CBX smokin'

twinegar · Post by **twinegar** » Thu Nov 01, 2007 5:15 pm

One of the CBX's I bought last week I smoking bad from both exhausts. It had Kerkers on it when I bought it home and the oil was barely registering on the stick and looks like it might be the same oil Honda put in when they built the bike. I didn't really notice that much smoke with the Kerkers but today I put the original exhaust on and when I started it it smoked like crazy. I ran it until it warmed and the smoke is the same. Smokes whether it is reving or idling. I drove it long enough to see that there is no engine or cam chain noise and shifts like new. It idles and runs better than my other CBX with 12K on it.

My thinking is to pull the top end and if the cylinders aren't worn much, just replacing all the rings and rebuild the head. I have never done one but I have all the tools and manuals. What I don't know how to do I learn how to do.

Any thoughts from other motorheads before I order parts?

Chris · Post by **Chris** » Thu Nov 01, 2007 5:23 pm

With only 12k miles, it may just be that the valve seals are dried out and need replaced. A compression test would be a good place to start.

twinegar · Post by **twinegar** » Thu Nov 01, 2007 5:26 pm

Sorry. I was referring to the other CBX that has 12K. The smoker has 24K and was not taken care of. The oil was black and thick. It smokes at idle, excellerating and decellerating that sounds like rings to me.

Chris · Post by **Chris** » Thu Nov 01, 2007 5:35 pm

Your right, if the oil changes were neglected, it could be the rings. A compression check would be good anyway. Easy to do and may clue you in to other problems such as a particularly bad cylinder. It will also give you a baseline to measure against after your rebuild (you can verify the improvements you made).

twinegar · Post by **twinegar** » Thu Nov 01, 2007 5:41 pm

Good idea. I wasn't going to check the compression but now I will. I will be changing all the ring sets anyway but keeping track of each cylinder could be helpful. Any ideas on how to clean all the oil pathways like maybe a special cleaning oil that would help remove sludge deposits.
You have been a lot of help as have others here. I have a headache from the oil smoke bath I took earlier.

The bike came with a big bag full of lifters and shims as well as springs and other stuff so maybe that is the reason it runs so nice.

Chris · Post by **Chris** » Thu Nov 01, 2007 5:48 pm

twinegar wrote:Good idea. I wasn't going to check the compression but now I will. I will be changing all the ring sets anyway but keeping track of each cylinder could be helpful. Any ideas on how to clean all the oil pathways like maybe a special cleaning oil that would help remove sludge deposits.
You have been a lot of help as have others here. I have a headache from the oil smoke bath I took earlier.

The bike came with a big bag full of lifters and shims as well as springs and other stuff so maybe that is the reason it runs so nice.

I just used kerosene to clean my engine parts but I'm sure there are dedicated solvents out there that are better.

The spare parts that your bike came with would hopefully indicate that some service work/repairs were done. My '79 was a one owner bike that looked like it had virtually no maintenance.

It took a LONG time to get it straightened out but alls well that ends well. I really like it now and will never sell it. I'm sure yours will be in your collection for a bunch of years as well.

Terry · Post by **Terry** » Thu Nov 01, 2007 5:50 pm

Wouldn't a cylinder leak down test provide better answers to the problem than a compression test? Just a suggestion...

Chris · Post by **Chris** » Thu Nov 01, 2007 5:54 pm

Terry wrote:Wouldn't a cylinder leak down test provide better answers to the problem than a compression test? Just a suggestion...

Compression would be first. A leak down would be helpful as well but it sounds from the description, it needs a complete top end overhaul.

alimey4u2 · Post by **alimey4u2** » Thu Nov 01, 2007 8:16 pm

What do the plugs say after a good run.. Wet carbon, if no, after town driving ??

Mike Barone #123 · Post by **Mike Barone #123** » Thu Nov 01, 2007 8:51 pm

twinegar wrote:One of the CBX's I bought last week I smoking bad from both exhausts. It had Kerkers on it when I bought it home and the oil was barely registering on the stick and looks like it might be the same oil Honda put in when they built the bike. I didn't really notice that much smoke with the Kerkers but today I put the original exhaust on and when I started it it smoked like crazy. I ran it until it warmed and the smoke is the same. Smokes whether it is reving or idling. I drove it long enough to see that there is no engine or cam chain noise and shifts like new. It idles and runs better than my other CBX with 12K on it.

My thinking is to pull the top end and if the cylinders aren't worn much, just replacing all the rings and rebuild the head. I have never done one but I have all the tools and manuals. What I don't know how to do I learn how to do.

Try this first. Put 15-50 Mobil 1 car oil in and give it a go for 500 miles. On some bikes that smoke this can reduce this to a min....yours could be one and this fix runs less than $30

Let us know how it turns out

Any thoughts from other motorheads before I order parts?

Terry · Post by **Terry** » Thu Nov 01, 2007 8:55 pm

Mechanic in a can or just a super detergent motor oil?

:)

twinegar · Post by **twinegar** » Tue Jun 10, 2008 1:23 pm

Just finished up a top end job replacing the cylinders, rings, valve seals and related gaskets. I started the bike and it runs great but after about 60 seconds it started smoking once again from the left exhaust. Maybe the 60 second delay before it smokes will help someone here to figure it out. There are no cracks in the head or cylinders and the valve guides are good. I don't get it. When I opened the dipstick oil spilled out so is it possible that that much oil could recycle through the intake to smoke that bad? I stuck it back into storage and don't intend to get it back out and may part it out. I don't know if I have the stomach to tear it down again.

alimey4u2 · Post by **alimey4u2** » Tue Jun 10, 2008 4:11 pm

twinegar wrote: When I opened the dipstick oil spilled out so is it possible that that much oil could recycle through

Hmmm.... What level of oil are you filling this bike to twinegear.. On the center stand, level parking place, screw the dipstick out, measure the oil with the dipstick un threaded. The level of the oil should be in the "hatching" marks....The bike ( by design ) has very little crank case pressure unless you are blowing by. Remove the crank case vent tube, connect a longer tube on, listen & feel. Tell us what you find.

Ps We all understand your disappointment, don't give up...

twinegar · Post by **twinegar** » Tue Jun 10, 2008 7:02 pm

There is no oil in the airbox so it probably isn't that. If the crankcase is over filled can it blow by the rings into the combustion chamber. Does the delay from engine start to smoking tell you anything?

alimey4u2 · Post by **alimey4u2** » Tue Jun 10, 2008 7:15 pm

twinegar wrote:There is no oil in the airbox so it probably isn't that. If the crankcase is over filled can it blow by the rings into the combustion chamber. Does the delay from engine start to smoking tell you anything?

Overfilling the engine with oil will cause excessive smoke.......Twinegar, this may well be your problem....

OK, This is how it works... You have reduced the "plenum" that is the crankcase volume, now there is also all this oil splashing about, so it migrates through the crankcase vent, into your airbox back into your combustion chambers....
As long as you haven't hydraulically locked the system ( almost impossible) all will be well when you drain to the correct level....Yes, you must drain.....

The International CBX Owners Association

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