information

Quenton Guenther

Well-Known Member
Vendor
Local time
10:59 AM
Joined
Aug 2, 2007
Messages
2,145
Location
Outer Banks North Carolina
I just want to pass along some important information about 4 stroke motors. I am not suggesting making any changes to the Whizzer motor, but just passing along general information.
If a 4 stroke motor has less than 100 pounds of compression, several events can take place, first possible poor gas mileage, secondly possible higher operating tempature, low torque, low power, less power when hot, and possible piston, and or cylinder wear. Motors that haven't completed the break-in process would check closer to 80 pounds, and the camshaft can lower the pressure numbers on lean burn motors.
Here is why, with lower compression the cylinder will run rich, and the gasoline can "wash" the oil from the top half of the piston, causing excessive wear and higher operating tempatures. A motor will low compression will also vibrate more [ever had a car with bad valves that shakes?]. It is a known fact that as a motor looses its compression it can be much harder to start, want to know why? More compression will "squish" the air/fuel mixture and put it under pressure, and it appears compressed fuel ignites much easier. Of course if the compression is raised too much, it can also have a similar effect, so the sweet spot on a small bore 4 cycle "flat head" motor is between 100 and 120 pounds when using regular gas. My personal tests have confirmed that hi test fuel is not needed unless the motor exceeds 150 pounds of compression.
I also noticed a comment about using the pedals on a Whizzer to get started and then release the clutch to use the motor, if any of my Whizzers required me to work that hard I would make a few changes to make the motor do the work, not me. A well tuned, completly stock, Whizzer should easily move without using the pedals on level ground.
Hope this information is helpful.

Whizzer OuterBanks LTD
A North Carolina Corporation
Quenton "Lee" Guenther
 
Last edited:

fsprandy

Member
Local time
11:59 AM
Joined
Jun 26, 2008
Messages
37
For further information on flathead engine design and compression ratio please refer to http://en.wikipedia.org/wiki/Flathead_engine. Note that the reference lists maximum compression ratio for flatheads at 7:1 (7*14.7=102.9 psi). This is a fundamental limit to flathead technology and one of the reasons you don't see them in cars anymore. I've had several flatheads that were between 5 and 6 to 1 (~70 to ~90 psi range).

If your engine is running rich I'd check the carburetor. Compression ratio has nothing to do with fuel mixture. Compression ratio is however linked to vibration. The more violent combustion of the higher compression ratio results in a harder initial push on the piston which causes an increase in vibration. An extreme example is the high vibration level of diesel engines with their 20:1 compression ratios.

I use pedals on my Whizzer too, I actually like using the pedals! These bikes are anemic to say the least. About what you'd expect from a small, low output engine, working through a single drive ratio. Add to that the less than ideal engagement characteristics of a slip belt clutch and pedaling from a stop is a nice option. Not pedaling from a stop feels like belt abuse.

I'm curious what the "auto" clutch would be like but the one Whizzer sells is way too overpriced for me. A great American made centrifugal clutch goes for around $50 and the "needs break in and grinding" Whizzer one is over $200! For that price I'll stick with the manual. The experiences of the fellow on here that test rode an Ambassador completely answered the question on the auto clutch for me. Wish I could remember his "garbage scow" quote.

I like some things about the Whizzer. It is fun to take for a spin but not nearly as practical as the folks at Whizzer represented it be. The difference in practicality between the Whizzer and a Honda moped is staggering to say the least. I really wish they would address the issues and make the Whizzer a more practical ride as well as fun.
 

Quenton Guenther

Well-Known Member
Vendor
Local time
10:59 AM
Joined
Aug 2, 2007
Messages
2,145
Location
Outer Banks North Carolina
While I agree with the numbers, and have viewed the information [great article about Harleys]. All my vintage Whizzers with the 6.75 to 1 ratio check at 115 pounds, All my vintage Whizzers with the 6.32 X 1 all check above 105 pounds. The Weber head rated at 7 to 1 checked in at 125 pounds. Maybe my guage isn't producing the right numbers.
I also agree if the compression is caried overboard [20 to 1] it surely would shake the ground with each explosion. I can assure you the Harleys I raced [including a few flatheads] never used ratios below 8 to 1, and most of the OHV were closer to 9 to 1, and some even higher. But you may find the following more interesting, by simply milling the head on a new edition motor, it suddently idles smoother, starts easier, gets better mileage, runs about 25 degrees cooler, develops more bottom end power, less motor vibration, and makes riding a lot easier.
I didn't mean to reduce or degrade the use of pedals, but at my age, I want my motorbike to do the work. Maybe I started riding the wrong Whizzer [no pedals- 1951 24" Ambassador] in my youth, and just expect the same results from my current versions. As you know the Sportsman & Ambassador were kick start models, no pedals, just foot pegs. The bad part of that story is the many times I "pushed" it somewhere, and wished I had pedals.
All of my new edition Whizzers use the automatic clutch, and all but one of my vintage Whizzers employ the slip clutch. The power band is very different between the old & the new, the old has a lot of low end torque, and works perfectly with the slip clutch [most of my rides were riding double], but the new edition power is higher up the RPM scale, and the automatic works easier.
Sure wish I could find a $50.00 american made clutch for a Whizzer. I have paid as high as $450.00 [Jerry Lane-American], and $300.00 [American made] for automatic clutches.
The 2008 Ambassador carries more weight, but also uses a lower ratio output drive. When I rode the Ambassador at the event in Dawson Springs, KY My bike easily stayed with all the Cushmans & Whizzers on the rides. There were several serious hills on some of the rides, and I saw a few "peddling" their Whizzers to reach the top, but my bike easily set the pace. Is the Ambassador faster than the classic version, nope. Does the Ambassador ride better, and stop quicker, yes. Do I ride the Ambassador more than my 1999 Whizzer, nope. Does my 1999 get better mileage, yes. Does my 1999 accelerate quicker, yes.
If I were asked to choose between pedals or no pedals, I would select the classic choice, pedals [even if I don't want to use them], but I am sure there are many that will like the softer ride, electric start, disc brakes, and foot pegs in place of the pedals.
Have fun,
Whizzer OuterBanks LTD
A North Carolina Corporation
Quenton "Lee" Guenther
 

fsprandy

Member
Local time
11:59 AM
Joined
Jun 26, 2008
Messages
37
The American made clutches don't fit the Whizzer. But you can bet they cost more to make than the low quality Chinese one that Whizzer sells.

I don't know why the cylinder pressures are so far off from the compression ratios. Maybe the website I got the equation from isn't correct. The equation they use is for an isothermal process but the rapid compression may be more adiabatic. If I get a minute I'll check and see how much of a difference this could make.

If the compression ratios are much lower than the readings suggest possibly the actual compression ratio of a stock Whizzer is too low. This would explain why you're finding they run better with the head milled.

It's a shame Whizzer doesn't make these things right.
 

peter nap

Member
Local time
10:59 AM
Joined
Mar 4, 2008
Messages
79
I just finished pulling my wife's clutch and to be honest, it's pretty well engineered.....except there is no bearing race and the steel the needle bearings ride on is soft. It also didn't have any grease, but that's not an engineering issue.

I expect the more experienced dealers here have dealt with the problem on rebuilds. Quenton, I'm sending you an email about a rebuild.

I think Bill said something about milling them to center them. Quenton's closer but I'll try Bill if he can't do anything.
 

fsprandy

Member
Local time
11:59 AM
Joined
Jun 26, 2008
Messages
37
I've had troubles with Chinese suppliers both properly hardening parts and using the wrong materials (not to mention shipping parts that only vaguely resemble the prints). If you're going to use Chinese suppliers you must have a very strong quality assurance process in place.

Back to compression ratios. The web source I used was indeed wrong. Cylinder compression testing is an adiabatic process so the formula underestimated the gauge pressure that would be measured. Here's a table that should be much more accurate:

CR Comp (psi)
4 63
5 87
6 111
7 137
8 163
9 190

Given this correction and assuming the information on the original site regarding flathead compression ratio's is correct it looks like pressures measuring up to 137 psi or so would be reasonable. So Quentin's findings of a 120 psi "sweet spot" look pretty darn good.
 

Quenton Guenther

Well-Known Member
Vendor
Local time
10:59 AM
Joined
Aug 2, 2007
Messages
2,145
Location
Outer Banks North Carolina
Hi everyone,
I have tested a lot of clutches made to work on the Whizzer motorbike. Way back when [1948], Whizzer made the Pacemaker model and had an automatic clutch model 270 made by Salsbury Corp. in LA, CA. In 1950 Whizzer offered a product called the Bi-Matic, a 2 speed version of the automatic clutch. The Bi-Matic was not a reliable product, and because of too little testing, it was brought to the market too quickly. Whizzer quickly pulled the Bi-Matic from production, and it became very un-popular as a choice for the Whizzer owner. Today it is one of the most prized and sought after vintage parts. Terry McAllister has developed a way to rebuild them, and I am on his waiting list [way down the list] to hopefully stumble across one for less than the national debt. I know he has re-designed some of the parts, and I know how durable they are because he uses them on his OHV Whizzers [you know the ones that play around 80++MPH]. I have ridden one of Terry's OHV Whizzers with the Bi-Matic [thanks Terry] and I can tell everyone, if I were rich all my Whizzers would have his clutches. My 1950 Pacemaker [first place Whizzer motorbike Portland, IN 2006] uses the model 270 automatic clutch and is just as good as it gets.
Arriving back to the present, I have also tested many clutches made for the new edition Whizzers. Some are American made, and I can tell you they were expensive. As far as I know, none are made in China, but several versions are from Tiawan. I won't spend much time on the American versions because of the high price, and a few issues concerning balance & replacement parts. One version [$450.00] had a vibration problem at higher RPMs, two other American clutches[$300.00 each] spent a lot of time on my shop floor waiting for replacement parts that never arrived. So much for the American versions. FTR I sold the $450.00 unit at Portland last year for $200.00, but told the buyer all I knew about it, and suggested having Terry McAllister look at it. The two other American made clutches [now that I rebuilt them] are filling up a box in my parts room.
Because I am a full service Whizzer dealer, and the fair amount of Automatic clutches I have sold, both vintage & new edition, I have set up the necessary equipment to rebuild most versions of the Whizzer clutch. Whizzer offers spare parts for thier auto clutch, and I plan to use OEM parts when possible. An extra sharp engineer [he owns a Whizzer]friend of mine discovered a minor modification to make the clutch "bullet proof". I am in the process of testing his engineering concepts on two of my bikes, and I know of two other engineers testing the exact same setup at the moment. It only has to do with different metals, not "rocket science".
When the current Whizzer clutch is setup and working correctly, it is a joy to use. Of all the clutches I have tested, the current model works best for me, because I like the way it enguages. Most of the clutches I tested a few years ago, would achieve lock all of a sudden, and climbing a small hill, it drags the motor down quickly, and won't release while under a load. The new version [after break-in] slides into lock, and lets the motor & speed regulate lock, and will un-lock at lower speeds. The auto clutch also allows you to ride the Whizzer at a lower speed without "lugging" the motor.
Peter, if the center bearings were dry, check the ramp, and the seals. If everything looks OK, then clean the bearings and use a good synt. grease [I use synt wheel bearing greese] on the bearings prior to re-assembly. If the ramp is damaged, it is possible to purchase that side of the clutch from your local Whizzer dealer or Whizzer USA, or use a rockwell #58 rated bearing sleeve to replace the bearing surface. I have replaced the bearing surface on several clutches, and have tested one for over 1000 miles, and another for under 400 miles so far and they look new every time I inspect them. To replace a damaged bearing race requires some machine shop work, because the original race must be removed and the new race pressed on and ground to length.
Hi fsprandy,
Sorry I didn't mean that Whizzers compression levels are too low, just wanted to point out that milling the head on almost all small 4 stroke motors will usually net a slightly smoother motor with more mid range power [a comment from Bill Green also suggested milling the head in an earlier post]. I read somewhere today that the 50 CC honda has a lot more power than most motors its size [49CC, etc] and one of the major differences was the compression ratio [Honda was the highest]

Hope I helped,

Whizzer OuterBanks LTD
A North Carolina Corporation
Quenton
 

Quenton Guenther

Well-Known Member
Vendor
Local time
10:59 AM
Joined
Aug 2, 2007
Messages
2,145
Location
Outer Banks North Carolina
Hi fsprandy,

Wow! thanks for the information. Thank you again! One of the Whizzer motors at Dawson Springs, KY event I was told had a 240 Lb compression, or maybe it was 280 Lb. The number was so high I just had a hard time accepting it, but if you saw the bike you had to believe it. It was an OHV motor with all hand made parts, chain driven, pulled wheelies at about 20 MPH. The owner told me he used 112 racing fuel, and I have no reason to doubt it. BTW my Sportsman won against him at the dirt drags [sorry Johnny].
Can you determine the ratio with both 240 & 280 Lbs?

Have fun,
Whizzer OuterBanks LTD
A North Carolina Corporation
Quenton
 

peter nap

Member
Local time
10:59 AM
Joined
Mar 4, 2008
Messages
79
Thank you Quenton.
I think my terminology went haywire. The bearing surface is what is showing damage, not severe, but enough roughness to concern me.

I did use bearing grease but it concerns me that it was run dry.

Thanks again. Your a wealth of information.
 

fsprandy

Member
Local time
11:59 AM
Joined
Jun 26, 2008
Messages
37
Using the same equation 240 psi is about 10.8:1, 280 psi ~ 12.2:1.

Pretty reasonable numbers for the sweet combustion chamber shapes possible with an overhead valve engine.
 
Top