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Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by WhereTheHellIsJames?, May 7, 2012.
Sorry for the lapse in time between posts!
On Saturday I picked up a leak-down tester from one of the local shops that I used to have a working relationship with. Actually, since they were cool enough to let me use their tools, I'll give SF Moto a plug here- all the folks there are awesome. If you're in the bay area, and in market for a scooter, a used motorcycle, or aftermarket or OEM parts, give Eric, Andy, Tony or Thomas a call... they'll treat you right, and it's good to support businesses that care about supporting the motorcycling community, not just about selling bikes.
Okay, back to the matter at hand here... just moments ago, I finished the leak-down test. The results came as no surprise to me, as I've confirmed that everything above the intake valves is good, and everything below the exhaust valves is good.
This afternoon, I tore down the bike for probably the dozenth time since the issue arose. Everything went smoothly, and I hae to admit, I feel like I'm getting pretty efficient at tear-down and build-up of the 950 Adventure. A skill that admittedly, I've never really wanted. I got the crash-bars, fairings, tanks, carbs, air-box, and valve covers off. Pulled the plugs, and set the front cylinder to TDC. I bought one of those bolt-like tools with the allen end to hold the cylinder in exactly TDC a couple weeks ago, but couldn't find it... so I just lined up the dots and confirmed the lobe positions on the cams. Plugging the hose into the spark-plug hole was a cinch, and I hooked up the air to the tester. I could hear that there was a leak somewhere. Just to confirm, I pulled the header from the front of the cylinder. Yep, definitely an exhaust valve leak... a big one too.
Looking at the valves, I was surprised to see how grungy the ports and stems were. There is all sorts of hard, crusty build-up in there. It almost looks like this bike never had an air cleaner on it. I've had a look at probably a hundred or more heads, and have never seen anything like it. Looks like caked on dirt / mud / creosote. Nasty.
Anyways, problem identified. Now what? Does anyone with experience have suggestions of where to (or for that matter, where not to) take / send the heads off for rework? I'm assuming that it's appropriate standard procedure to do both heads instead of just the one that's giving issues... can anyone confirm this? Since the bike will be torn down to the point where the heads are removed, is there anything else that might as well be done at his time while the engine is this far apart? FWIW, the bike has 12.5K miles on it.
Since you have some kind of experience mechanically, i would suggest yourself. It's not hard, you even have a manual to guide you trough it. (it's not like you have to do much to a 10k miles head, just take the valves out, inspect them, change the oil seals on the valves, clean, graduate valves and that's pretty much it.)
If the front is like that and the rear is not i would suggest into looking at two things, the engine breather oil seal (on the rotor side of the engine) gets damaged and it will start to eat a lot of oil, especially the front cylinder (which i believe you are experiencing this) also, the breather hose (the one that goes from the right side of the engine, rotor side, to the air box) well our models have a hose and that's it, later on they changed that for a hose with a one way valve.
So, to sum up, if your front looks ugly and the rear is perfect i would bet this is your problem altough it might have something to do with a valve with too little free play.
Still, 10k miles is NOTHING to these engines, so it's pretty weird to hear all this.
did you fix it?
Have you tried swapping the ignition coils? They may show spark out of the cylinder, but its another thing under compression.
Using a ampmeter, check the resistance in each. I've had these go bad on other bikes...
How about exhaust seals at the header? Pull the header and see if there is a seal, or any dust remnants of a seal. May be a long shot, but I saw something sort of similar happen to a buddy's SE. Good luck!
Edit to add- whoops _ it seems like you've gotten to the bottome of the problem. You got that far, you can go the rest of the way. It's not hard. Good luck again!
Happened to my son's 250 xcf... one month of trying to figure out why it's misfiring...broken spark plug cap, arching at odd times, wet and just close enough to cylinder... ya never know
+1. This JUST happened to me with a BRAND new 500 EXC- I switched out the exhaust and it would back fire and stall. I spent all day trying to figure out what I could have done wrong- only .1 hours on the clock.:eek1
I was comparing the plug on that bike to another 500 EXC and my greasy hands exposed the crack in the procelain.
I am the owner of this bike...James has been extremely nice and put a lot of work on it trying to figure out the problem...
It seems like we are now down to the exhaust valve, so I'll start working on it with him as soon as possible. Despite the problem (s), I am missing the bike right now and would love to ride it again.
thanks again for everyone's input on this - we will keep you posted!
I had a similar issue on my GS500. The screws holding my timing plate in place came loose, letting the timing advance in odd ways.
Didnt figure it out unitl they both came loose and the timing jumped 90 degrees :eek1. Bike didnt like that, at 40mph on a back road. luckily, i happened to stop in the driveway of a real nice fellow with a well stocked garage
Well, I think it's time for an update on this thread.
As I mentioned before, James spent countless hours trying to figure out the issue - well he was right.
I brought my KTM back to Tahoe a couple weeks ago and I finally had the time to take the engine out and look at it more carefully. I redid a leak down test just to be sure and there was enough air going out of the exhaust port to blow my hair. Well, the little I have left.
Turns out there is a pretty significant hole in the exhaust valve! I haven't removed the head yet but you can see it quite cleary from the exhaust port.
So that would probably explain the problem he has been having. I have no clue what may have caused that. The bike only has about 13000 miles on it.
So now the question is - what's next...
Do I spend more time learning about this engine, remove both heads and send them over somewhere?
Do I send the whole engine and let someone more qualified take over?
Does anyone know of a good shop in the Bay Area or Reno area?
thank you - I hate when threads don't have a conclusion so hopefully this may be useful to someone one day.
Very large picture:
Chester at Nevada Motorcycle Specialties in Reno, NV. is a great tech. He is one of the owners, they have had the shop for something like 30+ years, and he has a lot of LC8 experience. If you want to take it to a shop, this is a good, local start.
Time for some closure on this thread, almost a year later....
I am glad to report that the bike is back together and I have been enjoying some great rides with it!
I ended sending the engine to the KTM dealer in Reno and getting new valves/rings on both cylinders. about $900 of parts, $600 of labors and then taxes...ouch.
I put it back together and it had never ran that well. I really missed it!