harbor freight 79cc oil filler threads

A

atombikes

New Member
Thinking real hard about mounting my 79cc Greyhound engine vertically. Have the mounts, fabbed up a plywood plate, etc. But I am stuck on drilling and tapping the second oil filler hole. I have seen others use what appears to be a brass hose barb looking thing- are those 3/4" MHT threads?

Since I'm not a thread guru, I could use some direction on what fitting(s) to get and what type tap to get.

Thanks.
 
Just take your current plug down to the hardware or whatever. match that plug to a bolt to use for the one you just took out , now you know the size. Home depot sells taps get the one you need.
 
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This is what I used hope this helps you out. The brass fittings should be in the garden section.
 

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chainmaker,

Thanks, your advice makes sense. But rather than starting from scratch I was hoping to find out what others have done.

CCC,

Thanks for your parts info. So based on the tap shown, your threads are 1/2". On my engine, that recess in the molded boss appears to be more like 3/4" inside diameter. Did you only tap the bottom of the recess, or the side walls?

I'll go the Home Depot tomorrow and check out their selection.

Thanks again.
 
It's 1/2" pipe thread, use fittings that accommodate.





I use mine for a crank case breather and the oil filler as well. It works very well and is simple to use.
 
OK, so at Home Depot I found two garden hose adapters in the plumbing dept. Both are listed as "3/4" MHT (male hose thread) on one end. But on the other end, one is "1/2 NPT" and one is "3/4 in MIP- tapped 1/2 in FIP". I bought both (sorry for the crappy pic of the one). Also bought a cap.

I'm assuming FIP means female threads...so probably going to take that one back.

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alright, I think I am in business! Thanks guys for the assistance. Of course I still need to do the work, but at least I have the parts.

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I am curious about this mod. What is the purpose? Crank case breather? Oil fill? I am only asking because I am getting ready to start a HF 79cc build.....

This will be my first 4 stroke build as well.....
 
How are you mounting the motor, that would be the deciding factor if that item is needed. Vertical you would need it to add oil. You can vent the motor at the valve cover.
 
I am mounting the motor with the agk mounting plate. I wanted to mount it vertically, but my down tube is 1.65". Andy (Headtrama) was going to make me some mounts, but since they do not make the "rail buggy" clamps in that size I will just be mounting it with a traditional mounting plate.
 
I have already ordered it! Lol. Don't be surprised if I hit you up for some advice when I actually begin building.....
 
Quick question CCC.....when the engine arrives, besides removing the governor, I remove the stock exhaust, carb, gas tank, AND the throttle linkage???? Only asking since I will be using the 19mm carb and intake, as well as, agk exhaust.....
 
runnermike said:
I am curious about this mod. What is the purpose? Crank case breather? Oil fill? I am only asking because I am getting ready to start a HF 79cc build.....

This will be my first 4 stroke build as well.....
Click to expand...

Edited my post because I didn't see there was a whole second page of good answers to your question....
 
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I'm wondering if you drill out the metal and then tap it, What about the shavings that fall inside the motor? How do you get them out because wont they destroy the motor from the inside??
 
Jamesgregory said:
I'm wondering if you drill out the metal and then tap it, What about the shavings that fall inside the motor? How do you get them out because wont they destroy the motor from the inside??
Click to expand...

You'd have to remove the crankcase cover after draining the oil(some shavings would come out with the oil, then use a soft rag to get the rest out, reassemble and then refill with fresh oil. Just my two cents.
 
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