What can a stock 400ex crank/rod handle power-wise?

[cheater13]

Curious because I have a built 426ex with 13:1 compression and I've been told not to run the piss out of it. The builder said he kept it on the safe on top until I get a new crank/rod.. What can the stock setup handle?

[DragonGunner]

Curious because I have a built 426ex with 13:1 compression and I've been told not to run the piss out of it. I had the rev limiter adjusted down to be on the safe side but until I get a new crank/rod.. What can the stock setup handle?

I ran 12:5 440 in mine for awhile and no problems except it needed head studs, stockers couldn't handle it after a while, the 99' crank was able to handle it…..how do you adjust down the rev limiter?

[cheater13]

That makes me feel a little safer, but he said the pin has a little more play than he liked in it. I guess the bearings would go out before anything possibly.. I put head studs in mine too, but wonder how you and I's compare since you have a 440 and mine's a 426?

And sorry, he said "I'm keeping it safe on the top." Figured he was referring to the power curve on the dyno. He said it wasn't safe to have it revved up that high due to the crank/rod.

Did you run yours hard though? I drag race and do 1 barrel race a year.

[DragonGunner]

That makes me feel a little safer, but he said the pin has a little more play than he liked in it. I guess the bearings would go out before anything possibly.. I put head studs in mine too, but wonder how you and I's compare since you have a 440 and mine's a 426?

And sorry, he said "I'm keeping it safe on the top." Figured he was referring to the power curve on the dyno. He said it wasn't safe to have it revved up that high due to the crank/rod.

Did you run yours hard though? I drag race and do 1 barrel race a year.


When It was a 440 yes I did run it hard, ran on 100 AV fuel from local airport. I guess I took a chance not putting a better crank in, most do strongly suggest it…I always heard when they made the first year EX they built it with better parts…..never know for sure if thats true, but I still got original crank , clutch and plates…so maybe I was lucky…?

[cheater13]

When It was a 440 yes I did run it hard, ran on 100 AV fuel from local airport. I guess I took a chance not putting a better crank in, most do strongly suggest it…I always heard when they made the first year EX they built it with better parts…..never know for sure if thats true, but I still got original crank , clutch and plates…so maybe I was lucky…?

I'm running straight MR12 in mine. But I'll only be running it hard for 5 seconds and I'll shut it off. Barrel racing is a little longer duration but I hope it'll be fine for this year. Corilla (Think that's the correct spelling) makes a good rod but they're expensive. I might just stick to a Hotrods setup.

[400man]

http://i417.photobucket.com/albums/pp255/ky2stroker/Photo04271215_1_zpsef1b17dh.jpg (http://s417.photobucket.com/user/ky2stroker/media/Photo04271215_1_zpsef1b17dh.jpg.html)

http://i417.photobucket.com/albums/pp255/ky2stroker/Photo04271215_zpsfut7d7xo.jpg (http://s417.photobucket.com/user/ky2stroker/media/Photo04271215_zpsfut7d7xo.jpg.html)

http://i417.photobucket.com/albums/pp255/ky2stroker/Photo04271214_2_zps8owr5qpr.jpg (http://s417.photobucket.com/user/ky2stroker/media/Photo04271214_2_zps8owr5qpr.jpg.html)

heres my crank i sent to crankworks. it was a worn oem crank and I had them put the carrillo rod and true and weld it. the whole setup was 400$. I guess it was probably overkill for xc racing and trail riding and such, but I figured later on when or if I decide to build the topend alot bigger, I wont ever have to worry about the bottom end holding up. my setup with this crank is a 406cc 10.8:1 JE piston, stage 2 hotcam, lightened flywheel, 39mm fcr carb, and white bros R4 full exhaust.

[jcs003]

i had a 440 built by four stroke tech in 2001 and it ran for 10 years being regularly pounded. head studs are key. also the builder will play a very important part in its reliability.

John

[cheater13]

Yeah I got the HD studs. But he still said it should last the rest of season but I shouldn't hit the limiter too much. Still half afraid to run it. It gets hot QUICK! It actually started smoking from the crankcase breather and all cause I saw on my XR dipstick that it was in the 200* mark.

I'll just run it and shut if off every race. I'll get my fan hooked back up too.

[jcs003]

do you have an auxiliary oil cooler? do you have scoops? are you using the correct octane? is your carb jetted correctly? these all play a key role in engine temp.

john

[cheater13]

do you have an auxiliary oil cooler? do you have scoops? are you using the correct octane? is your carb jetted correctly? these all play a key role in engine temp.

john

I don't have another oil cooler. I do have scoops. I am running correct octane. (mr12, so it will run a hair hot), carb is jetted perfectly off a dyno.

I do have a fan hooked up to help though. It actually helps a good bit after a race when I turn it on.

[JOHNDOE83]

Curious because I have a built 426ex with 13:1 compression and I've been told not to run the piss out of it. The builder said he kept it on the safe on top until I get a new crank/rod.. What can the stock setup handle?

ericrip ran a 20hp shot of nos with hi comp and bigger valves and never had a issue with stock crank.