Compression Release

Discussion in 'Whizzer Motorized Bicycles' started by Zomby Builder, Mar 6, 2010.

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  1. Does anybody have a compression release that DOES NOT LEAK????

    I have bought several of these. The stock ones are junk. Or do I just get shoddy ones? I had Quenton modify one, it leaked too. I modded it further & guess what -- It still leaked. I tried Bills, It leaks too.

    This is not acceptable. Not a major leak, but still a leak. Have any of you had success in stopping this annoying problem or is this the way it will always be????????????

  2. 27 views & not one response

    Does this mean that you all live with this problem? WTF!! One response would be good.....
  3. whizzer48

    whizzer48 Member

    Do you have a gasket for it?
    If you talking about oil drip I use Gasgacinch for vw engine and any gasket.
    It help the seal out where the seal can't do it job.
    It like water down contact cement easy to clean up. Just wait a little to dry little and then put it on. Or do it went and have a rag ready to clean. Silcone in this case would be too thick. Most autopart store have it.
    Last edited: Mar 6, 2010
  4. It's not leaking from the gasket. From the seal (or lack of) between the lever & spring...



    Here is Quentons fix...... My smaller O-ring mod.. No working - Still leaking around the spring. Not sealing. Bill Greens leaks the same way. Stock whizzer part pours oil from HERE. This has got to be a common problem.. What is it?

    O-ring ??????
  5. Fabian

    Fabian Well-Known Member

    I've been screaming out for someone to install a compression release valve in the cylinder head of the Chinese 2-stroke bicycle engines, especially when used with the SBP Shift kit

    Below is a commonly used compression release valve used in many chainsaws.
    They are very compact, work with perfect reliability; don't leak and just do what they're designed to do.


    Attached Files:

  6. james65

    james65 Member

    Do you have to manualy depress the blue button to operate that valve ?
  7. Fabian

    Fabian Well-Known Member

    Yes, you just push on the blue button and when the engine fires, cylinder pressure pops it back out.

    Almost every chainsaw uses them these days, and every one of my chainsaws has a decompression release button.
    I've never had one fail - "ever"

  8. whizzer48

    whizzer48 Member

    If the oil just flood/ roll down the plate if it was me, I would try welding a halfmoon weld around the top. It may act like a house roof.

    I don't think a resign it worth it. If you running a pvc valve can it be make the blowby going out the o ring?
    Last edited: Mar 7, 2010
  9. whizzer48

    whizzer48 Member

    Here a good picture what is under the spring.

    Attached Files:

  10. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi Zomby,

    Installing the "O" ring normally stops the leak, however if you have exessive crankcase pressure the "O" ring won't stop the flow of oil.

    The best method so far is to remove the lever, remove the cam pin, and machine a ledge to allow the "O" ring to rest in the groove [between the cam and plate]. If you just install the "O" ring over the pin it won't stay against the cover to make a good seal.

    Using a fresh bore and a cam ground piston [stock new edition Whizzer pistons are NOT cam ground] normally drops the crankcase pressure right away. Not sure why you motor didn't drop the pressure if the bore is correct and you used a cam ground piston.

    The reason most Whizzer motors have high crankcase pressure is due to the piston & rings not sealing and allows blow-by into the crankcase. The majority of the Whizzer motors will settle down by the time 500 miles has been logged on the motor. Another cause is the breather system, and installing a small tube inside the tappet area will aid in reducing the amount of oil in the chamber. Insert tube in hole at the bottom of the NE cylinder and make the tube long enough to stop approx 1/8" from the top of the chamber. Drill 2 small holes at the base of the tube to allow the oil to drain back into the crankcase. The tube should be 1 1/2" long and the center hole should be 5/16". In order to press fit the tube into the hole at the base of the tappet area it needs to be .475" O.D.

    See attachments

    As far as the suggested use of the automatic compression release, Whizzer already installed the device on all the late model NE-Rs and Ambassadors and they leak compression badly and must be replaced with a 10 MM fine thread bolt.

    Using the compression release on a 2 stroke was used in the early 70s on the race track before anyone figured out the open release at high RPMs removed all the oil from the cylinder. I watched hundreds of race bikes blow up when the release was used at the end of the straight to slow the bike for corner entry. It is amazing how quickly a 2 stroke will lock when the oil is removed from the piston/cylinder at 8000 RPMs.

    Have fun,

    Attached Files:

    Last edited: Mar 7, 2010
  11. Here is what I did

    Hi zomby
    I had been frustrated by the same problem. I fixed the problem 100%. To solve this problem completely, the crank case pressure needs to be vented much better. The amount of oil I have seen spit out of the cover is a joke, thanks to such great engineering by the factory. This is what I did to solve the crank case pressure problem. I disasembled the motor completely except for the crank rod assembly, I milled out the interior dividers in the labyrinth in two of the case halves. There are two places where gas can vent into the labryrinth pocket one is for the gass and one is for oil to drain back into the bottom of the case. I opened thse two holes to about 1/4 inch.dia. When I reassembled the case halves I stuffed the now open pockets with copper plated steel scrub pad material. Oil collects better on this material then on the cast in labyrinth. My compression release cover has an enlarged hole for a bit of 3/8 brass pipe with a hose that goes to my homemade breather. The breather is made much as Quenton recomended except that my breather attaches to the case to allow gasses to vent from the modified crankcase breather (labyrinth) system as well as the hose from the compression cover.

    To fix the leaking at the compression cover I drilled out the shaft where the lever is crimped or stamped onto the cam shaft, drilled and threaded a hole so that a small allen bolt& washer could be used to reattach the lever. I reamed a bit of brass tubing to fit over the shaft with about .002 clearance, then I reamed the cover plate to the size of the brass tube and pressed it in with some sleeve retainer compound. Also I chucked the cam in my lathe and turned a small 1/4 radius around the back side so an o ring would have a better compression fit to the back side of the cover. The whole assembly works smoothly and has no play at all, the O ring has a nice seat and best of all it dosent leak, ask my wife she lets me park my Whizzer in our living room.

    Best of luck
    Brent Merkley
  12. Really Brent - you get to park in your living room.. Some guys have all the luck. I'm lucky that I don't have to sleep in the garage sometimes.

    I discovered something that I did out of sequence. The cover that I sent Quenton already had the lever welded. So he had no chance of taking the play out of that cam lever connection. I had a new one in my parts pile so I took it apart, machined a bevel on the interface so an o-ring would seat between the cam & the cover then I put a washer on the other side of the cover under the lever to take out the play. Then clamped the whole assembly together and welded the lever to the shaft so there was no play whatsoever. This worked like a charm.

    After it cooled I put the o-ring on & attached the spring. Not leaking at all now.

    The stock assembly is very deceiving because the spring puts tension on the cam & lever connection hiding the play between the parts. You have to take it apart & reassemble it without the spring to see how much play there really is. (There is a lot) Oil seeps through there very easily.

    Sorry that I didn't take pics of the steps now, but I didn't know it would work so well.

    I also made an oil collector with PCV valve similar to what a lot of you have modeled out of PVC except I just used Gates rubber hose & Chore Boy copper scrub. Same general idea just filled the rubber tubing with the Chore Boy & clamped the PCV valve to the end.
  13. Good fix

    Hi zomby
    Always more then one way to skin a cat. Glad you have a bike that stays clean and full of oil. I also drilled a pocket hole in my drain plug and installed a magnet, cant be too safe!!
  14. augidog

    augidog New Member

    guilty..but i always look at Zomby-posts...couldn't help so i just watched...looks like problem-solved :cool:
  15. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    It is possible to remove the exessive play between the pin and the hole in the cover by knurling the pin for a tighter fit, but still needs the "O' ring to make the best seal possible.

    BTW the pressure will drop when the motor breaks-in more. It can take up to 500 miles before the break-in process is complete.

    Have fun,
  16. Whizzer design engineers???

    Dear Mr. Whizzer:

    I was just tallying all the $$ that I spent on correcting this obvious (now) flaw in design of this part.

    I bought 3 at 18.85 each plus shipping from Whizzer USA.

    I sent one to Quenton (he did not charge me for the o-ring modification) but I had already welded the lever to the shaft without taking out the play so it still leaked a little.

    I spent at least 20 hours of my time trying on & taking off the covers on both motors.

    I stripped out the threads on my previous motor from all the on - off & had to use longer bolts.

    My new motor came with a stock one (although welded by Bill) (no o-ring) I installed the o-ring, but still had the play in the shaft so it still leaked.

    Finally got one to work without leaking. After failing & ruining two new ones.

    I didn't mention that the stock lever is very cheaply press fit onto the shaft, I discovered this the hard way when the first one I had came apart on the road. I thought I had fixed it by welding it together.

    How long has Whizzer been using this design on new bikes & selling this part? If they were Toyota or GM there would have been a massive recall. Oh how the California lawyers would get rich on this class action......................

    Last edited by a moderator: Mar 8, 2010
  17. Quenton you should sell these fully modified for around 75.00 make a little $$ & save future owners the frustration. I believe there are lots of folks like myself that have this same trouble.