smoking

[stock block]

ok i rebuilt my motor and it only has about 20 hours on it. i am guessing that my oil ring didnt seat because it freakin smokes like crazy. i have heard that your type of oil can do this. i think i am running 10 40. my question how do i know if my rings didnt seat? i have it taken apart i just dont know what to look for. my piston is covered in a dry black suite.help its embarrissing. my bike runs perfect.

[krt400ex]

I'm not sure how to tell if the rings are seated correctly, but the valves may be out of adjustment causing the bike to smoke. Do you mean that the whole piston is coated in black(pistonskirt and all) or just the top of the piston. let me know and I may be able to help you more.

[99TRX400EX]

Originally posted by stock block
ok i rebuilt my motor and it only has about 20 hours on it. i am guessing that my oil ring didnt seat because it freakin smokes like crazy. i have heard that your type of oil can do this. i think i am running 10 40. my question how do i know if my rings didnt seat? i have it taken apart i just dont know what to look for. my piston is covered in a dry black suite.help its embarrissing. my bike runs perfect. i have the same problem and just the top of my piston is black.

[krt400ex]

Originally posted by 99TRX400EX
i have the same problem and just the top of my piston is black.


then either your jetting is way to rich or your valves are out of adjustment. mine smokes a little during start up when the engine is cold, then stops after it's warmed up. does it smoke all the time or just when you get on the throttle? if it smokes only when you hit the throttle and your jetting is correct, then the only thing I can think of is your valves. other than that i'm clueless.

[SHADETREE101]

the valves being out of adjustment doesn't cause them to smoke, bad valve seals will. did you place your ring gaps correct on the piston on installation and keep them there. is any of the rings stuck. did you place oil on the rings when assembling. i was told that if you oil soak the rings they will seal with oil trapped inside the scraper ring causing it to float and cause it to smoke and never seal. if you have any ring gaps alinged on top of one another they will leak through one another.

edit JOEX- off topic:rolleyes:

[speedracer13t]

mine was just rebuilt too, it isn't running too rich, we actually had to make it richer, but it was smoking before too. i am just going to run it and see what happens

[99TRX400EX]

i'm thinking i have a bad valve seal i replace the valve seals when i rebuilt it and put new exhaust valves in it to the ring gaps were set right and i'm running a 150 jet and a 40 jet with a kn filter

[stock block]

to be honest with you i havnt even rode the thing in over two years and it was a year or so before that i rebuilt it, so i cant really remember what all i done during the whole process. what exactly is the gap supposed to be?(on the rings) i really dought its the valve seals because its on acceleration and its a whole lot of smoke, and i mean alot. it runs perfect though. i really appreicate your guys thoughts.

[SHADETREE101]

after sitting for a long time the rings can stick which will cause the same problems you have.

[DieselBoy]

Check the bore for scores, scratches, etc. Unfortunately there's no way to tell if the rings are good or bad, your best bet is to re-hone it, fresh piston and rings, and try again, this time breaking it in hard. Valve seals leak when the motor's cold, high rpm smoking is blowby. It shouldn't be smoking, though.

make sure to stager the rings, also.

if the engine is complete, you can run a compression test.

[400exowner]

The ring-ring groove clearence is
Top ring-0.030-0.065mm (new) 0.14mm (Service Limit)
Second ring-0.015-0.050mm (new) 0.12mm (Sefvice Limit)

Ring end gap
Top ring-0.20-0.35mm (new) 0.50mm (Service Limit)
Second Ring-0.35-0.50mm (new) 0.65mm (Service Limit)
Oil Ring (Side Rails)-0.20-0.70mm (new) 0.90mm (Service Limit)

Hope this helps