Author Topic: SE 300 2019 fouled plug and then erratic engine behavior  (Read 886 times)

mottaguedes

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SE 300 2019 fouled plug and then erratic engine behavior
« on: October 07, 2019, 09:52:33 AM »
Hi All!

I have a 2019 SE 300 Factory, it currently has 26 hours.

Last Thursday I went for an off road tour and fouled the plug (I think I added too much oil on my last fuel stop).

Later I installed a new plug (NGK BR8ES as I couldn't find a 7) but the bike has been showing a strange behavior.

First it started but I couldn't open the throttle or it would die down. I assumed it still had too much oil in the engine and was "flooding" the plug, so I revved it very progressively and it got a bit better. Even after some 2 hours of this it would die down if I just rolled the throttle and backfire in the end.

Yesterday I just started it and it seemed "normal", let it warm a bit, revved it a couple times, sounded good, but in the end it gave me that "bof" and died.

Today I started it, it idled a bit, but again backfiring and afterwards not wanting to start.

I should point out I had half tank of gas when it fouled the plug. Meanwhile, because I wouldn't be riding it, I just filled it up and added no more oil. So it should be around 1,3 or 1,5% right now.

My plan tomorrow is to drain the tank, add fresh gas with carefully measured oil, new plug, and then connect it to the computer to check for any error codes it might be showing.

Anymore ideas of where to start looking at this?

Thank you very much all!

MottaGuedes

Sherco SE 300 Factory 2019

Clay

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Re: SE 300 2019 fouled plug and then erratic engine behavior
« Reply #1 on: October 07, 2019, 10:23:43 AM »
Sherco had a plug fouling problem with the 2019 two strokes. You need the new map and a new coil from the 2020 model.
Clay Stuckey
Sherco Offroad  www.shercooffroad.com
email: clay@shercooffroad.com
cell: 615 347 6519
Tennessee, USA

mottaguedes

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Re: SE 300 2019 fouled plug and then erratic engine behavior
« Reply #2 on: October 08, 2019, 12:18:31 AM »
Thank you very much Clay!

Are you aware if anything will show in the OBD codes? I'll do that check today.
MottaGuedes

Sherco SE 300 Factory 2019

Clay

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Re: SE 300 2019 fouled plug and then erratic engine behavior
« Reply #3 on: October 08, 2019, 07:14:05 AM »
Thank you very much Clay!

Are you aware if anything will show in the OBD codes? I'll do that check today.
Honestly I never checked the codes. I knew what the issue was and what we needed to do so I just did it. I've probably remapped 20 bikes and sent out computers to remap dozens more.
Clay Stuckey
Sherco Offroad  www.shercooffroad.com
email: clay@shercooffroad.com
cell: 615 347 6519
Tennessee, USA

Strosek

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Re: SE 300 2019 fouled plug and then erratic engine behavior
« Reply #4 on: October 08, 2019, 02:33:26 PM »
Does it run much better after up upgraded map?

Thanks

mottaguedes

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Re: SE 300 2019 fouled plug and then erratic engine behavior
« Reply #5 on: October 09, 2019, 02:26:47 AM »
Thank you very much Clay!

Are you aware if anything will show in the OBD codes? I'll do that check today.
Honestly I never checked the codes. I knew what the issue was and what we needed to do so I just did it. I've probably remapped 20 bikes and sent out computers to remap dozens more.

Thank you Clay! I'll post after I've corrected it.
MottaGuedes

Sherco SE 300 Factory 2019

Clay

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Re: SE 300 2019 fouled plug and then erratic engine behavior
« Reply #6 on: October 09, 2019, 07:09:10 AM »
Does it run much better after up upgraded map?

Thanks
Not really. It just doesn't foul plugs on start up. They run fine with the old map and coil if it doesn't foul the plug.
Clay Stuckey
Sherco Offroad  www.shercooffroad.com
email: clay@shercooffroad.com
cell: 615 347 6519
Tennessee, USA

Strosek

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Re: SE 300 2019 fouled plug and then erratic engine behavior
« Reply #7 on: October 09, 2019, 08:25:58 AM »
Now will the new map work with the old coil?  I have the map enroute and plan on updating before replacing the coil... Just don't want any surprises while I await the new coil.

Thanks very much!

mottaguedes

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Re: SE 300 2019 fouled plug and then erratic engine behavior
« Reply #8 on: October 15, 2019, 06:12:03 AM »
I wanted to add that I plugged my bike to the diagnostic software and there was no code at all.
I'm now waiting for the new coil from the importer.

I did consider upgrading the map on the old coil but assumed it wouldn't really solve the issue so I didn't try anything.
MottaGuedes

Sherco SE 300 Factory 2019

Husky Steve

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Re: SE 300 2019 fouled plug and then erratic engine behavior
« Reply #9 on: June 27, 2020, 02:38:48 PM »
I have just encountered a similar problem on my 2020 se300. Rode for a couple of hours with no apparent problem other than an occasional flame out, which was unusual. Then on my home as I got back on tarmac, it just died.  First I thought fuel, so turned it to reserve. Started up and ran for a 100m and died again. Checked the petcock. OK. Started up and travelled about 6 miles home, ok. Washed the bike. Started it up to oil the chain and it wouldn't rev, it bogged, backfired and cut out. Now it will start, idle, but won't rev. It just bogs, backfires and cuts out.  It has 25hrs on it, so I though, repack the muffler, which did have a fair amount of spooge in it and I am going to fit a new spark plug. I haven't re-started it yet. What else should I be looking at? Any help would be appreciated.

Ps. I normally leave it in one map/power valve setting, but I did switch the maps a couple of times on that ride, but can't say that I noticed any difference. Could there be a problem there?
« Last Edit: June 27, 2020, 02:48:57 PM by Husky Steve »

JL4049

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Re: SE 300 2019 fouled plug and then erratic engine behavior
« Reply #10 on: June 28, 2020, 02:51:32 PM »
I have just encountered a similar problem on my 2020 se300. Rode for a couple of hours with no apparent problem other than an occasional flame out, which was unusual. Then on my home as I got back on tarmac, it just died.  First I thought fuel, so turned it to reserve. Started up and ran for a 100m and died again. Checked the petcock. OK. Started up and travelled about 6 miles home, ok. Washed the bike. Started it up to oil the chain and it wouldn't rev, it bogged, backfired and cut out. Now it will start, idle, but won't rev. It just bogs, backfires and cuts out.  It has 25hrs on it, so I though, repack the muffler, which did have a fair amount of spooge in it and I am going to fit a new spark plug. I haven't re-started it yet. What else should I be looking at? Any help would be appreciated.

Ps. I normally leave it in one map/power valve setting, but I did switch the maps a couple of times on that ride, but can't say that I noticed any difference. Could there be a problem there?


I have had this problem on my old KDX before when dirt got into the main jet. The screen on the petcock inlet tube had a hole in it... It would idle nicely but as soon as I tried to rev it, it would bog and die. When I released the throttle, it would fire again and idle nicely.

Husky Steve

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Re: SE 300 2019 fouled plug and then erratic engine behavior
« Reply #11 on: July 01, 2020, 12:09:05 PM »
I removed, cleaned the carburetor. Adjusted the float. Set and fitted a new plug. Replaced the muffler packing. I also stripped the petcock as it was extremely stiff to turn and leaked while you turned it. It now moves freely.
Started up and ran fine. Haven't ridden it yet. I will be going out on it tomorrow. I hope to report that all is well. I'm taking a tow strap though. 👍