CB750K5 breather pipe routes

[royhall]

Just come to fitting the breather pipes on the K5. The bike didn't have any pipes on it when it arrived so I have no idea of the routings. Any pictures available at all, or explanations. I need the rocker box breather, the crankcase breather, and the oil tank breather. Also, on the bottom rear of the oil tank is a small 6mm ish pipe that looks like a breather, what does that connect to. Thanks.


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[Nurse Julie]

There is no crank case breather. The pipe on the back of the engine goes to the oil tank. The top rocker cover breather pipe goes to atmosphere over the top of the air box and down the back and also the overflow from the oil tank goes to atmosphere.
Or you could have it like the K6, were the top breather pipe runs along the swing arm and had a little bracket on the back of the footpeg bolt.

[royhall]

Thanks Julie your a star. Just to clarify that I have it right, the top breather on the oil tank connects to the rear crankcase spigot, and the little spigot on the oil tank is an overflow to the ground. Cheers.

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[Nurse Julie]

The little spigot on the oil tank goes to the spigot on the back of the engine. This feeds oil for the chain oiler.
The top pipe on the oil tank is a overflow and the pipe goes to atmosphere
The top breather pipe from the rocker cover goes to atmosphere.

[royhall]

Lovely, got it. Cheers.

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[Martin6]

Roy,

Mine is a UK K6. Slight differences maybe? But, hope it helps.

The rocker box breather routes over the carb gantry, held under the frame (under the petrol tank) by a plastic tie and goes around and down behind the oil tank. It routes down to the right hand back of the engine case and is held by a metal bracket bolted at the top of the engine case, just beneath the right side rear engine mount. Then it goes horizontally back away from the engine, inside of the frame, under the swing arm, where it is held by a metal tie on the horizontal part of the frame that goes out to the rear footage/ exhaust bracket. It then drops down between the frame and the folded centre stand. The end is just below the height of the folded centre stand.

My oil tank is different to yours. It has a hose from the lower rear of the crank case, clamped onto the base of tha oil tank, which I had assumed was the breather. I also have two screwed on feed and return pipes.on the bottom of the tank.

[royhall]

Thanks guys, great help.

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[Nurse Julie]

Roy,

Mine is a UK K6. Slight differences maybe? But, hope it helps.

The rocker box breather routes over the carb gantry, held under the frame (under the petrol tank) by a plastic tie and goes around and down behind the oil tank. It routes down to the right hand back of the engine case and is held by a metal bracket bolted at the top of the engine case, just beneath the right side rear engine mount. Then it goes horizontally back away from the engine, inside of the frame, under the swing arm, where it is held by a metal tie on the horizontal part of the frame that goes out to the rear footage/ exhaust bracket. It then drops down between the frame and the folded centre stand. The end is just below the height of the folded centre stand.

My oil tank is different to yours. It has a hose from the lower rear of the crank case, clamped onto the base of tha oil tank, which I had assumed was the breather. I also have two screwed on feed and return pipes.on the bottom of the tank.

The K6 oil tank is only for the K6 and is the only 750 that has that pipe routing . 

[Martin6]

OK. Apologies.