Burning Oil - 84 CB700S

[Baileyman]

Hey all,

I just purchased an 84 CB700S with about 41K miles that seems to be burning a little oil, and leaking some too.  I'm new to these bikes, and fairly new to doing my own maintenance, so please pardon me if I get some of the terms / parts wrong...

I've done some searching in the forums and online, and I'm pretty sure my valve stem seals need replacing.  I am thinking this because when I am at a stop, idling I'm getting some smoke, and it seems to get worse upon initial acceleration, but then doesn't seem too bad while riding (although I do get a whiff of burnt oil here and there).

I pulled 3 of the 4 spark plugs and none of them had any wet, oily deposits.  They actually all looked just fine.  Those three that I pulled were not tightened down very well, and I was able to remove them with my just my fingers essentially.  The fourth (cylinder 3 I believe) I didn't pull because I didn't have the right socket.  I think I'm getting smoke out of both exhaust pipes.

My question is, wouldn't I expect to see some oily deposits / buildup on the spark plugs if it's burning oil?

Regarding the leaks, I'd like to get the engine steam cleaned, and replace some of the gaskets (oil pan gasket for sure, probably valve cover gasket).  It seems that one of the POs did some pretty lame attempts at fixing oil leaks using some kind of silicone sealant.  I want to get the engine nice and clean to 1) identify where the leaks are coming from, and 2) make it easier to work on.  Has anyone had their engines steam cleaned?  What do I need to be cautious about if I pursue this?  Anyone know of a place in the San Francisco area that does motorcycles for a reasonable price?

Thanks,
BaileyMan
'84 CB700S

[Hondo]

I am still working on the DOHC engine in my 1985 CB1000 Custom, dealing with the oil burning issue.

http://nighthawk-forums.com/index.php/topic,4346.0.html

That will give you an idea of what is involved.

[Baileyman]

Thanks for the thread link Hondo.  It looks like quite a job.  I don't know if I'm quite ready to get into all that work.  Bummer.  It wasn't smoking when I checked it out.  If it had been, I probably would have passed on it.  Perhaps it's time to put her up on Craigslist.

Anyone here looking for a project bike?

BaileyMan

[Brittles]

Anyone here looking for a project bike?

Where's the bike located?

[Baileyman]

In San Francisco...sorry I should have mentioned that in my last post...

BaileyMan

[Brittles]

In San Francisco...sorry I should have mentioned that in my last post...

BaileyMan

Little too far for me.

There are a lot of knowledgeable 700s members on here that would help out if you decide to fix it yourself.

Good luck in whatever you decide.

[happycommuter]

Shop explained to me that most likely the exhaust valve seals are worn.  Smokes on the way out, spark plugs always look gorgeous.

[Baileyman]

If it's just the valve seals I might be willing to tackle that job, but if it ends up that the valves need lapping, and yada yada yada, it's a bit much for me.  It's probably the kind of thing where you might as well do all the work as long as you're in there.

[Munkey]

It's not really too bad of a job. Just get a copy of the service manual. You'll need a gasket set, and a valve spring compressor and a decent set of tools. I bought a valve spring compressor for about $30. If you decide to do the job, I'll look up where I bought it from and give you the info.

Might want to replace the piston rings while your at it, won't add that much more work to the job.

[Baileyman]

It's been kinda tearing me up inside.  Not sure if I can tackle the job, and not sure if I want to deal with the hassle of selling it.  I figured I'd sleep on it and whatever I dreamed about that's the path I'd take...guess what I dreamed?  That I tore into it and did the work...I did already order a complete gasket set, should be here soon.  I think I'll start with the oil pan gasket today, maybe start working on getting the valve cover and head off too.

Thanks for the encouragement and for all the wonderful info that's here already, and hopefully more as I make my way through.

Cheers,
BaileyMan

[Munkey]

It's been kinda tearing me up inside.  Not sure if I can tackle the job, and not sure if I want to deal with the hassle of selling it.  I figured I'd sleep on it and whatever I dreamed about that's the path I'd take...guess what I dreamed?  That I tore into it and did the work...I did already order a complete gasket set, should be here soon.  I think I'll start with the oil pan gasket today, maybe start working on getting the valve cover and head off too.

Thanks for the encouragement and for all the wonderful info that's here already, and hopefully more as I make my way through.

Cheers,
BaileyMan

Cool, we're here to help. Do you have a service manual?

First tip:  As you remove parts, put the respective bolt, nuts, clips whatever, in some kind of container marked with whatever section of assembly they go with. Makes re-assembly much easier and less chance of leftovers or the wrong part used somewhere.

[hppants]

My 700 has 39,500K on it and has exactly the same symptoms and conditions.  The symptoms have not changed in the 5500 miles I've ridden the bike since August.  Under normal riding conditions, I burn a quart of oil in about 1200 miles, which is normal I believe.  When I ride it hard in the twisties, I'll burn a quart in about 900 miles, which is also similar to what others with no issues burn.  So, the problem is not causing me to consume a lot of oil.  As you have, I pulled my plugs as well and noticed the exact same thing you have - no deposits, no residue, just a golden brown normal color.  My fuel mileage is normal and she starts at the mere touch of the button every time the first time.

I might look into putting a seal conditioner in my oil, but otherwise, unless things progress much worse, my plan is to do nothing at this point but 

[Baileyman]

Cool, we're here to help. Do you have a service manual?

First tip:  As you remove parts, put the respective bolt, nuts, clips whatever, in some kind of container marked with whatever section of assembly they go with. Makes re-assembly much easier and less chance of leftovers or the wrong part used somewhere.

I do have the Honda Shop manual in PDF.  I'd like to maybe get the Clymer too so I can have another reference when the HSM doesn't make sense.

I have done a little maintenance before on bikes, and have mos def learned to rely on the parts in labeled containers process.  I even like to label the container with the page and step number just in case...

My 700 has 39,500K on it and has exactly the same symptoms and conditions.  The symptoms have not changed in the 5500 miles I've ridden the bike since August.  Under normal riding conditions, I burn a quart of oil in about 1200 miles, which is normal I believe.  When I ride it hard in the twisties, I'll burn a quart in about 900 miles, which is also similar to what others with no issues burn.  So, the problem is not causing me to consume a lot of oil.  As you have, I pulled my plugs as well and noticed the exact same thing you have - no deposits, no residue, just a golden brown normal color.  My fuel mileage is normal and she starts at the mere touch of the button every time the first time.

The PO said that it didn't consume much oil, and he wasn't too concerned about it.  But personally, I'd like to get it under control.  I'm glad to hear though that it hasn't been much of a problem for you.

BaileyMan

[SmokinFast]

If its not too late, I would recommend doing a compression check before you take apart the cylinder head. That will tell you if you need new rings or a valve job.

As for oil leaks, I just finished chasing down the source of the leaks on mine. Common leaks are the oil tubes, valve covers, side engine covers, and as you know the oil pan.

To find the leaks on mine, I start at the top and work down. I clean everything with hot soapy water and a brush to get the old oil and grime off. Some leaks only happen with the engine running.

I live in Rocklin (about 100 miles east of you). I have almost enough good spare parts to build an engine, so let me know if you need something.

Brett

[Baileyman]

Thanks Brett!  I'll pm about some parts I may need...

And it's not too late to do a compression test...

Thanks for the suggestion.
BaileyMan