just wonder where to start troubleshooting

[BDT]

The symptom . . . blows oil smoke when accelerating anywhere near redline (over about 10k).

It's a '93 CBR 900RR with about 46,000 miles. It's got a D&D pipe with a jet kit and K&N filter. Nothing too radical. I drive it mostly to work and back with a few mildly spirited jonts on weekends. I had it tuned up and the valves checked at the beginning of last year's riding season. The report card came back very good. The smoking's not real bad and I don't consider it a big issue unless someone convinces me that something big is going south.

What do ya'll think I should check out first?

[yakuza]

Just a guess, but with that many miles I might suspect the rings were letting some oil by. Perhaps a leak-down test to check the state of your motor...

[Anonymous]

Agreed, sounds like rings. If it was a head gasket you'd be blowing a lot more smoke than that. Was going to suggest valves but you said those were done already.

If it's just a little smoke, it's nothing too major. You're losing a little bit of power, and I'm sure freshening up the motor would make it run like new, but you may not want to put that much $$ into it unless you can do the work yourself.

[BladeRider]

The symptom . . . blows oil smoke when accelerating anywhere near redline (over about 10k).

What color is the smoke? White? Black? Brown? or Blue (like a 2stroke)?

Have you pulled the plugs yet to see what color the insulation near the tip is or whether they're fouled? That'll tell you the most info.

[Ripper]

yup just like they said, with that many miles the rings are surely worn, If you have the cash and the cyclinders are'nt sleeved you could bore it out and throw some oversized pistons in, and it would feel like a new bike.

Or you can just put new rings in it, but as long as your in there, again $

[BDT]

That's what I was thinking too. I was hoping you smart guys would come up with something like just run a hotter plug or something easy.

The smoke is fairly light colored. Not sure if you'd call it white or really light blue, but it's definitely oil. I buzzed it up a couple weeks ago and then had to come to a quick stop and the wind brought the cloud right up and over me. It was a lot more than I had suspected. A few people I've ridden with have mentioned it, but nobody told me how bad it really was. I've never even noticed it from the driver's seat.

And yeah, I've had problems with fouling the beginning of the last couple season. I didn't use fuel stabilizer, so that's what I blamed it on. This past winter I used stabilizer and a battery tender, so there weren't any issues. I haven't pulled the plugs lately to see what they look like now.

Anyway, the motor has never been opened up that I'm aware of. I bought it used, but don't think it had ever been cracked before I came along. The 900 has power to spare, so it still runs pretty strong, so I'm not convinced yet to tear it apart and spend the $.

Thanks for the thoughts.

[Ripper]

Yea the honda motor is bullet proof, and will be fun for 46,000 more miles, but if ya want to get rid of the smoke, it's time for a rebuild. It will only run better. you might want to try a compression test, if you know someone who has one, That way you would have hard numbers, do the math, your missing out on noticable power.

[BladeRider]

Are all the plugs fouling, or is it just one or two? Also, what color are the plugs? If they're black and possibly wet, it's probably oil. Though if the smokes light they may show dry.

If you test the compression and it's within specs, it may be valve guides and you'd only need to pull the head and have it reworked.