easy original whizzer performance mods
- Thread starter militarymonark
- Start date
Hello. I need a little more info. Basically I need to know what year Whizzer you want to modify. The vintage motors and the later models look similar but are very different.
Jim
Jim
Hi militarymonark,
There are many modifications to enhance the vintage Whizzer motor. The "H" motor is slightly more difficult to extract power because of the smaller ports.
Mill .060" from the head. Remove the "island" in the combustion chamber. Open the intake and exhaust ports. Because of cylinder design the exhaust on the "H" cylinder can't be opened as much as later versions. Install a slightly larger carburetor, such as the Carter N703, N665, or Tillotson MT12A.
Install the larger valves from the "300" or later cylinder, the "H" has 3/4" valves, whereas the later motors used 7/8" valves. If possible replace both valves with the larger units, or at minimum upgrade the intake to the 7/8" size.
There are Weber heads, camshafts, and special carburetors to "hop" up the "H", however the larger valve, reworked combustion chamber, milled head, and larger carburetor will offer similar results for a lot less money.
You can also replace the original head gasket with a .010" custom copper gasket for even more compression.
The average "H" will travel at 35 MPH with an average rider [225 pounds]. The average "300" or later motors will easily exceed 45 MPH in stock form. Modified vintage motors have been known to hit 70 MPH on Dyno tests, however they were stroked, bored, special tri-pattern head [165 pound compression], special lifters, hi-lift camshaft, electronic ignition, Cushman MT series carburetor, and radical fuel blends.
I have built several hi-performance vintage motors, and the results were better than expected. I still have a few cylinders with a very large piston [Clinton], and oversize valves, but might be too much for normal use.
If you need help modifying the parts, let me know.
Have fun,
There are many modifications to enhance the vintage Whizzer motor. The "H" motor is slightly more difficult to extract power because of the smaller ports.
Mill .060" from the head. Remove the "island" in the combustion chamber. Open the intake and exhaust ports. Because of cylinder design the exhaust on the "H" cylinder can't be opened as much as later versions. Install a slightly larger carburetor, such as the Carter N703, N665, or Tillotson MT12A.
Install the larger valves from the "300" or later cylinder, the "H" has 3/4" valves, whereas the later motors used 7/8" valves. If possible replace both valves with the larger units, or at minimum upgrade the intake to the 7/8" size.
There are Weber heads, camshafts, and special carburetors to "hop" up the "H", however the larger valve
You can also replace the original head gasket with a .010" custom copper gasket for even more compression.
The average "H" will travel at 35 MPH with an average rider [225 pounds]. The average "300" or later motors will easily exceed 45 MPH in stock form. Modified vintage motors have been known to hit 70 MPH on Dyno tests, however they were stroked, bored, special tri-pattern head [165 pound compression], special lifters, hi-lift camshaft, electronic ignition, Cushman MT series carburetor, and radical fuel blends.
I have built several hi-performance vintage motors, and the results were better than expected. I still have a few cylinders with a very large piston [Clinton], and oversize valves, but might be too much for normal use.
If you need help modifying the parts, let me know.
Have fun,
Wow. There you go! All the answers in one post. Cool. Hey Quenton, does my H motor you built for me have any of these enhancements?
Jim
Jim
Hi Jim,
Your motor is 100% original, and the majority of the parts used in the rebuilding process were NOS.
Remember the vintage motors have a lot more bottom to mid range torque [can you say Tractor power?] and pull much harder.
have fun,
Your motor is 100% original, and the majority of the parts used in the rebuilding process were NOS.
Remember the vintage motors have a lot more bottom to mid range torque [can you say Tractor power?] and pull much harder.
have fun,
Hi militarymonark,
Cost to mill head & rework combustion chamber $50.00 [plus shipping].
Re-cut valve seats, lap valves, deck cylinder, hone cylinder, rework intake and exhaust ports, paint cylinder with black cylinder paint $100.00 [plus shipping].
Have fun,
Cost to mill head & rework combustion chamber $50.00 [plus shipping].
Re-cut valve seats, lap valves, deck cylinder, hone cylinder, rework intake and exhaust ports, paint cylinder with black cylinder paint $100.00 [plus shipping].
Have fun,
well sir looks like you'll be doing some work for me in the near future, so what gains will this do for my top speed, acceleration and HP?
Hi Militarymonark,
If you have the head milled & reworked and the cylinder ported, decked, etc, you should easily reach speeds of 45 MPH.
If you upgrade to the larger valves, hi-compression head, high lift camshaft [Weber], and a larger carburetor, the top speed should easliy hit 55 MPH.
The biggest gain will be in top end speeds, however the power increase will show up throughout the entire power band. The amount of additional torque will allow the Whizzer to easily climb most hills.
Have fun,
If you have the head milled & reworked and the cylinder ported, decked, etc, you should easily reach speeds of 45 MPH.
If you upgrade to the larger valves, hi-compression head, high lift camshaft [Weber], and a larger carburetor, the top speed should easliy hit 55 MPH.
The biggest gain will be in top end speeds, however the power increase will show up throughout the entire power band. The amount of additional torque will allow the Whizzer to easily climb most hills.
Have fun,
I already have the hi-compression head at least thats what Im told. So where can I find a larger carb and hi lift camshaft? and how much would those cost + the cost of the head and combustion chamber work and the valve work?
Hi militarymonark,
The hi-compression head will also need to be milled and a little chamber work.
Because of the outrageous cost of vintage Whizzer racing carburetors [NOS Tillotson/Weber $350.00] it might be wise to consider using the Carter N665 or N703 because of the larger venturi. The larger Carter units were used on the later "300" series motors with the bigger valves.
Best to concentrate on the cylinder, valves, porting, etc. A lot of power can be pulled from the motor by just making it "breathe" better. Increasing the size of the intake valve would make a large difference in getting the motor to rev higher [more top end]. Adding another 500 RPMs will add another 5 MPH to the top end.
The camshaft for the vintage Whizzer is a very costly item, as an example the NOS "Weber" competition version is worth from $250.00 to $300.00. It is possible to pull a lot of power from the motor with the stock camshaft.
Cylinder work with larger intake valve $165.00 to $175.00
Mill head & rework $45.00.
Rebuilt Carter carburetor $175.00
Plus gaskets & shipping.
Speed costs, how fast do you want to go???
"J" cylinder with larger intake valve & port work $235.00
"300" cylinder with large valves, large ports, ported $300.00
NOS Tillotson "Weber" ML3 carburetor $350.00
NOS "Weber" high lift camshaft $275.00
Ported Cushman MT63 Carburetor $200.00
Hope this answered a few of your questions. This post is not intended to solicit business, but to answer questions.
You are welcome to call me on my cell phone for more options & details.
252-475-0406
Have fun,
The hi-compression head will also need to be milled and a little chamber work.
Because of the outrageous cost of vintage Whizzer racing carburetors [NOS Tillotson/Weber $350.00] it might be wise to consider using the Carter N665 or N703 because of the larger venturi. The larger Carter units were used on the later "300" series motors with the bigger valves.
Best to concentrate on the cylinder, valves, porting, etc. A lot of power can be pulled from the motor by just making it "breathe" better. Increasing the size of the intake valve would make a large difference in getting the motor to rev higher [more top end]. Adding another 500 RPMs will add another 5 MPH to the top end.
The camshaft for the vintage Whizzer is a very costly item, as an example the NOS "Weber" competition version is worth from $250.00 to $300.00. It is possible to pull a lot of power from the motor with the stock camshaft.
Cylinder work with larger intake valve $165.00 to $175.00
Mill head & rework $45.00.
Rebuilt Carter carburetor $175.00
Plus gaskets & shipping.
Speed costs, how fast do you want to go???
"J" cylinder with larger intake valve & port work $235.00
"300" cylinder with large valves, large ports, ported $300.00
NOS Tillotson "Weber" ML3 carburetor $350.00
NOS "Weber" high lift camshaft $275.00
Ported Cushman MT63 Carburetor $200.00
Hope this answered a few of your questions. This post is not intended to solicit business, but to answer questions.
You are welcome to call me on my cell phone for more options & details.
252-475-0406
Have fun,
since we are two hours apart and I dont get much time to talk until its after 10 eastern time Its kinda late unless you dont mind talking, I know I called last time but for some reason I thought you were in cali , I do want to talk on the phone though
