Still smokin'

twinegar · Post by **twinegar** » Wed Jun 11, 2008 1:10 pm

...............I also ran the engine again and timed how long it takes the smoking to start and it was about 3 minutes which tells me that it must be in the head and the oil is taking time to work it's way into the combustion chamber. Maybe the heat thins the oil enough to allow it to flow.

cbxtacy · Post by **cbxtacy** » Wed Jun 11, 2008 1:26 pm

or the pipe gets hot enough to start burning the oil?

alimey4u2 · Post by **alimey4u2** » Wed Jun 11, 2008 2:09 pm

twinegar wrote:Was I supposed to install any o'rings between the head and cylinders? I used the shop manual and the exploded view doesn't show anything other than the gasket. I pulled the left side plugs out last night and #1 was covered with a guey black substance so oil is getting in from somewhere. If I wind up pulling the head again I will have to have it checked for any fractures that are invisible to the naked eye because with new valve seals and no obvious cracks I just can't guess my way thru this problem.

Cylinder base gasket then 6 sleeve O-Rings but none that I can see or remember on the head gasket...Hmmm...I wonder ??

alimey4u2 · Post by **alimey4u2** » Wed Jun 11, 2008 2:52 pm

Been racking my brain here ( & editing at the same time) to think what the problem could be.

OK, So you have narrowed this down to # 1 cylinder & the plug has black goo on it...
On a short run that would seem to be copious amounts of oil as what you see is "heavies" the "light" ends have burned off (smoke)
That amount of oil getting into the cylinder so quickly tells me it's getting pulled in. Throttle & choke buttefly's closed, pull quite a vacuum in the inlet tract. Seeing that you have replaced the valve guide seals with new ( (may still be a problem there) I would look for a crack ( or a loose guide/s)around & about the inlet valve area, inside the inlet tract.

EMS · Post by **EMS** » Wed Jun 11, 2008 3:09 pm

Is the bike on the sidestand when it is running? Leaning over to the left, the oil level under the No 1 cylinder in the sump is higher than under the rest. Maybe the level is still too high and it pulls in oil from below the piston

twinegar · Post by **twinegar** » Wed Jun 11, 2008 3:27 pm

Today I finally was able to check the oil level with the bike on the center stand and it is at the top of the threads. I drained it to the proper level and took a short ride (no tags) and saw no smoke. I kept it running for a bit upon return and a miniscule amount of smoke showed up but that could be residue burning off. I will be going tomorrow or Friday to get it inspected and tagged so if it is going to smoke it will have plenty of opportunity. If the high oil level turns out to be the culprit then oil was getting past the rings from the bottom and not thru the airbox as it is dry.

As a side note, when I picked up the bike last fall I failed to check the oil and when I got it home checked and the oil didn't register on the dipstick. My 2 CBX's are an excellent example of a well maintained bike and a poorly maintained bike. One took a few weeks to bring to original condition and the second is still being restored. Lots of missing parts and wrong fasteners some of which are no longer offered by Honda. Cracked headlamp can, missing cable clips under the handlebars and so on.

EMS · Post by **EMS** » Wed Jun 11, 2008 4:52 pm

I see a silver shine on the horizon

alimey4u2 · Post by **alimey4u2** » Wed Jun 11, 2008 6:34 pm

Sometimes the biggest problems seem to end up as simple ones....

Now go out & thrash the hell out of her, she wont break if you keep the revs below red & ENJOY....

twinegar · Post by **twinegar** » Sun Jun 15, 2008 10:44 am

It is still smoking, probably from a crack in the head someplace. If I drive it gently it doesn't smoke so now I will just move on to adding other missing parts. It has become a money pit and even though I got the bike rather cheaply, it has sucked a good deal of cash from my account and I will be a few years before the value on CBX's catches up with my investment. Overall I have done pretty well in my bike purchases with the exception of this one. I will just enjoy driving the other CBX and step away from the table on the money pit for a while. Maybe in the end I will just part it out.

bobber · Post by **bobber** » Mon Jun 16, 2008 7:59 am

Few years ago had my '80 rebuilt. Took it for a few rides, worked great. Being from the East Coast decided to ride across Canada from Alberta. About a day into trip bike started to puff some smoke. In Dryden, Ontario it REALLY started. Between Dryden and Nfld used about 27 liters of oil. Brought it to a shop there where it turned out an oil control ring had come out of groove, probably during re-assembly. Could something similar be your issue, seeing has how engine just had new rings?
As for the 6 o-rings, are those the ones which fit up between the extensions of the cylinder sleeves and cylinder? I beleive they just fit into the recesses at the bottom, something to do with vibration?

twinegar · Post by **twinegar** » Mon Jun 16, 2008 9:10 am

It was smoking from the same cylinder before the re-build and I paid special attention to the rings during re-assembly so I am pretty sure that they aren't the problem. The large o'rings under the cylinders shouldn't have anything to do with the smoking. I am now convinced that it is either a valve guide base leak or a hairline crack in the head, both of which require disassembly again so it will have to wait. Thanks for the suggestion.

EMS · Post by **EMS** » Mon Jun 16, 2008 9:54 am

I don't know, but I doubt - and hope!! - that it is not a hairline crack. I want to think you should have bigger problems if that were the case. Like, if the crack allows oil to seep into the combustion chamber, it would also allow combustion pressure to escape....

Maybe the valve shaft is scraped and doesn't seal properly in the new seal

twinegar · Post by **twinegar** » Mon Jun 16, 2008 12:11 pm

I am sure it is a crack. The intake plenium that mounts to the carbs is in 2 pieces with the front piece screwing to the back piece and when it is smoking smoke seeps out around the joint. The only way for smoke to get there is through the breather pipe which tells me that the smoke is blowing into the head under compression and down the oil return into the crankcase and out the breather pipe. Under intake vacuum it is sucking oil into the combustion chamber repeating the process. I can drive all day without smoking as long g as I go light on the throttle. An expert told me that there is a seal under the valve guide base that will cause the same problem if it is damaged or missing. There is no mention of the seal in the Honda shop manual so I am not sure. This winter I will pull the head and have it inspected to get to the bottom of it. This really sucks but that is what I get for buying a "kicked around" bike I guess.

EMS · Post by **EMS** » Mon Jun 16, 2008 1:29 pm

twinegar wrote: An expert told me that there is a seal under the valve guide base that will cause the same problem if it is damaged or missing. There is no mention of the seal in the Honda shop manual so I am not sure. .

There is an O-ring under the valve guide. It is 91301-200-000, 10x1.6

twinegar · Post by **twinegar** » Mon Jun 16, 2008 1:35 pm

Well maybe that is it then since I didn't see any cracks in the head. I will know this winter I guess.