Engine smoking

[400ex2fast4u]

Ok i have a honda 350x i know its not a 400ex but i figured it would see the most replies in the 400ex section, but my problem is it smokes really bad under a load (in gear) and a little in neutral or with clutch in, im gonna tear it apart put new piston and ring and valve stem seals but the bike still seems like it has a lot of power no problem wheeling it and it pulls like a SOB . Now my question is if its smoking that bad could it be a bad bore because i really dont want to bore it out and can you bore out the stock sleeve and if you can generally how much. Im just praying that its the rings or valve stem seals. Thanks

[underpowered]

i would say that if it has not lost much power it is the valve seals. take a compression test befroe you tear it all the way down. you can bore it out, stock is an 81mm bore, with a wiseco piston you can go either .5 or 1mm over stock with either 10.25:1 or 12:1 compression.

[400ex2fast4u]

thanks im just worried about the bore i mean if im in there why not do the rings while im at it

[FoxMxRiders]

What is the color of the smoke?? blue,black,white??

If it's your valves seal,he will smoke only when the motor is cold.

[400ex2fast4u]

Its blue smoke and it does it all the time but the bike doesnt feel like it lost any power it still moves very well

[FoxMxRiders]

Then your motor take oil.That's not too serious but just check your oil level often.

That can be the oil ring that's shot.You can just change it if your clearance piston/cylinder is not to big and if your cylinder is not oval.

FoxMxRiders

[400ex2fast4u]

Yea thats what im hoping that the cylinder in not screwed up the only thing i have going for me now is that it still makes the same power as it did when it didnt smoke so hopefully its just the rings. And do you recommend me buying a new piston or will just the rings do.

[FoxMxRiders]

Depending of your piston/cylinder wear (ovality and piston/cylinder clearance) I cannot tell you if your piston and cylinder is on the bike.

But the best that you can do is to bore the cylinder and to put a oversize piston.

You can simply change the ring but the problem can return not to much longer after the job.

FoxMxRiders

[400ex2fast4u]

But if the bore is bad or i have an worn cylinder wouldnt i lose compression which would result in lost power. im sorry for all the questions its just because i want to order the parts tomorrow and i want to get the right ones.