Question on Smoking just a Little

[2qk4u]

How many of you have a 400ex and it smokes a little. Ever since i put this 11:1 piston in i notice it smoke just a little when i start it up and after it warms up i can rev it and it will smoke just a little and when it revs back down. I have a couple of friends that have new 02 400ex's and i think theres might smoke just a little more than mine. theres is all stock. Is this kinda commin for them to do? Has anyone else done engine mopds and there smoke a little also? Bike is all broke in also. Bike runs great.

Thanks

[RED121572]

Hey bud..

I have a 11:1 piston also. Yours smokes from either one or two reasons...or both;

Your valves arent seating properly and/or your piston ring gaps are positioned to closely to one another.

Mine started smoking about 8 months ago just before I rebuild it. It was caused by a worn stock piston and rings.

To answer your other question, it really should not smoke at all.

:D

[indygncc]

They will smoke when they are like new when they are under a load. I wouldnt worry about it unless it smokes all the time.

[SUPERFLY 400]

First of all What color is the smoke, blue (oil), or black (fuel too rich)? If its blue then your leaking oil into your combustion chamber. It could be possible that your ring gaps are line up or you installed a ring upside down. Worn valve seals will also cause excessive smoking. If its black smoke then your fuel mixture is rich rejet and adjust your pilot screw as neccessary and check your aircleaner.
For the guy who says they smoke when they are brand new. BULL*****. Yours probally smokes because you didn't "break it in" correctly. Think about it, when you buy a brand new auto, does it smoke..NO!!:mad:

[4punksdad]

I have noticed that mine will puff a little smoke when the oil gets thin & is ready to be changed.

[deansfastway]

When you slipped in that trick piston did you check the bore size for wear or did you have it rebored , maybe its a little loose . I work on a lot of these and they do smoke when the oil gets beat , they might also smoke a little when warming up. The big question is how bad does it smpke or how much oil is it using, does it have blow by , does the oil separater reservoir breather device ever get filled up if it does then you have a problem, maybe your new rings didnt seat yet?

[Matt400ex_17]

This is becasue if you put it back together right you would have put a little oil on the valve springs before assembly and now the engine is burning it off. Did the same to mine when i put high compression valve springs in..

[RED121572]

Hey Superfly.....

I second your reply to the smoking issue.

[SUPERFLY 400]

:D

[Rastus]

Mine does that alittle. Course, i just had it rebuilt, and it only smokes alittle bit under loads.Or, if ill gun it sitting still, it will puf alittle bit of smoke, but soon as i let off, it stops. Its not a dark blue, just a really light blue, if your not looking into the light,(i.e. Under a tree) you cant even see it.

[SUPERFLY 400]

If its blue your burnin oil.

[GrounD PoundeR]

SuperFly did you forget something?

[RED121572]

Just after I rebuilt it, mine did smoke on the first start up. It was cause by when I coated the bore and cylinder with oil before installation.

[deansfastway]

I like GPs mods ; MUD and some other doo dads . Thats kool.

sounds like your bike is a good one to take riding when the mosquitos get bad!!!!!

[2qk4u]

hey smokin 400 it is not near that bad. my buddies both have new 400's and theirs smokes worse than mine. im hoping it is more fuel than anything. AND YES IAM 2QK4U, SO JUST KEEP YOURS IN THE GARAGE.

[RED121572]

Hey Superfly!!

Your pilot screw...how many turns out is yours??

[SUPERFLY 400]

i had it at 2.5 turns out but went 3 turns out i feel more throttle response with the 3 turns out.

[Wired]

ok boys i think my 400's going to the $hit house. she's really burning oil and im adding oil now it seems every week. whats the easiest way to diagnose this problem and get it solved? im not a happy camper becuase i was skeptical to coming to a 4 stroke:mad: HELP PLEASE!

[RED121572]

Is your machine stock? My buddy souped us his Warrior not long ago. He didnt jet it correctly and ended up melting the piston and rings within two hours of ride time. Instead of spending 700 bucks on his motor, I think his total bill is now around 1200 bucks. LOL

My stock machine wore out the piston and rings in just two years.

From my experience, it would be a safe bet that your piston and rings are ready to be replaced.

Good luck man, let us know how things pan out for ya!

[deansfastway]

Is the plug and exhaust real oily? The most conclusive way to check is either a wet / dry compression test or a cylinder leakdown test . With a wet / dry test youkll check compression with a guage in the spark plug hole . first crank the motor over dry , record the readings then squirt a little bit of motor oil (tablespoon full or so ) into the plug hole ,then crank the motor and record the readings . compare them , if they are off by more than like 15% -20% then you need a top end job as the rings are worn out . The idea behind this is that the oil seals up gaps around the rings and helps hold up the compression . Leak down testers are @ $80 and require an air compressor to operate ., for best resolts youll also have to fabricate a piston stop or a device to hold the motor at TDC , you can use a longer bolt the same thread and pitch as the TDC check hole on the L/S alternator cover. 4/stroke flywheel pullers work well for that. With a leak down tester you will put air in the cyl and record how much leaks down and from where. Your quad could also smoke from valve guides & seals being worn out or toasted. Oftentimes well get TRX (espescially worker quads) motors where the piston & cylinder is all scuffed (slight seizure) this is usually due to an overheat problem , letting the bike Idle for a long time or clogged oilcoolers . There is no air moving around the cyl or motor to cool it down . Sometimes the rings will just get stuck or the cyl will just get glazed you can try running some MOTOR MEDIC or TECHRON in the gas to help clean this up. How bad does it smoke does it fowl plugs and fill the crankcase breather ? Maybe its not so bad /or maybe now its time to build that custom engine. FASTWAYMOTOSPORTS

[DiceMan400]

SMOKING IS BAD FOR YOUR HEALTH

[Wired]

its actually still on its first spark plug and it doesnt smoke constantly, only when its ideling and you crack it open a little puff comes out. but its definatly burning oil though cause like i said i have to add oil bout once a week. im thinking something wrong with either the piston or valves cause i adjusted them myself and this problem happend a week or two after the adjustment.