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General Category >> Rubber Side Down! >> Crankcase breather hose problem!
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Message started by johnnyboy on 05/23/08 at 15:45:32

Title: Crankcase breather hose problem!
Post by johnnyboy on 05/23/08 at 15:45:32

Hey y'all, I'm a new member to the forum here, and the owner of an '86 Savage for about two and a half years now. I'm in the process of trying to get her up and running again after being deployed and I'm running into a problem I don't know how to deal with. When I first got it to start then turned it off, a gasoline drip began from the air box drain tubes. It turned out to be a significant amount of fuel, and not knowing what to do about it, I left it until a had more time to deal with it. Today, I researched the hose connections to the air cleaner and decided to try checking the breather hose that runs from the top of the head to the top of the air box. There is a LOT of fuel (and oil as well, as it appears dirty) coming out of this thing! It is not an issue I had the last time I had the bike out, and I'm confounded for the time being. I gather that it may indicate a larger problem in the engine, but figured I'd ask y'all before I crack the thing open. Thanks in advance for any help you can give.

Johnny

Title: Re: Crankcase breather hose problem!
Post by Reelthing on 05/23/08 at 15:59:29

actually a known problem as the bikes age - the diaphram in the petcock has failed - draining the fuel tank into the intake through the vacuum hose that connects from the carb to the back of the petcock - you need to square this away before you start it as likely the crankcase is also full of gasoline now

Title: Re: Crankcase breather hose problem!
Post by johnnyboy on 05/23/08 at 16:10:23

Reelthing,

Thanks for the quick reply! I believe that I've seen a post on this site involving the alteration of the petcock to a non-vacuum operation. I'm guessing this may fix the problem in lieu of replacing the whole assembly. Also I gather that the amount of oil that came out with the fuel (seems like a lot) should make sense given that it's coming right out of the crankcase. Should I be thinking about opening the case to drain the gas, or is safe to assume the remainder will come out the breather?

Thanks again!

Johnny

Title: Re: Crankcase breather hose problem!
Post by Gort on 05/23/08 at 16:24:35

If you even think you've got gas in your crankcase, I would drain the oil and remove the oil filter. Then, with the drain plug open and the filter cover off, I'd leave it sit overnight to allow any residual gas to vaporise. Then I would replace the filter and O-ring with a new one, re-fill the engine with cheap oil and run it for a few minutes to allow it to mix with any residual gasoline that didn't drain out of the engine the first time, like what sits at the top of the engine. Then I would dump that oil and refill with synthetic oil sold for motorcycles, such as Mobil 1 V-twin. Sure, maybe you could get away with just dumping the present oil and leaving the filter alone, but for the few dollars it costs to be sure, why not be sure?

Title: Re: Crankcase breather hose problem!
Post by verslagen1 on 05/23/08 at 17:32:30

it's normal for some oil to blow into the air box via the breather tube.
but do check the crankcase for gas.
also a stuck float valve can flood the carb. it has a choice of either running into the air box or the cylinder then down into the case.
a bad petcock will do the same thing but thru the vac line. check the vac line for gas. gas in line bad.

Title: Re: Crankcase breather hose problem!
Post by thumperclone on 05/23/08 at 18:53:51

age of ls? miles ? how long you've owned...
if bike is used and you just got it......
theres a drain for the air box..
get on your back from the right side and look for a hose below the rear of the air box ..
it has a plastic thumb screw turn it to the left and drain into a fire starter receptacle...
pull air cleaner and wipe out your air box..
install new air flter...
your done!!!

Title: Re: Crankcase breather hose problem!
Post by rigidchop on 05/24/08 at 05:26:59

it says its an 86 and hes owned it for 2.5 years

Title: Re: Crankcase breather hose problem!
Post by Kustomjim on 05/24/08 at 06:57:24

It also helps to install a reed valve type pvc off of the top engine breather hose.Put one on our shop bike,creates a small vacuum effect in the crankcase,works great! Any engine can benefit from this addition,keeps gasket leaks down. K.J.

Title: Re: Crankcase breather hose problem!
Post by Sandy Koocanusa on 05/24/08 at 07:06:38

5E6066617A787F7C78150 wrote:

I'd be interested in a little elaboration on that idea, K.J. A picture would be worth a thousand words, but words are good too. I have some minor leaks ("seepages" would be more accurate) that I'm not about to tear the engine apart to fix. If I walk into NAPA, what should I be asking for? A particular make/model? They always want to know everything about the vehicle before they can find the part. Already knowing the part would be handy.

Title: Re: Crankcase breather hose problem!
Post by Kustomjim on 05/24/08 at 07:27:56

Sandy,if you go to my site,out there kustom shop.com,click on "kustom bikes",then scroll down to "bomber 59".Click on the first pic twice to fully enlarge,and you will see the pvc in it's temporary location. It is a small valve we found overseas.Not sure what it originally came off of,but i have used them on a few different bikes with good results.It actually shows a small increase in power on a dyno! Nothing you can feel,but it's there. We are out of stock on them @ this time,but will have more in later this summer.Don't know if the stealerships or parts houses would have one that would work as good as this one. Kustom Harleys have been using this type of system for years. Without proper crank case breathing/vacuum,cylinder base gaskets,etc. tend to "weep. Thanks,K.J.

Title: Re: Crankcase breather hose problem!
Post by Gort on 05/24/08 at 11:45:12

The subject of the crankcase breather hose and it's need for vacuum was discussed on this site a long time ago. It was in reference to those who had removed the airbox and replaced it with a cone filter. The question was what to do with the crankcase breather hose since it was connected to the airbox, and, was it necessary for it to EVACUATE the oil fumes from the crankcase?

People experienced with the Savage pointed out that the airbox is a leaky design and therefore the breather hose sees no useful vacuum. I verified this by replacing the breather hose with a longer hose and then putting my tonque over the crankcase end of it while reving the engine. I felt no vacuum. It was suggested that the breather hose on this engine was just a "puffer" which blew its fumes into the airbox, to satisfy Federal emission regulations.

Those who had removed the airbox put an oil breather filter on the end of the hose and called it good. One person recommended having the breather higher than the engine. After reading all of this, I made the conversion and have had no seepage or leaks from the engine.

Title: Re: Crankcase breather hose problem!
Post by Reelthing on 05/24/08 at 12:44:56

On this single cylinder it's just a huffer and a puffer - 652cc of air out when the piston goes down and 652cc of air back in as the piston goes up, plus a little from blow by.

Always thought it might be interesting to install dual reed type valves - one at say the oil filler cap that let fitered air in and one at the head to let the air out - keep a steady flow of fresh air through the engine - would need to get the oil mist from the air out reed back to the air in reed I guess, might reduce the temp a bit.