Boosted Apex questions...

[JROD]

My riding buddy has an 06 Apex with an MPI Stage 1 supercharger that has gone through 3 or 4 fuel control boxes and has been custom tuned by TJs Sports in Wyoming. It pulls plenty of RPM, pulls very hard with any kind of base but when it comes to the deep, it seems like that track just spins so fast that it digs a hole to china before it can even accelerate. It has a Fabcraft rear skid with Floats, lightweight seat, lightweight front end, Camo 162 challenger extreme and not even 1000 miles all set up and tuned for the conditions.

When at idle it seems like it's all over the place as far as RPM goes, not consistantly but not all the time. Sometimes it idles like it's stock. The new control box is brand new and appears to be working as such. When the last few boxes went out, it wouldn't rev above idle. Depending on the day (sunny or overcast), the sled runs night and day different, similar to a two stroke. Sunny days, it is unstoppable. On overcast days it doesn't run nearly as good but not terrible.

Personally I've done plenty of two stroke modding but not quite as knowledgeable with the four strokes. From all the rumors I hear, the four strokes hardly ever need a wrench and this one appears to act more like a two stroke mod as far as tuning and maintenance goes.

Is this common? Are these issues that the rest of you have run into? He's put close to $4000 dollars into doing everything right as far as set up goes and starting to get frustrated. Any good advice or extra info would be good to hear from those of you more familiar with the nature of the beast. Thanks in advance.

 

[JROD]

ttt, seriously, nobody is running one of these?

 

[PUNISHER]

Hey man, sorry to hear about your Bud's ride. I have no experience with superchargers, but running a turbo on my new Nytro.

I can only address 2 parts of your post to help you and him out....

1) The only dislike I have about the supers vs. turbos...is how fast they hit on the bottom and create the ultimate trenching effect vs. a smoother consistent pull all the way through the rpm range. I've found and many can attest that 4stroke torque is very advantageous if you can slowly start moving from a stop and then hammer the throttle, instead of just hammering the throttle from a complete stop. The bottom end on stockers is enough to trench and bury them plenty well, and now he's added some serious bottom end torque/hp with the blower. How does he have his weight transfer setup? Is it stiff or loose to transfer more?

2) A boosted yamaha WILL be wrench-free or as close as it comes...but after you get her dialed in and have spent some time wrenching on it. With so many components and clutching woe's it makes it time consuming. After the sled is set-up...he'll never look back. Tell him to keep the route and steadily it will all come together.

A couple of good resources on here and if he can't find the info he's after...I know Allan from Timbersled has a lot of MPI experience and might be able to give a helpful insight into his issues. I'd have him call and leave a message for Allan, as he's super busy but will eventually return his call.

Good luck and safe riding.

 

[obile]

im running a stage 1 on an 07 apex and have had some of the issues you describe but a little different. first run through the diagnostic on your speedo and see if there is any trouble codes stored. 15 throttle position sensor and 13 intake air pressure sensor showed up in the history but showed no fault on the screen had to go into diagnostic to find them. replaced tps and air pressure sensor and it runs awsome now. ran 500 plus miles last year before the tps went bad and again this year 170 miles and the 2 sensors went out. dielectric greased all electrical connections and it rips now. as far as trenching the boost comes on smooth from idle on up if ya hammer it its gonna trench to china but ive found it to be as easy to get on plain as a stock. ive ridden turbos and find that the super is smoother off the bottom than a turbo but when the turbo spools up it will pull harder on the top end. throttle control on these are key to not trenching but with the added track speed it will usually pull you up and out anyway. seal the fuel controller with silicone. moisture can get in there and mess with things as well. run it through the diagnostic and let us know if it shows any codes. where does he have the controller located?

 

[JROD]

Controller is located next to the reverse handle and siliconed. TJ claimed that water was still getting into the controller because of condensation built up from thawing sleds in the trailer with propane. We quit doing that and haven't had another one go down yet.

He's got the sled set up to transfer too hard right now but we'll suck the straps up until it sits completely flat on concrete with just taut limiter straps. Thought that would be a good place to start.

Will check the sensors, Thanks