Apex engine gurus... Help needed...

[Theicor]

My subject is a 2006 Apex Mountain that is natuarally aspirated with about 3500 miles on it. It has a gutted airbox and LCC under tunnel exhaust and runs CR10EK plugs, otherwise, the engine is stock. For the past couple of years I have been struggling with what I can describe best as an overall loss of power and inability of the engine to maintain power when put under any sort of a load. Numerous sarches have yielded me little information with respect to some things to look for in terms of engine related issues and or power loss. I have tried numerous clutching adjustments from stock to custom setups all with miserable results. Any sort of a load on this machine will cause it to fall on its face, like you crack the throttle at the base of a small hill and the tach nearly bounces off the limiter settles in around just above 10K RPM, and once you start loading the machine or getting it into any type of snow with depth, that tach will just unravel to like 7K RPM and there I sit. It seems like it might be defueling or something, but I don't know really where to start. My first step this week is going to be to do a compression check on the engine and then my next thought was to get it to a good dyno tuner who is familiar with these engines and work through it from there... Any suggestions? Anyone have any suggestions for a good dyno shop in MN? I'm at the end of my line with this thing and I know it is capable of being a good riding sled, its really just been falling apart the last couple of years or so and is very disappointing. Any help or ideas would be greatly appreciated!

Corey

 

[kinger]

Its the exhaust, the snow is plugging it and bogging the engine. You need to route it out the side or out back like stock.

 

[raginyamaha]

Its the exhaust, the snow is plugging it and bogging the engine. You need to route it out the side or out back like stock.

x2...

 

[Theicor]

I'm sorry, but I've been around and around on the exhaust thing too and tried a number of different things... Different exhaust, vent kits, etc... No dice... This sled falls on its face on hardpack, not just deep snow... I've been dinking around with this thing for over two years attacking the obvious with no luck, thqat's why I am wondering if there is something fundamentally wrong with the power train... It's my luck, it could be the most reliable machine in the world, but I would happen to get the one that has an unexplainable problem...

 

[crxtasee]

My 06 apex did the same thing, bang right up to 10k then fall on its face....Took it to hauck and it was in the clutching, what a difference now.....Just a thought.

 

[helmic]

Engine

Sounds like a lack of fuel under power.Your intank fuel pump could be malfunctioning.Get a cheap inline pump and wire it to the intank pump wires try it out very simple test and could save you a lot of problems and money.You actually could leave it there eaven if its not that just for peace of mined.

 

[sledneck22]

This may have been tried already by I am thinking of simple fixes... Have you tried a new belt?

 

[kinger]

So it wont hold WOT on a hardpack lake for more then say 10 seconds? EVER?

 

[FLYBYU]

I'm going to go with both ideas, exhaust in tunnel even on hard pack snow can be a problem. To much pressure in the tunnel. You bring the exhaust out of the tunnel and then we'll start playing with clutch. This problem has been on here many times. There's a reason it's not in the tunnel from the factory. Also check your headers pipe flanges, if it's a 2006 it has the titanium pipes and will always crack. Always only do one change at a time.

 

[Theicor]

Yeah, kinger, that is pretty much what this thing does, it's baaaaaad...
I run new ultimax belts, and I also had/installed Hartman clutching. My first clue that something was wrong was the fact I had to take 6 grams out of the weights just to get the motor to rev with that setup!!! WTF? I have since monkeyed with the secondary thinking I was running too much helix and around and around with numerous changes...

I like the lack of fuel idea and I want to get the fuel pressure tested hopefully in the next couple of days. It really does feel like that would be the case, like a plugged fuel filter or something...

I hate to blow it off, because some many people are suggesting the exhaust issue, but I have tried three different variations of exhaust to chase this and I have ridden the sled when it did make power with an undertunnel setup... But I'll keep it in mind... I also have recently tore the exhaust apart and inspected the header flanges...

Thanks for the ideas though, keep 'em coming.

 

[bulldogbones]

From what you have said it sounds like a fuel flow issue. Maybe bad injectors???

 

[suprfst]

My first guess would be fuel or stator. Ive seen bad stators do Exactly what your sled is doing. Performance keeps dropping and dropping untill it fails.

 

[rxwhopper]

had this problem on my supercharged sled one time. try ditching the 10ek and putting the stockers back in. mine was just a bad plug. ran fun but cut out under load

 

[kinger]

Its not uncommon that you need to reclutch when using the ultimax belts they are softer and grip better then stock.

Here is what I would do:

Swap plugs back to stock
Get factory airbox back in place
Test the stator by service manual test procedure

I assume it idles and cruises just fine? It would be overkill but it sure would be nice to have a air fuel gauge on it and watch it during the bog down to see what its doing. It might be going rich or lean hard to tell.

 

[Attack gt]

A fuel system pressure test is a good start. Only thing is that test wont show you a bad injector. I have a feeling this problem is fuel delivary related and likely a bad injector.