compression ratio for 416

[ridein'red7]

i building one and need to know what compression to go to and still run on pump gas thanks

[CJM]

I went 11:1, I think highest you go is 12:1.

[ridein'red7]

yea will 10:1 do work?

[CJM]

10:1 is stock if I recall, so yea it will work fine.

I just did an entire 416 build, hotcams stage 2, 416 bore out, wiseco 11:1 piston, timing chain, etc. It wasnt even properly jetted and it ran like raped ape. Im gonna wind up using 93 octane if anything, stations around here dont sell more than that, least that I can find.

10:1 should run on 87-89

[ridein'red7]

yea but ill notice it over stock rite?

[CJM]

Originally posted by ridein'red7
yea but ill notice it over stock rite?

Of course, your adding displacement.

My engine was totally stock as far as I can tell. Piston had no markings, stock cam and everything-I paid the dealer (my dealer is actually awesome) to tune my carb as despite me being able to build an engine I cant do carb work to well. They tuned it and it RIPPED vs my friends brand new 07 400's. All I had was some douglass wheels, and kenda klaw 20's and 21 stock like dunlops, lexx exhaust and I adjusted the throttle cable.

When I redid the topend and put the 11:1 I could tell a difference but I threw in some 89 octane I had laying about and the jetting was off (backfire on decel) and it still ran pretty good-def could feel more power just taking it for a test ride or two.

I would say go to 11:1, it will give you more power b/c of more compression. Caveat is you should run 93 octane or it may ping, it might be fine tho. Also should use a timing key without 100+ octane tho b/c it probably will ping due to the timing advance.

[ridein'red7]

id like to stay at 10:1 because i dont want to do studs

[honda400ex2003]

11:1 is fine on 93 octane
10:1 fine with 89 or 91 89 at the very least and not with every tank
both will be fine with the stock studs for most people. unless they get overheated or something like that they will be fine. most of the time this is when they pull anyway. keep them cool and you will be fine.

12.5:1 will need race gas at least 105 octane to get going good and needs to have hd studs without a doubt

all are over the stock compression of 9.1:1. hope this clears up the previous untrue statements for you. all are good for certain applications. steve

[honda400ex2003]

also none of these are actual values unless you run JE pistons. these are all measured using the xr engine which uses thinner gaskets compared to the ex. if you want the true compression use the xr gaskets. so you can take off about .4:1 for each of them when using the ex gaskets. so theoretically the 10:1 is not really that much more over the stock pistons but it is a great improvement none the less with other items such as a cam. steve

[ridein'red7]

well as far as i know it has stage 1 cam and it has a full yoshi system and a full intake with aluminum intake as far as i know of maybe more but i just want to do a 416 but was wondering if the 10:1 would be great over stock

[ridein'red7]

also using xr400 gaskets are they ALL the same gasket as in if i got a full gasket set itdd be the same just thickness?

[Kentang4]

I just finished a build using a 416 11:1 wiseco with standard gaskets, stage 2 hotcam and a +2 timing key. The motor runs great on 93 octane. Since you are going through the trouble of replacing the piston I'd consider the 11:1. There really isn't a down side.

[honda400ex2003]

I love my 10:1 416! i would do it again if i needed to in a heart beat. steve

[ridein'red7]

do u think my set up will be sweet?

[TRXRacer1]

I did a 416 10:1 with a stg 1 cam and it was a stump pullin' monster. Opened up well on the track too.

[Kentang4]

I'm sure the 10:1 is a nice motor too. I spent lots of time reading this board before making a decision and just didn't see any reason not to go with 11:1. My concerns were primarily whether or not I could use pump gas, which I can and whether or not it would require HD head bolts, which it apparently doesn't. I know for sure it doesn't ping or detonate, even with a +2 advance key but I guess I'll have to concede that the jury is still out on the HD studs since the motor is fresh. It does seem that lots of folks have sucessfully run 11:1 with stock studs though so I feel pretty good about it after carefully measuring mine to make sure they weren't stretched and then torquing them to spec.

As for cams... I actually have very recent experience riding a 416 with a stage 1 cam and now riding mine with the stage 2. The stage one cam is definitely an amazing stump puller. It's a ton of fun to ride and would be my choice hands down if I primarily rode on the trails. However, I ride primarily on open farms and mx tracks so I felt the stage 1 ran out of steam a bit early. The atv I rode had an after market rev box also and while the advance timing curve it provides is usefull the 10,000 rpm rev limit is pointless and only allows friends to abuse the machine.

After watching others ride, knowing my own tendencies and spending lots of time reading posts and reviewing dyno charts I decided the stage 2 was the best choice for my atv. It doesn't have the off-idle torque that the stage 1 provides but the mid-range is superior and the cam pulls higher and harder. It seems to be a great match with the factory rev limit of 9000 since the stage 2 falls off just past 8000 making an 8500 rpm shift point just about perfect. In the end it's all about what you plan to do with your machine. The joy of having massive low end grunt can't be discounted but if your riding style is just a tad more aggressive I think the stage 2 is a great choice and still gives you good low rpm rideability. I was actually a bit hesitant to try a stage 2 since I knew the stage 1 was so good, but I'm glad I did and in the end it was the right choice for me.

[TRXRacer1]

Originally posted by Kentang4
I'm sure the 10:1 is a nice motor too. I spent lots of time reading this board before making a decision and just didn't see any reason not to go with 11:1. My concerns were primarily whether or not I could use pump gas, I would not have been able to run pump gas with an 11:1 because I needed more then 93 on some of my deep woods adventures with 10:1 in order to prevent detonation. Detonation can happen in such a mild manner that most back yard builders don't even know it's happening. Ever heard someone honestly say they felt more power with more octane? They are the ones that needed it and didn't even know. If you abuse your machines at all like I do just have a plan "b" on fuel choices.