Chain tenson and sproket alignment

Discussion in 'General Questions' started by Robot, Nov 28, 2014.

  1. Robot

    Robot New Member

    Well as you can see my progress has ceased for a few minuets on this old Wards build. I've got the jackshaft mounted and sprocket alignment is within a few degrees of perfect very close but these sprockets will not allow the chain a close fit and I've found that common on the other bike I'd assembled. Has anyone had to correct the sprockets with a file or grinder ? I've noted the problem appears the sprocket set in the jackshaft kit likely to be the cause I'd change these out for a stainless steel set a replace all of them to get this smooth glide the only way this set works is with running loose chain all way around on it.. Any suggestions ?

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  2. Bzura

    Bzura Member

    First suggestion - toss that exhaust pipe in the trash! Those do NOTHING at all for performance.

    I've never had a problem with the sprocket's working with either chain on several SBP shift kits I've used. There are several knock-off kits out there, but I never took a chance with one. You definitely DO NOT WANT LOOSE CHAINS when running a shift kit.
  3. Robot

    Robot New Member

  4. Robot

    Robot New Member

    Well it's simply location of sprockets on this set up accord the number of teeth the number is correct the chain can't be shortened the only option is a larger sprocket to create more tension on this setup I've had to switch to 17 t to the 11 t off the 10 t that works best on this setup and I did install the steel spacer but had to reposition it and reset the mounting bolts to line up both sprockets. These sprockets can only be tensioned by changing the diameter of sprocket or adding an idler the number of links can't be changed. Although the chain appears loose it's not and will not allow stretching beyond placing the master link there's no slack on one side or the other in that respect.
  5. Robot

    Robot New Member

    The bottom or final chain won't fit without the 1/2 link ...That's why it's not connected .
  6. Robot

    Robot New Member

    The Nexus 3 speed is 1.3 /1/ .67 off the final which is nearer 55 teeth by eye I didn't count the teeth but this arrangement should be good from stop without much effort and hope is with the power curve of the 2 stroke just above an idle to 4000 rpm or so without stretching the Lucas #2 mixed with 89 octane beyond that to constant full throttle operation ...some of them only operate at full throttle
  7. Robot

    Robot New Member

    Yeah must be my imagination thought I was assembling a motorized bike for one computer animated minuet wow was that frightening ...
  8. Fabian

    Fabian Well-Known Member

    @ Robot

    make sure you have the correct centre to centre shaft measurement between the engine output shaft and the 17T Jackshaft sprocket. This is achieved by filing down the engine mount boss; enabling the chain to fit around the sprockets at the tightest point in the accentric 415 10T output shaft sprocket.
    The issue will be (every single time) that there will be way too much chain slack at the loosest point in the rotation of the 415 10T sprocket. This problem is easily fixed by installation of the optional left hand side chain tensioner, which also doubles as a secondary stabilistation device for the jackshaft; reducing wear and chain vibration to minimal levels.

    I set up the chain on the right hand side in a loose fashion; looping it around the large jackshaft sprocket; attached to the freewheel and the bottom bracket cartridge assembly, then rotating the pedals to pop it on the standard 44T or optional 48T. This method gives easy installation of a new chain; allowing you to set the engine in position in the frame, and never again needing to adjust chain tension with the chain tensioning rod, albeit with the addition of the right hand side chain tensioner, which will take up the slack all the way to 100% chain stretch.

    I option the right hand side chain tensioner with TerraTrike (Deluxe) 10 tooth flanged ball bearing idler wheels, as shown below:

    and can be purchased either through Greenspeed or through any of these locations:

    or here:

    or here:
    Last edited: Dec 3, 2014
  9. Robot

    Robot New Member

    Well I've noted that and thanks for the review. This project is out of the box without instructions. I've assembled the jackshaft correctly after making two annoying mistakes and correcting them. The engine mounts tightly to the unfiled spacer steel block the position of mounting studs lowered. This allows the sprockets to line up on both sides nearly as well or as poorly, take your pick as the method advised by all whom I've reviewed installing the engine/jackshaft steel mount which by the way was not nearly accurate enough to feed the sprocket mount through the bearings without a fight. Well I'm sure most will disagree but I'm running 1/8'' x 1/2'' bell 300 and more slack than recommended but the kit is on and in working condition which I'd expect as light but tough as the chains are they will likely work until they are worn out without banging the three speed by dumping the clutch at full throttle or shifting at full throttle hours on end and in attempts to make the little Nexus 3 speed vomit parts out the side of the housing.. And now the struggle to mount a single side pull brake on the bike frame and the correct angle in a steel setting well enough to grind 999 silver off the rough diamond countersunk and set in the AS7's . Yeah I'm insisting the brakes work once center well enough to scarcely touch them if the dust stay in place likely they will. I'll run this setup if I find the chains too lose I'll increase the sprocket diameter a tooth or closet size that will fit. This is the easiest for this setup without more cutting or filing on the engine case or the steel mount.
    More the problem currently with this frame is the bicycle frame itself was not correctly centered when manufactured as it is the chain will not follow the two sprockets thus the axel must be cheated creating a dogleg the tires will not follow a perfect centerline on this likely it was common on this bicycle but I've never heard only seen that the set screws mounted in front of the axel correct chains alignment and as well create the dogleg. Well it will cause excessive tire wear likely but I'll keep the frame as I'd received it. I can or can not correct the chain alignment well enough to allow the chain to remain on the sprockets you decide.. Now I see why this bike is rare or possibly priceless if there is a difference between the that and worthless. I'd actually think the sprocket on this original bike was outside the bicycle frame due the manner in which it is constructed it does appear undamaged and original. No need mention I've reviewed the condition of the bicycle frame and sprockets on the final drive off the jack shaft. The wheel must be removed the frame may need to be filed to align the two sprockets the slack in the chain can be corrected but the position of the wheel itself is enough to cause delay in progress. Yet another edit this is the 4th or 5th After one more look at the bicycle frame I'm convinced it is ether custom made or was motorized due the offset in the lower half of the tubing. I'm not sure it's original and of the 1930's or earlier it could be. It will take more time to center the peddle crank sprocket and 3 speed sprocket than I'd prefer. Simply angling the wheel is not going to be reliable and rater than file the bike frame I'll get the ~1/4'' from the wheel somehow. This project has been beyond difficult without a machine shop and advanced tools of every description..
    Last edited: Dec 5, 2014
  10. KCvale

    KCvale Motorized Bicycle Vendor

    Hey Robot,
    did you know you can hit the hit the Enter key now and again to put some space between your ranting's so they are least readable?

    There are instructions galore for everything SickBikes sales here

    This is the 2-stroke shift kit manual. Manual001 Rev A.pdf

    Considering I have built 18 2-stroke shifters with none of your problems perhaps you might to read the instructions?

    Just a thought considering your insistent new topics about how nothing works for you.
  11. Fabian

    Fabian Well-Known Member

    I am in total agreement with that advise

    :iagree: I have no idea why Robot keeps making noise about endless problems with the shift kit, of which i have experienced nothing but ease of assembly and success with my shift kits, especially with SickBikeParts now offerening left hand side and right hand side chain tensioners.

    I have wanted to say what you have said, and thankfully you have said what you have said, so i don't need to say it.

    :iagree: and another +1 from me !!!
  12. fattirejack

    fattirejack Member

  13. Robot

    Robot New Member


    Sure I'm not the best poet on the website OK ..

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