Raptor Forum banner

1 - 20 of 45 Posts
G

·
Discussion Starter · #1 ·
I was offered a good price on a 13.1 high compression and stock bore piston, and I am thinking about buying it. I need your opinions though, If I put this 13.1 piston in my 700 raptor, I know that I will need to run race fuel, but what would be the BEST race fuel/octane to run in this quad. I was told by a mechanic at my dealer that U4 fuel has been known to leave a residue and it must be drained after every ride, is this true? Is there a better race fuel that will work with this 13.1 piston that will not require all the hassles?
 

·
Registered
Joined
·
783 Posts
What else are you going to do besides the piston? Cam? Port work? etc. I personally would not run such a high comp piston even in an all out drag machine just for reliability reason alone. 12:1 would be my max for a dragger and 11:1 for a drag / trail / duner machine.

You can probably get away with running:
VP Red and be ok (105 octane)
VP 110 (110 octane)
c12 (108 octane)

The U4 is oxygenated fuel and there is no reason to run it unless your motor is seriously. That stuff stinks like rotten eggs and clogs the fuel system. Again I wouldnt run the 13:1 unless I was comfortable and OK with changing out head gaskets quite often as well as comfortable with teh fact your machine is not nearly as reliabiable. Also be prepared to take that $$$ you saved and dump it into fuel thats $6-8 a gallon + and not as readily available. I ran race gas in prior drag machines and it was a pain in the arse to get. Just my .02
 
G

·
Discussion Starter · #4 ·
Thank you for the heads up. I think that I will stay away from the 13:1 piston. I want to be able to keep the stock rod and crank and I want to be reliable, so I will go with a 12:1
Thank you all again
 

·
Premium Member
Joined
·
5,119 Posts
j700 said:
Thank you for the heads up. I think that I will stay away from the 13:1 piston. I want to be able to keep the stock rod and crank and I want to be reliable, so I will go with a 12:1
Thank you all again



I wouldn't even run a 12:1 piston on the stock rod. The highest compression I would go with the stock rod is 10.75:1 or 11:1 max. I run a 12.5:1 in my 780 on VP110 or R-tech 110 race gas and it's dunable as all get out, but it has a crank works crank and falcion rod to take the higher HP and TQ it makes and maintain reliability.

If it were me and I was on a tight budget and wanted good bang for my buck that would go a long time between freshen ups I would build a 11:1 stock bore with a Mega cycle X1 cam, port & polish and a custom fuel map and run a set of LTE or barker duals and ride the shit out of it. I'm sure you would be pleased with that combination
 

·
Registered
Joined
·
684 Posts
Look at it like this. If the bike is stock with a pipe. You will gain more hp and usable rpm range with porting than you would with a 13-1 piston. And the best part is porting still leaves the engine 100% reliable. I could do a trail port on your head for just a little more than the piston would cost you.
 

·
Registered
Joined
·
100 Posts
can anyone tell me the stock compression ratio? Also if you go with a higher compression piston say 11:1 do you have to change the cam or is it just recommended
thanks
 

·
Registered
Joined
·
305 Posts

·
Registered
Joined
·
429 Posts
13:1 would be a pretty hi-strung set up. I agree with sparky about never going above 12:1 an 11:5 would still run fine on 92 octane if you had to! Most of the stock 450 bikes are 12 or a little over, they run fine on pump gas.. You have a shop sparky? I might be interested in porting the head. I would like to go 11:1 but am unsure about the cam, I'm not afraid of the rev-limiter so I want to make a good choice the first time...lol
 

·
Registered
Joined
·
153 Posts
I have ran a 12:1 piston for about a year now. I am at 6k ft and above, 91 octane. I also rode for 2 weeks in MN, 91 octane. I just pulled the head off to have some work done, piston looks brand new. (after cleaning) No problems with detonation, pits, ect. Runs very strong and was a pretty significant gain over stock. It is a CP piston. Always good to consider where you ride when deciding on the compression ratio and if it will create high strain on cranks, rods, ect.
 

·
Registered
Joined
·
684 Posts
GEARHEAD9969 said:
13:1 would be a pretty hi-strung set up. I agree with sparky about never going above 12:1 an 11:5 would still run fine on 92 octane if you had to! Most of the stock 450 bikes are 12 or a little over, they run fine on pump gas.. You have a shop sparky? I might be interested in porting the head. I would like to go 11:1 but am unsure about the cam, I'm not afraid of the rev-limiter so I want to make a good choice the first time...lol
Yes my shop is Sand Demons Motorsports. If you need anything just call me at 530 832 1065 or 530 927 9827, and the new shop # will be 1 877 got dyno, as soon as SBC can get off there duff and set me up at the new building.
 

·
Registered
Joined
·
52 Posts
I am out in Utah. How much for a good port job I am running just intake, dobeck, and pipe? would love to go into the motor and change piston, vavles, and cam. what would put me ahead on the hill?
 

·
Just a 78HP trail bike
Joined
·
2,426 Posts
RaptorRandy27 said:
j700 said:
Thank you for the heads up. I think that I will stay away from the 13:1 piston. I want to be able to keep the stock rod and crank and I want to be reliable, so I will go with a 12:1
Thank you all again



I wouldn't even run a 12:1 piston on the stock rod. The highest compression I would go with the stock rod is 10.75:1 or 11:1 max. I run a 12.5:1 in my 780 on VP110 or R-tech 110 race gas and it's dunable as all get out, but it has a crank works crank and falcion rod to take the higher HP and TQ it makes and maintain reliability.

If it were me and I was on a tight budget and wanted good bang for my buck that would go a long time between freshen ups I would build a 11:1 stock bore with a Mega cycle X1 cam, port & polish and a custom fuel map and run a set of LTE or barker duals and ride the shit out of it. I'm sure you would be pleased with that combination
Oh really? :grin_nod: :grin_nod:
 

·
Premium Member
Joined
·
5,119 Posts
pw383426 said:
Wow, old thread. Look today how many people are running 13:1+ on their stock rods

Yep, and wait till you see how many people have had rod failures this time next year..I'm not talking about the guys that only put 4 or 5 weekends a year on em. I have already seen 3 different 700R's in my area break the stock rod off after going to high comp pistons....but these guys put a lot of time on their machines. Some may get away with it...but why take the chance?
 

·
Just a 78HP trail bike
Joined
·
2,426 Posts
J-HILT Rap700 said:
Damn I'm running 14:1
Damn Hilt, were DOOMED :'( :'(

Sounds like an excuse to get a good stroker setup
 

·
Premium Member
Joined
·
5,119 Posts
Why would you do that? To me if you can afford the mods to get the HP you guys are getting with these stock bores....why not put a good rod on the crank and have it trued, welded and balanced? I wouldn't even consider doing it any other way myself.
 

·
Premium Member
Joined
·
5,119 Posts
preddy08 said:
J-HILT Rap700 said:
Damn I'm running 14:1
Damn Hilt, were DOOMED :'( :'(

Sounds like an excuse to get a good stroker setup



Just remember.....if it's got tits or wheels, sooner or later it's gonna give you trouble ;)

Might as well do everything possible to prevent it IMHO.
 
1 - 20 of 45 Posts
Top