Raptor Forum banner

41 - 60 of 74 Posts

·
Registered
Joined
·
5 Posts
Hey everyone im John and im a little new to the 4 wheeler scene ive been a dirtbiker since i was 6.. anyway i just got a raptor 660 its got an aftermarket carb(with new jets) and a full yoshi exhaust. My exhaust turns cherry red after about 5-10 min of riding..any thoughts?
 

·
Hellbound Raptor Rider
Joined
·
1,030 Posts
Hey everyone im John and im a little new to the 4 wheeler scene ive been a dirtbiker since i was 6.. anyway i just got a raptor 660 its got an aftermarket carb(with new jets) and a full yoshi exhaust. My exhaust turns cherry red after about 5-10 min of riding..any thoughts?
its a common thing with some rappys, i think theres a sticky on this if u look around
 

·
Registered
Joined
·
31 Posts
What happens when.....?

My brother in law and I have had several conversations regarding what gas we should be running in our 660r's. I have explained to him that according to everything I have read about our stock raptors we don't need to run anything better than 87 octane. Well the other day we were out riding and I noticed as the day got hotter and the longer I rode sometimes when I hit the throttle the motor would rev, but it would not make any power. Furthermore, when it revved like this, the sound was much different than it usually is. I paid no attention to it at first then I got to thinking that I must be getting predetonation due to the ambient temperature and the additional heat generated by the motor. He runs 93 and was not having this problem. I was running 87 and I think that predetonation was what was happening. What does this sound like to you guys?
 

·
Registered
Joined
·
20 Posts
i have had that problem before also.... but now i fill up with 92 one week and 87 the next... seems to run fine
 

·
Registered
Joined
·
2,417 Posts
depends on where you live. here 89-91 is midgrade and 93 is premium
 

·
Its all about the trophy!
Joined
·
2,507 Posts
And incase anyone is wondering what (R+M)/2 means that is "R" RON "+" PLUS "M" MOTOR "/" DIVIDED BY "2" TWO
 

·
Registered
Joined
·
4,986 Posts
My brother in law and I have had several conversations regarding what gas we should be running in our 660r's. I have explained to him that according to everything I have read about our stock raptors we don't need to run anything better than 87 octane. Well the other day we were out riding and I noticed as the day got hotter and the longer I rode sometimes when I hit the throttle the motor would rev, but it would not make any power. Furthermore, when it revved like this, the sound was much different than it usually is. I paid no attention to it at first then I got to thinking that I must be getting predetonation due to the ambient temperature and the additional heat generated by the motor. He runs 93 and was not having this problem. I was running 87 and I think that predetonation was what was happening. What does this sound like to you guys?
You werent detonating! It sounds like ball bearings in a soda can. You will know it if you hear it. Sounds like you have some valve train problems to me. Or a lack of compression issue. JMO
 

·
Registered
Joined
·
155 Posts
Here in Portugal i think we only have 91 and 95 octane gas, being 95 the "ultimate" or "premium" or whatever they call it.
I've been using "ultimate" on my raptor 350, so i guess thats not good?
Also i was considering getting a 10.25/1 wiseco piston. What should i use then? Other mods i have in the engine, dont know if they're relevant, are lrd full exhaust, gytr intake and jetted carb...
 

·
Super Moderator
Joined
·
17,057 Posts
Not sure about the octane requirements for the Raptor 350, you're better off asking about that in the 350 section.

You need to find out how your octane levels at the pump are presented, whether it's R+M/2 or just RON. Then consult your owners manual for proper octane requirements on a stock engine.
 

·
Registered
Joined
·
70 Posts
Interesting comments....I run the highest octane I can get..usually 92 or 93 octane with full exhaust, procircuit filter set up and jetted out carb...I have a question about ethenal ( if I spelled that right )....I was wandering.... and using a little common sense...would it be better to try to find high octane gas withOUT ethenal in it??? Would it run cleaner and possibly better????
Any thoughts ??
 

·
Master of the Electron
Joined
·
14,760 Posts
Rider4 - The question is - why are you looking for a high octane gas at all? As stated above, without high compression mods, it does you absolutely no good, actually reducing performance slightly.

The more ethanol in your fuel, the more maintenance that will be required to overcome the crap that ethanol leaves behind and the corrosion it induces.

And for those still confused about the manual's 91 RON requirement - US fuels are rated in AKI (anti-knock index) which is the (R+M)/2 described above... 85 AKI = 90 RON, so unleaded regular (87 octane AKI displayed at the pump = 92 RON) surpasses the 91 RON requirement for stock compression Raptor 660's.

The primary things that affect octane requirements are air/fuel mixture, compression and temperature - if your carbs are tuned correctly, your cooling system is working properly and the compression is stock, there is no need for anything above 86-87 octane [AKI or (R+M)/2] at US pumps or 91 octane [RON] elsewhere in the world.
 

·
Registered
Joined
·
373 Posts
What octane should I run on my 720 rappy. I'm runnin 11:1 cp piston stage 3 cam 39mm fcr , monster duals and small port job. I know 11:1 states I could use pump gas like premiuM
But would that be the best to run on my bike?
 

·
Premium Member
Joined
·
956 Posts
41 - 60 of 74 Posts
Top