'07 D7 burn down

[laugy]

Hi All,

Just got back from a long back pack trip the last several days. Coming back to the cabin across Lake Gogibic we were running 70MPH, the engine just died, dash shut down right away. The mag side (exhaust side) had some detonation on the plug and on top of the piston. We just filled up with fuel prior and everything was running fine. Towed sled back to cabin as it appeared to be in limp home mode and only idled at 1400, not the 1800 or so it should be. Brought it back home today and did compression test. Clutch side at 120PSI, and mag side had 60PSI after three pulls on recoil and then compression went to zero. Plugged sled into the computer and no unusual fault codes came up. The sled has 3488 miles on it. I pulled the exhaust valve and all looked ok. We will pull head off later in the week to find extent of damage. My question is why did the engine just completely shut down? I don't want to rebuild the motor and find there was another root cause that did this. I know reading some threads there was a stator issue, however seems to have great spark. Please provide any feed back. Thanks

 

[ezra]

I don't think a stator would cause a burn down if anything you would be not burning fuel and running pig fat if you had a bad stator.

 

[jim_golding]

I burned down one piston on a sled and it would not run on the one good piston, died immediately. I took it apart and found just one piston leaned out. I used muratic acid and honed the cylinder. Ran fine until I sold it. I don't think you have a problem.

 

[teamditchpickle]

where did you get gas from?

I filled up at the gogebic store and my f1000 burned down 4 miles later at 60 mph, we were following a group.

it costed me 3 days riding and now 1800 to fix.

My sled was in perfect shape, and dealer said it was gas... and gas only.

Shawn

 

[snoeatr]

laugy- My 07 D7 burned down last season. The cause was it spun a ring. There is an update on pistons from Polaris that is supposed to not have a problem anymore. You should check into that when rebuilding if you plan on using OEM. As far as your situation, how do you know there is detonation on top of the piston and plug without pulling the head off? If you look down the spark plug hole and see damage in the center, that would not be detonation. I'm sure the plug has a grey powder on it if there is only 60 psi, but you won't know much until you tear it down. Keep us posted on what you find, hopefully it won't be too bad.
After the rebuild, mine runs perfect, had 5k miles when it let loose, now 7k and rockin.

 

[laugy]

Pulled the head last night. Looks like it could have been from cold seisure. Engine temp when I did the long pull was in the 70 degree range. When she let go it was another 10-15 min later and engine was plent warm. The long pull most likely pushed it to the limit and the last crack of the throttle put it over the edge. There were no hot spots on the piston. The piston was pretty scuffed up and looks like the cylinder may need to be re-nikd. Thinking about sending cylinders to SLP for ther performance addition porting and ecu remap. I am told the engine will run cooler temps, and have the same if not more durability. I already have their pipe and can on it with intake and flow-rites. I will also be having the injectors cleaned and flow tested, replace fuel filter, and oil filter since it is apart. I will fill you in as things progress.

 

[vic_junior]

(2006 Fusion 700) I had the exact same thing happen to me, expect I was on top of Brockway Mountain right after I filled up the tank in Copper Harbor. We were about 4 miles out and I had her pinned around 3/4 throttle going down one the hills and she just bogged down, so i tried giving it more gas and again she just bogged down. So I came to a stop and she was barely running so I turned it off. I thought I maybe fouled some plugs with bad gas. Ended up burning the mag side piston. Just over 4000 miles. The shop told me that the crankshaft seal went. I posted a question about it further down a couple days ago, take a look. (Fusion 755 Crankshaft seal)

 

[srt20]

A few things with these motors.

Never touch the throttle until engine temps are 80-90*f min. And dont ride it hard til the themostat has opened approx 120*F

Never hold the throttle as one steady speed. Especially in the mid range 5000-7000 rpm. I will actually hold mine pinned long periods. The mapping is stupidly lean in the mid range to meet the EPA crap. The SLP pipe doesnt help this, but I have one on mine to.

Seal up around the headlight with silicone. Alot of snow dust gets sucked in right there. Guess what, your air intake is right behind the headlight. Many burndowns occur because of snow intake here.

I will be the first to admit, these sleds arent designed very well. But with a few preventative measures, these sleds can all out rock. I have a 08, and its pretty much the same except the mapping is slightly richer on top. I absolutely love my sled.

 

[laugy]

Thank you all for the help. Looked at the engine more closely tonight. I have already taped off the head light adjuster and put weater striping on the inside of the headlight shroud. I will be sending the cylinders to slp for their mild porting and ecu remap. The cylinders also need to be re-nikd. It is only $100 more going thru them than just doing a cylinder exchange and re-nik. Hopefully it is money well spent. They tell me durability should be the same if not better. From what I have heard I will be using the stock OEM pistons. Sounds like these are the best option. While apart I am going to have the injectors cleaned and flow tested, replace fuel filter and oil filter. She should be good as new again. According to SLP I should be in the 152 to 153HP range with the pipe, can, intake, flow-rites, and cylinder porting.