1949 or 50 pacemaker h engine rebuild

Discussion in 'Whizzer Motorized Bicycles' started by billy the kid, Oct 21, 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?

    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

  2. WZ507

    WZ507 Member

    H Engine Rebuild

    I'd try to start it as is just to hear it run and see where you're at. Stuck exhaust valves on Whizzers are very common and can typically be freed with a generous application of WD40 through the exhaust port and gentle tapping on the valve head. Be sure intake valve is wide open when you're doing this to assure that the exhaust valve is free to close as you tap. Once it drops, rotate the engine to lift it again and repeat process until it is free. Replace the gaskets that are damaged, put an eyedropper of gas in the carb throat or down the sparkpug hole and see if you can light it off. If yes, then the ignition is probably OK for the interim, but I'd suspect the carb would be full of varnish and debris and you would very likely benefit from a cleaning. I've been surpised several times that these seemingly neglected engines that have stood for decades can be started and perform OK for what they are.

    Let us know how you make out.
    Last edited by a moderator: Dec 15, 2015
  3. Traveler

    Traveler Member

    I had the same problem with the exhaust valve. The WD40 and tap did the trick. I used a block of wood and a light tap with a small hammer. There is a lot of help on this forum. I know it definitely was easier to get my H engine running with the help on this forum. I already knew how to work on it because I had a J engine and pacemaker when I was 15 years old, but I was surprised how much I really didn't know about certain things. I'm pretty sure Quenton Guenther on this forum does rebuilds. After I rode the bike a few times, I removed the engine to lap the head and valves, plus replace all the gaskets. I may wind up replacing the piston rings. Memory Lane Classics is where I bought most of the parts I needed. There are other suppliers as well. Both the J engine back in the late 50s and the H engine I have now needed the coil replaced. That seems to be a common problem.
  4. billy the kid

    billy the kid New Member

    Thanks for all the help guys! So I have an a 1950 pacemaker frame (dimples on each loop on the frame in near the rear brake) with an H motor with a serial number in the 100,000’s and found out I have a high fin head, roller crank, and high performance cam. So I have the wrong engine for the frame, so I can either look for the correct engine or the correct frame. I took apart the engine and found that the rod that sits on top of the cam the lift the exhaust valve was stuck in the block. When I finally removed it with a lot of oil, twisting and pulling…I cleaned up the rod and the hole it goes in the block and it wont glide in smoothly no matter how much oil I use. The intake rod slides very smooth and the exhaust rod is nothing like it. I cant even fit it all the way in it. The piston also looks quite scratched so I hope the rod isn’t bent. It looks like I have a bigger project than I thought… thanks for the help guys, ill keep ya posted.
  5. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi Billythekid,

    Just locate a "300" case and install the parts from your current motor. Sounds like you need a lifter [I have them in stock].

    You might also need a "300" cylinder [I also have in stock] if the current cylinder is an "H" or "J". The "300" has larger valves & ports for more power.

    You can call me at 252-475-0406 if you need more information, parts, or rebuild services.

    Have fun,