The 101 Association, Inc.
For the preservation and enjoyment of 1928 to 1931 Indian Scout Motocycles
"You can't wear out an Indian Scout"

NPT Drain and Level Plugs

  • 19 Oct 2017 8:53 PM
    Message # 5323030


    Introduction here, point of post is way down below. Jump if you like. I'm usually "wordy."

    Its a bit hard to admit to being a newbie. Especially because I have owned, worked on, and ridden so many 1939-1947 Indians.

    Now, I just acquired a somewhat neglected but pretty good 1928 101 Scout. New things to learn. I already posted my idea for my missing Corbin speedometer. I'm serious about implementing that in time.

    I learned the oiling operation and its maintenance from online literature. I'm waiting for my copy of the R&O.

    The plugs looked pretty old - I cleaned off the oily carbon crusts, but I ordered new ones from Walkers (both heat retaining and cold). I drained all fluids and refilled to correct levels, pumping to fill the sump to correct starting level. Using what I had in bulk supply: Brad Penn No. 1 50W racing oil (though I learned 60W oil is best) and B&M Trick Shift ATF I use in all my primaries - all costly fluids and possibly well beyond the requirements of a 101.  I checked the that two oil lines were flowing clear (I bled). And I changed the old, stale air left in the tires with fresh air (ha, that's a joke). 

    The 101 started easily (amazingly) and ran great on its first test. Just a little too much oil accumulation in the sump checked on its return after an est. 5 mile test run, but I was idling a lot and going easy on off-roads with some brief high RPM'S in 2nd gear on asphalt (not liability insured yet for the long road haul). Not excessive smoking! It held very steady running fast in 1st on rough country dirt and gravel roads where my others would make me tighten my arm muscles for fear of a spill. I relaxed when it was clear this was like a self-correcting tracker and kept up the speed.

    On cooling, plugs looked pretty good. A bit more carbon than I normally expect and I chalked this up to burning off oil. But clean enough to spark again. Carb is M16. I added some Marvel Mystery Oil to the oil tank thinking it may make cleaner burning. Then poured some in the gas just in case. Was that OK? Hey, its a mystery.

    Point is:

    In this fluid changing I encountered some annoying NPT threaded plug issues. I have big fat fingers and even on my later Chiefs there are access issues, especially the transmission level plugs. Frame is sometimes in the way - as if a bad design issue. Also, I find past owners tighten threaded steel too much into threaded aluminum. Please!!! just clean plug threads, then apply Loctite 567 PTFE and lightly tighten - even finger tighten. It seals. Don't wrench them down hard! No torque specs here apply.

    The issues I encountered: The crank (sump) drain was a nifty hex socket that a T-wrench quickly undid. That was great! Is this original? Nice! But the crank (sump) oil level plug was a square head. Annoying. I thought a hex socket would be a great NPT plug here at the oil level check hole just for using a hex T-wrench for quickly checking too much oil accumulation while on trips. But no, the frame tubing is in the way! Design flaw? I don't need quick access to the drain with a hex T-wrench. Better to have quick and easy access to the level plug. What's original here? What improvements are suggested.

    Now, the gear box bottom drain plug was a slotted screw and I was planning to extract that to drain both the transmission and the primary. Crap - a slotted screw there! And it was tightened in hard as nails by someone probably insecure about leaking oil. More crap. If that's original, that is really stupid thinking. Who can apply pressure of a slotted screwdriver in a tight under space and upwards? I tried building a wedged leverage against the screwdriver handle but still that drain plug would not turn. Bad plug choice and someone with fear of oil dripping over tightened it. I could see I was not the first to try to loosen it and that slot was well distorted by other's attempts. I'd have to drain all fluids and lay the 101 down to get that over-tightened and damaged slotted plug out using a hammer slotted driver that we use to open old hatch screws. Drives downward while making turns. What was original for the transmission drain NPT plug? Anyhow, I drained the transmission and the primary from the hex head bolt plug on the side of the transmission. What was that for originally? - maybe as a backup for situations where someone stupid installed a slotted NPT drain plug in the bottom of the transmission and tightened the steel plug's threads into the aluminum threads as hard as they possibly could. That side hex head plug was easy to remove. But the frame and other features made getting my fingers in there to re-start its insertion threading extremely difficult. It seemed like bad design by Indian.


    Last modified: 19 Oct 2017 9:31 PM | Robert Lodge
  • 20 Oct 2017 5:13 AM
    Reply # 5323355 on 5323030

    I agree, it is a bad design, crammed behind the frame tube and the conical thread of the plugs makes the alum. crankcase threads vulnerable to over torquing with leaking as a result and at worst, risk of lost plug and seized engine. Really those plugs that are often detatched should be mechanically secured in some way. Just wedge a piece of rubber sponge between the frame and case is a good idea.

    There is a choice of head configurations on those plugs, slotted, square or hex heads, with or without a magnetic insert, and I think I have seen one with insex head. Original for the 101 is slotted but often occurring square head plugs, you'll find them at Walker machine

    and he might have a choice of different ones if you ask. You'll find that all the "big 3" Stark, Greer and KIWI

    is selling those plugs, and several other Indian retailers. Also a quick drain valve can be used instead of the drain plug but that might restrict the access to the level plug, I don't know. 

    Last modified: 25 Oct 2017 6:31 PM | Carl-Erik Renquist
  • 20 Oct 2017 5:39 AM
    Reply # 5323359 on 5323030

    With a hard sitting plugs or bolts of some kind, heat is your friend here. A hot air gun is heating more gently than open flame. I prefer to heat the case with a prof. hair dryer, mine is really blowing some surprisingly hot air, I imagine it can light hair ablaze!

  • 20 Oct 2017 6:03 AM
    Reply # 5323365 on 5323030

    Carbon accumulation is a big problem. Some oils are horrible and big cakes of carbon will accumulate in the combustion chamber very quickly. I don't have any recommendation on brands that is better or worse in that case, as there is so many different oils on the market, but I have been tipsed about use a dollop of good quality synthetic 2 stroke oil in the gas now and then. 

    Those oils have a high flame point and contain a additive that infuse existing carbon and allow it to be burned off, to keep 2 strokers clean of carbon. I have heard people using 2 stroke oils instead of engine oil, and that should be OK in a lubrication point of view but the oil is usually about SAE 30 or thinner and might make the engine a bit noisy. And 2 stroke oils are a bit more expensive than regular engine oil. 

    Last modified: 20 Oct 2017 6:10 AM | Carl-Erik Renquist
  • 20 Oct 2017 5:20 PM
    Reply # 5324185 on 5323030
    Tim Raindle (Administrator)

    Hey Bob, the plug in the side of the primary case is a level plug for the oil in the tranny and primary. 

    The slotted plug in the bottom of the transmission might have been a hex head originally, probably the drain in you crankcase, as these were slotted originally. Try it when the motor is hot, the steel will expand less than the aluminum, and it may ease out. ( Note also this is a damn fine reason NOT to by cheap brass plugs from the hardware store, as the coefficient of expansion of brass is similar to aluminum, and if overtightened by someone when hot they will be really difficult to get out. I have had to drill out two of these in the last couple of years on customers bikes. Not a pleasant thing to do in a rare as hens teeth good condition 101 tranny case )

    I like to use a shut off tap in the level plug in the crankcase, so that I can easily switch lever to drain. 

    Glad you are enjoying the handling, they are a revelation, aren't they ?


  • 24 Oct 2017 10:08 PM
    Reply # 5341380 on 5323030

    So I just discovered there are pneumatic impact screwdrivers. Y'all didn't mention that.

    Prices range from $14.00 to nearly $2,000.

    Well, that will take some research.

    Slotted screws really are bad in mechanical construction though they look nice.

    I now recall I knew about hand-hammered drivers. Now its pneumatic with one (or more) available battery operated tools.

    I need to take off the pump for a new gasket and those slotted screws are tight!

  • 25 Oct 2017 5:59 PM
    Reply # 5355409 on 5323030

    Impact tools on an Indian makes me shudder! The slots in those screws are probably cut with a circular machine saw. That makes the slot sides parallell and the bottom convex -concave or rounded whatever-, so the slot outer ends are very shallow, weak and sensitive to slipups. Much different propertys than a normal impact formed screw head where you can use a normal wedge blade screwdriver.

    I use a special ground screwdriver, long and with very big handle so I can push on hard and turn with force. I have ground it with a convex tip and parallell blade with thickness exact fit in the slot. Important especially with worn screws is that the screwdriver edges are perfectly sharp so it can grip the little that is remaining. A slipup and I have to sharpen it again because any twist or slightest dullness at the tip is making the screwdriver slip! 

    Last modified: 25 Oct 2017 6:21 PM | Carl-Erik Renquist
  • 26 Oct 2017 8:34 AM
    Reply # 5364568 on 5323030
    Tim Raindle (Administrator)

    Yup, I am with Carl-Erik on that one. 90 year old parts deserve and need Gentle treatment. Have seen a few crankcases with cracks between the two plug openings, presumeabley a plug overtightened when hot, but I would be very careful about using too much force in this area, and a transmission case is just as hard to find in good condition, so extra time and less force is the best way to approach seized plugs. 

  • 26 Oct 2017 10:34 AM
    Reply # 5365627 on 5323030

    Hey Tim do you have a source for a shut off tap to use on the crankcase fill level hole? I check it everytime and I am paranoid I am going to strip the crankcase 

    Last modified: 26 Oct 2017 12:31 PM | Anonymous
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