1975 GT185 UPPER ENGINE CASE OPEN HOLE

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KRAMSSUAG
Still in the Driveway
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Joined: Sun Nov 07, 2021 5:33 pm
Country: USA
Suzuki 2-Strokes: 1975 gt185
Location: Colorado, 81240, USA

1975 GT185 UPPER ENGINE CASE OPEN HOLE

Post by KRAMSSUAG »

Hello, I am new to this forum and forums in general. Please forgive and educate me if I violate any rules or standards of etiquette.

I am restoring a 1975 GT185 and have removed the oil pump cover to to repair some cracks in it. In the process of cleaning up the years of crud around the oil pump, I have found an opening cast into the upper engine case that I do not understand. When the oil pump cover is in place it is not visible. It is surrounded by a protrusion that sticks up from the engine case about 1/2 inch and is about 1/2 inch in diameter. The opening at the bottom of this protrusion is about 1/4 inch in diameter and does not appear to be threaded. At first I thought it was a blank hole, but it definitely seems to be open into the transmission case above the kick start shaft. One of the two photos shows a rubber plug in the hole to identify it. Could this be some sort of vent for the transmission case ? Should it be blocked to prevent oil from escaping, or water or crap entering ? Please help me understand the purpose of this opening.
karl pa
To the on ramp
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Country: us
Suzuki 2-Strokes: GT
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Re: 1975 GT185 UPPER ENGINE CASE OPEN HOLE

Post by karl pa »

I believe the hole you are referring to is the transmission breather. If you look at Alpha sports website, under 75 GT185 transmission, part number 42 (24829-36101) it states (reflector,oil breather) It bolts inside of upper crankcase. The reflector is to keep oil from coming out, the hole being under the oil pump cover is to prevent water and dirt from getting in, does it work :?: You want to keep the pump cover on for sure.
76 GT185
77 GT250
77 GT380
76 GT500
73 GT550
73 GT750
74 GT750
71 T250 scrambler
75 T500 cafe
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Alan H
Moto GP
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Suzuki 2-Strokes: 4 x GT550s - J, M, A, B.
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Re: 1975 GT185 UPPER ENGINE CASE OPEN HOLE

Post by Alan H »

Welcome to the forum Mark. It's always nice to do a quick intro - who and general area where you are and a bit about your biking experience.
The forum is world wide, so there's lots of experience on different bikes on here.

Alan.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
KRAMSSUAG
Still in the Driveway
Posts: 3
Joined: Sun Nov 07, 2021 5:33 pm
Country: USA
Suzuki 2-Strokes: 1975 gt185
Location: Colorado, 81240, USA

Re: 1975 GT185 UPPER ENGINE CASE OPEN HOLE

Post by KRAMSSUAG »

Thanks karl pa for your quick response. The information you provided leads me to agree that this is indeed a transmission vent. I would have expected a transmission vent would have a hose leading to a location that would be better shielded from water, such as under the gas tank. I guess that the raised protrusion would divert water around the hole and allow it to drain off of the rear of the engine case. The oil pump cable mounts to the oil pump cover, so it needs to be in place to provide oil to the engine. The oil pump cover does shield the vent from direct water intrusion, but I don't feel this is an example of good engineering. Thanks for your insight !
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