I have a 2001 400ex.I just rebuilt it with a weisco 85.5mm 12:1piston and a magnum stage 2 cam with a white brothers rev box.I also put new valve seals in it.I have a hmf pipe to.On the start up i broke in the cam for atleast 15min.I've putted around for a couple of tanks and now I've rode it full throttle for a day.It's very very strong.Well this morning I start it up and it automaticly starts smoking.Its a white smoke more than blue so i didnt thing it was fuel but im clueless.It will smoke when idling and when i rev it smokes more.its a disaster and there is less oil in it now.???????so help me please.It makes since that it would be burning oil but the rings were installed properly and gaps are good.i adjusted the valves 005 intake and .006 exhaust which thats what the cam called for.and i run 93 pump gas in it.Just trying to giv alota info so i can get it fixed thank you

 

Don't sound good it sounds like some how oil is getting past your rings and this is the white smoke you will proably need to start tearing it back down and see what you got sorry that's a bummer let us know what you find out.

 

Just some thoughts here.
#1 12 to 1 with pump gas does not sound good to me. IMHO that is race gas territory. Sounds like you detonated the hell out of it and tore up the ring package.
#2 How did you break in the cam? Exactly?
#3 What was the end gap of the rings when you installed them?

I would do a leakdown and see what comes up?

 

ok guys i'm sorry its took me forever to reply. yea I know pump gas isnt the best and I always add octane boost to it.So that cant be great either.After I had set my valve clearance and got everything together, or at startup I held the throttle to about 3000 3500rpms while riding,for 15minutes.I checked the oil after i had rode it then.It was turning black because all the left over oil that hadnt go drained.oh top ring was .004 and bottom was .005.....I changed the oil and ran it for another 30min and not lugging around but at the same time not givin it hell.So for the next 2 days I started riding it normal.It was very strong and absolutely no smoke until startup the next day.After I changed the oil again it was watery.So i put 20w50 in it and ran for ten minutes or so then changed it again with the same oil.did the same thing and it was milky and so runny then also.so Then after i figured that all the old oil was out i put 10w30 mobil in it.It has helped and dnt smoke when just running or putting aroung but when I get on it hard you can still see a little smoke.

 

so now it only smokes on start up pretty bad but when it gets hott you cant really tell.Ill keep an eye on the oil and see how much it drops tomorrow.And again im sorry its taken me so long to reply it wont next time.Thank you guys........Do you guys thing those wiesco rings have already went?????? or what i really dont kno and sorry if im coming across so stupid

 

Sounds like you broke the cam in correctly. The rings sound a little on the tight side but??? Is that what they called for?

Whats the deal with the oil? Milky? Milky means water got in it? If it's just thin, did the oil smell fuelly? Not much can thin out the oil in a short time except fuel.

Could the carb float have hung up and put a bunch of fuel in the crank case and thinned out the oil? If so, this can cause it to burn oil.

Just some ideas for you to ponder.

 

That could be very likely.I had the carb a part before it started smoking like that. Then sometimes when i try to start it at first is wont start I have to choke it and give it extra gas then it will hit.Then take the choke off and it'l fire right up.I thought it was timing at first then it was just like the choke wasn't working.But after it starts back there aint a problem.But the pilot is a 38 so it should still be fine so maybe it is the float.And the smoke don'nt really smell gassy either.But thank you to continue my troubleshooting.O and yea the rings didn't seem right but thats what they called for. thank you

 

93 doesnt seem like the best choice with 12:1 IMO. Also you could change out your pilot for better starting I run a 42 pilot and I never need the choke anymore. Did you rejet your main after the build? You could try that and ajust your a/f screw and needle and clip possibly. Check out www.exriders.com those guys over there always help me out when im in a pinch and need some info they will be able to give you some good ideas.

 

ok i have a diff question. i just recently rebuilt my 440ex but it had been sitting in some building when i bought it for like 2 years. after i got it running i lost spark i can take the spark plug boot off and feel a light spark when i touch the wire but when i put the boot back on and put a plug in it theres no spark at all???? could it be my coil? any advice greatly appreciated

 

yea i've got a 162 main jet in it and i was going to go to either a 40 or 42 pilot so i could eliminate the choke.I've tried the needle on every clip and it seems to be the best on the 3rd just like it would stock.