best performance mods VS pump gas

[bmf400ex]

whats the best performance one can get while still using pump gas(93 octane) what i mean is what engine mods can be done while staying with 93 octane and not mixing race fuel in. not looking for a race winning quad just the most power i can make without having to buy race fuel. can a cam be used, bigger bore? what?

[cals400ex]

most definately a cam and piston can be used. most people agree that you probally don't want to go higher than 10.8:1 using pump gas though. there are many 416's on this site. i personally run a 406 and i like it a lot. you will get really good gains out of a cam/piston. a new carb will also give great gains. you can use all of this on pump gas.

[wilkin250r]

Higher compression is the only reason you would need race gas. You can build yourself a 500cc big-bore stroker motor with a high-performance cam, and still run pump gas as long as you don't get a really high compression. Some people have been able to run 11:1 compression with pump gas, but others have had problems, You're probably OK running 10.5:1 compression with pump gas.

[bmf400ex]

so what is the standard compression of a 400ex? are those aftermarket 440 kits available in 10.5 or less compression?

[remlapr]

stock compression is 9.1:1 I'm pretty sure. I'm sure you can get 10.5:1 440 kit. I would suggest called Colby at C&D racing - he has helped many people on here build up their motors...

[wilkin250r]

Why don't you want to use race gas?

[K_Fulk]

Originally posted by wilkin250r
Higher compression is the only reason you would need race gas. You can build yourself a 500cc big-bore stroker motor with a high-performance cam, and still run pump gas as long as you don't get a really high compression. Some people have been able to run 11:1 compression with pump gas, but others have had problems, You're probably OK running 10.5:1 compression with pump gas.

Like he said you can do pretty much anything to it, just keep you compression under 11:1. You can still get put oversized valves, have it fully ported and stroke itand whatever else.

[bmf400ex]

why do you think? $$$ i wanna just pull up to a pump and go.




Originally posted by wilkin250r
Why don't you want to use race gas?

[bmf400ex]

i'm not lookin for a huge stroker or anything. i am in a transitional period where i trying to decide. Modify, or sell and get something else.

[wilkin250r]

Originally posted by bmf400ex
why do you think? $$$ i wanna just pull up to a pump and go.

I figured it was money. Are you looking for a basic compromise of price and performance, or are you looking for "the best" as your first question asked?

A 440cc kit is about $500 more than a 416 kit. Why? Because a 416 doesn't require you to split and machine the cases to accept the bigger sleeve. For the cylinder, a 416 just requires a $60 bore, and not a $150 re-sleeve.

However, a 416 with a high 13:1 compression (which needs race gas) will beat a 440 with a 10.5:1 compression. That $500 you save in the motor will buy a lot of race gas.

So, it really depends on how much performance you want. You're first question was "whats the best performance"? If you truly want the best performance, you are going to need to spend a doller in your engine to save a dime on gas. A 416 with a cam (about $500) with a high compression will outrun a $1500 motor running pump gas.

[Glamis400ex]

the 10.5:1 piston only comes in stock bore and 10.8 and higher in the 416 kit.

Glamis

[hondafox440]

Depending on the 440 kit you purchase, boring the cases is not necesary. I know for my 440 kit, the outer sleeve diameter is the same as stock so nothing other than pressing the old sleeve out and pressing the new one in was necesary. For under 300$ you can have a 440EX that outruns 416s. The kids are like 160$ on eBay, plus about 100$ for a machine shop to press the new sleeve in. Rebuild it yourself and you're set. Runs on pump gas too.

Wilkin, doesn't altitude also affect the need for race gas? Like a 10.5:1 engine may run fine on pump gas at sea level, but at 4000 feet up it may need a race gas mix (say around 95 octane) due to the lesser amounts of oxygen present in the air?

[remlapr]

Originally posted by Glamis400ex
the 10.5:1 piston only comes in stock bore and 10.8 and higher in the 416 kit.

Glamis

How sure are you about that?? I was told mine was 10.5:1 - see mods below...

[Glamis400ex]

Remlapr,

Hmmm, I believe thats what Colby told me. I told him that I didn't want to run a mix of race gas so he told me about the 10.5:1, but said it was only stock bore. The 10.1:1 is also available in the 416 I believe.

I could have those 2 mixed up and backwards...???:confused:

I ended up going with 10.8:1 and mix pump w/ race gas. It's a few extra bux, no biggie.

Glamis

[cals400ex]

Originally posted by hondafox440
Depending on the 440 kit you purchase, boring the cases is not necesary. I know for my 440 kit, the outer sleeve diameter is the same as stock so nothing other than pressing the old sleeve out and pressing the new one in was necesary. For under 300$ you can have a 440EX that outruns 416s. The kids are like 160$ on eBay, plus about 100$ for a machine shop to press the new sleeve in. Rebuild it yourself and you're set. Runs on pump gas too.

Wilkin, doesn't altitude also affect the need for race gas? Like a 10.5:1 engine may run fine on pump gas at sea level, but at 4000 feet up it may need a race gas mix (say around 95 octane) due to the lesser amounts of oxygen present in the air?


i don't see how it is possible for the outer sleeve diameter on a 440 can be the same as the stock sleeve??? also, i know many 440 sleeves will fit in the case but there is not enough play as there should be. i hear this extra play is really important for the best "quench" area.

[JOEX]

Originally posted by Glamis400ex
the 10.5:1 piston only comes in stock bore and 10.8 and higher in the 416 kit.

Glamis
I suppose that is advertised compression?

From what I have been reading on this subjet there are many variable to be considered when measuring compression ratios such as piston manufacturer, head gasket thickness, base gasket if any, cylinder decking, head shaving.....

I wish things were a little clearer on this....

From what I have read 10.8 is the highest compression to run safely on pump 93 octane.

Joe

[bmf400ex]

Originally posted by wilkin250r
I figured it was money. Are you looking for a basic compromise of price and performance, or are you looking for "the best" as your first question asked?

A 440cc kit is about $500 more than a 416 kit. Why? Because a 416 doesn't require you to split and machine the cases to accept the bigger sleeve. For the cylinder, a 416 just requires a $60 bore, and not a $150 re-sleeve.

However, a 416 with a high 13:1 compression (which needs race gas) will beat a 440 with a 10.5:1 compression. That $500 you save in the motor will buy a lot of race gas.

So, it really depends on how much performance you want. You're first question was "whats the best performance"? If you truly want the best performance, you are going to need to spend a doller in your engine to save a dime on gas. A 416 with a cam (about $500) with a high compression will outrun a $1500 motor running pump gas.

so if i went with a 13:1 416 kit how much race gas would i need to mix with regular for it to run its best? and would it run at all or like total **** with pump gas.

[wilkin250r]

Originally posted by bmf400ex
so if i went with a 13:1 416 kit how much race gas would i need to mix with regular for it to run its best? and would it run at all or like total **** with pump gas.

With a 13:1, you would probably need to run straight race gas. You can probably run a 50/50 mix all the way up to 12:1.

Low octane can damage your motor. Race gas is high octane, typically 110 to 120. Pump gas, as you have seen, is generally 87, 89, 91 or 93 octane, depending on the "grade" Octane is not power, it is the ability to withstand heat without igniting. When you compress a gas, it heats up. If you compress it MORE (high compression motor) than your fuel could ignite before the spark plug fires. This is called detonation. If your fuel ignites while the piston is still moving upwards, you create TOO much pressure, and it could blow your head gasket, or damage your piston and rod. This is why you need a high-octane fuel. The higher octane can tolerate the higher tempuratures and pressures so you don't get detonation. The extra power comes from the higher compression, not the higher octane.

The reason I bring this all up is that there is alot of power in compression. If you're just looking to get a little more power without too much hassle, then certainly get a 10.8:1 compression and call it good, you'll definitly feel an improvement over stock. However, if you are looking to get LOTS more power, maybe outrun a banshee or Raptor, higher compression and race gas is cheaper than major engine mods running pump gas.

All the advice you are getting on this forum is pretty good, but it's just that. Advice. Don't take all this as gospel, make sure you go over your options with whoever is building your engine. If YOU are doing your own work, go over your options with whoever you are buying your parts from ( like Colby at C&D) and discuss your needs in depth.

[bmf400ex]

i may be solving the problem for free. just got a call from someone who wants to trade me for a banshee. :D won't cost me a dime and its already got atleast 15 more HP.

[Quadzilla]

And you get the added bonus of crappier suspension, horrible brakes, frequent motor rebuilds (2-stroke w 2-cylinders!), fouled plugs and 15+ year old technology. Gee, where do I sign up???? :D :D

[Glamis400ex]

yup, just like Quadzilla stated...when the motor needs work it's 2 pistons, 2 bore jobs, 2 set of gaskets, 2 carbs, 2 pipes, and you'll wrenching on it more than riding it...good luck with that...:rolleyes:

Glamis

[bmf400ex]

you guys may think i'm crazy but i've owned more 2-strokes than 4 and they have been calling me back. i dig the 4-stroke low end grunt and reliability but i honestly was not that impressed with the 400ex. in my opinion all stock suspension on any quad is substandard so i don't really consider it applicable. i plan on replacing the suspension any way so its a wash. however if a 2-stroke setup properly will run just as long as a 4 stroke without problems. i do agree 2-strokes require rebuilds much sooner than 4 strokes, however 2-stroke engines are cheaper to do a top end if you include redoing the head on the 4 stroke. i think the 250R guys see where i am coming from. i must admit that 400 is one helluva quad and the first 4-stroke i've owned that actually had any balls in stock form. plus i think now is a good time to get rid of the 400 seeing as how the 450R is coming and i would imagine the 400ex bandwagon will shrink wtih people selling it to get the 450R, i see them droppping their value fast in the market. what can i say, i've always had a heart for the 2-stroke.