2018 850 spark plug issue

S

Skidoo bachelor

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• Jan 28, 2018

• #1

My sled started running real bad, 200 miles on it. I thought I may have damaged the reeds with an over rev but they are perfect. While in the area noticed alot of oil from spark plug holes, I have not touched the spark plugs in the machine. I found that they had backed out about 1.5 revolutions, so I removed them and found one of them the porcelain had came loose and slid down eclosing the electrode tip and insulating it from the ground tip. No way it could fire, tried to upload a pic but couldn't. By the time I got to the trailer the thing would not even start. I've never seen a plug fail like this? Has any had this situation??

 

A

ak

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• Jan 28, 2018

• #2

You running a turbo?

 

S

Skidoo bachelor

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• Jan 28, 2018

• #3

Yes silber 7 pounds

 

F

fredw

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medicine hat

• Jan 28, 2018

• #4

Heard the same story from another Sibler owner a few weeks back, replaced plug and fine..

Think a guy is hitting rev limiter from to low of gearing, they since geared up and all fine..

Still running in stock forum and my belt is running at very top of sheives on primary, meaning I should be gearing up with out turbo..

Try two teeth up on top sprocket and I bet your problem is healed up

 

S

sledsrock

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Nov 26, 2007

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Grand Junction, Co.

• Jan 28, 2018

• #5

Detonation

Will loosen SP.

 

T

TheRedrooster

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• Jan 28, 2018

• #6

The motor is detonating because it’s lacking fuel. Your afr is away to high probably in the 13's You can only run so long like that before you do big damage to the motor. Give it fuel and problem solved. Turbo motors need fuel

 

Last edited: Jan 28, 2018

F

fredw

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medicine hat

• Jan 29, 2018

• #7

Ecm will pull fuel out above 8300rpm wanting sled to fall back, but turbo is making bigger power and go to a severe lean postion then, causing det and plug damage..

My 850 is still stock and after a long pull i was surprised to see how close the belt is to top of primary, even in stock fourm it could use a gear up, now adding a turbo this would have to be done, or a over rev will happen..

 

mountainhorse

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• Jan 29, 2018

• #8

What are the stock plugs on an 850 ? NGK?? What number??




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S

Skidoo bachelor

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• Jan 29, 2018

• #9

ilkr8q7

 

A

ak

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• Jan 29, 2018

• #10

Pic

 

mountainhorse

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• Jan 30, 2018

• #11

ILKR8Q7
NGK-93819

Pretty fancy plug... supposed to be very anti fouling.
Good thing, considering the amount of oil it burns.

Iridium center electrode
25.6mm thread reach
12mm x 1.25mm pitch thread
Resistor
8 = mid heat range (Hot, 2 - 12,cold)
Platinum tipped ground electrode
.7mm gap






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P

pepperhouse

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• Feb 3, 2018

• #12

Silber kit, @ #5
Fouled a plug in first ten mins running kit, chalked it up to being winterized and first day out. New plugs installed all good.
Have about 250k on now kit

Today
Kept falling on its face about 10seconds after wot.
Pulled plugs and found one of them had porcelain missing on electrode.....
Installed new plugs and will try it again this week

Had two knock codes first day I ran kit 200km ago
Have hit over rev a bunch getting clutches dialed

Running 91/108 race gas shooting for 93 octane
BJ clutch kit

 

mountainhorse

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• Feb 8, 2018

• #13

PepperHouse....

Did you try to set the gap on the plugs??

How much oil are you using (have you figured out the oil ratio your sled is injecting)??





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P

pepperhouse

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• Feb 9, 2018

• #14

Didn’t gap plugs just put them in outa box.
Parts counter said no need to change/check gap?

And no haven’t calculated oil use.

Thinking detonation took out my plug.
Going to add more race fuel and try again this weekend.

 

J

JJ_0909

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• Feb 9, 2018

• #15

Just wanted to reiterate you need to keep RPM in check and fuel accordingly. It is *paramount* to the sled functioning properly.

If you are having issues keeping RPM in check, there are solutions. Unfortunately, it may require you buy some weights from SHR or ZRP, but it will fix the problem.

 

mountainhorse

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• Feb 9, 2018

• #16

pepperhouse said:

Didn’t gap plugs just put them in outa box.
Parts counter said no need to change/check gap?

And no haven’t calculated oil use.

Thinking detonation took out my plug.
Going to add more race fuel and try again this weekend.

Click to expand...

Just checking....
Many don't know that iridium plugs require a very specific gaping procedure... many people gap the plug... and crack the insulator around the tip.




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Last edited: Feb 14, 2018