike will not run right if you do) and yet they provide the cap you need to use to cover the hole when you remove the SAS valve. I am now focused on fuel map and ignition map modifications. There is a ton of confusion out there on those issues. Scott, do you have any wisdom to share?
 

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This was the BEST modification i've made to my EXC to date. I later went ahead and ordered the OE bold for the head (that goes on the XC-W) for a clean look both other than that, I never need choke for cold starts and this bike runs so much better.

I've also done down to a 13 tooth front sprocket, leaving everything else the same, and that has made a very large difference for hill climbing etc and my top speed has really only dropped from 95 to 80 MPH.

Love this bike!
scott
 

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You might want to mess with the air fuel mixture because of how high up you live the higher the altitude the less air there is for the bike to breathe
 
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