Fuel

[keepitpinned]

Im looking into getting a 416 for my 400ex. it would have a compression of 11:1. I heard that people say i can and cant use pumped gas. im just going to be safe and run 50/50. i called a local place up and they said for 35 buck i can get a 5 gallons of 108 octane. is this a high price. Is their such thing as to high of an octane. how long can i let the gas sit and not go bad? also with a 11:1 compression ratio will i be blowng head gaskets? and if yes is it easy to put another one on or too complicated?

[Quadzilla]

Ross 10.8:1 416 piston w XR gaskets, problem solved.....

[keepitpinned]

with a Ross 10.8:1 416 piston w XR gaskets wont it run better on race gas? is their any difference between the Ross 10.8:1 416 piston w XR gaskets and a true 11:1 piston? if any how much. also did you ever blow a head gasket with ur set up

[miken]

Generally speaking, at 11:1 you should be in the 101 and higher octane bracket. Check this link and you can mix race gas and pump gas as needed if 101 isn't available at the pump.

http://www.qrckarts.com/main.php?page=techinfo

Mike -

[keepitpinned]

interesting:D

[keepitpinned]

Quadzilla could you answer my questions?

[Quadzilla]

THe Ross 10.8:1 will run on good pump gas (like Sunoco 94 Ultra). 11:1 is about the extreme limit if not over the limit of running pump gas with XR gaskets. Race fuel will run better in either...

[rngprerunner]

Some thing to think about.... Suzuki Z400's have a stock compression ratio of 11.3:1 and are designed to run on 87 pump gas.....

[Quadzilla]

Yes, it's called water cooling. Heat is the main issue here. More heat = more pre-detonation. Because of this, water cooled motors can run higher compression ratios and not pre-detonate on lower octane fuels like air cooled motors are more prone to doing...

[Ryan]

Originally posted by Quadzilla
Yes, it's called water cooling. Heat is the main issue here. More heat = more pre-detonation. Because of this, water cooled motors can run higher compression ratios and not pre-detonate on lower octane fuels like air cooled motors are more prone to doing...


Correct.


And I believe on the 400ex, the 10.8:1 with the XR gasket becomes an 11:1 . The XR gasket is thinner then the stock 400ex gasket.

And from what I've heard, if your running 11:1, play it safe and run a 50/50 mixture Or 93 (Or the highest octane you can get at the pump) and race gas.

Also, $35 for 108 octane is a decent price.

[rngprerunner]

Originally posted by Quadzilla
Yes, it's called water cooling. Heat is the main issue here. More heat = more pre-detonation. Because of this, water cooled motors can run higher compression ratios and not pre-detonate on lower octane fuels like air cooled motors are more prone to doing...

Ok, thanks for clearing that up.

Dont 400ex's only have a compresion ratio of 7.5:1 stock?

[cals400ex]

stock compression for the 400ex's is 9.1:1

[rngprerunner]

Thanks.... I'll learn all this eventually :D

[keepitpinned]

50/50 mixture of 93 or 94 and 108 good?

[keepitpinned]

also what is their any noticable differnece in power from a 416 and 426 with the same compression ratio? if i just got a 11:1 and xr head gasket will it be reliable? i dont want to be blowing head gaskets. and is that why the z400 has a couple more hp over the 400ex bc of higher compression

[cals400ex]

i doubt you notice a difference between the 426 and 416. a 50/50 ratio will be more than enough for around 10.8-11:1.

the z400 is just a newer bike. the technology is a little better with the dual over head cams and better flowing head. the head will have a lot to do with how well the bike can disipate heat.

if your head studs are not pulling out, you shouldn't be blowing head gaskets. just make sure the surfaces are clean.

[keepitpinned]

what is the highest compression you can get and still have a reliable quad?

[DantheEXman]

I have a 416, 11:1 and run 93 Sunoco no problem. I ran 87 on accident once. Just runs a little crappier and much much hotter.

[BIGRED400]

I am running a 416 with this compression and have tryed 50/50 with 93/100 but the best combo is 93/110 wihich is around 104 I'm told Octane mixed...........tryed straight and mixed......works best 4 me

[keepitpinned]

what is the highest compression piston you can have and still have a reliable quad?

[keepitpinned]

can anybody help??

[outofsight]

I would say 12:1 up is when you start to get unrelaible.

[keepitpinned]

what is the next step down from a 12:1?

[BIGRED400]

I have a 11:1, you can keep reliabilty I believe 11:1 and down, 10.8:1 you can run pump hi-test, 11:1 race fuel or race fuel mix which is what I do.............personally unless you just race I would'nt reccommend anymore than 11:1...others may tell you different but what good is it if runs hard but only for a short time.:D