piston & valves

[isaac_]

I am by no means a gear head. I've never really tinkered with mechanical objects. That's never been me. That said, I've taken it upon myself to learn my bike. With that in mind, I really don't have any clue with regards to what things should or shouldn't look like but I can make educated guesses. Shiny = good. Black = bad.

There's a longer story to why I had to pull the cylinder head off the block. But nonetheless, I pulled the front cylinder head cover off my SV tonight and my piston and valves looked like this.

1. I don't think there's supposed be little pebbles on the piston
2. I don't think the piston and valves are supposed to look like that

My questions are,

1. Do my piston and valve look OK? I don't think so but this is my first time pulling this apart. I will assume the rear looks the same.
2. What corrective action should be taken?

Also, what do y'all make of this spark plug?


Thanks.

[csmutty]

The black on the piston and spark plug indicate that it was running very rich. It was getting too much fuel in the mixture. The valves look ok, but the pebbles on the piston look like flakes of metal. Have to figure out where those metal flakes came from. How does the cylinder wall look? If the piston crown looks like that I can only assume that the cylinder wall has also taken a beating.

The rich mixture would not cause any engine problems. It would only cause the carbon buildup that makes the parts black. If the bike was running rich it would actually help to keep the piston crown temps down. Is the bike fi or carbed? Bringing it to a dyno and tuning it will make it run better for sure after the motor is fixed.

[Chippertheripper]

I've seen worse. What is the longer story?

[stoinkythepig]

The head and piston do not look too rich to me, and the carbon build-up looks pretty typical, IMO. Shiny would be very bad unless the engine was brand new or you just ran a bunch of water through it to steam clean it. What color is the inside of the header where it attaches to the head? Black is good there.

Impossible to read the plug correctly since we don't know what you were doing just prior to pulling it and the important part to read on a race engine (I'm making an assumption here that this is a race engine based on your avatar) is way up inside. That said, it does not look to me like there's anything overtly wrong with mixture, heat range or timing. Really need a close up to know for sure though.

The "pebbles" are worrisome, you'll need to figure out where they came from. What are they made of?

[timmyho414]

The valves look ok to me too. My only concern would be the carbon build up, it looks shiny in the picture. That plus how clean the very outside of the piston is. If the rings were loosing bit of oil it would build the carbon(shiny carbon, normal carbon is more matte looking) in the center and clean the outside of piston like that. To really tell if the piston is ok you need to look at the skirt. I had an engine where the cylinder wall looked nice but that one cylinder burn a shit ton of oil and I mean james bond smoke screen amounts of oil. I'd have someone look at it in person for you pictures can be hard. Did it ever use oil or smoke?

As for the pebbles, when I pulled my bike apart I forgot to blow all the crap off the outside of the motor. There was some sand that had gotten in the nooks and crannies. When I pulled the air box some fell into the intake. Any chance of that happening?

[dontpanic]

I was thinking something similar about the pebbles.

The spark-plug recess (the front one, in particular) tends to collect sand and grit, which might fall into the cylinder if you didn't blow it clean before removing the plug.

[isaac_]

Thanks for the input everyone.

It's a gen2 SV, so FI.

The little pebbles had the consistency of coarse sand not metal. And you caught me, ... I didn't blow the crud out of the way before removing the engine. Whoops :/

There was never anything wrong with the motor per se. The slightly longer story is towards the end of the season, I noticed my frame slider would vibrate a little lose. It would tighten back up. But when I removed it this winter all the threads came with it. I couldn't properly rethread because of a spacer so I can't to move forward or lower the engine. Both options requiring the removal of the exhaust. Which is where things take a turn for the worse. I snapped one of the bolts on the engine block. So now I'm trying to get that out but because of the angle on the front I can't properly square out the drill to make it center. I decided that if I could remove the cylinder head and put it on a press my life would be much easier.

[R7]

I'd fix your broken stud, blow all loose crud/sand out of the cylinder and put it back together. There's nothing unusual about any of the pics, except the result of your carelessness (letting sand/dirt get in) taking the head off

[isaac_]

I'd fix your broken stud, blow all loose crud/sand out of the cylinder and put it back together. There's nothing unusual about any of the pics, except the result of your carelessness (letting sand/dirt get in) taking the head off

But yes that's the plan. Put it back together once I fix this stud.

[Paul_E_D]

All looks AOK to me as well. FYI, you can't "read" the colors of a 4 stroke with any sort of reliability. They operate at a much wider range than a 2 stroke, so the carbon is meaningless, unless it's WHITE. Then you're fucked.

[isaac_]

Great, happy to hear things look OK. Not knowing what to expect kills me sometimes.

[Stromper]

broken stud
Get Left Handed drill bit about 40% the diameter of the stud McMaster-Carr
There also removers something bit
4 times
Heat to hot with torch
spray with a break away oil like kroil or liquid wrench also at mcmaster

The heating cooling helps draw in the liquid wrench

Drill out with the drill turning Counter Clockwise... If the left handed drill binds it will
UNSCREW the stud

If You fail take the jug to a machine shop they can replace it
Might as well get new valve seals at this point

[isaac_]

Already took the head to the shop. I tried the left handed bits, easy outs, pb blaster etc except for heating with torch. No luck with it.

[dontpanic]

Dynamite. Works every time.