Topic: What is this and how do you remove the rear axle

[briancwynn]

Hello wealth of information team.  What is this thing attached to the battery box and is it needed? Its some type of breather box assuming but it does attach to the oil tank. I cant take the battery box out with removing this and I have not removed any oil from the engine or oil tank.   
I never see this thing on rebuilds?

Also how do you take out the rear axle. I was able to take off the head bold but its not budging!

Last question I am trying to remove the electronics without breaking anything so I can paint the frame. The bike was working great before I took everything apart and I am hoping to put it all back together but I worry about the electronics and if there are something that I should worry about when taking everything out besides how they go back together?  New wiring harness will be going in. 

Thanks all. 

[brandEn]

That connects to the air box and is not needed. I think most of us remove them and toss em in the trash. It's a gizmo they installed to satisfy the EPA is my understanding.

[madmtnmotors]

it does attach to the oil tank

Look again. One tube (up high) should route to the airbox, one tube just below that routes up to the back of the valve cover, and the one out the bottom routes around the front of the swingarm, and then down to the rear. This is indeed a crankcase breather and water separator. If you eliminate it be sure to at least leave the vent at the back of the valve cover open to the atmosphere. Those that follow this route typically use some sort of filter on this tube. It will expel an oily mist. I have left them in place on all (6) of my K8's and F3's and service them regularly during basic tune up. The green foam air filters for lawn mowers make a nice substitute (cut to fit) for the original filter media.

It is hung from a single bolt on the bottom of the battery box. Remove the bolt and you can lift out the battery tray.

[70CB750]

The rear axle may need some hammering to get out, the fit in bearings is tight and just a little bit if rust will make it hard to come out.

Once you have it out, it does not hurt to polish it and grease it little.

Electronics, watch for the rectifier, use only elements that look like nut to loosen it up, the cooling boards are not to be used for wrenching.

Oregon electronics offer modern replacement for these bikes.

[dhall57]

Im guessing you have a CB750. If you have the axle nut off and the bike on the center stand loosen up the chain adjusting screws on both sides and slide wheel forward enough to take chain off sprocket. Tap the end of the shaft and should start moving. If its been years the taps might turn into hits to get it moving. Just don't mess up the end of the shaft. Used a rubber hammer if you have one. I always put a thin board that just slides under the rear wheel so when the axle clears and comes out of the left swing arm the wheel doesn't drop on that one side. I grab and move the board up and down a little witch helps that axle slide out and also supports the wheel so it doesn't just drop down when the axle comes out. If you still have the factory pipes the left #2 will have to be removed to let axle slide all the way out and maybe the #3 pipe also be able to get a good hit on the axle. On then other end of axle their is a hole through the chrome end. A screwdriver can be inserted and allows you do pull and twist shaft also.

Brian you must be doing a complete ground up restore. Can't think of any reason other than that to be taking a bike apart that was working great before hand like you said. Best of luck with it

[Oldtech]

Most common problem with removing axles on older bikes is that the spacers rust to the axle. It can be a real bear to free up the axle. I have a 4 inch long piece of 2 inch diameter aluminum round bar that I put against the end of the axle and then beat on it with a very heavy hammer. If this doesn't work then I drill the end of the axle to make a shallow hole and use an air hammer with a pointed bit. The hole is to keep the bit from sliding around when you pull the trigger. Still no joy then I heat up the spacers with a torch then use the air hammer. This will trash the grease seals. Last resort is to cut the axle out of the swingarm and believe me I've had to do this on several occasions. 

[briancwynn]

Brian you must be doing a complete ground up restore. Can't think of any reason other than that to be taking a bike apart that was working great before hand like you said. Best of luck with it

It was running good but I want to paint the frame and get rid of all of the rust.  Do i have to remove the swing arm if I am painting the frame?  I am going to use spray paint.    etc.

[briancwynn]

Why can't I get this bolt off for the oil filter? Should I force it?

[MiGhost]

That oil filter bolt has already had the life it is going to have. Notice how the head has been filed square. It is time to replace it.

If the heat and breaker bar does not do the trick. The easiest method that i have found is to drill out the head like a rivet. Once the head pops off the cover follows easily. Then you can use pliers, vice grips or pipe wrench to remove the rest of the bolt.

[briancwynn]

Thanks all. I used PB blast and it came off with vice grips. This bolt can be purchased I hope. Also taking these things off to remove the engine which is currently working fine. Do I have to worry about putting oil back in ...within some type of time frame? Newb questions I'm sure.

[Don R]

Get the replacement filter bolt with the large bolt head. Take lots of pictures and download the manual at the top of the page. I print a section at a time, someday I might have it all. The page numbers are off a few.

[madmtnmotors]

Do I have to worry about putting oil back in within some type of time frame?

Yes....

before starting! 

[754]

Take the knackered oil bolt, shorten a 3/8 socket,weld it to the oil bolt..done..

[Bankerdanny]

Thanks all. I used PB blast and it came off with vice grips. This bolt can be purchased I hope. Also taking these things off to remove the engine which is currently working fine. Do I have to worry about putting oil back in ...within some type of time frame? Newb questions I'm sure.

Welcome to the 70's Honda brotherhood. Stuck oil filter bolts are a right of passage for pretty much every Honda from the 70's.

Replacement bolts are readily available on eBay. Make sure its the one with the larger head (17mm I think).

If you want to spend a bit more you can install an adapter for a modern spin on style filter.

[MCRider]

Yes the 17mm head is nice. But to be clear, its purpose is not for cranking down on the bolt, but rather to tighten it gingerly and have some more leverage to get it off once it corrodes itself to the filter cover again.

[Patrick]

Don't forget when you are removing the back axle that, if you have the bike on the center stand, the axle is bearing the weight of the wheel. Another of my bikes came stock with a strap to lift and hold the back wheel just a little to make the axle easier to remove. Lift on the wheel slightly as you tap the end of the axle with a rubber mallet or a deadblow hammer.

Patrick

[briancwynn]

Thanks all!...

[754]

I assume this is 750 wheel, so it should pull out the back.
 If axle is stuck lube up both sides and work it back and forth, driving it straight out usually caused more damage. Once the brake plate and sprocket carrier comes off, fairly easy to get lube into the rest of it. Be careful not to oil foul the brake shoes.

[briancwynn]

Thanks all for the help. I'm in paint mode.