3.2 hours, 2021 KTM 50SX wont start

mtndoc_842
Profile picture for user mtndoc_842
Posts
71
Joined
2/10/2019
Location
Cortez, CO, USA
mtndoc_842
Tearing my hair out on this one. Anyone have any ideas?

Brand new 2021 KTM 50SX, has 3.2 hours on it. Started out the day running decent and then it started bogging like it was running out of gas, would re start initially but not rev out. Sounded like it was running out of gas (stuck float or when you forget the paper towel in your airbox) or when a plug fouls.

So I pulled the plug, still getting spark and jetting looked good, nice tan color. Then I pulled the carb, sprayed all the jets out, cleaned the float, needle was moving fine. Airbox is clear. Stator had 450ohms on it.

I put everything back together and it won't even attempt to start, thought maybe it was flooded so I tipped the bike over to try and drain the fuel out of the bottom end, nothing came out. Finally I broke down and sprayed some starter fluid in the cylinder, still nothing.

Pulled the reeds after that and they looked fine.

I'm out of ideas, any smart people have any thoughts?
|
Factor E
Profile picture for user Factor E
Posts
983
Joined
9/22/2011
Location
So Cal, CA, USA
Factor E 1/17/2021 9:39am
1/17/2021 9:39am
Have heard of petcock being clogged from factory with plastic particals
Drain tank and blow out
mtndoc_842
Profile picture for user mtndoc_842
Posts
71
Joined
2/10/2019
Location
Cortez, CO, USA
mtndoc_842 1/17/2021 10:51am
1/17/2021 10:51am
Factor E wrote:
Have heard of petcock being clogged from factory with plastic particals
Drain tank and blow out
Good thought, I'll do that even if that doesn't end up being the problem. I forgot to add I did run fuel from the tank and it was flowing from the tank freely. I know that fuel is filling the float bowl at least.
dkurtd
Profile picture for user dkurtd
Posts
1148
Joined
4/15/2018
Location
USA
dkurtd 1/17/2021 6:02pm
1/17/2021 6:02pm Edited Date/Time 1/17/2021 6:02pm
Was the plug wet or dry? Also did you change the plug? Even a fouled plug can intermittently spark when removed. Also these can be a pain to start if not on a stand due to clutch drag.
mtndoc_842
Profile picture for user mtndoc_842
Posts
71
Joined
2/10/2019
Location
Cortez, CO, USA
mtndoc_842 1/17/2021 6:03pm
1/17/2021 6:03pm
dkurtd wrote:
Was the plug wet or dry? Also did you change the plug? Even a fouled plug can intermittently spark when removed. Also these can be a...
Was the plug wet or dry? Also did you change the plug? Even a fouled plug can intermittently spark when removed. Also these can be a pain to start if not on a stand due to clutch drag.
Plug was dry, but swapped it anyways, still wouldn't start. Bike was warm when it stopped running and was trying to start it on a stand.

The Shop

See All »
dkurtd
Profile picture for user dkurtd
Posts
1148
Joined
4/15/2018
Location
USA
dkurtd 1/17/2021 6:15pm
1/17/2021 6:15pm
If the plug is dry then it has to be carb. I know on my grandsons KTM50 if you give it any throttle it's hard to start, never seen a bike so temperamental about starting. I would also consider running a compression check, I understand you say it only has 3 hours but if it's low it won't create enough vacuum to pull fuel out of the carb. Pull the carb back apart and focus on ensuring the pilot circuit is free of debris.
mtndoc_842
Profile picture for user mtndoc_842
Posts
71
Joined
2/10/2019
Location
Cortez, CO, USA
mtndoc_842 1/17/2021 6:19pm
1/17/2021 6:19pm Edited Date/Time 1/17/2021 6:20pm
dkurtd wrote:
If the plug is dry then it has to be carb. I know on my grandsons KTM50 if you give it any throttle it's hard to...
If the plug is dry then it has to be carb. I know on my grandsons KTM50 if you give it any throttle it's hard to start, never seen a bike so temperamental about starting. I would also consider running a compression check, I understand you say it only has 3 hours but if it's low it won't create enough vacuum to pull fuel out of the carb. Pull the carb back apart and focus on ensuring the pilot circuit is free of debris.
I suspect you are right, I'll do a full carb swap tomorrow off my boys bike (this is my girls) and see if that fixes it. I had hoped that pulling all the jets and spraying them would fix it but I guess not.

It makes sense it would be the carb because when I tipped the bike upside down to try and drain the fuel out of the crank through the spark plug hole I didn't get any fuel out.

These bikes are a complete PIA, I can't wait until they are on 65's
FGR01
Profile picture for user FGR01
Posts
6162
Joined
10/1/2006
Location
USA
Fantasy
910th
FGR01 1/17/2021 9:33pm
1/17/2021 9:33pm
mtndoc_842 wrote:
I suspect you are right, I'll do a full carb swap tomorrow off my boys bike (this is my girls) and see if that fixes it...
I suspect you are right, I'll do a full carb swap tomorrow off my boys bike (this is my girls) and see if that fixes it. I had hoped that pulling all the jets and spraying them would fix it but I guess not.

It makes sense it would be the carb because when I tipped the bike upside down to try and drain the fuel out of the crank through the spark plug hole I didn't get any fuel out.

These bikes are a complete PIA, I can't wait until they are on 65's
Don't get your hopes too high about issues and maintenance on the 65's.
1
cwel11
Profile picture for user cwel11
Posts
2794
Joined
12/4/2019
Location
Orangeville, PA, USA
cwel11 1/18/2021 9:01am
1/18/2021 9:01am
65s are waaaay easier to deal with. Happiest day of my life was watching our 50 go down the road in someone else’s truck
mtndoc_842
Profile picture for user mtndoc_842
Posts
71
Joined
2/10/2019
Location
Cortez, CO, USA
mtndoc_842 1/18/2021 9:50am
1/18/2021 9:50am
Update: pulled the whole carb apart on my bench and spray everything out. Then flipped the bike over and pumped everything out of the bottom end. Kicked for about 5mins and it finally lit.

Counting down the days until they are on 65s. Having 2 kids on 50s is a massive headache.
1
charlie68
Profile picture for user charlie68
Posts
161
Joined
6/28/2019
Location
North Windham, CT, USA
charlie68 1/18/2021 9:54am
1/18/2021 9:54am
If it wont fire on starting fluid, its ignition, it should at least attempt to fire on starting fluid. Put a little gas in the cylinder and kick it over.
1
yz133rider
Profile picture for user yz133rider
Posts
5027
Joined
8/1/2013
Location
Avondale, PA, USA
yz133rider 1/18/2021 11:09am
1/18/2021 11:09am
Those electric 50s could be the move for you! Lol
Falcon
Profile picture for user Falcon
Posts
12674
Joined
11/16/2011
Location
Menifee, CA, USA
Falcon 1/18/2021 12:51pm
1/18/2021 12:51pm
I tried to fix a friend's 50SX a few summers ago and had the same problems. Congrats to you; I never did get the thing to fire. She had a mechanic friend try it and he couldn't get it, either.
FGR01
Profile picture for user FGR01
Posts
6162
Joined
10/1/2006
Location
USA
Fantasy
910th
FGR01 1/18/2021 4:03pm
1/18/2021 4:03pm
cwel11 wrote:
65s are waaaay easier to deal with. Happiest day of my life was watching our 50 go down the road in someone else’s truck
I've got a bunch of time with both. Yes, the 65 is better. I'd say waaay better if you're just play/recreational riding and marginally better if you're hard core racing.
peltier626 3/8/2021 1:51pm
3/8/2021 1:51pm
Check the overflow tubes on the carb for pluggage. Cut and slit them. I had the same issues
1

Post a reply to: 3.2 hours, 2021 KTM 50SX wont start