WhatTheHellIsWrong with WhereTheHelliIsJames' bike?

I’m at a loss. I can’t seem to figure out what is going on with this bike, and it’s driving me nuts. It all started towards the end of March on the n00bs ride in Death Valley. Many people there heard about ‘the broken KTM’, but so far, nobody has been able to present the solution.

Details of the bike: 2006 KTM 950 Adventure. Canisterectomy, flappendectomy, SAS removed, ran fine, then just started not running fine- no major event, no revving, no nothing. Out of nowhere, while maintaining a steady RPM on the highway, it just started running crappy on the front cylinder.

Here’s the deal…
Riding along the highway between Panamint Springs and Furnace Creek, something happened. No clunk, no thud, no whap, no nothing… it just started not wanting to run right below 6k RPM. When we pulled into the fuel station at Furnace Creek, the clutch was pulled in to coast up to the pump, and the engine died. Weird, but whatever- thinkgs like that happen sometimes. When we go to ht the trail, the bike is hard to start, wont idle, and is popping a bit. I figure that maybe it’s flooded, or there’s a piece of debris in the carb that’ll work its way out in a couple of miles, so we head up the road. Things don’t get any better after a few miles, so the decision is made to stop, figure out what’s going on, and try to fix it.

Turns out that it’s the front cylinder that’s popping, and it’s acting like the jet is clogged. Off come the crash-bars, fuel tanks, glovebox, airbox, and carbs, and I opened them up for a quick service right there in the middle of the desert. Nothing- those jets are clean as a whistle. Thinking that maybe whatever was stuck in the jet had fallen out when I drained the float bowl, it all went back together. Turn the key, fire it up, and pop, hmm hmm pop pop hmm pop. Still the problem persists. At this point I’d been holding up my friends for an hour in the middle of the day while we tried to fix the bike. I knew that my ride was over, so I sent them on their way and headed back to Panamint Springs on the bike.

On the highway, it rode like one might expect- not as good as it does when all is running perfectly J It did keet a normal temperature though, and didn’t seem to be struggling terribly. When I got back to camp, a thorough cleaning was in order. I spent the rest of the day pulling it apart, going through that front carb extra carefully, then put it all back together. Turn the key, and … hmmm pop hmm hmm pop pop hmm pop. WTF?! I sought outside help, and Lior stepped up to the plate and offered assistance. We worked on that bike until around midnight, and never did out whet the heck was wrong with it. Some other forum members offered up some spares, so we replaced the plugs on the spot, swapped coil packs front to back, as well as bypassed the fuel pump and used brand new super out of Liors tank. A valant effort on the part of the community, yet the problem persisted, and the front cylinder continued to pop and backfire. We were out of ideas, and it was late.

The next day, a VERY COOL forum member set me up with a loaner bike for the day, and I got to go ride. It was my first trip to DV, and I was super stoked to be a part of a community so caring, that they offer up a spare bike when mine was beyond field repair. Another VERY COOL forum member drove me and the KTM all the way back to San Francisco when the trip was over. To all that contributed- you know who you are and what you did for me, and I’m so grateful. Thank you.

Continuing on… the bike is back home, and I’ve had it apart now more times than I care to admit, and it’s still misfiring on the front cylinder. Seriously, WTF. I’m at a total loss here. The carb is probably cleaner than it came from KTM, the valves are in spec, the cams are where they should be, fuel is getting to the carbs, new boots (not that there was anything wrong with the old ones) but still, that front cylinder keeps on backfiring!

It seems to be a lean condition…
When the bike is running, and you look down the carbs, the slide on the rear carb is going crazy like it should, but the front is hardly moving. It pops humms pops pops humms, etc. When I put my hand over the front carb, the popping stops (this is why I say a lean condition).

Here’s what I’ve done:
* Cleaned that front carb like I never have before… like 5 times. Carb cleaner, compressed air, banjo string, the works. Lior cleaned it twice too.
* Checked and confirmed that the valves and cams are in spec. They were. I thought that maybe the cam chain had somehow skipped a tooth, but it didn’t.
*Replaced spark plugs, and swapped coil packs front to back to see if the problem switched cylinders. It didn’t.
* Replaced intake boots.
* Drained old fuel completely, and put some fresh non-ethanol stuff that I bought while in Oregon last week in it.
* Checked all the fuses, and moved them around / swapped positions.
* Cleaned fuel lines from the connection halfway down the left side all the way up through the T and to the carbs.
* Thoroughly checked/cleaned (not that it needed it) the bellow that the needle attaches to.
* Removed the SAS system and installed block-off plates / plugs.
* Confirmed that there is no air leak where the canisterectomy bolts were installed.
* Replaced the vacuum lines (for carb-synching) on the right side of the manifolds.
* Ran the bike without the airbox on it, placed my hand over the front carb, and sprayed carb cleaner and starting fluid around the boots and intakes to confirm that there were no air leaks there.
* Confirmed that the valves seating by turning the engine to TDC, and spraying carb cleaner in the manifold. It pooled and sat on the valves overnight, with no change in fluid level. (yes, I sucked it all
out before turning the engine over again)
* Slaughtered a chicken and lit some candles.
* Finally, after a month of trying to fix this on my own, I wrote this long-winded post.

So that’s where I’m at… out of ideas. If your suggestion turns out to be the fix to the mysterious front cylinder backfire problem (and no, taking it to a shop doesn’t count), I’ll send you a set of Pie-Hole makers. Also, if you have a spare front carb, and you’re 100% certain that it is 100% good, and you’re willing to loan it to me for a quick test to confirm that I'm not completely inept at cleaning the carb that's on this bike, I’ll gladly pay the shipping costs both ways, and do something cool for you.

Some very bright KTM folks are stumped on this one. If you figure it out, you’re a hero.

I had that happen to me once, double check to make sure the front carb is seated in the rubber boot to head, its a son of a gun to get it seated, I use a long bar and pry it down to snap it in place. If it isn't seated completely it will run way too lean, something to check for anyway

Have you tried to swap the diaphragms between the carbs? It has been noticed that some times they might get hard with age and reluctunt to move properly. Do your slides rise in tune with each other?
Also, a long shot as I don't remember if it is possible, but can you reverse the carbs for a static test?
Alternatively, find a friend with time and appetite and swap carbs.

How about the hall effect sensor that signals the front spark?

Seems like there is something here!
Cheers.

Double check all vacuum caps. You mention two lines, but there are four vacuum ports on the manifolds. If you use an air flow meter to check carb sync, you can remove all lines and seal the four ports. It removes one possible source of problems. Also, carbs way out of sync will do just what you describe. I don't know why they would jump out of sync, but when my bike goes a little out of sync, it pops just like that.

Intake valves on front cylinder may be out. Mate had the same symptoms on 03 950 and it was tight intake clearances and carb sync.

Well, hell, I've got nuthin for ya, but this:

* Slaughtered a chicken and lit some candles.

takes me back to so many fun places from my racing days..

That I had to say thanks!

Steve

+1 This would be my next step. Check for pin holes or tears as well.

Thanks for the ideas, folks!

Peeps who mentioned the diaphragms:
* I cleaned and inspected that diaphragm a couple of times while the carbs were apart, and it was good and plyable (as opposed to tough and brittle).
* I didn't try swapping the two (since it really appears to be just fine), but I will give it a shot either today or tomorrow.

Peeps who mentioned other stuff:
* The intake valves are in spec, not tight, not loose.
* There are 2 remaining vacuum ports on the manifolds, as 2 were permanently sealed. for the two that remain, I installed new hoses, clamps, and caps.
* The front carb is definitely seated correctly.
* The front spark is strong.

Regarding swapping the carbs for a static test:
* I didn't do this since the carbs are asymmetrical.
However, I wonder if I could disconnect all the cables, remove the airbox, and pop them on the manifolds backwards for a hand-operated static test. I could definitely leave the TPS connected, and I think there might be enough slack in the choke cable to connect that too... if I unlaced in from the frame and kept the bars turned to the left... this might just work.

I'll report back later today or tomorrow with my findings after swapping the diaphragms (if they're swappable), as well as to report the results of the static carb swap... if in fact it can be done.

Seems off point, but could your fuel pump be dying?

That maybe wouldn't explain the popping, but could definitely explain some of the other things. It will cause some weird stuff to happen on its way out and will work most of the time, but quit unexpectedly at others.

The fuel line goes from the pump to a T connection, where it splits to each carb. If the pump was going out, then the problem should exist in both cylinders, and not just the front. The pump seems to have good pressure, and equal amounts of fuel look to be going through the carbs into each cylinder.

FWIW, I tried bypassing the fuel pump, and fed gas through an IV canister to the carbs, both when it happened out in DV, and once since. The rear cylinder ran fine, and the front didn't.

ok, my $.02 and i hope i get something right just so you can enjoy your bike.

First, sounds like your front cylinder is not moving air properly (because you mentioned the diaphragm) check your whole exhaust, maybe you have a clogged cat for the front cylinder, also check for dents on the exhaust, all the way.

Second, try spraying starting fluid or carb cleaner on the front carb with the engine on, see if it makes a difference. (please be very carefull with this, don't burn yourself)

Third, have you check the pick up coil? you mentioned you had spark, and that makes me think it doesn't has anything to do with it, but check it none-the-less.

Fourth, have you checked your choke cables? if they get stuck open for some reason it will make your symptoms.

Remember something, you need 3 things for combustion, spark, fuel and air.
i have blackberry messenger and whatsapp, i can give you that info so we can chat and talk about possible faults, I'm a mechanic.

Today I did all the things that were suggested...

I swapped the carbs front to back, and guess what... it didn't make a difference. The front cylinder still sputtered and popped and backfired, etc. The good news, is that this tells me that I'm capable of cleaning a carb out just fine, and that I'm not crazy thinking that it's spotless and perfectly operational. Just for kicks, I swapped the coil packs and intake boots at the same time, and nothing had any effect on the condition.

Knowing that its not the carbs, I put the bike back together, then started at the other end. As suggested, I checked the pipes for dents/kinks/cracks all the way down, and (as I already knew) there were none. I removed both cats/silencers, and fired the bike up. Good thing that I had my Remmington headphones that I use for trap shooting on, because man that sucker was loud running on open headers!! (my neighbors must love me)

The good news, is that I can also eliminate the cat/can's from being the problem here, since the backfiring and poor running condition remains the same with or without them. Just for kicks, I swapped sides when I put them back on. The bad news of course, is that if the problem isn't being caused by anything on either end, then it's somewhere in the middle... which is always more difficult. At least it's getting chased down a bit.

FWIW, after the engine warmed, I checked the oil again, just because, and it was perfectly full to spec.

So... if it's not the carbs, not the cans, not the manifold boots, not the coil packs, the valves are within spec, and the cams are where they should be, what's next?

Next would be compression and leak down test, because if it has spark, fuel is fine and air is fine then the problem is "the pump" meaning rings or something like that.

How many miles does this engine has?

It seems to me to be an ignition problem. I am new to these bikes, but is there separate cdi boxes for each cylinder? If so try switching them. Also check out the ignition pulsers make sure the one bad cylinder has not moved.

Keep at it you will figure it out.

-John

This is a tough one, IMO I would try checking your plug wires, plug caps, plug wire connection to coils. I also would check your battery cables, battery connections, especially your ground connection to your frame. Lastly, try checking your voltage regulator.

Time for a leak down test. You checked the intake valve with carb cleaner but what about the exhaust? The symptoms could be caused by a burned or leaky exhaust valve. Listen to the exhaust pipe, the carb (with throttle open) and the crankcase vent when you have air in the cylinder. That will give you an idea of what is leaking if you have a problem.

I think you guys are right here. I don't have a leak down tester, but maybe I can borrow one from someone. I'll ask around and see if anyone locally has one that I can use. BTW, on a bike like this, should I just run it up in the same neighborhood as I would on a car (around 100 psi)?

Just a little over 12k miles.

You can do the same test on the exhaust valves as you did on your intakes, pull the exhaust pipe and pour some gasoline on the valves with the engine at TDC. Sounds fishy to me, I don't think it's the valves.