Topic: Breather hose diameter?

[Odge]

I recently installed an f2 motor in a 74 cb750k frame. There are a few differences to sort out, but it looks like I may be nearing the finish line. One problem I am having is the crankcase breather. I know it is routed to the oil tank- the trouble is the f2 breather spigot out of the case is a larger diameter than the old 74k one, so I have a mismatch with my 74 tank, which has the smaller diameter spigot. Basically I need a big hose for the crancase and a small hose for the tank Has anybody encountered this situation? Can I find some kind of adaptor fitting that could make the two ends match? My first ride revealed a few issues, but as this issue is dumping oil all over the ground it seems like I should deal with it first. I'm hoping somebodies wisdom will save me from getting too "creative".

[mystic_1]

Which breather nipple on the engine?  There's a big one at the head the either dumps to atmosphere (early 750s) or routes back to the airbox (later models).  There's a smaller nipple at the back of the transmission that connects to the oil tank.  The smaller nipple is actually to return oil from the tank's oil separator to the engine.

mystic_1

[Odge]

Thanks for the reply. The crankcase breather is out of the back of the engine- it is the one that seems to be bigger on my f2 engine than on my old k motor. That is why I have an oil line mismatch between it and the k oil tank, which has the smaller spigot.

[mystic_1]

Ok, good to go then, just make up an adapter.

mystic_1

[Old Scrambler]

I will be doing the same next year..........I plan to use an adaptor from my local NAPA store........I have also seen similar adaptors at a stock-car racing supply store. Hope you adapted the 10mm sprocket alighnment for this mixture of frame and motor.

[Odge]

Just wondering- 10mm sprocket alignment?

[mystic_1]

F series 750's had the chain running 10mm further away from the engine/tire than on the earlier bikes.  Different output shaft, and wider rear sprocket carrier at the rear wheel.  You should use an earlier rear sprocket carrier in order to have proper chain alignment.

Go to the Cycle Exchange website to the Honda 750 page and scroll down about 2/3 of the way for some pics and info about the sprocket carriers.

http://www.cyclexchange.net/Honda%20Page.htm



mystic_1