Discussion in 'Whizzer Motorized Bicycles' started by Quenton Guenther, Jul 2, 2008.

  1. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    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: Jul 2, 2008

  2. fsprandy

    fsprandy Member

    For further information on flathead engine design and compression ratio please refer to 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.
  3. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    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
  4. fsprandy

    fsprandy Member

    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.
  5. peter nap

    peter nap Member

    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.
  6. fsprandy

    fsprandy Member

    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.
  7. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    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
  8. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    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
  9. peter nap

    peter nap Member

    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.
  10. fsprandy

    fsprandy Member

    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.
  11. KilroyCD

    KilroyCD Active Member

    As Quenton pointed out in his subsequent post, the clutches are made in either the USA or Taiwan. I'd like to further point out that the bike as a whole is not made in China, but Taiwan. To some, that means little difference. To me that means a world of difference when it comes to quality.
  12. fsprandy

    fsprandy Member

    I'm very surprised as several of the components look unmistakeably Chinese. Take a good look at the carb or the front hub castings. Also suspicious is that there is no country of origin cast in to either of these assemblies (typical with China). Maybe they're assembled in Taiwan from Chinese components? I can't remember ever seeing Taiwan made castings at this quality level.
  13. Don Brown

    Don Brown New Member

    Hi Quenton, I just wanted to add my 2cts. After 7yrs. of using the slip clutch on my whizzer, using the auto clutch for a year now is great. I must have the new version because it works just as you say. It does wind up a little getting started but it sure runs smooth at slow speeds. And keep on posting your info. is great!
  14. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi fsprandy,
    Thanks for the info. I think I know why he used the camshaft to start it, because at 12 to 1 it would be hard to start with the regular belt setup. If I remember correctly he had a chain from the pedal crank up to the end of the camshaft as the starter system the camshaft is 2 to 1, so it would be easier to use. I do remember when I rode it the brake was a disc setup mounted on a jackshaft with the chain going to a large sproket attached to the rear hub. I just located a picture of the bike if anyone wants to see it, very wild, and quick too! I would post it here, but not exactly sure of the rules and file size.

    Just another quick comment to add fun to the post, it appears the "flat head" Whizzers are knocking on the door of the OHV versions, and in a few recent cases the ol' flat head Whizzers crossed the finish line ahead of the state of the art OHV motors.
    As you can tell, I like the 4 stroke flat head motor, mainly because of the simplicity, and the old time power band.
    Have fun,
    Whizzer OuterBanks LTD
    A North Carolina Corporation
    Last edited: Jul 5, 2008
  15. fsprandy

    fsprandy Member


    I think there is a photo of that bike in the pictures section. It has a torque converter style clutch on it. Ironic it has a huge disk on the jackshaft for braking the rear wheel but no front brake??

    I like the flatheads too. They make a-lot of sense when the engine has to be compact like a Whizzer should be. Can't beat the simplicity either. The flathead should also cool much better than an overhead valve setup.

    If you're racing against Whizzer's with overhead valves and torque converters you're going to have to be much better at tuning than the competition in order to beat them!
  16. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi fsprandy,

    The only bike that would have been competitive was Kenny Thomas's Whizzer, but Kenny had me ride it for him, and I couldn't find a way to ride both at the same time. None of the OHV entered were able to offer any competition to my flat head, in fact none of the Whizzers could. Guess you are right about the tuning I must have done something right.

    Whizzer OuterBanks LTD
    A North Carolina Corporation
  17. n8ygn

    n8ygn Member

    Torque Converter Question

    Has anyone experimented with a torque converter like those sold by Northern Tool + Equipment I saw they come in 3/4" and 1" bore size I'm not sure what the whizzer would take just thinking out loud. The 1" is rated to 8hp somewhat sounds like the cvt on my Ambassador the way they describe it. Another question I have notice diecast models of whizzers on ebay are they new are from the 40's wouldn't mind having one of those. I can't find anything on the web about 1:6 whizzers diecast models. Dane
  18. WZ507

    WZ507 Member

    Die cast model Whizzers

    The die cast model Whizzers are new (in the last decade or so) and made overseas.
  19. WZ507

    WZ507 Member

    Compression ratio and cranking compression

    Regarding the earlier compression ratio discussion in this thread, one thing that has been neglected in the discussion is whether the subject is static compression ratio (determined by measuring head and bore volume) or cranking compression (the number obtained when motoring the engine). The actual static compression ratio can be easily determined by measuring the amount of light oil, introduced through the spark plug hole, required to fill the bore/head area of the assembled engine, with the piston at TDC and at BDC. Knowing these two volumes allows you to calculate the static compression ratio (CR = TDC volume / BDC volume).

    The cranking (dynamic) compression (CC) is another story all together, and is dominated by the timing of the IN valve closing (the earlier the closing the higher the CC, the later the closing the lower the CC), but is also affected by several other factors (see link below). You can get widely different results from the same engine depending on the cam duration and the IN valve closing event. As an example a friend of mine had a motorcycle engine having about 11.5:1 static CR. Depending on which of two cams he put in the bike (one shorter and one longer duration) it had either 190 psi or 240 psi cranking compression respectively.

    In my experience, I have not observed cranking compression numbers higher than about 240 psi, and this goes for engines having static compression ratio in the range of 14-17:1. Such high compression ratio engines typically employ very long duration cams, thus have relatively late IN valve closing, which in turn serves to lower the CC.

    To read more than you'd likely ever want to know about CR and all the factors affecting it, check out the following link.
    Last edited by a moderator: Dec 15, 2015
  20. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi Dane, I have several of the models. They were a limited production of the 1948 Whizzer motor kit installed on a Shwinnn WZ/S4 bicycle. Schwinn and several other companies [Huffy & Roadmaster] made a special bicycle and was painted using the Whizzer maroon color.
    Have fun,