I understand there is a check valve that is supposed to keep the oil in the tank from draining into the crankcase while the bike is not running. Is it at the inlet of the oil pump? What's involved in cleaning or replacing it?

I have a 1988 1200 that I bought new. For years I never had a problem with excessive oil draining into the crankcase even when the bike sat for weeks, or even months over the winter. As the years have gone by however, it is becoming a problem. At first the only symptom was the low oil level in the tank which would come back up once the bike was started.

These days a lot of oil drains down even after relatively short storage times. Yesterday was the first day with no snow or ice on the roads for a good while so I decided to take a ride. Pretty much all the oil had drained down, or so it seemed as the tank looked about empty. I figured it would pump back up, so I started the bike.

It did in fact pump back up, but there were two problems. There was a lot of oil puked into the air cleaner from the breather, which proceeded to make a real mess. I guess there was so much oil in the case that it got pushed up the breather hose. That wasn't much fun, but not the worst problem.

When the bike first started the oil pressure light went out like it normally would, but after a short time, it came back on. When it stayed lit for 5 or 10 seconds, I shut her down and checked the oil level in the tank, which was back to full. The only thing I could think of was maybe an air pocket in the oil feed line to the pump, so I waited a little while and restarted it. Same thing happened, light went out, but then came back on after 10 seconds or so. So I shut her down again, and waited a half hour or so, this time the light went out and stayed out. I went for a ride, light stayed out and the bike ran fine.

I could be wrong but I think this is all related to the check valve being worn and not working properly.

What are your thoughts on this?

 

thanks for the heads up, i also have a 1988, but its a 883 turned 1200 (im 85% sure it is anyway haha)

sounds like a worn out valve, i guess you'll just have to find a way to clean or replace it and let us know how that goes and if it helped.

 

I have an 88 as well and have not experienced this problem. The only check valve I'm aware of is in the oil filter mount. I don't think there is one in the pump assembly. Others that have had the problem may have better info.

 

I know Ironheadsare notorius for spitting oil out of the crankcaes due to a worn outball valve.If the bike would sit for long periods of time it would spit a puddle of oil on the ground on the first start.Isn't the crankcase breather located toward the front of the motor near the bottom of the frame by the oil pump on an '88?It is on my '90 1200 and they're essentially the same bikes.I would think it would spit oil on the ground,kind of behind your front wheel or right under the down tubes on the frame.

 

Yes that's where my breather is located, but there's a hose running from it up to the air cleaner so the fumes get burned up and don't pollute the air. At least that's how it was hooked up when the bike was new. I have an aftermarket carb and air cleaner on mine so the hose isn't actually attached at that end, it's just stuffed up behind the air cleaner cover. I used to have the hose zip tied to the bottom frame rail, but it had a bad habit of puking oil right where the back tire would run over it. Since I have the end of the hose elevated now it only throws out oil if the bike has been parked long enough for most of the oil in the tank to leak down into the crankcase.

The problem you describe with the ironheads sounds exactly like what I'm having. I wonder if the oiling systems are similar.

 

Ok....mine just hangs below like you described.I've run several different carbs on my bike but I don't think the hose ever ran up to the original CV.Anyway,I brought up the Ironheads because you're problem sounds exactly the same.Not exactly sure what needs to be done to replace that valve(I've never had to address that problem)but I can tell you that it really wasn't much of an issue with the older bikes except having to top off the oil that was spit out....and of course the puddle it left.

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The ball in the oil pump for shovels are famous for wearing down and letting oil seep, I use to silver solder the ball and lap it to seal again. Looking at the service manual for sportster, looks like they moved the check ball for 1987 and later in the oil filter housing unit. For 1987 and 1986 earlier it was and acual check valve. There is also a spring in there too check that out to see if it is bad, you never know. Reference for information provided Clymer HD sportster 1986-1990 pg. 108 exploded view.

 

I'm looking at the oiling system diagram in the factory service manual and I see there is a check ball and spring in the oil filter housing. It says the check valve should open at 4-6 lbs of oil pressure. From what I can see it looks like if the check ball is not seating properly it would let oil seep past and end up in the gearcase. So I'm thinking that's the problem.

It should be easy to change out so I'll have to go to the dealer and see what outragous proce they want to charge for a new check ball and spring. I might even be able to pump one of the techs for info on whether that is the likely cause of the problem.