how to get the most torque without boring the motor

[MoToX199]

my friend just bought a 400ex and put a pro circuit exhaust on,but he says hes bored with it,so he asked me what he should do to make his 400 have alot of bottom end,he wants the most torque he can get out of it with out boring the motor,what do you suggest doing to it,thanks for all the help!

www.boondockers.com

there aint much you can do without opening the engine.

Jesse

[jdb8297]

CAMSHAFT!!!!!!!! Find close to stock cam with a little faster ramps do not go over board. Change the jet in the carb.

[F-16Guy]

Put in a stock bore 11:1 piston and a stage 1 HotCams cam. Along with rejetting, that will make a huge difference (and for under $300!!!).

[cals400ex]

lower the gearing and make sure the throttle cable is adjusted too.

[Juggalo]

Originally posted by cals400ex
lower the gearing and make sure the throttle cable is adjusted too.


yep hes right. throw a 14 tooth front sprocket on there and it'll have some nice low power. only the earl EX's had the throttle adjustment problem but it still wouldnt hurt to check that out. also maybe he should check out a cam for cross country racing.

[chad502ex]

without boring the motor? stroke the crank. that don't require boring :D

[400exrider707]

Originally posted by F-16Guy
Put in a stock bore 11:1 piston and a stage 1 HotCams cam. Along with rejetting, that will make a huge difference (and for under $300!!!).

I have these mods with open air box, uni filter, and FMF Ti-4 slip on. HELLO. :eek2: The cam and piston really woke up the 400. I highly suggest it.

[F-16Guy]

Originally posted by 400exrider707
I have these mods with open air box, uni filter, and FMF Ti-4 slip on. HELLO. :eek2: The cam and piston really woke up the 400. I highly suggest it.
By far, the best bang for your buck! I don't care what anyone says about the stage 1 cam, it makes my bike pull hard through the WHOLE rpm range.

[cals400ex]

i agree with you too, the stage 1 pulls constantly from bottom end to the rev limiter. it ticks too damn loud for me though. the stage 3 suits my style a bit more though (higher rpm power). if you don't want to change the piston, you can put in a thinner head gasket along with the xr400 cam, stage 1 cam, or even try out the new stage 2 cam (i don't know much about this one yet).

[F-16Guy]

Originally posted by cals400ex
i agree with you too, the stage 1 pulls constantly from bottom end to the rev limiter. it ticks too damn loud for me though. the stage 3 suits my style a bit more though (higher rpm power). if you don't want to change the piston, you can put in a thinner head gasket along with the xr400 cam, stage 1 cam, or even try out the new stage 2 cam (i don't know much about this one yet).
Yeah, it is loud. I always feel like I need to adjust the valves. :D

[nosliw]

Originally posted by chad502ex
without boring the motor? stroke the crank. that don't require boring :D

how much more displacement can you get from just a stroke no bore? how much would it be?

[MIKE400EX]

I've tried lashing a stage 1 .001 tighter than the spec sheet. So far it's been over a year of daily use and is barely louder than stock. Performance wise there seems to be no change. Pulls like a tractor and hard all the way to the limiter. IMO a much more versatile grind than the stage 2. With a ported head there is not much difference on the top end either.

[chad502ex]

Originally posted by nosliw
how much more displacement can you get from just a stroke no bore? how much would it be?

not really suggesting stroking a crank without getting bore done, but,...

85 x 70mm = 398cc
85 x 77 = 437cc and tuns of torque to boot!

[cals400ex]

yeah, don't waste the time stroking it without using a different piston. if you just want a nice upgrade at an easy cost, go with a drop in cam and a stock bore high compression piston. you will still need to have a shop make sure your sleeve is good and have them hone it out.



we also ran the valves snug with the stage 1. it was still loud for us. however, it did help quite it down some.