Apex engine gurus... Help needed...

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

I've run everything from bone stock clutching to custom Hartmann setups and everything in between. I clutch for 7000-9000 feet. Stock secondaries, team secondaries, oodles of springs and countless weight combinations have given me nothing. Which leads me back to the suspicion on the engine. The weight I have had to remove from the primary just to get the sled to spin up is staggering... It just doesn't seem to be making any power.

I first noticed this on my first trip out in the 2009-2010 season. I had a brand new Hartmann clutch setup and I was ready to rock. After the first day I took 3 grams of weight out of the clutch, after the second day I took three more out and that was to ge the motor to rev at 6000 feet! The next day I bought a hood vent kit... It goes on and on... Its been like this ever since, no amount of time or money I have been trying to throw at it has made a difference.

The one common that just comes to mind now that I think about it is that I have always been trying to get a Team secondary to work with that last clutch setup... I don't think I have ever put the stock secondary run with that custom primary setup since... I always kept them on the sled as a pair... Honestly, I've never really had good luck with the Team except for ditch banging... Quite honestly, I don't know why it hasn't accidentally gotten thrown in my beer can pile...:face-icon-small-ton

I'm pretty particular about my maintenance on my machine particularly my clutches, and I inspect them constantly for worn bushings, binding, alignments etc. Bearings are good and have been checked last season when I flipped the track around and will be checked again when I throw that POS track away...

I've tried numerous different things to the exhaust thinking it was not breathing, but I have ridden this sled with under tunnel exhaust when it ran good. But I'm not ruling it out...

I agree with you phil, and that makes sense. One other idea that comes to mind is to check my fuel pressure, cuz it feels just like what I would imagine if it were defueling... Hopefully I can get that done in a day or so...

Thanks for the replies! Any more ideas are welcome!

Thanks again for the additional feedback! I hope everyone had a happy holiday weekend! I finally got back around to getting an update on where I am at. Over the weekend, I got the following items completed. Performed a compression check and didn't find anything out of the the ordinary ~190 psi +/- 10 psi. Plugs all looked about the same, the only thing I noted was that they seem to be awfully dark in color. I would expect that they would have been burning a little cleaner... Any comments on this? I replaced the plugs while I was at it I confirmed the fuel pressure. That all checked out pretty decent. Fuel pressure was at about ~40 psi on my gauge and didn't fluctuate at all all the way through the powerband, so that looks to be working correctly, but this is with no load of course.

Sooo, no smoking gun from the engine as of now. Based on the overwhelming feedback I have gotten so far I am going to tear back into the clutches and start over with that and re-evaluate my exhaust situation and look into diverting the exhaust outlet out the side of the tunnel.

Clutching I am going to go back to the bone stock settings and I'll probably never put that TEAM secondary back on a sled that I own. By the way I did forget to mention that I am geared with a 19 tooth top gear in the chaincase, so any suggestions with respect to the stock clutching tweaks that I might want to try with the different gearing would be appreciated...

I forgot to bring my "custom" clutching spec sheet this morning so I could at least let you know where my setup is at to give you an idea of my baseline and how far off it may be... : ( I'll get that up in the next post. What I can remember off hand is I am using 89A weights, 14.5 rollers and supposed to be swinging like 54.6 grams with the Y-P-Y spring, and I am actually down to closer to about 50 grams to get the thing to rev... TEAM Secondary is something like a 48-32 helix with the red-black spring...

I'm still not conviced about the engine though and i would still like a dyno run for a little bit of peace of mind, and I may still do this... I'l keep you posted...

Eric! How have you been? I don't know if you remember me, but this is your old sled! PM or E-mail me if you wanna talk some more!

I think I found something!!!

Based on a suggestion for the TY forum, I checked out the stator last night...

Here is what I found... This was all done with a calibrated Fluke meter...

Stator coil spec is .19-.24 ohms.
Mine tested at .3-.4 ohms.

Here is the big one though!

Pickup coil spec is 189-231 ohms.
Mine tested at 501.8 repeatedly!!!

Did I find the root of my headaches?!?!? Any thoughts on this find??? Anyone else experience this type of failure???

I'm kinda excited now!

Well, the Stator should be coming in this week sometime and I should get that in early next week. I have been thinking lately as I have been waiting for the stator to arrive. What do I do with my clutching if that is the problem and I have all this new found power??? Basically, should I start off with the bone stock clutching? I don't know if that will work so well with the different gearing and etc... Should I start off with the "custom" setup??? Here is that setup... Y-P-Y spring, 14.5 rollers, 89A-10 Weights, 10.3 inner, 13.3 outer, 54.6 grams. Recommended secondary setting for the team is a 58-42 with the red-black spring. Gearing is at 19-40... I'm kinda thinking a combination of both, custom primary with the stock secondary... But that is just one idea, I guess I've never been overly impressed with the stock settings, but I am open to suggestions... Thanks everyone, I'll keep you posted!

Corey