Photos from Joacim Nilsen Wallgren's post



I'm wondering what the blue arrow is pointing to? It was years since I took the bike apart and my Clymer doesn't give any guidance. I guess a tube should be connected since the hole is spitting out a little oil. But what should I connect it to?

I also wonder if I need to connect the carburetor drain tubes to the carburetor, or if I can leave it as it is. Maybe this is basic knowledge, but I have not required it yet. As you can see I have switched to cone filters. The build is, except for this, complete and the bike runs good, but I have only driven it one mile to test everything.

%d comments
  • Its a crankcase breather, normally it would go back to the airbox. Put a hose on it and route somewhere where the oil mist doesn't get on the exhaust or the rear wheel. There's a similar one the other side.

    If you don't have drain tubes on the carbs then when they overflow (and they will - due to sticking floats), the fuel will go everywhere, including (possibly) your starter motor (the sparky electrical thing). Normally the drain tubes would run down behind the engine but not in front of the rear wheel.

    Expect problems getting the carbs set-up (jetting) unless you have put a dynojet kit in it, as they really, really don't like having the airbox removed. Lots of us have done it, but it takes work to get them to run right.

  • This is how some people do it also.

    This Works pk

  • That look much better than a hose/tube. That way the oil won't spill as well I guess?

  • Thanks Max! On old Harleys I think the breather hose was routed so the oil lubricated the chain. But I should just let it spill on the ground?

    Can i route the drain tubes to the left side of the bike? That will be in front of the rear wheel (every place will be of course), but not immediately in front.

    I have changed the nozzles in the carburetor to 120's, and a friend of mine will calibrate the carbs with a gasometer. But you think I need to switch to dynojet as well? I've heard problems can arise when removing the airbox, but it's looks so much better with cones.

  • Well I think soo too! As you Can see on this pic, On the other side I had the hoose routed backwards... but also with a "filter"... the filter I have were cheap... so when they look bad, I just buy new ones

  • It really does! Do you have a picture from the other side fellow Swede? Where do you buy the filters? Biltema?

  • Mine get routed down behind the engine, to the chain on the left and below the exhaust on the right. Really you shouldn't be getting much more than steam from the breathers, anything else and you're likely to be having other problems.

    Many of us use pod filters, and many of us have spent a long time (and money) getting the bike running right. I use a dynojet kit, and then spent time on a dynamometer to get the needle and jets right. Others have had success with just changing jets. It is very unpredictable. These carbs can be made to work with pods, but it is usually hard work.

  • Biltema

  • I have checked the carbs, and everything looks clean and nice. So hopefully steam is all I will get.

    It's 150 USD to get it so Sweden, so for now I will just try with changing jets and see how it turns out. Hopefully the snow will stay away for a couple of more days so I can try it out. Thanks for taking the time Max, appreciate it!

  • Thanks Jonas, appreciate the help!

  • Jag håller på att bygga cafe...

  • Cool! Best of luck! 100 days to go before "spring".

  • Haha.... I know

  • Did the 900 not get a oil/air separator tank?

  • Not on My boldor from 1980. There were hoses routed up the airbox.

  • Nope, the hoses joined and fed into the airbox.

  • On the 900 there's a hose from the back of the airbox to a plastic tank clipped underneath the battery box.

    Looks like this;

  • From what year is the bike?

  • not sure, it's in my box of spares.

    Just checked for you and according to the parts book it's only fitted to 82 & 83 models.

  • Thanks. Mine's a -81, and I don't recognize that part.

  • The one on the R is big . . The reclaimed oil runs back into the engine. .

  • Fills the toolbox ...

  • This is also on my '80 CB750F

  • Yes the air box catch tank with plug in pipe to drain occasionally wasn't on early bikes , it just catches oil and water so you can drain rather than just seeping out was a thing lots of bikes started to have as cleaner rules came in , many have them now especially scooters but tends to be a pipe with cap in rather than a tank