A friend of mine suggested to me I could run race gas in my Raptor to eliminate a slight hesitation it has at about quarter throttle.

I currently run 93 octane with these motor mods: K&N pro design filter no lid, LRD Pro4 full exhaust, Hotcam Stage 1, Wiseco 11:1 high compression piston. My friend suggested mixing a higher octane race fuel like Cam2 with 94 octane 50/50. It runs great, just a slight hesitation and delayed throttle response. The plug reading is good, it's just a little darker than tan brown.

What do you guys think? Can I even run race fuel with these mods, or am I asking to detonate my quad?

 

well, according to my engine builder I can. so those of you out there wondering, there you go.

 

Race gas burns slower, it helps prevent detonation/pre-ingnition.
It' won't hurt your motor nor will it help you "make" any power (all by itself). It will actually produce less HP..
Now if you up the comp. and add timing along with other mods then yes, it will give you more power..

 

You certainly wont hurt your engine. I Run 100% 104-105 octane race fuel ,and notice a nice performance dif. @12/1 comp. ratio

 

Well, the raptor is running better with the mixture of 94 octane and Cam2 at 50/50.

There is still a hesitation at about a quarter throttle in first and second gear. It's not there in third. I'm going to try adjusting my needle next week when I have some time to see if it helps.

My needle is currently on the 4th clip from the top. The last time I made a needle adjustment, I dropped it down by placing the needle in the third clip from the top, but this adjustment made it worse.

So I'm thinking I'm going to take the clip to the fifth and final spot from the top. If that doesn't work, then I'll try the second clip from the top. If that doesn't work, then I have no clue.

Right now I'm running 155/160 mains with the larger pilots in the GYT-R jet kit. I have a K&N filter with no airbox lid and an LRD Pro4 full exhaust system. Any ideas would be appreciated. thanks.

 

First suggestion, drop the race gas...on second thought see below...

1/4 throttle can be a tricky spot. I'd suggest tweaking your fuel screws while you're at it.

You're in ohio, so I'm guessing that the elevation isn't all that high. With a full exhaust, no airbox lid, high comp piston and stage 1 hotcam running mikuni jets YOU ARE WAY TOO LEAN!!! The big gun doesn't flow all that well, but it flows better than that.

That's probably why the bike is running better, the fuel is not pre-igniting as badly. Your bike will run better on 91-94 octane when it's jetted properly.

With a stock head you should start out at 170/175 mains and go a bit richer from there.

 

I didn't think I was running too lean. When I pull my plug, it is dark, not light. I was running 165/170 mains when I first put it back together, and it completely ran like crap.

Since going down in the mains, it has improved. I figured if I went up, it would run even worse.

 

I ran 165/170 mains with K&N and no lid with CT pipe and an otherwise stock bike at 500' above sea level and it was only a touch rich in midrange from the CT needles that came in the kit.

With an 11:1 stock bore, stage 2 hotcam, oem valves/head, Pro-design K&N with no lid, and ct pipe with 16 discs I was running 185/190 mikuni mains, 4th clip on CT needle, 30 pilots (for winter warmup only) at 500' above sea level and the midrange was prone to hiccups in this setup as well. Finally fixed it by swapping back to OEM needles.

We ran 160/165 mains on a FMF piped, K&N no lid bike and it still popped occasionally on decelleration.

We're running 155/160 on a Yoshi piped, full airboxed, K&N drop in bike at the same elevation and it runs well.



I guess I wont tell you how your bike should run and how to tune it, but in my experience you're choking and burning up that engine.

 

OK, I may be jetted too lean on the mains.

I corrected the adjustments on my air/fuel mixture screws, and now my plug is showing the quad is running lean. So I may need to bump up the mains. I'm going to take the quad for an exhaust gas reading to see where it is lean and make the adjustments.

Hopefully I can straighten it out and get it running right. There is only a slight hesitation now in first gear. It's close, but I still need to rejet.

 

is this a 350 or 660 raptor?