The Whizzer

WHIZZER: For information contact Fred at 714-534-6700

PBS has been involved with the 1930′s Whizzer bicycle conversion for many years. We have decided to make available these upgraded components to all interested parties.

The masthead photo shows the new overhead valve cylinder head and cylinder installed on the Whizzer case. The kit includes the head complete with valves and intake



This kit is designed to be used with original whizzer engines of 1946-1952 vintage. These include H, J, 300, 500, 600 and 700 series engines. The engine must be equipped with the roller crank/rod assembly. The plain bearing assemblies will not withstand the increased power and rpm range of the O.H.V. engine.

Read these instructions completely and inspect and identify the parts included with the PBS kit before starting the conversion process.

Dissemble, clean and inspect your stock original engine. The lower end of the engine must be in good condition. The four stock cylinder hold down studs must be removed from the case. Heat the case to about 200 F and double nut the studs to remove them. Inspect the case carefully for any problems. The threaded holes must all be in good condition.

We suggest replacing the crankshaft main ball bearing and needle bearing with new parts. Check the fit of the con-rod roller bearing. The bearing should have a diametral clearance of about .0015 inches and should turn smoothly and freely.

Check clearances between the crank/rod assembly and the inside of the case. The cranks counterweight should clear the side of the case by about 1.8″ when the crank pin is at bottom dead center. Also check for clearance between the rod bolts and the lifter boss area in the top of the case. If necessary, grind the case for adequate clearance and deburr the inside of the case as needed.

The con-rod small end wrist pin bushing must be changed to the new one supplied with the kit. Remove the stock bushing and press in the new bushing. After pressing in place, drill an oil hole thru it in the top of the rod with an 1/8″ drill. The new bushing must then be honed to fit the wrist pin after installation and drilling the oil hole. If you are not equipped to perform this operation, you can ship your con-rod and the new bushing to PBS and we will do this for a fee of $5.00 plus shipping. If you would like to send your con-rod with your order we will return it modified when we ship your kit.

Check the timing gears to be sure that they are in good condition. The crank gear should be snug on the crank and the teeth must all be good on both gears. Only use a stock cam shaft. The rocker arms multiply the cam lift by a factor of 1.5. The valve springs will coil bind and something will break if you try to use a higher lift cam than stock. The lift at the cam must not exceed .150″.

We suggest opening up the case top deck rod clearance slot adjacent to the valve lifter bores. Increase the slot length toward the rear of the engine by about 1/8″. Don’t increase the width of the slot from side to side. This lengthening allows oil to be thrown off of the crank/rod assembly up to the top of the engine to insure adequate lubrication for the rocker arm assembly and the valve stems.

Install the four new cylinder hold down studs into the top of the case with the coarse end of the studs in the case. Double nut the studs and use red or green loctite on the stud lower threads. Tighten the studs down to the end of the threads. If they won’t tighten this far, tap the holes deeper until they do.

The right rear stud adjacent to the cam shaft gear will protrude thru the case into the cam gear area.. After tightening and after the loctite hardens so that it wont rotate, grind off the bottom of this stud as necessary to clear the cam gear.

Install the crank and side cover to check crank shaft end play. This should be between .005″ and .008″. Adjust with the thrust shims required. The thrust shim must have oil grooves top to bottom on the surface next to the crank timing gear. These can be ground in with an abrasive cut off disk if necessary. Be sure to check the crank end play using the side cover gasket which will be used on the final assembly. Different gaskets may be different thickness and change the crank play, The crank should turn freely.

Remove the stock valve lash adjusting screws and ¼-28 lock nuts from the stock valve lifters. Save the large washer on the exhaust lifter as this is used for the compression release and will be used with the conversion kit.

Inspect the lifters, if they are pitted or worn replace them. Replace the valve adjusting screws with the two special ¼-28 hex head cap screws supplied with the kit. These have hemispherical sockets cut in the screw heads to accept the push rods. Don’t use the ¼-28 lock nuts. Use a ¼ inch AN washer (supplied with the kit) under the head of the intake lifter capscrew. Use the large flat washer on the exhaust lifter for the compression release. Inspect this large washer, it must not be larger than 7/8 ” out side diameter and the I.D. and O.D. must be concentric to prevent rubbing of the washer on the cylinder. Use loctite on these screws and bottom them out against the washers.

When you install the lifters put grease on the push rod sockets and on the lifter body help hold the parts in place during assembly. Be careful not to drop the push rods into the oil passage slot in the top of the crankcase.

Install the piston on the con rod so that the triangular mark on the piston crown is toward the valve lifters, be sure that the wire circlips which retain the piston wrist pin are seated in their grooves in the pin bosses. They must be snug after the installation (be careful not to bend them during installation).

Install the rings on the piston. The bottom oil ring is wider and will only fit in the bottom groove. The 2nd ring is black in color all over. The top ring has a chrome outer surface. Be careful not to break the rings during installation. Individual rings are not available. They are only available as a set. Stagger the ring end gaps about 120 degrees apart.

To assemble the cylinder to the case use Silicone sealer, We use Permatex Ultra Grey because its color matches the aluminum parts. Put a thin of silicone sealer (about .004 inches thick) on the bottom surface of the cylinder everywhere except around the oil passage area between the lifters. Wipe it off at the I.D. of the cylinder so that the sealer doesn’t ooze into the inside of the crankcase. The lifters must be in place and don’t put silicone sealer where it will get on the lifters.

Install the cylinder before installing the piston/rod assembly. After installing the cylinder check to be sure the lifters rotate and can move up and down. You can stack a couple of 3/8 inch nuts over a couple of the cylinder studs for spacers and put two 5/16-24 nuts on the studs to hold the cylinder in place while the piston/rod assembly is installed.

Put oil on the cylinder I.D. and the piston skirt and rings and the wrist pin bushing etc. before installation. Verify that the ring end gaps are staggered. Carefully put a ring compressor on the piston and check to be sure that the rings are seated in their grooves as you tighten the ring compressor. Lower the rod and piston skirt into the bore and tap on the ring compressor to square it up with the top of the cylinder.

The crank rod throws should be about 20 degrees before top dead center when the rod is installed in order to clear the crank counterweights. Then tap the piston down slowly with a wooden hammer handle while guiding the rod big end onto the crank throw. Rotate the crank back as the piston descends in the bore until you can access the rod cap and cap screws. When the engine is positioned at its normal angle the rod cap split line should be about vertical. If it isn’t, the rod is backwards and must be turned around.

Check to be sure that the rod roller bearing cage index pin is in the groove in the roller cage. Install the rod cap and tighten the 6mm rod cap bolts with a 5mm allen wrench. The rod must have a little side play after installation. Safety wire the cap bolts.

Check to see that the piston is below the top surface of the cylinder at top dead center by about .035 inches. This allows for rod stretch at s7000 rpm. No head gasket is used so the piston must be below the surface.

Install the .032 inch dia. copper wire “O” ring wire in the groove in the top of the cylinder. Start adjacent to one head stud with one end of the copper wire. Push it into the groove using the end of a hard plastic screw driver handle. Push down the wire and work it around the cylinder until the wire overlaps its starting point. Cut the wire off flush using a sharp single edge razor blade. Push the end down into the groove so that the two ends butt together. Don’t hammer or distort the wire as you install it. A small end gap will fill in with silicone sealer.

Line up the two zeros on the cam gears and install the camshaft. Lift up the lifters as required to install the cam. Install the side cover gasket on the alignment pins and put the camshaft thrust washer using grease to hold it in place. Don’t put grease inside the bearing hole as it would push out the plug in the side cover. Put on the side cover and put a small amount of silicone sealer on the threads of the side cover screws. This will seal the threads and also prevent the screws from vibrating loose, Tighten the screws.

Install the key in the crankshaft to locate the flywheel. Use a conical style heavy washer with its flat side against the flywheel. Put loctite on the fly wheel retaining bolt. Don’t use an impact wrench to tighten the flywheel bolt because it may cause the crank halves to rotate out of alignment, Wrap an old v-belt around the flywheel pulley and grip it with a large pair of vice grip pliers to hold the flywheel while you tighten the bolt.

Prepare the cylinder head for assembly. PBS pus the rocker arm assembly and valve cover in place for shipping purposes. These must be removed from the head before installation. The valve cover is retained by two 10-24 socket head capscrews and the rocker arm assembly is attached with two ¼-28 nuts and washers. The rocker arm mounting block is a snug fit on the head and must be carefully pried off.

Put a thin film of silicone sealer around the cylinder just outside of the copper sealing wire. Also put a thin film of sealer around the pushrod area to keep oil from leaking to the outside of the head/cylinder interface.

Then install the two pushrods using grease on both ends to help hold them in place during assembly. Be careful not to drop the pushrods into the oil passage slot in the top of the crankcase.

Install the head part way onto the four (4) studs. Install the four 5/16 AN flat washers on the studs and start the two front 5/16-24 stainless steel nuts on the two front studs. Then slide the head down the studs as you tighten the front nuts down to the top of the studs.

Install the 2 rear head nuts inside the cylinder head. Tighten all four nuts evenly to seat the head on the cylinder. Use an open end ½” wrench no more than 6″ long to tighten the front 2 nuts and a ¼” drive ½” socket wrench to tighten the rear two nuts.

Install the rocker arm assembly when the piston is at top dead center on the compression stoke (both lifters will be down). Loosen the rocker adjusting screws so that you have some clearance at the push rods. Assemble the ¼” lock washers and nuts on the rocker hold down block and securely tighten them.

Adjust the valve lash using a .004″ feeler gauge between the rocker arm and the valve stems. When you adjust the clearance and tighten the lock nut, the clearance will increase slightly. Start with the clearance a little tight so that it loosens to .004″ when you tighten the nut. The crank should be set at top dead center on compression when checking the valve lash so that both valves are closed.

Put a little oil on the rocker pivots and valve stems etc. before installing the valve cover. Install the champion RA8HC spark plug and verify that the engine has compression when you rotate the crank. Put silicone sealer on the compression release cover and install it.

Note that with rocker arm overhead valve conversion, you only need a small amount of lift at the exhaust lifter to release the compression for easy starting. If you have too much lift the piston will hit the exhaust valve.

Put a thin film of silicone sealer on the valve cover and install it. Check the crankcase breather and make sure that it is in good condition.

Use a piece of 1″ O.D. steel tubing to connect your exhaust system to the O.H.V. exhaust manifold. The hole in the manifold is reamed to 1″ for a good fit. Heat the manifold to expand it and put some oil on the steel tubing to facilitate assembly. We suggest that you drill thru the manifold and one wall of the I” tube with a #7 drill after installation the tube. Then run a ¼-20 tap thru the tube wall so that the retaining bolt threads into the tube. This prevents the retaining bolt from distorting the tube.

`We use 8 oz of motor oil in the crankcase. Assuming that the breather is in good condition the engine should not lose oil. After running some oil will be retained in the cylinder head.

For best results use an electronic ignition rather than the ignition points. The electronic system gives more accurate and consistent timing.

The carburetor and phenolic spacer can be removed from the head and a small amount of silicone sealer used between the spacer and the head, don’t put so much on that it oozes into the intake port. Similarly, the exhaust manifold can be removed and sealed to the head with silicone sealer.