Whizzer restrictor mod

That took all of about 15 minutes and was super easy! Thanks for the info that enabled me to do this.

I took pictures along the way in case another noob like me comes along and is wondering what everything looks like.

In the photos you will notice the black spacer is cracked along the bottom - this is a brand new Whizzer and it came that way - doesn't look like it will cause any issues at the moment. The same thing with the restrictor plate itself - stress cracks around one of the holes where the bolt goes through.

All I did was remove the carb - held on by two 10mm nuts to two threaded posts. Removing one nut was tricky as there is a part of the carb that does not allow it to come all the way off without a little work.

Once both nuts were removed the carb was not moving. I used a rubber mallet very gently to give it an initial nudge. Then I was very careful as I had to force it off...gently so as not to damage the threads on the posts.

Once I had it off I used a small jewelers screwdriver to gently pry each layer off - the black spacer - the gasket - the restrictor plate - then the last gasket.

I hand screwed the restrictor plate to a block of wood - hand screwed to make sure I didn't damage it by making it too tight with a drill - and I wanted it to be steady when I widened the opening.

I used a brand new 11/16 in. spade bit - it is 17.46 mm and just about the right size. I did it very slowly - slow RPMs and made sure everything was steady.

When all was done I took a small jewelers file and went along the edges to widen it to exactly 18mm - this took about 5 minutes - and it also smoothed the edges and removed any pieces of the restrictor that were hanging on the edge of the newly drilled hole.

I wiped off the restrictor with a clean patch of cloth - as well as doing the same near the dirty inlet to the engine. Then I simply slipped them on in the reverse order I took everything off - except I used some blue loctite on the threaded stems. As a matter of fact, it was Blue Locktite Sunday - I went around and used it on a bunch of screws and bolts that I noticed were vibrating loose.

Again, thank you all for the tips and information. I hope my post and pictures will be able to help someone like you all helped me.

Oh, and there was quite the performance improvement - about 10 MPH faster - I had the speedo at 43 MPH - just what I was hoping for!

Best regards,



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Nicely done. Don't forget that your still breaking in the engine. About 500 miles and it should be broken in.
Good luck


BTW It will run even stronger after it's broken. It will keep getting better and better.
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Aye, Jim - I am ever mindful of the break-in period. Tomorrow I will start using it to commute to work since the weather is getting a bit nicer here in blustery Kansas - It's a good commute of about 7 miles each way - city traffic with lots of stops and variable speeds - perfect "break-in" driving!

Have a great week.
Greetings to all the Whizzer lovers out there - this sight is the best! This is what I was looking at doing to my NE5, should I wait 'till the 500 mile break in befor opening the restrictor, also I have 150 miles on the bike. I am a freekin' nube, any help goes a long way - I have been sponging all that I can, does anyone out there have directions (it would be great with pics -again I am a nube) of installing the mushroom lifters and the copper head gasket for the NE5 engine? Also, how do I know If my bike has a high flow muffler insert? Thanks to all out there in advance for the help, this is my 1st Whizzer, and it is great!

Hello moonpup
Please stop by the Introduction Forum and tell us a little about yourself. It's nice to know where everyone comes from. It already sounds like you have been reading a lot. There is much great info to be found here. The head gasket is easy but you need an inch pound torque wrench for reinstalling the head and you need to tighten them in the right order. The high flow insert has an opening in the back that is about 1 inch in diameter any smaller and it's not the hi-flow. PM me and I can give you more info. Please stop by the Intro Forum. Thanks.
Have fun

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Hey Moonpup,
Sure is nice to find so much Whizzer information in one location.
Here is a little more food for thought. Changing to mushroom lifters "yesterday" might be a good idea. Some NE and all SE motors have a higher lift camshaft than the original WC-1 motors [1999 to 2004]. And no matter which camshaft, the mushroom lifters do several good things, including changing the duration of the camshaft, reducing the lifter stress on the camshaft lobes, and allowing the camshaft timing to increase low end torque. All current production Whizzers use mushroom lifters, including the current NE5 and Ambassador models. One caution, however all mushroom lifters are not the same, some are made too tight for the case [not Whizzer products], some are too heavy, and of course mine are just right. Actually you can order them from any Whizzer parts dealer, and drill out the center to make a perfect set [if any one wants details just ask]. Installing the mushroom lifters however is more of a task, and requires removing the side cover, the camshaft, the carburetor, and the compression cover. The mushroom lifters must be installed from the bottom, and the entire process takes about 1 hour, but be sure to also purchase gasket #2217 [compression cover] because it is very fragile and usually breaks during removal of the cover. The copper head gasket is also a plus item because it helps reduce the operating tempature of the motor, but as RDKryton stated you mush have a good inch pound torque wrench, and know the correct pattern. and as always he is "on the money" when describing the muffler insert.
Have fun,
Whizzer OuterBanks