Ever seen this??? Sparkplug gap closed?

towny · Dec 30, 2007

07 Summit 800r w/SLP head. Using BR9-ES plugs gaped at .031.
Have rode over 300 miles on them so far. The other day it started missing acting like a fouled plug.
Pulled them and found one that the gap had closed completely up on??
Any ideas as to why?

the fix-it guy · Dec 30, 2007

detonation, or possible contact with foreign object. Also check rod and pin bearings.

Highmarker · Dec 30, 2007

my guess would be foreign object. Something got into your cylinder.

Wheel House Motorsports · Dec 30, 2007

mine looked like that, but it had dents in it, and i had piston that was falling apart.

GONRIDIN · Dec 30, 2007

It could be caused by detonation if you are running the wrong SLP head for your elevation or you got a bad batch of fuel. You may want to call SLP and ask them to double check the part number on your domes to make sure they are corect for where you ride.

anziconda · Dec 30, 2007

Last time I saw that, I changed the plug and tried to get back to the truck...ran good for a few minutes...then...boooooommmmmmmmm!!!

kingofbikes · Dec 30, 2007

8 out of 10 times it's detnonation.... look for small specks around base and electrode... the specs are from the piston and a tell tale sign of detnonation...

towny · Dec 30, 2007

Is there any truth too: BR9-ECS plugs help with controlling detonation?
Verses the BR9-ES’s
I thought they were just a pre-gapped plug only nothing more?

Vern · Dec 30, 2007

my old 99 rmk started missing one day and i pulled the plugs and had the same problem, put new plugs in and about an hour later was climbing a hill and the crank snapped at the bottom rod pin, but atleast it still had enough umph to finish the hill

shortstop20 · Dec 30, 2007

towny said:
Is there any truth too: BR9-ECS plugs help with controlling detonation?
Verses the BR9-ES’s
I thought they were just a pre-gapped plug only nothing more?

The BR9ECS is a dual heat range plug. It runs cooler at WOT than the BR9ES. I've never seen any plugs that are pre-gapped, not for my sleds anyway.

sledsrock · Dec 30, 2007

I'm not saying it's not detonation, but someone needs to explain to me how in the heck detonation is going to close a spark plug gap??? Educate me.........please.

knee deep in it · Dec 30, 2007

i only ever saw that once, 10 minutes later , my crank let go.

D_EDGE · Dec 30, 2007

Same happened on one of my older sleds. Started missing on one cylinder, pulled the plug and it was smashed. The lower rod bearing was out. Since most two stroke sled cranks are pressed together you have to send it somewhere to get it rebuilt. I would pull your cylinder and check the play in your rod bearing before I took it out riding again.

Rixster · Dec 30, 2007

I am going to agree with ost of these post. Your motor has ingested something and didnt like it.

89sandman · Dec 31, 2007

would say bad piston, crank, rod. bet if you pull the head you'll be able to see where the top of the piston has hit the plug. better check it out before she blows!!!

jaxnjil · Dec 31, 2007

knee deep in it said:
i only ever saw that once, 10 minutes later , my crank let go.

same here missed-change bent plug-!/2 back to truck crank locked up

A CAT · Dec 31, 2007

pull head or scop it look at top ring land for pices missing, det.

portgrinder · Dec 31, 2007

I had one similar to that but wasn't all the way closed. I had the plug in my backpack/toolkit for a long time before I put it in though. I think the gap closed from being beat around without that cardboard thing on the threads.

BOOST · Jan 1, 2008

Piston skirt is broken. Had a sled do the same thing and is was the skirt breaking off and workning its way to the top end and flattening the gap on the plug. Still had good compression, but not for long

Mntryder · Jan 1, 2008

Had one like that right after the crank bearing decided to head North.

Ever seen this??? Sparkplug gap closed?

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