Question on 91 pump fuel

[my yammi vice]

Is it safe to trail ride an Apex with 91 premium fuel running the 26/24 pulley combo and about 10 lbs boost? Considering a Stage 1 from MPI. Mostly trail riding at up to 1000 feet elevation and the odd line up on the trails with buddies...

 

[Ski-Dooin' it]

thats definately getting up there as far as what you can run... what kinda compression would the setup have?? play with the octane calculator on the top of the page. might be alright for just messing around, but not sure.. 1000 feet is below my relm of thought.

 

[stone88]

Is it safe to trail ride an Apex with 91 premium fuel running the 26/24 pulley combo and about 10 lbs boost? Considering a Stage 1 from MPI. Mostly trail riding at up to 1000 feet elevation and the odd line up on the trails with buddies...

No you WILL blow it up if you try. I would take the head off and put 3 head gaskets on and you should be fine according to the boost calculator.

 

[kinger]

Your correct I run a 10:1 head shim and run on 91 with the same set up your proposing. If you didn't want to shim the head then you need a 50/50 mix of race fuel and premium.

Great set up runs like a crazy machine!!

 

[my yammi vice]

Thanks folks,
Is this a setup that needs to be wrenched a bunch or can I set it up and ride??? Three head gaskets or a head shim shouldn't be a problem if it is reliable. I don't mind doing that. I think that I would set up for 5-7lbs for the first year and then shim add b/o valve...later. Or I suppose that once you have it apart, I may as well do the whole job, eh?

 

[kinger]

No the head shim is a whole other project you can defintily install the super and enjoy at 5-7psi then next year swap pullies around (lower to upper and upper to lower) (you will need two sets of taper locks make sure to tell MPI when you order) to make 10-11 psi once you shim the head.

Works awesome you will just shake your head after the first pull in amazment of how fast it is compared to a normal sled. I still shake my head after a 1500 mile season I never lifted the hood! just beat the snot out of it and it loved it. Very awesome sleds these boosted yamahas are.

 

[Ski-Dooin' it]

If you have the time, its so easy to install a headshim, then you can just go straight to 10#.... its to fun not to have! I run 10# in the hills and its fast, but i guess I dont think I can ever have enough power, I also ran mine at 15/16 once... so it makes 10 feel slow..

just throw the hsim in so you can swap straight into big boost when your ready.

 

[rxrider]

 

[spddmon]

i would recomend a bov even at 5 psi also a must have is an afr aem is decent bang for the buck, fjo is the best, 5 psi the sled is sneaky fast on the trails corners come fast i cant imagine running 10 on local trails its a handful on the lake

 

[kinger]

I was worried about 10-11 psi on the trails and I find it very easily controllable. I was pleasently surprised. I think I could lumber this sled around with my 2 yr old niece on it putzing in the yard then take it out myself and whoop up on 800 mod 2 smokes like they were sitting still.

This sled is the performance standard for trail sleds IMO. Nothing can touch it and I never have to lift the hood! Its everything I hoped it would be. I was really expecting to have to tinker all the time and I wouldn't hesitate to go back to stock for reliability but you can have your cake and eat it too with a SC system!

 

[mulot30th]

10 psi, headshim, and be done, its fast enough for trail fun and occasionnal buddies run.

 

[HURRICANE]

We have been lowering the compression and setting the cam timing on the supercharged Apexes.We find that the sleds come in with stock engine,we shim the head and set the cam timing with our jig and the clutching is about the same at the same boost.To me the power then is the same with the safety of lower compression

 

[mulot30th]

Honestly, I made about 20 more hp on dyno on stock rx1 engine running c16 and pump gaz mix ar 11 psi.


than same boot at 9-1 compression and pump gaz.

 

[my yammi vice]

Thanks for all of the input, I am reading up on this like crazy...I am liking what I am hearing so far. Head shim, BOV, rear heat exchanger try 5 lbs and maybe 10lbs. Scratchers, Cooling is key eh? This going to be my trail sled and I don't want to be wrenching all the time. I love to put on miles.