426ex

[honda123]

I've been reading all the pros and cons regrading 416 kits, 426 kits, and 440 kits. I finally decided to go with the 426 kit. dropped it off today @ a local well known engine builder today. This is what he is going to do let me know if I should have him change anything?

1. JE 13.5 piston
2. New gasket kit
3. Jet kit
4. hot cam stage 1
5. New timing chain
6. boar cyclinder
7. port head
I was told when the jetting is done correctly I can still run pump gas?

[underpowered]

Originally posted by honda123

1. JE 13.5 piston
correctly I can still run pump gas?

not a chance. 12:1 requires striaght race gas, with 13.5 1 race fuel is an absolute must! i would install heavy duty head studs with that high of compression and possible a new rod, but thats just me. sounds like a winner but i doubt it will last very long with stock studs and rod.

[honda123]

I stand corrected its a JE 13:1 piston. My engine builder claims w/ the proper jetting lager jetts he claims you can run pump gas???

[WheelerBob]

11:1 is pushing it on 93 octane pump gas.

[400exmkt]

It depends what moter it is. The guy that did my motor has a 1200 ninja punched out to 1273 w/ 13:1 pistons and he runs pump gas. In a quad i wouldnt even try it with anything over 11:1. Make sure he is talking about quads for sure, if he is then i would probly find someone else to do my motor. Just my opinion. Good luck

[honda123]

okay,

I stopped in to see my engine builder today and told him to use the JE 11.1 piston instead of the 13.1. he is also going to install a 14 tooth front sproket., hot cam stage 1, port head, prep selvee for new piston. bike already has a hmf full exhaust with a kn&n air filter do you think this is a good set-up for woods riding.

[400exrider99]

how much did all that engine work cost

[honda123]

700.00

[QuadJunkies]

Originally posted by underpowered
not a chance. 12:1 requires striaght race gas, with 13.5 1 race fuel is an absolute must! i would install heavy duty head studs with that high of compression and possible a new rod, but thats just me. sounds like a winner but i doubt it will last very long with stock studs and rod. You can actually run 50/50 pump and race fuel . I run C-12 and prem. mix in mine.(12:1) some will tell you you SHOULD run straight but you dont HAVE to. ;)

[tooanxiousii]

When I put my 426 11:1 piston in I called JE and they told me to run 50/50 on the fuel unless you don't run it hard ... With the 400ex being air cooled it will run hotter with the 11:1 and if you run it like everybody does you will need a 50/50 mix to make it last you

[Brehmmotorsport]

you CAN run pump gas on a big bore it just needs jetted right as you said and timing needs adjusted though to keep the head studs from pulling.

[underpowered]

Originally posted by Brehmmotorsport
you CAN run pump gas on a big bore it just needs jetted right as you said and timing needs adjusted though to keep the head studs from pulling.

yes, i run pump on my 426, but it is only 10.8:1 comp ratio. he was talking about 13:1 on pump gas, which IMO you should not do.