The International CBX Owners Association

I had a friend following me today, and he noticed a considerble amount of smoke when I down shifted. Is this a sign of major wear or do some CBX's blow the blue?

That's usually caused by bad valve guide seals

A good time to send the head in to the machine shop to be rebuilt

Don

Don #6141 wrote:That's usually caused by bad valve guide seals

A good time to send the head in to the machine shop to be rebuilt

Don

Just to install new valve guides, you shouldn't have to send the head to a machine shop, should you What else would you "rebuild" other than the valve seats?

No - You could put new seals on with the head still on the engine . . . . . possibly (with much difficulty) even with the engine still in the bike . . . . but it would be a good time to check the valveguide wear, clean things up do a valve job and have a look at the cylinder walls and piston tops

Sometimes you wind up spending more money and time when you try to minimize things . . . .

Don

DevonCbx wrote:I had a friend following me today, and he noticed a considerble amount of smoke when I down shifted. Is this a sign of major wear or do some CBX's blow the blue?

Blue smoke on downshift is not good news, but there is an interium thing to try that worked when mine it started that at 40k miles.

Background: I must admit I ran my 80 hard......very hard esp on downshifts at high rpms getting slowed down and set up for tight turns. Try what I estmate to be 2000+ or so of these a day on sport rides at rallies in the mountains here and 2000 upshifts at red line the same day........then do this day after day ...year after year....and you get the picture.

When mine started smoking blue on downshifts like yours at 40k miles I changed over to Mobil 15-45 or 15-50 car oil and no blue smoke for the next 60k miles. Problem solved.

Check This: Here is a video showing Dave McMunn taking the cylinder off my 80 for the first time in 100k miles. http://www.youtube.com/watch?v=O_u-D4vfUjw&feature=user

Sooooo...I think it is worth a try for $25, but yet again I have been the only owner of mine and as such knew all the stress/strain it had over the years and knew for certain it had never been apart.....in your case.... you might have had some moron that couldnt change the plug in his mower give your X a motor tear down try before you bought it (it happens all to often)........and in this case it could take alot more than Mobil 1 to cure the damage

Sidebar: Long ago my son bought a 5.0 Mustang cheap with a four or five speed that would not shift good. Same approach.....Mobil 1 gear oil per Ford specs in the transmission............95% of the shifting problem went away.

Let us know how it all turns out


Mike

Thanks for the info. I'm not ready for an oil change yet. When I am, I'll try the Mobil 01

Thanks

Duane