Topic: Cb750f1 Oil vents true air hole in dipstick

[Remcod]

So when i rev my engine the oil vents true the dipstick air hole.

Engine is rebuild and runs fine.

Oil level is to the top of the mark with the dipstick not screwed in.

To much oil?

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[BenelliSEI]

Don’t remember mine having a vent hole? Been a while. Are checking your oil level after a 20-30 minute ride?

[Remcod]

Can you please confirm if this is some po invention to prevent exhaust rust?

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[BenelliSEI]

More input required but that hole is not suppose to be there.

[69cb750]

Two bikes have arrived with engine and tank tubes blocked with mud from bees.
An owner drilled that hole.

[Remcod]

Omg unbelievable what people do

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[ekpent]

Two bikes have arrived with engine and tank tubes blocked with mud from bees.
An owner drilled that hole.

Happened with a K model bike I bought and got running.Vent tube from valve cover was blocked with bug stuff and made the oil take overflow.
  New dip stick time for the original poster.

[Jerry Rxman Griffin aka MuthaF'er]

Plug it

[Tracksnblades1]

My 76 F1 didn’t have that hole..

It does have the crankcase filter though..
I’d look to see where the valve cover and crankcase vent hoses are terminated at.
OEM is to the crankcase breather then to air cleaner box.

[Tracksnblades1]

The attached picture is of the original Honda crankcase breather and where it’s located at on the F1..
It’s a good system on a good condition engine…😇

Item 7, the actual foam filter may be deteriorated to nothing after 47 years…😜
But some small engines have the same or similar type foam if it’s not available at Honda…

[Don R]

 I made a filter media from scotchbrite and I agree the hole should not be there.

[BenelliSEI]

I made a filter media from scotchbrite and I agree the hold should not be there.

Me too, Green. It works great.

[Jerry Rxman Griffin aka MuthaF'er]

And it won't deteriorate and get sucked into the engine like foam

[turkey4me]

Probably a hole for inserting a temperature probe.
You should replace it or have a passenger put a finger on it

[Floshenbarnical]

You should replace it or have a passenger put a finger on it

best comment

[Remcod]

You should replace it or have a passenger put a finger on it

best comment

Then i have to drill a hole in the sidecover to put the finger true. I will try the replacement i have from a F2. Plastic unfortunately and will try when the rain finally stops.

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[Remcod]

Found a f1 metal one in my stash, all good now, no more oil leaks. Thanks.

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[Don R]

 Thanks for the report of a solution, too often we never hear what happened.