2010 Assault... HELP!

[chunkysoup]

I just bought a 2010 Assault this year with just over 1000 miles on it. I dont know what stock map is in it but the dealer i bought it from thinks it is the latest map cuz he knew the guy that had it and he was having a midrange stumble problem before they reflashed it.

I took my first trip with it to Mercer, WI and we put on about 150 miles. It had the midrange stumble pretty bad especially when riding down the railroad grade for awhile. The sled was setup basically stock obviously with heavier weights for the elevation:
10-68 weights, 140-330 primary spring, 56/42.36 helix, 160/240 secondary spring. Stock exhaust and Stock 2.125 Assault track would hit 8600 rpms and only got it up to 73 mph recall.

I got home and wanted to change a few things for how I like to ride. I removed the primary spring to find it was broken so i installed a 165-310 spring (all i had at the time) Changed the helix to a 66/44.46 and i cut the Assault track down to 1.5". With this setup I was running 8400 rpm and 84 mph recall. I was pretty happy with it running wise besides the midrange stumble and that my buddy on his switchback assault was killing me.

I ended up ordering a 140-310 primary spring to bring the engagement down a bit cuz the 165 was way too high. I also ordered a 155-222 secondary spring with a delrin washer because it felt like it wasnt shifting out all the way.

Before I got those parts in my buddies stuck a cpi can on my sled from one of their 09 dragon 800s that they had lying around. I didnt like the can cuz it was too loud and apparently they didnt get it installed right cuz they burned a hole in my bellypan next to the exhaust outlet. Not happy about that!!! Anyway, with that can the midrange stumble was more noticeable but it also developed a backfire when going on/off the throttle.

When we got back i put the stock can back in it and went for another ride. Now with the stock can I had a midrange stumble, a backfire and a severe topend bog and couldnt pull over 8000 rpms. WTF?! I checked the valves and they seem to be in working order. There was no fuel in the pipe which i thought there may be from it overfueling??? The compression is 117psi pto side and 116psi mag side which seemed kinda low. I ordered a power commander from all the talk of how they fix all these problems.

I installed the power commander with the Stoutner 157 hp map and installed my new springs and took it for a ride. Now it revs 8100 rpm and the topend bog is gone but i still get a tiny midrange stumble every now and then. But now my sled wont start right and it backfires almost everytime when starting.

Can someone please help me figure out what is going on? I think i am losing my mind over this thing! I have a trip coming up on friday and its not a big deal if i dont have it fixed cuz i can ride it this way but i would just like some answers as to what happened.

 

[300rummt]

Take a look at the pistons. I would def put the fix kit on with the PA head your sled will eat your friends

 

[chunkysoup]

I am going to do the fix kit but i was hoping to wait til this summer to purchase it. If i bought it now i would be done riding for the year.

 

[capnkirk]

are you using the RTV silicone to seal the connection between the pipe and can? Not saying this is the problem, but could be causing some issues! Improper back pressure, etc...

 

[chunkysoup]

I didnt put any silicone in it when changing the cans. but the stock didnt have any in it when it was running well to start. keep the ideas coming! any help is appreciated.

 

[NapaMatt]

Double Check!!!!

Fuel Lines IN the TANK!!!

Loose conection will cause short term lean conditions!!! and hard starting!

X2 on Sealing up pipe and can with RTV Black

You might want to try 10-70 weights??

 

[chunkysoup]

10-70s would bring the rpms down even farther. It feels and sounds more like a rich condition than a lean condition.

 

[capnkirk]

I didnt put any silicone in it when changing the cans. but the stock didnt have any in it when it was running well to start. keep the ideas coming! any help is appreciated.

that's odd, as my 2010 Assault had the silicone between the pipe and stock can when I swapped to my MBRP, from the factory. I ran about 250 miles in DA U.P. over that weekend, without the sealing it, and went into limp mode twice. Ran like crap the whole time. Upon arriving home I applied the Black RTV Silicone to the connection and haven't had a problem since.

As far as the mid range stumble, I still have that. I've just learned to live with it. Running pure ethanol free gas seems to help.

All food for thought, I don't pretend to be an expert! Good luck!!

 

[chunkysoup]

that's odd, as my 2010 Assault had the silicone between the pipe and stock can when I swapped to my MBRP, from the factory. I ran about 250 miles in DA U.P. over that weekend, without the sealing it, and went into limp mode twice. Ran like crap the whole time. Upon arriving home I applied the Black RTV Silicone to the connection and haven't had a problem since.

As far as the mid range stumble, I still have that. I've just learned to live with it. Running pure ethanol free gas seems to help.

All food for thought, I don't pretend to be an expert! Good luck!!

That is odd, but hey if its gonna work its worth a try! I have some in the garage so i will apply some of that tonight. Im getting some help with my DTR map in my sled so hopefully that will help the stumble a little bit. Thanks guys. Any other ideas or things to check. I have a list going for when i get home! lol

 

[augerin]

IMO you are gambling with $2500 by not putting in the "fix" kit now. That is the cost of the new case halves and cylinder mono block when it rattles itself apart with the wind chime pistons in there. Pull the Y pipe and check your pistons and if you can get a mirror or something around the bottom of the engine look for cracks or worse yet holes in your cases. I think mine had a hole in it from the piston skirt before the cylinder skirt went. Best of luck to you on this. The good new is with the fix kit in there mine runs better than ever.

 

[300rummt]

the Fix only takes about 3 to 4 hours to get in.

 

[chunkysoup]

Its not the time... Its the cost. If i spend the $600 my sledding budget is gone so no more trips but if i wait til the offseason i can afford it. I know its a gamble but i guess if it blows it blows cuz i want to get a little more than no riding in this year.

 

[augerin]

I know the feeling. Mine blew up in March of last year and I couldn't afford the 3k to fix it so my season was done. Worse yet that is when it started to snow around here.

 

[X2Freeride]

Jason I didn't realize you were running 10-68's Throw a set of 10-66's in it That's too much weight for that helix and spring combo. If you dont have a set I have 3 laying around I can send you.

 

[diamonddave]

115-120 lbs. of compression at sea level is normal for the 2010 800 CFI head and pistons.

For your mid range symptom, the PCV seems to be a big improvement. I would also clean your exhaust valves, replace the fuel filter, and check and set the TPS.