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


  • 19 Apr 2021 8:42 AM
    Message # 10328065

    I need bowl setup advice on my M741-1 Linkert for my 1929 DGP Scout.The bike will start & run for 2 seconds,then gas will flow from mouth of carb,from main nozzle.*Prior to starting, carb did not leak gas at all with petcock on*.I've had the bowl removed 6 times,checked  1/4" [new]float setting-slightly offset to the side,NEW needle/seat,tapped needle to set seat with plastic hammer. High speed 2 turns out,low speed 4 turns out to begin. My Question is where does float bowl need to be in relation with carb body.I have moved it around a few times to clear carb casting.Now 11/16" brass nut for float lever  is near choke lever position with same results as when it was toward engine front cylinder.Any suggestions will be tried.[Venturi is stock size] Thanks in advance

  • 20 Apr 2021 9:08 PM
    Reply # 10333462 on 10328065

    I don't know enough about Linkerts to say anything. What I am talking here is about the DLX. Bash me for hijacking the thread but it is in the same topic and some things might be useful on both Indianapolis wc... (just joking!)

    Make a tight and reusable rubber plug for the bowl bottom hole that can be used without interfere with the float. That's an important tool that might come in handy in the future. Preferably the plug should have some sort of drain or ability to lower the gas level in the bowl for testing purposes. (a thin hose with a stopper clamp on, down into a collecting can will make a less messy test session) A small bar across the bowl with a pin to measure depth is another useful special tool.

    Loosen the gas line fitting at the tank, swing the tube out and reattach the bowl to the tube. Check with a carpenters bubble level that the bowl is level in all directions.

    Fill the bowl from the tank and check that the flow stops. The float should settle in as close to horizontal position as possible in all directions. That is important. The fork for the needle should be as close to horizontal as possible for best working range, but might need to be bent slightly when adjusting the level of petrol.

    Tap the bowl lightly. The gas level might rise slightly with vibrations but should immediately stop and stay. Drain the bowl until the needle does flow fuel in again and repeat test, have an assistant lean and tilt the bike a little, tap the bowl. Tap and agitate and manipulate the float to different positions to check that the flow stops immediately and the float does not hang up or cock the needle in any way. Leave it be for a time to check for slow leakage.

    The way the Schebler and Linkert service instruction say the float level should be measured on top surface of the float, is wrong. Well, not wrong for the time when new factory manufactured cork floats could be obtained and those did have a fresh coat of lacquer applied. 

    Floats might have different buoyancy because it change with time, change shape, change density, repaired, broken, or even might be for a different version of float bowl. Modern ethanol diluted petrol might have different surface tension. Repro manufactures might use different float materials, thickness, size, shape, weight or something else that affect the level of petrol in the bowl. Practically it does not matter what kind of float used, your float might very well work fine, but the level of the petrol in the bowl must be measured in a correct way. The method of measuring float height the way the old instruction book is saying, is wrong. Maybe not wrong in all cases, but unsafe today!

    The one and only thing that the carburetor cares about for it to work properly is the level that the petrol (gas) settles in the bowl, so the only true, repeatable, reliable way to measure "float height" is down to the surface of the petrol in center of the bowl. Not measured on top of the float. 

    That measure, down to the petrol, is not noted in any instruction book that I have seen for our old carbs.

    Wrong level of petrol might result is a number of troubles. Hard to start cold, or hard to start hot, backfiring, coughing, hesitation, surging, hard to dial in, dribbling, flooding, engine overheating, high consumption and general pain in the ass is just some from the top of my head. 

    The Schebler service manual has a measure, but that is a dry measure with a service tool (needle seated) in a new bowl with all new factory parts. However that measure is same for both DLX 1" and 1-1/4"

    I have a petrol level measure for my DLX carb. I am not saying it is right and would really appreciate inputs from others that has done the same measurement. I am reluctant to reveal that just because too low or high level might be damaging your engine. Be careful. The distance I measured is about 18mm or 0.7" 

    My engine was running fine, starting cold with short time choke and when hot  without choke.

    I use the lightest and most modern petrol mixture resilient repro float available as a light float keeps the level more stabile and makes less wear on the needle and seat.

    Float from Tom Cotten

    For the record, all our bikes are audience sensitive, the more onlookers, the more you have to kick...and kick...and kick...kickkickkickkick....dang nabbit.

    Last modified: 20 Apr 2021 10:11 PM | Carl-Erik Renquist
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