Lakota 300 / Bayou 300 crankcase breather tube

[beast6228]

I've been trying to piece this Lakota 300 back together, slowly. It's been a rabbit hole however. I replace one thing, then it leads to replacing other things. Anyway, When I got this thing I noticed that the hose coming off the camshaft cover wasn't attached to anything, it was just hanging loose. (It's literally just a foot long hose attached to nothing) I figured since it was venting the head it would be ok and I am sure it is.

However, last night I was looking at the service manual and noticed that it mentioned that this atv has a crankcase breather tube as well. Mine does not have one, so I looked at Partzilla and looked at the parts diagram and sure enough, it's definitely supposed to have one. The problem however is, the service manual does not show how it hooks up and the parts diagram only shows the exploded view of the assembly. I just find that kind of strange, nowhere in the manual does it show how it connects. Does it have it connector, attach to a nipple? It just doesn't say and it bothers me that there is a hole there without anything attached to it.  If anyone has a Bayou 300 or Lakota 300 with an intact breather vent system and could possibly take some clear photos of it or know how it connects I would be very grateful. I have searched high and low and cannot find any information on it.

 

Thanks

[Mech]

Most service manuals have a section where they show exactly where the wires, control cables and hoses get routed and attached. In some yamaha manuals it's in the appendices section.

[beast6228]

I have the pdf service manual and searched the entire manual, but still doesn't show it, just what I posted above, that's it.

[Gwbarm]

I havent worked on a Lakota but it should be similar to others, most that i have seen route into the aiir box. You might look around there and see if there are any vacant slots for it to hook into.

[Mech]

I just checked in a bayou manual that covers that year and it does have the routing diagrams in the appendix section.

It doesn't show any hose going to the crankcase though, only from the head to the airbox, and in some years a branched hose going from the head to airbox with the branched hose capped off. That capped hose is for draining water out almost certainly and it will dangle down behind the engine.

If your bike has a breather off the head, and another breather on the crankcase they are probably both meant to be joined and connected to the airbox. That's almost always how quads are. There shouldn't be any open hoses that could suck water in. If there's a hose going nowhere, it's a drain hose and will either have a rubber lipped end that lets pressure out but stops water going in, or it will have a removable cap for routine draining.

 

 

[beast6228]

If you look at the photo I posted above (breather_Lines2.png), you can see the diagram of how it goes down into the gear/sprocket cover.  (verified by grabbing a glimpse from Youtube videos ) So basically, the camshaft cover vent tube and the crankcase vent tube are connected together, then one more tube from those two tubes goes back down the frame  (so it can drain downwards) and is basically zip tied to the frame. (this is what I have seen from videos, it's hard to see when people are moving around) On California models that vent tube goes to the air chamber case (the first air tank that feeds the carburetor) but this isn't a California model and those connections are capped off from the factory.  I will post a photo of my atv and show you the case. Then I will post another photo of someone else's atv where that hose goes into their crankcase.  Anyway, I wouldn't be here if someone hadn't pulled that tube out. As I discovered, the gear box / sprocket cover was cracked, someone JB welded it back together probably though to themself that the crankcase breather tube was not needed OR it was damaged when the drive chain smacked it. (I will never know) BUT I want to replace it. I am going to leave this here, but if you currently own a Lakota 300 and have spare time, I would love to see some photos of these areas. I am sure I am not the only person who is looking for this information. Maybe a Clymers manual shows it, but I can't keep throwing money into this atv.  The aftermarket gearbox cover, OEM gaskets and the vent system is going to add yet another $250+ dollars into this thing and I have yet to discover if I will need to rebuild the top end and possibly gears. I appreciate all those who have commented on this post, you have been trying. I have also posted on Facebook groups dedicated to these atvs and no one has responded.  Thanks again!

[beast6228]

Apparently that tube just sits in there between the transmission/sprocket cover and the stater cover, it's wedged in and is held by a metal tab/clip, but it's not connected to anything. (Kinda stupid design if you ask me, why bother at all?)  This was according to someone else who is currently in the process of changing out their broken cover. So, I guess I can save $80 dollars or so and can put that money into other things. I will just buy some Goodyear hose and make my own breather tubes.

[Gwbarm]

Thats different, i havent seen one arranged quite like that. I even  pulled up an exploded parts diagram and didnt see anywhere it hooks to, but it did show some sort of pressure relief valve in there but it didnt look like a hose should attach to it.

[Mech]

if there's no tube to the airbox to let air in if you drove into water, then the two dangling down tubes would suck water up when you drove into deep water with a hot engine. I'd run one of the hoses to the airbox.

It is quite common to have a rubber lipped end in breather hoses to let air out but stop water getting in.

[beast6228]

It's definitely different, rather a poor design. There is only one tube that vents -the two tubes that come from the head and the crankcase are tied together (as the diagram shows)  On Non-California models that final and only vent is strapped on the frame. California models it goes to the airbox. You would think that a crankcase vent would be similar to the vent on the head. (which is a fitting)  Venting the crankcase is to prevent pressure build up, which could potentially blow out the engine seals. Here is a better photo, this is what the factory breather tube to the crankcase looks like.  Of course, I will attach the photo from the service manual again.  (actually it's above in the first post) You can see the Left side view of the engine and how the breather system tubing looks, in addition to how that tube is routed down into the case. (Just doesn't show how that is achieved) Perhaps since these were sport atvs, they didn't figure people would need to know about that since they weren't advertised for riding in the swamps.  The world will never know! I do know one thing though, I have had a hard time getting this thing to run right, it's running super lean and will only rev normally with the choke, not because of the carb (I rebuilt it to factory specs),  but it's sucking too much air. I need to cap off the vent on the air filter box (Yes, that is what diagrams show) and check for potential leaks on the carburetor intake boot.

 

[Mech]

Reading through the manual I see they use a "breather chamber", which is presumably in behind or made up of that outer case. In most engines there is some sort of chamber to separate out the air from the oil as it breathes, and in most bikes that separation chamber is cast inside and a part of the crankcases and does have a spigot on the case for the hose to fit onto. In this case I think the hose is just meant to be a good fit into the case. The hole it goes into must be sealed and in communication with, or is, the "breather chamber".

In the manual it's described in the emission control section...

"1. Crankcase Emission Control System
A sealed-type crankcase emission control system is used to eliminate blow-by gases. The blow
-by gases are led to the breather chamber through the crankcase. Then, it is led to the air cleaner.
Oil is separated from the gases while passing through the inside of the breather chamber from
the crankcase, and then returned back to the bottom of crankcase.".

[Mech]

Not getting at you in particular Beast, but for everyone reading through the thread...

Service manuals, well the Jap ones anyway, are very well written, and tell us everything we need to know. Sometimes though we need to read right through them to garner the information we are after. Sometimes the information is mentioned in conjuncture with some other aspect of the bike. This is especially so with the diagnosis of fuel injection, electronic and  and transmission diagnosis.

The manuals are written for trained mechanics, and trained specifically on the make the manual relates to. The information we need as mechanics is always there somewhere though.

It's always a good idea to read right through the manual from cover to cover familiarising yourself with how it's layed out and what is in there.. before starting to read any particular part that relates to what we are working on.

[beast6228]

You must have a different manual than me, mine has no such text referring to emission control.

[beast6228]

I went and downloaded the Bayou 300 manual and can see the references to emissions. Overall the quality of the manual is superior. The images in mine look like someone scanned it at a gas station copy machine. The images in the Bayou 300 manual are very clear. It's also more detailed with information.  With that said, the Bayou 300 and Lakota 300 had the same engines, but they setup things differently between the two.  Even more so if you bought a California compliant model.

[Mech]

I searched for a lacota service manual but couldn't find one, but there will be one out there somewhere..  A decent one.

[beast6228]

Someone gave me a copy of one. The one on this site appears to be the same thing, but isn't searchable in Adobe for some reason.  Anyway, I wish this manual was as nice as the Bayou 300 one, especially since I actually printed off a copy of the Lakota manual. The photos in it are horrible, very dark and blurry. These two images below are from that manual and are better than most in it.

[Mech]

The photos in most manuals are generally pretty poor. The diagrams in parts listings, or the diagrams in the service manuals, are normally much easier to understand.

What country are you in Beast ? The lacota is supposedly only for Euro and Oceania markets. I'm in New Zealand though and hadn't heard of one.. not that that means much.. haha.

[Gwbarm]

I have never seen one either, just the Bayou, they are fairly popular. Im in the US.

[beast6228]

The Lakota, which is an American Indian name, they are very common here. Lots of people have them.

[Mech]

Oh ok, perhaps that owners manual I found was only for the Euro and Oceania markets..

[KellyG]

I have what I think is a 2000 model definitely KLF 300 Bayou four wheeler that has an issue with a lot of compression in the crankcase. The hoses that go to and from the head to the crankcase are free of any kind of obstruction but when you pull the oil cap off there is a lot of compression coming out of the crankcase. It sounded like in this thread that people have discovered the hose going into the lower engine doesn’t connect to anything so perhaps there is no nipple out fixture inside the case for this to connect with. Does anybody any solid ideas why there isn’t any venting going on inside the crankcase?

 There is compression coming from the head nipple for venting but something else must be going on. Thanks in advance. Kelly

[Mech]

You may have too much compression leaking past the rings, pressurising the crankcases..