KTM 350sxf hard starting

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2/8/2018 8:17 AM

I have a 2016 KTM 350sxf with 20 hours and it is having trouble starting. When you try to start it, it pops and back fires and acts like it wants to start but won’t. I changed the plug and inline fuel filter but still nothing. Once it starts, it will start right back up Though. Any thoughts? I haven’t heckled the TPS yet and will do that tonight.

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2/8/2018 8:59 AM

Have you checked valve clearance? That is usually a sign, hard start then runs okay after it warms up.

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The older I get, the faster I was.

2/8/2018 9:05 AM

First guess would be the valve timing is off a tooth.

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2/8/2018 9:23 AM

A two year old bike with only 20 hours tells me that it sets a lot between rides. This causes issues of crud developing in the fuel injector. I would suggest using a good fuel stabilizer in your bike fuel after doing a fuel injector cleaning using ultra sound. Dried fuel in the injector creates a very lean condition for the first start after setting a while. Most of it will clear with use, but not all. A good cleaning and the use of a good fuel stabilizer will go along way to curing this.

Paw Paw

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2/8/2018 9:53 AM

I dont see the valves being out of spec that fast or the timing being off unless your tensioner gave out. Injector sounds likely. You could start by checking the red and yellow knobs on the TB. The yellow if turned clockwise our counter will effect the butterfly position. The red knobs controls the idle. If ether one of these is out of adjustment it can effect the way it starts and runs.

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2/8/2018 10:01 AM

Thanks guys, I’ll check all that out this afternoon.

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2/8/2018 10:06 AM

dirtmike86 wrote:

I dont see the valves being out of spec that fast or the timing being off unless your tensioner gave out. Injector sounds likely. You could start by checking the red and yellow knobs on the TB. The yellow if turned clockwise our counter will effect the butterfly position. The red knobs controls the idle. If ether one of these is out of adjustment it can effect the way it starts and runs.

X2

Paw Paw

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2/8/2018 10:21 AM

What kind of ultra sonic solution should I use to clean the injector?

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2/8/2018 10:58 AM

My 16 250sxf was doing the same thing, mine seems to be a stock battery issue( for 16 and 17 models)? I upgraded to the larger battery box and battery, and it fires right up now, so you may want to research that as a possibility

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2/13/2018 9:58 PM

dirtmike86 wrote:

I dont see the valves being out of spec that fast or the timing being off unless your tensioner gave out. Injector sounds likely. You could start by checking the red and yellow knobs on the TB. The yellow if turned clockwise our counter will effect the butterfly position. The red knobs controls the idle. If ether one of these is out of adjustment it can effect the way it starts and runs.

^ This. Guys new to KTM get the yellow knob (cold start) and idle all out of whack. Yellow knob OUT is for riding BTW. You can also mess around during start with knob in and push it FURTHER in to see if this has any affect. It is possible your TPS is not optimally set, this has a big effect on starting. Do you see any blinking codes on FI light during starting? Check the wires going into the fuel injector that they aren’t broken...they get abused if you use the cold start knob as they’re in the way.
Lastly have heard of fuel pump relays going bad.

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2/14/2018 12:09 PM

I believe it was a clogged fuel injector and weak battery. I drained the tank and ran some race gas through it and charged the battery and it’s been starting right up. Thanks!

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