Anybody run 13:1 comp? [Archive]

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carlj75

07-22-2003, 08:04 AM

What do you have to do differently when building the motor compared to 11:1. I know that you would probably have to use straight race gas. Other than that, what needs to be done? And is the increase in power worth it?

wilkin250r

07-22-2003, 08:45 AM

I personally have never run that high a compression, but the only person I know that does says he does a 50/50 with VP C12 and premium pump gas.

chad502ex

07-22-2003, 10:30 AM

Originally posted by carlj75
What do you have to do differently when building the motor compared to 11:1. I know that you would probably have to use straight race gas. Other than that, what needs to be done? And is the increase in power worth it?

carl, If I were you I'd install a high quality metal head gasket (cometics) and stronger head bolts to hold all that compression in your cylinder,.... :)

Chad502ex.com

Varmit57

07-22-2003, 10:50 AM

Curtis Sparks sells longer and stronger headbolts for high comp. setups. there $15 each and you need two. You have to drill out and tap for the longer bolts, But it will stop it from blowing the headgaskets....

norcalatver

07-22-2003, 12:37 PM

I ran a 13:1 compression 440 from LRD for almost 4 years. Never had a problem with anything except connecting rod failure. I always ran C-12 108 octane race gas straight.

buckeye400ex

07-22-2003, 02:29 PM

I have this setup now. I just got the first head gasket replaced. They replaced the blown one with a steel cometic gasket. The head bolts were helicoiled and they said the head bolts were NOT the reason for the blown gasket. ??? They blamed a faulty or weak gasket, since Cometic has the same part number on a steel gasket now. Who knows...

I also was lucky in the fact that they found a detoriating HotCams cam in my engine. (Two teeth from the spline had broken off)
They replaced that with a White Bros cam. The engine is definitely quieter than before. Feels powerful too.

I run straight 110 octane Cam2 gas. It's one less thing to worry about and it smells so good. :D

As far as the differences, I haven't really had a chance to run head to head with a lot of similarly set up (gear ratios and tire size etc...) 11:1 quads. I feel like my quad has a ton of torque and is very powerful in the mid range. Perfect for the woods, my style of riding. Just drag raced a KFX700 down a gravel road on Sunday, where I basically had to let off, once hitting 5th gear and I beat him 4 out of 5 drags. Spun the tires way too much the race I lost. I think he'd come back on me on the top end, but up to 5th gear I had him. ???

F-16Guy

07-23-2003, 03:38 AM

I would definitely consider running an aftermarket rod. I'm only running 11:1, but I bought the Carrillo anyway. Even after paying parts and labor, it's cheaper than a new motor. I've seen the damage a broken rod does, and it ain't purdy.:eek:

07-23-2003, 03:43 AM

13:1 + stock rod = kabooom

sickmojave

07-23-2003, 03:50 AM

can you tell me what the stock C.R. is on the 400 ex ?:confused:

07-23-2003, 03:58 AM

Originally posted by sickmojave
can you tell me what the stock C.R. is on the 400 ex ?:confused:

I';m pretty sure it's 9:1

hondafox440

07-23-2003, 03:59 AM

It doesn't say on thier website, but I belive it's like 9.5:1..

Running 13:1 on without larger head bolts and a stronger rod is like trying to fly transatlantic in a homeade paper airplane. Not too smart. The torque on that thing must be incredible :macho . After blowing a head gasket with the 11:1 compression in the 440, we went ahead and got those oversized studs, and have yet to have any trouble.

buckeye400ex

07-23-2003, 09:01 AM

GREAT!! Now I've already went off on the dealer and told them to go you know where! Maybe I'll just tear it down this winter and replace the stock rod. So far everything else predicted on here has come true. :(

Think it will last until the snow flies? hmm....

RideRed400StYlE

07-23-2003, 09:25 AM

I run a 13:1 I have oversized headstuds, metal head gasket, gt thunder rod(same as carrillo) run straight 110 octane, along with a gt thunder cam, ported head, and fcr 39mm carb. this thing flat out hauls.. lol

07-23-2003, 09:38 AM

Chef

07-23-2003, 09:55 AM

Originally posted by RideRed400StYlE
I run a 13:1 I have oversized headstuds, metal head gasket, gt thunder rod(same as carrillo) run straight 110 octane, along with a gt thunder cam, ported head, and fcr 39mm carb. this thing flat out hauls.. lol

Yep, I run a 13.5:1, maybe closer to 14, oversized studs, custom cut head gasket, carillo rod, VP Ultimate 4, a billet Megacycle top end cam, custom 3mm oversize intake valves, 1.5mm oversize exhaust valves, FCR 41 with a billet add on intake bell, ported, etc etc, and it hauls the mail as well. :)

Doibugu2

07-23-2003, 10:08 AM

Originally posted by Chef
Yep, I run a 13.5:1, maybe closer to 14, oversized studs, custom cut head gasket, carillo rod, VP Ultimate 4, a billet Megacycle top end cam, custom 3mm oversize intake valves, 1.5mm oversize exhaust valves, FCR 41 with a billet add on intake bell, ported, etc etc, and it hauls the mail as well. :)

Yea right. You don't have any place to hold the mail!

Chef

07-23-2003, 10:13 AM

Originally posted by Doibugu2
Yea right. You don't have any place to hold the mail!

Yea...that could be a problem...:ermm: