Ok so I'm not exactly new just lazy!!

Discussion in 'Introduce Yourself' started by SKARYFAST, Jan 20, 2007.



    Hi all I'm Mark from Brisbane in Australia. I've been meaning to introduce myself for a while but am just getting around to it now for reasons stated in the title. My story is that when the local police came across me out for a little spurt to clear the cobwebs at 2 in the morning and decided that the speed I was driven my car at was no longer funny they decided that perhaps I should walk for 6 months to spend some time thinking things over. :mad: As a much younger man I had built a motorized push bike for a young guy working for me so he could get to work and decided it was time to do the same for myself. Heres a pic the right way up for all you guys in the northern hemisphere.

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      And this is how we see it in Australia!! :grin:






  2. Tom

    Tom Active Member

    hahahahah, i was wondering why that picture was upsidedown... or right-side up... or whatever.

    That engine is a tight fit. What size sprocket do you have??
  3. cyclemotors

    cyclemotors Guest

    Wow, thats such a nice bike... Please explain how you fitted it into such a small frame..

    Is that a custom intake manifold you made yourself?

    If not where did you get it and does it affect the performance fitted at an angle?

    But seriousely thats really neat...
  4. Cookie

    Cookie Guest

    kooo kul that is a sweet bike welcome and come on in sit and chat a while



    The motor is a tight fit cos I bought it first and then took it out shopping for a bike. I wanted it as neat as possible to get that "Factory Fitted" look. Everything is custom by now. The front and rear engine mounts are built to offset the motor 5mm to the chain side for clearance. On the front the engine mount is cut to clear the frame and plate mounted to the drink bottle mounts. The rear is also plate mounted with new bracketing. If you have an oversized frame this is an easy way to get your bolt centers wider and allows you to put the motor exactly where you want it. The inlet manifold is just the standard one cut and welded then ported. The transfer and exhaust ports are reworked and the entire guts of the exhaust got the secret recipe treatment and .5mm shaved from the bottom of the barrel. Did a quick balance on the crank but want to do it again to closer tolerances as I am planing a new CDI, main bearings and more revs. I did have a NOS kit on it but took it of in the interests of longevity!! I run 3 different sprockets from 52 teeth for bush bashing to 32 for long rides. These just bolt on to the standard sprocket and with the quick release rear wheel they are easy to swap. I used to snap chains particularly when landing after getting air but an SLC Pro comp 415 chain off a dirt bike has put an end to that. I use short chain pieces to change between sprockets and a half link to take up the slack . The tensioner idea SUX!!!!


    By the way sorry forgot my manners!!!! :sad: Hi all and thanks!! :smile:
  7. Wheels

    Wheels Guest

    Welcome, looks like the shredder from oz.

  8. gone_fishin

    gone_fishin Guest

    that is one skaryfast looking bike, man 8)

    oh, yeah...welcome to MBc :D
  9. etheric

    etheric Guest

  10. cyclemotors

    cyclemotors Guest

    Mark, is that an alluminium frame or steel ?

    Would you say its better to install on an alluminium or a steel one, what im tryin to say is would a steel frame produce less vibration than lets say an alluminium one.

    Also you know how you mounted the front of the engine to the bottle holder slots with a steel custom mount, well does that affect the vibration too?

    Id be really interested in finding out thanks...


    Ok my frame is all alloy and very very light. In fact my motor weighs more than the bike!! I can't recommend it highly enough. Its all about power to weight. As far as vibration goes its important to be thinking right!! Sorry but you just asked a mechanical engineer a question that can't be answered with a yes or no. So its gona be a long answer!! First the frame transmits vibration the engine produces it. The lighter the frame and the firmer the mount the more vibration is transmitted. So in other words if you filled your frame with lead the mass of the out of balance crank would not be able to efficiently move the mass of the frame and you would hardly feel any vibration. You would also hardly be able to get the motor to pull you on flat ground but it would be smooth!!! So to have a bike that performs and dampen the vibration you have two things to work on. Firstly eliminate as much vibration as possible at the source and secondly introduce a buffer or dampening zone between the source and the frame. The vibration in these motors comes mainly from 2 sources. The standard front sprocket meshing and releasing from the chain and the poorly balanced crank. The front sprocket needs to be reworked to allow free mesh and release. Just look at a small push bike sprocket and compare the difference at the points of the teeth. File your drive sprocket like that and you will have less chain wear, stretching and vibration. Secondly balance your crank. This is simply done by placing your crank and con rod on a set of parallels with the con rod end supported and removing metal from the side that swings to the bottom. Don't get all hung up on crank case volume cos it will not have any effect on performance on these motors that you will ever notice but you will notice a big improvement not only in smoothness but in the way the motor spins up. Now my motor is mounted on 3mm thick pieces of aircraft ally. This is to allow it to flex a bit and reduce the strain on the crank case casting.


    As it comes out of the box the 80cc motor is a nasty piece of work but with a bit of carefully loving it will become a smooth powerful reliable power plant. !! Vroom vroom!!!!


    The light is just an old bike light screwed to the disk break caliper mount of my forks. Haven't wired it up yet but it needs to be there to be legal in Aus. The inlet manifold is just the stock one cut turned to an angle and welded back together!! Too easy!!
  13. cyclemotors

    cyclemotors Guest

    Thank you so much for that detailed answer and picture illustrations, i have learnt so much..

    Cant wait to get started on my new bike, will post some pictures when im done and you can let me know what you think.

    really appreciate it man....
  14. gone_fishin

    gone_fishin Guest

    skaryfast, that WAS an xlent explaination 8)

    my older HD-steel mtb frame does absorb a ton-o-vibration...
  15. Vongould

    Vongould Guest

    rear sprocket

    Skaryfast, please give us more details and pics on how you attached the rear sprocket to the wheel. It looks like it is not bolted to the spokes.
  16. SlicerDicer

    SlicerDicer Guest

    Re: rear sprocket

    Not only that unless me eyes are deceiving me it looks to be 2 sprockets side by side :? :?

    And speaking of Australia. I am curious if you know the legal grey area there on the use of those bikes? I know the coppers are pretty strict there about everything from chirping the tyres :) to tread depth to road cancer (rust).
  17. Chopper

    Chopper Guest

    hey Mark, I need to do a similar thing with my inlet as I have no room for an air filter.
  18. i can't answer for QLD where skaryfast is from, but here in Victoria, if the bike puts out more than 200 watts it technically needs to be registered, which is nigh on impossible to do. i think 200 watts is put out be like a 20cc motor, so almost all are technically illigal.
  19. Vongould

    Vongould Guest

    balance the crank

    Can you give us more detail on how to balance the crank. Pictures maybe?
  20. gone_fishin

    gone_fishin Guest

    please make sure to take the tech talk into the proper area, we don't wanna miss out on something good 8)