Roadmaster take 3.

I want to mount my 79cc vertically as well, and the only part I am stuck on is the oil fill hole. I see that there is a hole that's filled in on the crankcase that I can drill and tap, just wondering what size bolt I should use and whether I need a gasket, I have a bunch of different size o-rings if those could be used, just need a little advice.

Cool, so an o-ring will work. I wonder if the aluminum is soft enough to tap the bolt straight in? I have forced bolts into aluminum in the past, basically steel is harder than aluminum so it might work. I don't have a tap set.

Good point, I'll look on Friday cause I'm going there anyway to pick up a new multimeter, they have the cheep ones for $6, had one for about two years now and it finally gave up the ghost.

I remove the side cover and drill through the casting using (as I recall) a 49/64" drill bit. From there I tap at 1/2" NPT and do it CAREFULLY. You can crack the case if not careful. You can also drill and tap successfully anly to crack the cover if you over tighten the pipe thread. Jeff from CCC started using a 1/2" NPT by hose adapter fitting and brass garden hose cap. These fittings are available at any hardware store.

I would really like to see what you're talking about, Pat. I don't know anything about garden hose fittings.

I'm thinking about just drilling a hole through where its filled in, then tapping the top part for a plastic cap/dipstick.

dtv5403 said:

I would really like to see what you're talking about, Pat. I don't know anything about garden hose fittings.

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Take a look in the brass fittings at a place like Home Depot. There will be a section for garden hose stuff. If I understand correctly what Pat is describing is a hose union which is threaded at each end. I use these for my gas tanks by grinding down the threads at one end, soldering in the union for a gas filler and using a brass garden hose cap as a filler cap. Good, well made brass for pretty cheap since it is common. I believe what Pat is doing is drilling a hole in the crankcase, tapping the hole for threads and then screwing in the brass union. Add a brass hose end and you cap it off. I haven't seen this done, but this is what it sounds like he's talking about. Someone correct me if I have misunderstood.
SB

I'm just gonna use a plastic cap.

I really wanted to do as much as I could using tools and supplies that I had on hand, so here is what I did. I found a large bolt, don't know what size or anything just the biggest bolt I could find in my pile. I then took a drill bit, no idea what size just eyed it up to the bolt, looked like the right size. Drilled through the casting, then sprayed the hole with chain lube. Got the bolt positioned and started tightening, very carefully and slowly, with a socket and the bolt just tapped itself right in. I noticed how if I tightened the bolt too far, it might sink down into the recess and I might not be able to get it out, so I grabbed an axle nut and reamed it out with my drill so the bolt would fit through it. Then I filed the shoulders of the axle nut down so it would fit inside the recess. The axle nut is turned upside down so the flat part is against the edges of the recess, and prevents the plug bolt from being tightened down into the recess. It works, looks good, is clean, simple and the bolt holds. I just have to tighten it very carefully so that I don't over tighten it and crack the casting. But yes, I got the bolt in without a tap and without cracking the casting.