Sprocket and chain confusion

Discussion in 'General Questions' started by Hittin1, Jul 7, 2014.

  1. Hittin1

    Hittin1 New Member

    ok, i have 3 current builds going. none of which are utilizing any kits.
    2 of the bikes will be using 1/2 x 1/8 chains and one will be using 1/2 x 3/32 chain.
    i need to know what the 9 hole sprockets and mounts for sale on the web use for chain size. If they wont work with my chain setups, do they sell a sprocket that will work with my chain and fit with the mount kit?

    if not, does anyone know of a good way to mount a 14 speed crank set on the rear tire, opposite the cassette?

    all will be powered by various weedeater engines. any help woukd be appreciated.

  2. crassius

    crassius Well-Known Member

    assuming you meant 1/2 x 3/16 chain which is 415 and an industrial 1/2 x 1/8 which is #41 chain, each should work with a standard rear sprocket (assuming sprocket is mounted straight)
    Hittin1 likes this.
  3. Hittin1

    Hittin1 New Member

    Im pretty sure 3/32 is the width im working with.. Its the most common on multi speed bikes if that helps.

    But what i am curious about are the 9 hole sprockets that are sold with the 80 cc bike kits etc. with mounts.... What chains to they use? And will those chains work with an 18t and 13t sprocket off of a shimano cassette which it what im using as a drive sprocket.
  4. HeadSmess

    HeadSmess Well-Known Member

    any pushbike chain is 1/2".

    derailleur chain is the thinnest.

    the narrow chains tend to vibrate a lot. also weaker. etc etc etc.

    HD bmx chain is the next step up, i like, but also...tends to vibrate a lot at certain speeds. yes, the chain vibrates, with this nasty side to side motion... unless used in short runs.

    then we move to "motorcycle/industrial" types.

    as long as the first digit is a 4, it is 1/2" pitch (4/8 of an inch...get it yet? if its a 5 it would be 5/8 of an inch, etc, etc.)

    the next two numbers are widths.

    410 is skinniest.

    428 is super side, too wide to fit into the HT engine case without grinding things.

    410 to 420 is ideal.

    heavy chain...less chance of breaking, but has a lot more force if it breaks, and if it runs at engine speed at any point... and of course, the chains speed is faster as the engine sprocket gets bigger. a 13t 1/2" sprocket is quite large!

    light chain, suitable for the primary drive, ie from the engine to first redux, but not good as the final drive.

    if going the weedwacker engine route, may i suggest using #25 or #35 chain, as the finer pitch not only runs smoother, it also takes up a lot less space for a given ratio...

    have you calculated the redux you need yet? cus 1/2 inch pitch is very hard to get enough redux without resorting to 3 sets of sprockets. just whacking some chain and sprockets together doesnt work :(
    Hittin1 likes this.
  5. Hittin1

    Hittin1 New Member

    Yes! You sir are the man... That is exactly what i needed to know About the chains.

    Now due to your comments and questions about the gear ratios, i started doing what i should have done in the first place, and further researched this topic. That being said i dont see any feasible way of doing this without the budget going too high. The 80cc bike kits in the $150 range seem to be the best route for my needs. But before i go that route i have a few more questions that will likely determine what i need to do. Hopefully you can and will answer them as best you can or anyone who can answer them will do so.

    Anyone have any idea about what the rpm range is for an echo srm-225 or srm-2210 weedeater motor is?

    For a 26" bike- what would the ideal gear ratio be for a chain drive setup using a weedeater engine? 66/80cc kit?

    Same questions for a 20" bike...

    Any other useful points i should consider?
  6. HeadSmess

    HeadSmess Well-Known Member

    hard to say. i take most "generic" two strokers as being in the 8000rpm range. theres a fine line between reasonable speed, usability and not being vibrated to death... calculate for 9000@35mph. gear too high, it wont ever get there, gear too low and things start falling off.

    26" about 18:1.
    the HT engines, with internal redux are... 20t on the engine to 82t on the clutch, followed by 10t on the sprocket to 44t on the wheel. do your own maths! thats the standard setup... each stage being just over 4:1, total redux has to be just over 16:1. this can be fiddled with at the rear wheel. i use a 36t myself. i think that gives 15.8 or so...

    20" i use a 28t on the wheel, everything else remaining the same. im also light, have a tuned pipe so have a bit more grunt, and while i may live in "the hills district", dont have too many steep ones around... just lots of little ones! could push 24, but felt much more user friendly with a 33.

    theres a calculator somewhere if you search for it on here... dont expect, or aim for, much over 30mph...

    yes, it can get expensive when experimenting and finding just one tooth in the wrong place can make a major difference... plus all the associated costs of bearings and such forth.

    the kit engines...be prepared to do some fiddling to get them spot on and...um...reliable isnt really the word, but you can be riding in just a few hours after opening the box. they also dont get in the way for when you DO have to pedal, be it the lack of fuel, or some other issue.

    make it yourself... scavenge the scrap yards, open the wallet, and if you havent got a lathe and a welder handy...give up :) or go friction drive, in which case i use 1/2" ID star washers on a bolt but thats a completely different kettle of fish!
  7. LewieBike

    LewieBike New Member

    What is the displacement of the Echo 225, Is it about 25 cc's? Most Echo small weedies including my ancient Kioritz 32cc, are best run fast and not loaded excessively. So I'd suggest gearing it for an engine maximum RPM of about 7000~8000 at about 25 mph. This works out to about a 28:1 ratio with a 26" MTB wheel. It's a small engine, you're not going to get a lot of speed from one, and forcing it to push a taller gear is going to burn it up.
  8. Hittin1

    Hittin1 New Member

    Yeah, One of the reasons i joined this forum was to ask you in particular a (probably stupid) question about a friction drive setup using star washers after running across an old thread where you poster a diagram of that setup. Here goes the dumb question. The star washers you refer too... Are they the ones with the points facing outwards (smooth inside diameter) or where the pointy parts are pointing inwards with a smooth outer diameter. I wanted to price them after reading your post and ran across both types with the same ID. I assumed it was the 1st ones i described but not 100% sure.

    And thanks for the other info as well. Your sense of humor and borderline sarcasm at times make the monotony of all the technical info a little easier. Anyways I'm glad you found my little thread and glad you helped out with all the info. Thanks again
  9. Hittin1

    Hittin1 New Member

    They are both 22.5cc echo's

    I also have a john deer 25cc w/clutch
    Weedeater featherlite plus 21cc no clutch
    All running

    Plus a few that need work but can run.

    One of the motors will be used for an outboard motor
    And i have a razor mini chopper (perfect cosmetic condition) that needs $80 worth if parts (batts and electronic controller) just aching for a weedeater motor w/jackshaft conversion.
  10. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    41 chain is 1/16" wider than 415

    415 is 3/16"
    41 is 1/4"
    Both are 1/2" pitch.
  11. HeadSmess

    HeadSmess Well-Known Member

    precisely :) 1/2 ID, and the OD was something like 7/8 from memory. too cold to sift through a box that maynt even have one at the bottom anyway... but you end up with a splined shaft that can be re-used several times as it wears, easily replaced if designed right, and as you saw by the price...costs virtually nil...

    why thankyou :)