Looking to buy a 310 hp mcx apex... got a few q's

[Octanee]

hi guys, so the plan is, is this weekend to pick up a nicely done out apex, its got piaa headlights, lighter panels, fox floats all around, timbersled rear skid... adjustable helix in the secondary, and the mcxpress 310 kit for it.

The owner says it has a switch for like 270 horse or 310, its got the head shim i know that much...

guy said he'd run 40% 111 race and 60% 89 octane pump fuel... at 310 hp, guy said he still ran a mix of like 30/70 on 270, but i know others on the lower hp like 270 run pump gas?...

so my q being, at 270 horse i should be able to run 91 octane pump fuel or some sort of pump fuel right?

i know a guy with a 07 apex with the mcxpress, he had it from day 1 and so far 0 issues, 100% pull and go, and he runs 89 pump gas

so thats the only question that comes to mind right here, also if theres anything more i should know about these beasts or some pointers, let me know, Thanks!

 

[Turbo X]

Start working out so your strong enough to hang on all day !!!!!! 310hp pulls like no other . good luck!!!

 

[Octanee]

Start working out so your strong enough to hang on all day !!!!!! 310hp pulls like no other . good luck!!!

im told it has the switch to turn it down to 270, which is my plan, ive got a ski doo 1000 which i turbo'd and its been all TLC and it blows up. or seizes on me due to who knows what other reasons, (i think bad re-nik job on my cylinders)

but yeah the ski doo 1000 is a somewhat heavier sled, then throw a turbo on it.... i figure i may as well of been riding a big 4 stroke

but it should be a ton of fun im sure!, thing id worry about on 310, is sourcing i guess av gas? and that it would guzzle that fuel back like no tomorrow, i think theres nothing worse than being worried about fuel when your out riding

 

[Climbmax]

There were a few different variations. Original was a 260 kit. Fuel box looked like a sardine can with wires coming out of it. You could run that all day on Pump Premium. Next gen was still a 260 but there was an upgrade to 310 with an extra fuel pump and some altered fuel mapping in the box. I ran one to 310 @ 17psi on 50/50 Pump Premium and C12 mixed. That one got 10,000 k on it and still going strong. The box was a little more refined and was a billet piece. Then they built a 290 kit which is their latest pump fuel program. Also has external fuel pump....it runs approx 15psi on pump fuel and rips hard. Have one in an EPS 174 Apex...love it.

So rule of thumb....if you are under 14psi you should be fine on pump premium........over that I'd use some Race mixed @ 50/50 to 17lbs.....after that maybe more race fuel.
Apex motors are solid....they only ever detonate on poor fuel. And the RPM is amazing.

Cheers
RS

 

[Bendy]

290 MCX

I've rode my buddies 290 Apex. It rocks! Turn key from day one on 91 pump gas.

 

[BigFish BC]

another thing to go with what climbmax said the higher elevation you plan to ride will make a diff to, you need less oct the higher you go.all of randy recommendations are perfect for 4500-7500ft above that you can start to run less oct.

 

[Octanee]

i ride about 4k to 8k ish,

also the highest octane i can get is 94 octane fuel, from pump, 2nd would be aviation fuel, would a 50/50 of 94/ 100LL be fine for say 310? or 100% av gas?

or all together, is av gas alright to even run in a 4 stroke? or should i try to stay away?

i dont want to run race fuel, that stuffs wayy to expensive... my other sled i have/ done with i ran av gas with it, but av is only about 30C more per liter than 94, so not a big deal, but race fuel 107 vp is about 3.60/L if i buy a barrel, so thats just way too much money i'd say, :O but im not on the extreme, id imagine running pump all day, however.... im sure there may be a day here or there i wouldnt mind to turn it up, so thats why i ask about the av gas, Thanks!

 

[1100]

I just recently parted out my turbo RT, and bought an turbo nytro. Your going to be a very happy guy. Only regret I have is not doing it 3 years earlier.

 

[Climbmax]

I know some guys who have used Av......mixed @ 50/50 same as race. It worked for them. Some will say AV is too "dry" of a fuel......lots of debate on here about that.

Best of luck
RS

 

[Octanee]

my only concern of av is the lead, idk how a 4 stroke might handle it or if it will coat valves, etc, thats all

 

[icr]

Any leaded fuel will burn out oxygen sensors faster and eventually coat the valves.

 

[1100]

I'm pretty sure race fuel has more lead then av gas does.

 

[Boosted Brad]

Mcx 310 apex strait av gas 6000 + miles no problem with fuel have fun mine still puts a grin on my face every time I ride her

 

[Octanee]

Mcx 310 apex strait av gas 6000 + miles no problem with fuel have fun mine still puts a grin on my face every time I ride her

good to know that it would be safe on straight av atleast for 310... its hell of alot cheaper than race fuel anyways...

have you had issues with sensors, 02 sensors like others had mentioned?

 

[freeflorider]

good to know that it would be safe on straight av atleast for 310... its hell of alot cheaper than race fuel anyways...

have you had issues with sensors, 02 sensors like others had mentioned?

Lots of us here run two stroke turbos on strait av and very few o2 sensors go...I just pack a spare and if there's a a/f issue or other just pop it in and move on, there cheap enough.
I've also heard of this dry fuel issue, not sure if its just relates to the 4 strokes but I'm thinking there is a additive out there you could add to help out the valves and cylinders...can't put my finger on it right now but it's out there.

 

[Octanee]

Lots of us here run two stroke turbos on strait av and very few o2 sensors go...I just pack a spare and if there's a a/f issue or other just pop it in and move on, there cheap enough.
I've also heard of this dry fuel issue, not sure if its just relates to the 4 strokes but I'm thinking there is a additive out there you could add to help out the valves and cylinders...can't put my finger on it right now but it's out there.

hmm, perhaps mix a little 2 stroke motor oil in? at a very fine ratio of like 100:1 if that? 200:1? but i know that oil would take up space of the fuel... so not sure if that could cause a lean condition that would be damaging?, and yeah my 2stroke turbo i ran 100% av gas, but it would be nice to get away from it.... atleast for now i suppose

 

[freeflorider]

hmm, perhaps mix a little 2 stroke motor oil in? at a very fine ratio of like 100:1 if that? 200:1? but i know that oil would take up space of the fuel... so not sure if that could cause a lean condition that would be damaging?, and yeah my 2stroke turbo i ran 100% av gas, but it would be nice to get away from it.... atleast for now i suppose

Yah I never worried about dry fuel as I mix 40:1 for the two stroke. I could not see any harm in regards to a lean condition when placing mix oil with the fuel in a 4 stroke,Worse case scenario is the plugs would fowl. Just be running rich if anything.
I'm sure at 270 ponies if you run peremum you should be fine...as you know with the two stroke that's a lot of power under your thumb....now your adding torque. It's a rush.

 

[up-high]

Don't mix two stroke oil with the fuel of a 4 stroke. The Apex is fuel injected. Lots of sensors to think about. Run 50/50 av gas and 91 and go ride the damn thing at 17 lbs if you want. If you want to forget about fuel, get some low comp pistons. I had one with a shim and another with lc pistons. I ran some av gas for my own peace of mind. Unless you ride sea level you'll be fine.

 

[pelon]

I'm pretty sure race fuel has more lead then av gas does.

Buy 100 unleaded Race!

 

[sledfvr]

Lots of us here run two stroke turbos on strait av and very few o2 sensors go...I just pack a spare and if there's a a/f issue or other just pop it in and move on, there cheap enough.
I've also heard of this dry fuel issue, not sure if its just relates to the 4 strokes but I'm thinking there is a additive out there you could add to help out the valves and cylinders...can't put my finger on it right now but it's out there.

The misconception of avgas being "dry" is that it has additives to make sure there is no water in it. A pilot wouldn't want his airplane to start dying because there is water in the fuel...lol. Av gas is 100LL, LL=low lead. Lead is good lube for valves. Pump fuel is obviously unleaded. In octane tests that have been done, avgas tests out to be very similar to 110 sonoco. My feeling is that avgas is probably the most consistent fuel you will find. I used to run race fuel and now I run avgas and couldn't be happier. Race fuel also loses octane as it sits and avgas does not. So if you think 100LL is dry fuel because of low lead then what does that say for unleaded 91?