rebuilding whizzer h engine!

Discussion in 'Whizzer Motorized Bicycles' started by billy the kid, Oct 20, 2009.

  1. billy the kid

    billy the kid New Member

    hey everyone, im new and i am rebuilding a 49 or 50 whizzer pacemaker and im planning on rebuilding the engine and have never done it before... im kinda on a strict budget so i kinda have to do it and im also excited to learn how. so where should i begin?

  2. billy the kid

    billy the kid New Member

    ok well maybe the first step is how do i know if even need to rebuild it? well, it looks like it hasn't been run in years, i took off the head and the exhaust valve is stuck, gaskets are shot some are even missing. does anyone know approximately how much someone would charge me to rebuild it for me? thanks guys
  3. Chances are your going to have to find someone that specializes in whizzer engines if you want to have someone else do it. I don't know much about the whizzer engine in particular but on old engines its usually a good idea to inspect everything and at least replace the bearings, seals, and gaskets. You'll also want to clean everything well when you have it apart. Of course that's up to you, some people may look it over and run it as-is. I'd recommend looking for a repair manual if such a thing exists.
  4. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi Billy the kid,
    Having rebuilt several hundred Whizzer motors I will be able to help you control your costs. If you want to do it yourself, you will need a few special tools and find a few hard to locate parts.
    If your Pacemaker is a 1949 the correct motor is the "J" series. If your Pacemaker is a 1950 the correct motor is the "300" series.
    The 1949 & 1950 Pacemakers are almost identical and many alter the final year depending on the parts available and the cost.

    The 1949 is far less expensive to restore than the 1950 for several reasons. First they both have the "loop" frame, however the 1949 has a rear coaster brake whereas the 1950 has the 5" rear Whizzer brake [approx $1000.00 in good condition]. The 1950 "300" series motor is much more expensive than the "J" motor because there were far less of them made. The most common Whizzer motor is the "H" but it was only used on a very few early Pacemakers [very first 1948 models]. The 1948 Pacemaker also has the "Loop" frame, but the seat is installed on a seat post like a regular bicycle, whereas all later Pacemakers have the motorcycle style seat and is much lower to the ground.

    Another problem with the 1950 Pacemaker with the 5" brake is the "loop" frame because it takes a special tool to spread the frame to install the rear wheel.

    Both 1949 ["J" motor] and the 1950 ["300" motor] use the Carter "N" carburetor.

    Best way to start your project is to find out the serial number of the motor. The serial number is located below the flywheel and to the right of the drain plug. If the numbers start with "J" then a series of numbers it is a 1948 or 1949 motor. If the serial number is 300XXX then it is a 1950 or 1951 motor. If the serial number starts with 700XXX then it is a 1952 motor. There are also a series of "300" motors that aren't corect for the Pacemaker but he numbers start with 350XXX and were only used in the motor kits. As a collector I make all my Whizzers 100% correct, however the vintage Whizzer motors were made backwards compatable, meaning almost all parts are interchangeable between the different series of motors. Which brings a lot into the possibilities. For instance when Whizzer changed to the Carter carburetor on the "J" motor they supplied a version of the carburetor with slotted mounting holes so that it could also fit the earlier "H" motor. When they made the hi fin head they also made a kit to install it on the earlier "J" motors. So what is correct? If in 1952 the head needed replaced on a "J" motor the hi fin head was the replacement for the earlier head, etc, etc.

    There are a lot of parts available for the vintage motors and a few that are no longer available. Rod bearings and the needle bearing in the side cover are difficult to find, if not impossible because the companies that originally made them discontinued them. Most likely the hardest part to find is the side cover bearing [made by Torrington].

    Enough history! The biggest area of concern is the crankshaft. 99% have an insert style rod/crankshaft assembly. Check the play on the rod where it connects to the crankshaft, if it is loose, then get the crankshaft rebuilt [about $150.00 average cost].
    All gaskets are available [approx $25.00 per set]. Piston & rings are available if needed but most pistons are reworked new edition versions [not as good as original, but will work fine]. Magnetos are also available but are reworked editions [approx $90.00].
    Carburetor rebuild kits are available [approx $25.00]. Points are available [approx. $25.00], but use the electronic module [approx $20.00] because it is MUCH better.

    One last important comment..... DO NOT start the motor untill you check the crankshaft for exessive play or you might completely destroy the motor past cost effective repair.

    If needed I have a large supply of vintage parts, and many are even NOS parts. If I don't have or don't want to sell certain parts I can easily guide you to someone that can help you.

    Have fun,
  5. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi Saabsonettguy,

    Where in eastern NC? I live on the Outer Banks [Nags Haed, Kitty Hawk, Kill Devil Hills]

    Have fun,
  6. billy the kid

    billy the kid New Member

  7. DadNamedSteve

    DadNamedSteve New Member

    Loop Frame spreading

    What can you tell me about how that special tool works that is needed with the '49/'50 loop frame whizzer pacemaker to install the rear wheel? I have restored my whizzer to the point that I need to install the rear wheel and can already see I have a problem with clearance. I don't have the tool you spoke of but thought if I new how it worked I could rig something up.


    Attached Files:

    Last edited: Aug 7, 2012
  8. DadNamedSteve

    DadNamedSteve New Member

    Compression numbers

    Billy the Kid,

    Does anyone have the compression specs for the H, J, and 300 engine? I am getting around 50 #s and don't know if this indicates that I need to do a rebuild or not.

  9. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    I used a fixture made by Kenny homas in KY to spread the frame on my 1950 Pacemaker and install the wheel. It was a simple stand with a "U" shaped top with hooks and turn-buckles. You can also use a small jack to spread the frame and insert a small piece of wood and remove jack. All that needs to be opened is the "loop" section to clear the axel, once the axel passes the "loop" the wood can be removed to allow the wheel to move forward to slide into the cut-outs.

    Compression numbers on the "H" & "J" should be close to 100 pounds and the "300" and up closer to 110 pounds. Look for a blown head gasket or leaking valves before suspecting the bore, piston & rings.

    Have fun,