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08-02-2001, 07:33 AM
I'm going to put a high comp. JE piston in my bike real soon with XR cam,,,,I plan on running pump gas (93 octane) what compression piston would you guys suggest,,:confused:

08-02-2001, 07:48 AM
I am getting ready to go to a 416 and my friend is gonna do the 440, so we've been checking with shops around here on that exact same question. They say 11:1 is a good norm, 12:1 with stock cam and might have to boost the accelerator pump to feed it. We are probably gonna do 11:1 just to keep costs down.

08-02-2001, 08:15 AM
Yeah a buddy of mine suggested the 11:1 JE piston,,JE pistons are lighter than wiseco so that should help...Also there are 3 head gaskets and dropping down to using 1 was also recomended,,more compression this way..You'll love that 416 kit if you get all the bells and whistles added with it,,,my racin buddy that has one is a real rocket ship..

08-02-2001, 08:28 AM
Yeah I hope it's as good as I've heard, the other guys we ride with have some pretty intense bikes. One is a DS650 that has been in the shop since it was new being stroked, ported, cammed, and you name it. The other two are a Raptor and a built 250R. So we are gonna see how the 416 and 440's do against those. We've been reading a lot, and asking a lot so I hope to get a decent build that will do some talking out there. You know any specifics on your buddy's that has made it so good?

08-02-2001, 09:43 AM
I had a little work done to mine and it goes great. I didn't want to have to run race gas and the engine man said I would not have to but.... when I run 93 it pings when it starts to wind out. If I run 110 or a strong mix of more 110 than 93 it screams!! With bald tires I can run a banshee and walk a stock 400. I am ready to see how some traction out back helps!!

Later,

08-02-2001, 10:10 AM
Originally posted by WJW77
You know any specifics on your buddy's that has made it so good? [/B]

bored .80 over w/ 12:1 JE piston, TC racing cam, TC ported head, heavy duty valves, Flywheels been lightend, Hinson clutch basket, 38mm Lectron carb, K&N filter w/ outerwears wrap, Engine built by Rocky Ridge Racing.

Its a real handful

400exRacerX
08-02-2001, 11:33 AM
My buddy has a 11:1 comp je piston and when he runs pump gas (93 octane) it pings. From what team pompton racing told me is that 10:1 is the highest comp you can go on 93 octane.

08-02-2001, 01:54 PM
My 416 is a Wiseco 10:1 with an XR400 Web cam, and trust me, it can boogie. I couldnt make up my mind whether I wanted the Wiseco 10:1 or 11:1, but I do not want to have to bother with race fuel or pinging due to 90-ish octane pump-gas...

I have zero regrets having gone with the 10:1, and acutally, I believe the camshaft makes more of a difference on the overall power increase...choose your cam carefully, meaning, get as agressive as you can afford WITHOUT having to rebuild the internals of the engine. For example, my 416 with the cam I have ALWAYS beats my 2 friends' 430's, with 11:1 pistons & diff. cams than me.

Oh, and I didn't want to sacrafice ANY reliability -- another key reason in going with the 10:1 -- it adds a good dose of power, without putting all the stress of super-high compression on the engine's internals.

08-02-2001, 02:34 PM
Whats the stock compression of the 400 from the factory???

#77
08-02-2001, 02:36 PM
9:1

400exRacerX
08-02-2001, 09:51 PM
incorrect #77 the stock compression is 9.1:1

rhandw69
08-02-2001, 11:45 PM
Im in the middle of putting my 416 kit back together, im now hesitant on putting it all together because im kinda not sure about what to do with my stock cam. Replace with XR or not?
Heres my worry:
1. Losing too much low end!
2. Reliability
3. LOW END!! (Im really worried about that)

I dont race on any tracks, but i tend to just stick to riding poker runs, and steep soft sand hill shoots. And alot of sand hill dragging.

Now, lets just say I put the XR cam in, i hear Ill lose low end, but if I am already putting in the higher comp piston, wont that make up for it, or not? Will it be more or less than stock when it comes to bottom end.
Sure I want mid to top to increase, but I like the bottom end power to tourque my way out of the hills that i virtually have to start at directly on the base, with no chance of getting a run.
Does this make any sense?
Looking for suggestions.
Rhan
SOrry this is so long.

NVR2L8
08-03-2001, 12:07 AM
Here's what I learned after recently upgrading my engine to a 416.

If you upgrade your engine to a 416cc with a JE 10.8:1 piston it will boost power everywhere--no specific gain in any particular area...just everywhere! What changes, shifts, or moves the powerband is your camshaft selection. The more of an agressive cam you go with the more high end power you'll gain, but at the same time also lose some in the bottom end. If you add an XR400 cam you will lose a little bit of your newly added power in the bottom end, but it will be very little. Mine feels just as powerful in the bottom end as when it was stock, if not a tad bit more!

My advice would be to install the XR400 cam. You won't notice any difference in low end power, and will really like how the engine pulls once the revs start to build (thanks to the cam). You might also think about adding a larger carb such as an Edelbrock or FCR. I have the FCR and really like it...the carb also makes a noticable difference with these mods.

xcntry
08-03-2001, 11:12 PM
NVR2L8, Are you running race gas or just 93octane. Also are you guys talking about the stock honda xr400 cam? This sounds like somthing i would be interested in I've talked myself out of the Sparks 416 kit . I dont want to spend that much to just trail ride and enter a hare scramble or two each summer.

NVR2L8
08-04-2001, 12:41 AM
I run a 50/50 mix of 111 octane leaded race fuel with 92 octane unleaded premium--about an effective octane rating of 101. From what I've been told you can run premium pump gas with compression ratios up to 11:1...I did run mine for a while on 92 octane though and it seemed fine. I decided to run the 50/50 mix since I do a lot of hard riding at the dunes, and wanted a higher octane fuel for the times when I really work the motor hard. For my mods the fuel ratio is probably overkill, but it does help it to run cooler and eliminates the possibility of detonation.

max400EX
08-04-2001, 09:33 PM
go 11:1 run ur 93 octane and some octane boost in the mix. I know a guy who did tht on his 426EX and he has had no problems yet!

papaw
08-21-2001, 03:05 PM
or even better,
protect your investments,run race fuel when at 11:1.theres too much money in built motors of any kind.i heard that 10:1 on any type of motor is questionable...(maybe not a 2 stroke)

08-21-2001, 04:21 PM
11:1 is the highest that you should run with 93 octane.

papaw
08-21-2001, 07:49 PM
426 i'm not sure?since my 11:1 i have ran race fuel since i built my motor.i've heard that it will use 93 and i've heard that it takes a mixture of 93 and 110.i'm just protecting my investment.....

nakomis0
08-23-2001, 08:44 AM
your motor runs cooler with 110 fuel? I know it burns slower and hotter and needs compression so it will ignite quick and not sit there and burn.... so did someone say it makes your bike run cooler? how does it do that? I could have misread this.

08-23-2001, 02:19 PM
I have ran 92 octane for a while now with a touch of octane boost. I never have any problems. I have ran 50/50 mix before, I have ran 110 octane race gas, the only difference is in my wallet. My firm belief is 11/1 92/93 octane and anything more,= race gas.

Even The GT Thunder website says 11/1 = 93 octane!