79 kz1000 LTD smoking, valve replacement??

Hey again guys,

So my bike is smoking a bit out the left side black smoke and it smells bad... I think it's burning oil as well. Some friends I know told me I should check the valves but I really don't know how to do that. I think it might be loosing a bit of power too. It backfires a lot and sometimes is hard to get started it sounds like it's running on 3 of the 4 cylinders then once it warms up it idles fine, just it burns oil and smokes out the one side. Can anyone help me on this?
Trevor

Several things can cause those symptoms. Did this happensuddenly, or dI'd it come on slowly over several months?

If suddenly, did you change anything or perform any maintenance that is engine related?

A look atthe spark plugs may give you a clue. The ceramic insulator near the tip should be light tan. If one or more are black and smell like fuel, the problem could be carburetion or ignition.
If one or more are black and oily, it could be valve oil seals or a broken ring.
Pay attention to the sparkplug wires. Are they soft and flexible or hard and cracked?

It would be helpful if you put your bike info in the signature line. One of the moderators will be along shortly with instructions.

Bore wear, Piston rings, Valve stem seals.
If the smoke clears after initial start up then the stem seals are the primary suspect.
Get someone to follow you on a ride and if the smoke appears on acceleration only then most likely stem seals.
If the smoking is constant then bore wear or piston rings are the culprit.
Being hard to start, excessively smoky and initially running on 3 or less cyls after standing overnight indicates oil seeping past the stem seals and temporarily fouling the spark plug until the engine is hot enough to burn off the oil that has accumulated .

zed1015 wrote: if the smoke appears on acceleration only then most likely stem seals.

Don't you mean deceleration?

Check your plugs.
Steve

etbike3135 wrote:

zed1015 wrote: if the smoke appears on acceleration only then most likely stem seals.

Don't you mean deceleration?

Well! on deceleration the oil is drawn down the guides by the pressure drop in the cylinders and then burnt when accelerating immediately after.
I should have made that more clear.
Of course there will be a slight increase in smoke output on deceleration as the excess oil hits the hot exhaust pipes but the majority is expelled on opening the throttle so generally the bike will smoke more when accelerating out of a corner etc immediately after shutting the throttle prior to braking .

Rings will do that too. If the bike is 10 years or older, the guide seals are hard and shot no matter how many miles on it. They have to be replaced. While in there all the other things come into question. I'll say this much. Depending on your wallet and what you can afford, will decide how far you can go. Change them and go or make a full blown project out of it. Your choice.
Steve

Also is there a yoshimura exhaust system for this bike??