apex mcx 290

[yamaha4life]

i seem to have a run into a problem with my apex again 2 weekends ago my sled was making too much boost compared to what i was usually seeing 15.5lbs compared to 12lbs. once i noticed it i didn't drive it that hard for the rest of the day, was only running 94 octane gas so i didn't know if i had enough octane for 15 lbs so i took it easy just to be safe. this week i took it out again and it seemed to be sluggish (not really making any boost, but i didn't really look down) it seems like it wants too die if you give it too much gas, perhaps a boost leak. any ideas would be appreciated and also note this machine had the mcx injectors replaced about 400km ago.

 

[summitboy]

Altitude ? 15-16 at 6500-7000 is normal on the 290 kit. I run that on 91 Shell premium. 12 psi is like 260HP at SL.


Apex 16T 260 HP (180 KPA)
Sea 12 psi
6500 14.5 psi

Apex 19T 290 HP (200 KPA)
Sea 14.5 psi
6500 17.4 psi

Nytro 16T 180 HP (140 KPA)
Sea 6 psi
6500 8.7 psi

Nytro 16T 240 HP (190 KPA)
Sea 13 psi
6500 15.9 psi

Nytro 19T 270 HP (210 KPA)
Sea 15.9 psi
6500 18.9 psi

Keep in mind these are a little rounded and using 100KPA sea and 80KPA 6500.

 

[up-high]

Make a plug for your intake. I used a piece of abs. Drilled a hole slightly smaller than an air plug and then heated it up and screwed it in. Put 15 or 20 psi into the system and leaks are easy to find.

 

[summitboy]

Black injectors are pure chit ! MCX won't tell you that but i am LOL. I have 12000km on orange (which are brown in the MCX world) injectors and never have had a injector issue. Since they switched to black nothing but issues making their kits look unreliable. I guess having a part number protected injector is more important than reliability. They sell you that black was made so they can have one injector for all kits. The blacks aren't holding up the same plain and simple. If your not making boost the next trip i would be looking at the injectors instead of a boost leak. Ive had cracked pipes and old donuts and have never had boost issues. I did blow a bellows about 4 years ago and it ran chitty in the bottom end but still made boost. Why were the injectors replaced ? LOL not working ! Who would of thought.

 

[yamaha4life]

Thanks guys for the reply ill try couple of those suggestions. don't really know what the elevation was but normally the max boost i could get was 12or so psi when i rode there before near price george bc. But from my last ride the symptoms i got were similar to when my injectors went down, so it might be another set of injectors, the las ones were both stuck open. Other possibilities other than some sort of boost leak, could there possibly be moisture in some of the connections or lines? Thanks again for the information

 

[summitboy]

Which generation of fuel box is this ? When was it built ? Ask for brown injectors and a remap lol and see what they say ! At 12 psi your only getting 250-260hp at sea level.

 

[yamaha4life]

well i took at look at it this weekend and didn't find anything wrong with it, but didn't check the injectors. it still does the same thing boosts up to 10lbs and then falls right on its face, and starts almost back firing, then i can here the BOV open. it kinda sounds like those launch controls you can get for these so I'm thinking it might be the BOV or the injectors. this sled was built last year and has the mid mount mcx 290 kit on it. But I'm gone take it to pg yamaha again this week and see if they can find something else wrong with it.

 

[summitboy]

Cant see it being the BOV really. Jmo

 

[BOOSTD]

One thing to try is to make sure the mcx box is still sensing pressure and firing the external injectors. You can pressurize the box with air at idle and it should fire the injectors and kill the motor, this will eliminate a bad mcx box which is very rare but possible. Be sure to not over pressurize the box by using a boost gauge inline on a T or something but add about 12psi and it should flood out the motor.

 

[Menace1]

Injector

well i took at look at it this weekend and didn't find anything wrong with it, but didn't check the injectors. it still does the same thing boosts up to 10lbs and then falls right on its face, and starts almost back firing, then i can here the BOV open. it kinda sounds like those launch controls you can get for these so I'm thinking it might be the BOV or the injectors. this sled was built last year and has the mid mount mcx 290 kit on it. But I'm gone take it to pg yamaha again this week and see if they can find something else wrong with it.

This sounds identical to what my previous mcx apex was doing and guess what, it was an injector issue. Take it in get them tested.

 

[mitty26]

Oh the good old black injector issues again , it don't surprise me , pure junk.

 

[yamaha4life]

thanks guys the sled is currently back at the dealership getting looked at ill see if they did stest the injectors the only thing that pisses me off the injectors were replaced like 6 rides ago

 

[mitty26]

I had an injector fail after twenty feet, I had just gotten them back from getting tested , installed them and as soon as they fired one failed. Hope you get it figured out.