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-   -   help me figure this one out! (http://www.advrider.com/forums/showthread.php?t=923471)

borborygmus 09-29-2013 10:06 AM

help me figure this one out!
 
05 950 adv. went on brutal ride, bike went down on rt. side with the tires higher than the handle bars. I couldn't lift the pig so I had to wait 10 minutes or so for the next rider to come along and help up right the 950. In the mean time I did shut of the fuel, however when I tried to start it, it was obvious the bike was flooded so I held the throttle open to clear things out and when it started it back fired thru the carb. Instantly I could tell it was running on one cylinder, at about 2500 rpm it would run on both cylinders and would pop on decal a lot but only at partial throttle openings, at complete throttle closing there was no popping.
Now I have the bike home with the air cleaner off and at idle there is NO vacuum from the front carb-at all. I can put my hand over the carb opening with no change/ill effect. If I open the throttle it will start to fire on the front cylinder but does back fire thru the carb.
OK, looks like I jumped a tooth some where. I will get it apart today and do a leak-down test and assuming I did not bend a valve, where do I start looking for the problem?

Ramv 09-29-2013 10:11 AM

Do you have the emissions still in place ? You may have loaded the charcoal canister with fuel.

borborygmus 09-29-2013 10:20 AM

no, all ectomy's performed. I know the chain can jump but how bout the cams? How can I tell which one? am I over looking something simple?

mdfehrmann 09-29-2013 02:57 PM

The 950's are getting to the age where the carb diaphragms are starting to fail. I've seen more than one at this point so that's an easy check and fix.

Matthew

Tangai 09-30-2013 07:29 AM

Sounds like when the bike back fired, it blew the front carb off from its mount.

Orangecicle 09-30-2013 07:51 AM

Check for any vacuum leak, such as a boot issue as mentioned. If you find nothing, pull the carbs and clean them well. You might have dislodged some trash in a bowl and stopped up your pilot/idle circuit.

borborygmus 09-30-2013 12:21 PM

thanks, I will do tonite and report back!

borborygmus 10-01-2013 07:19 PM

no vacuum leak. My leak down tester does not have a fitting small enough so this will have to wait till I can get the proper part. sure seems the cam chain jumped. Has anyone had this happened and what did your bike run like when it did? I have read here some where that you never start the bike with the throttle open cause the hydraulic tensioner is not up to psi yet. what say u-guys?

Sumi 10-01-2013 08:05 PM

+1 on the carb boot leak.. Are you sure it didn't blew off the carb (or tore the boot)?

IMO pull & reinstall the carbs (check for cracks on the boot during this, also you should check the front carb at least - as some serious backfire could cause the slide/diaphragm to melt, and as written before it's easy to clog the idle circuit as well), and if it's still producing the problem only then check the timing.

Also you should check the vacuum ports on the manifold if they are still in place / not leaking.

If the timing chain jumped (which IMO is quite rare to happen), then - because of the cams are gear driven - both intake and exhaust cams will be off, and you will probably need a degree wheel to readjust it properly.. Should this be the case, play attention to get it right (infos about firing order and proper crank degrees are on ktm950.info) - don't configure it for a bigbang setup:)

borborygmus 10-02-2013 06:43 AM

checked all the points of vacuum, even put the carbs back on with out the air box because it is difficult to see all around the boots. One weird thing is the slide on the back cylinder (the only one running at idle) flutters, a lot! it moves up and down rapidly 1/4 an inch. I know crank case air moves this way but.....?

sstewart 10-06-2013 07:11 AM

Carb
 
Check that diaphragm closely. I let a bad one deal me misery once.

renogeorge 10-06-2013 08:52 AM

Did you check front cylinder plug? I know you said you have low/no vacuum. But pushing an unexploded mixture through the combustion chamber doesn't produce normal vacuum at the carb.

Good luck

borborygmus 10-06-2013 07:47 PM

just did a leak down test and the front cylinder will not hold any psi. I even loosened the cam towers in case the valves got tight on me and the cam was pushing down on the buckets w/out lobe contact. When blowing air into the cylinder I can feel air coming out of the intake. Burnt or bent valves????

Zuber 10-06-2013 11:32 PM

Quote:

Originally Posted by borborygmus (Post 22495646)
just did a leak down test and the front cylinder will not hold any psi. I even loosened the cam towers in case the valves got tight on me and the cam was pushing down on the buckets w/out lobe contact. When blowing air into the cylinder I can feel air coming out of the intake. Burnt or bent valves????

Yes.

borborygmus 10-08-2013 01:15 PM

Is it possible to skip the chain on the cam gears if you start the engine with the throttle open(flooded) and the hydraulic tensioner does not have a stiffie yet? I know the "what" now just trying to figure out the "why". And also does anybody have a line on valves or do stick with OEM?


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