What's This 45 Mph Talk?

[Hal the Elder]

I've opened up my intake restrictor to match the venturi opening of my carb and opened up my muffler baffles to 1" diameter. My camshaft has also been advanced one tooth.

I don't think I can make 35 MPH, let alone 45 MPH. I've had it to 33 MPH on level ground with no headwind and 40 PSI in the tires, and there didn't feel like there was much reserve.

I live at 3000 ft. elevation...would that have an effect on power?

Frankly, I don't even like going as fast as 30 MPH! Those 2 drum brakes don't have that much emergency stopping power for a 104-pound motorbike and a 225-pound rider.

HAL

 

[RdKryton]

Hi again Hal
Your engine will gain power as it breaks in. This will take about 500 miles. You will be able to hit 45 mph if you are jetted correctly. I have hit 40+ on mine and I don't like going that fast on a bike. 25-30mph is fine by me. I just like having the power to carry the hills here.

Jim

 

[Quenton Guenther]

Hi Hal,
"opened up my muffler baffles to 1" diameter" ? Why didn't you replace the defective Whizzer muffler? Opening the original muffler insert will never equal the Hi flow insert, never! If the replacement wasn't quickly available, maybe Whizzer was out of stock. Don't plan on your Whizzer breaking any speed records with the original "modified" insert. My tests have revealed the center flow tube must go all the way through the insert and equal the size of the holes in the mounting ends.

Have fun,

 

[Hal the Elder]

Hey Jim:

25-30 MPH is fine by me too, but I really feel cool at 20-25 MPH!

How do I know if I'm jetted correctly?

My idle mixture screw doesn't seem to make any difference whether it's turned all the way in or backed out 5 turns!

I would like a little extra power, but not for speed; just for accelleration and for the few mild hills in my area.

Thanks...
HAL

 

[Hal the Elder]

Hey Quenton:

Didn't you read my post that said my Hi-Flow muffler fell apart after 10 miles?

The Whizzer muffler wasn't defective...the Hi Flow was! The stock Whizzer muffler has proper, substantial welds on the baffle plates, but the Hi-Flow had small, inadequate welds, which is why it failed right away!

I opened up the baffles on my stock muffler to the EXACT DIAMETER (1.015") as the Hi-Flow muffler, which now provides the same unrestricted exhaust flow. I used rotary files to do the job.

You and others may be getting 45 MPH performance, but I don't!

HAL

 

[Quenton Guenther]

Hi Hal,
I remember the bad luck with the Whizzer muffler insert you had, and I will admit I am somewhat surprized. I have sold hundreds of the inserts and not a single one failed. I will tell a story about exhaust sytems on the NE Whizzer motor that may help your lack of power. I once agreed to modify a new motor for someone in Texas, but was having real problems making it run like all the other motors I had modified prior to this one. It was real important that this motor produce a lot of power because like I said it was going to a company in Texas. I won't mention the company, but everyone should be able to figure it out. The person that ordered the motor might have worked for a motorbike company and the first name might have started with the letter "D", or maybe not. Anyway the motor ran really poor, and I was having a hard time getting it up to 35 MPH. After exchanging the head, cylinder, carburetor, ignition system, and camshaft, I just couldn't seem to find the problem. By accident the problem went away and I proceeded to continue the break-in process. Still unaware of the accidential fix, it was time to box up the motor and the exhaust pipe. I suddently realized I had accidently installed a different pipe during one of the earlier changes. I took the muffler insert out of the original pipe and exchanged it for the one I had just tested, guess what! the bike started running like carp again. After careful inspection I noticed the insert didn't have the long center pipe installed and in fact was trapping the exhaust in the center and distrupting the exhaust pulse. I exchanged the insert again and it ran great.
Moral of the story is; the long perferated tube in the center makes a major difference in performance.
BTW if one of my NE Whizzers only went 45 MPH I would consider putting it out of its misery. If the head is milled, the combustion chamber is re-worked, the carburetor jetted close, mushroom lifters, correct tappet clearance, and the exhaust flow is correct it should easily take a 200 pound rider past 45 MPH on level ground.
I will gladly help you get the most from your motor, but I strongly suggest you re-consider the exhaust insert you use. If the insert has broken welds, consider getting a warranty replacement, because I don't think it is a common problem.
Are you still using the soft lifters? Did you re-work the combustion chamber in the head? Are the lifters set at .006" intake, and the exhaust at .008"? Are you using a 90 MM clutch?
Let me know, and I assure you I can help you pull a bunch of power from the motor.

Have fun,

 

[Hal the Elder]

Here's my story:

The first thing I did was to open up the intake restrictor spacer to match the I.D. of the carb and the intake port of the engine.

This made a small, but noticeable difference in performance.

Then I ordered a Hi-Flow insert from Mike Simpson. I installed it, and it made another moderate improvement in performance, but it lasted for only one 10-mile ride before the weld broke loose on the rear baffle. I threw it away, because it was junk.

I couldn't get a warranty replacement on the Hi-Flow insert, because IT ISN'T A WHIZZER PART! Instead, I asked Mike for a refund.

Then I bored out both baffles on my STOCK WHIZZER MUFFLER to match the diameter of the Hi-Flow baffles. This is what I am running now.

To reiterate, the stock Whizzer muffler never had any problems...it was the Hi-Flow insert that failed!

That's it!
HAL

 

[Quenton Guenther]

Bad news Hal,
The insert was in fact a Whizzer part! Mike purchased it from Whizzer and would be under warranty. You shouldn't thrown it away, now Mike can't warranty it and you shouldn't expect him to eat the money. He didn't make the part! See if you can find it as I am sure he could and would replace it under warranty. The part had a one year warranty from Whizzer.

Have fun,

 

[Hal the Elder]

I Still Have The Bad Insert!

HEY QUENTON:

I still have the failed insert, with the rear baffle broken off.

I didn't realize THAT was a Whizzer part...I thought it was made by a small manufacturer as an aftermarket accesssory to fit the Whizzer.

You mean that was a "performance" part made by Whizzer, and would be under warranty even though it didn't come with the bike?

This is really getting confusing!

HAL

 

[Quenton Guenther]

Hi Hal, It is not considered a performance part by Whizzer. It is however the best choice for good exhaust flow. Contact the dealer for the best way to warranty the part, it will be in your best interest to do so. Really happy you found it.

Have fun,