help with new 400

[rojorider530]

i just got a 400ex and was wondering how to break in the engine , my dealer told to to take it nice and easy, and one of my dads friends said to take it full throttle in every gear beacuse then the cylinder will not have any air gaps as it forams into the piston can someone please help me!!!!!!!!!!!

[MSL]

I wouldnt do what your dads friend told you:eek2:

You will get several different opinions on this but i would ride 2 to 3 tanks of gas in it at no more than half throttel.
JMO

Maybe someone else has a more correct proceedure for this.

[Narly R]

Originally posted by MSL
I wouldnt do what your dads friend told you:eek2:

You will get several different opinions on this but i would ride 2 to 3 tanks of gas in it at no more than half throttel.
JMO

Maybe someone else has a more correct proceedure for this.

Sounds good!;) WOW! I cant belive your friends dad told u that!:eek2: :confused2

I"d explain it but go to duncan racing's site or sparks racing site. they have it written in very good detail...

[RiPPiNiTuP7]

take it easy the first few tanks making sure to vary the rpms.....

[firedawg805]

break it in like your going to be riding it all the time. my .02

[chrisp333]

i agree w/ firedawg. i was told to break it in as you are going to ride it all the time. you just need to make sure you warm it up before you go and tear it up. i could be wrong but mine runs like a king.

[skemp]

I like to vary the RPMs a lot without holding back on it. You do not have long to wear the rings and cylinder into each other so by babying it for 3 tanks of gas you increase the chance of glazing the cylinder or obtaining a poor ring to cylinder seal. Just my method, but not saying this is the way it has to be done.

[cals400ex]

i also think you need to rev it out. first, make sure the bike is warmed up. then take it out and run it through the gears. don't stay at constant speeds, don't let the bike sit at idle, and don't lug it around. i would rev it through each gear getting the rpm's up but not flooring it. i also believe its important for the rings to seal properly. from what i read, the rings will be 80% broke-in within the first 20 miles of riding the bike. this is not much riding, so i think glazing the clylinder wall is possible if you putt around. the 20% percent left will take a little longer. also, it is recommended you change the oil after the first 20 miles of riding. don't use synthetic until the bike is completely broke in.

[rojorider530]

thanks alot for all of your help!!!

[ewalker302]

Hope it's not too late, but here's the best info 2 break in a 400.
Trust this!

Here is all u need to know, & as simple as possible.


Do not use synthetic oil for the break in.
Do not let it sit and idle at anytime during the break in.
On the first ride try to vary the rpm as much as possible, everything from an idle on up to about 1/4 throttle, then do the same thing up to 1/2, 3/4, and full.
Heat and cooldown cycles are needed.
Adjust valves and change oil after first couple hours.
After engine is fully broken in you can switch to synthetic oil if you want.

Lots of old guys say to break in engines hard & they will always run hard.

This probably worked fine for engines in the 40s-60s' but a lot's changed since then.

Enjoy your new bike.
:bandit: