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Oddball countershaft sprocket needed

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  • Oddball countershaft sprocket needed

    Was headed to Alaska on my motorbike and the countershaft splines failed. Looks like they were bad off before hand, and the sprocket was installed incorrectly. Replacing the shaft is out due to time/money. I can make a flange that attaches to the shaft using existing threads and lock in place with a bolt. Then bolt a sprocket to the flange. The flange is no issue, but I've not been able to come up with a sprocket that would either work as is, or be easily modified. What I need is:

    520 Chain, 16 Tooth
    No hub
    ~1.375" center bore
    5-1/4" holes on ~2" circle
    Reasonably high strength alloy, heat treated.

    Can do any necessary machining for the bore and bolt circle, and get heat treated in town, but can't find a suitable blank. I could thin down a blank #50 sprocket to work with, but I can't find one in any specified alloy. McMaster, MSC, etc. all list material as 'steel.' Have called a couple custom bike sprocket shops, but most only manufacture rear sprockets in house.

    Any ideas?

  • #2
    There's a UK based company that will make you any size, shape, hub, spline front sprocket for any bike for a very good price - but you'll have to phone him as he has no web page. No idea if he posts overseas but you can find out easily by picking up the phone:

    John Hemming Engineering Tel: (044) 1547 530759
    Peter - novice home machinist, modern motorcycle enthusiast.

    Denford Viceroy 280 Synchro (11 x 24)
    Herbert 0V adapted to R8 by 'Sir John'.
    Monarch 10EE 1942


    • #3
      Year, make, and model of bike? And or a picture?


      • #4
        Buy "steel" of whatever composition is available. Make more than one. If you wear one out replace it. Enjoy Alaska.


        • #5
          Are you stuck on the road somewhere? If so, where?
          Free software for calculating bolt circles and similar: Click Here


          • #6
            Industrial use off-the-shelf sprockets will all come with hardened teeth, the core of the sprocket will be softer and machinable. A 520 sprocket is .227 thick, which is an ideal match for the .250" bolts that hold it in place even if its only hardware grade steel, which it won't be.
            For a touring bike I can't see a problem with using a McMaster sprocket, if you are worried about its longevity make a spare or 2 while you are at it.


            • #7
              1997 BMW F650. No pics on this machine. Was stranded in southern Illinois, but caught a ride home to Tennessee with some friends returning from Kansas. This happened on day one of 2 month trip. Better southern IL than northern Alaska I suppose.

              Nice to hear the industrial type have hardened teeth. I've got a friend who's uncle's shop regularly machines hardened bits, so he's going to modify a couple stock motorcycle sprockets. One less thing to worry about. But if that falls through I'll get in a few from McMaster and get on with it.

              Thanks for all the suggestions! When I get this bodge in place I'll throw a photo up in this thread.


              • #8
                Come up Hiway 97 through central BC and stop and visit here, for repairs if necessary. It's a direct route to the Alaska Hiway. Go back via the Banf/Jasper National Park. Spectacular scenery. Or, the other way around. PM if you are interested.
                Free software for calculating bolt circles and similar: Click Here


                • #9
                  $18, in stock, 16tooth 520 chain sprocket for your model bike:


                  • #10
                    If you take highway 97 north, consider taking highway 16 west through Smithers to the Stewart-Cassiar "highway" - joins the AlCan just west of Watson lake.
                    You'll have to drive some gravel, but the scenery is spectacular, and you only have to cross one steel decked bridge - over the Skeena river. Going the other way through Prince George at least 2 steel decked bridges.


                    • #11
                      +1 on the Cassiar (HWY 37)
                      On the up side it is 200 miles shorter than HWY 97 and has better scenery imho.
                      On the down side.
                      Lots of loose gravel.
                      RV's driven by folks who received "Official" drivers licenses from Cracker Jacks looking at the scenery.
                      Trucks at night trying to get by the RV's.
                      Very few services.
                      Can be in excess of 250 miles between gas points (lots of marginal gas stations closed due to the economy).
                      NO CELL SERVICE!
                      You miss Evan and the Liard Hot Springs.
                      Last edited by MetalMunger; 06-03-2011, 03:07 PM.


                      • #12
                        I'm south of Prince George by 150 miles. There are several ways to go north from the western US. I assume that because there is no point in crossing Canada since from Winnipeg west it is flatter than piss on a plate and just as interesting until you get to Alberta.

                        If you cross into Alberta then the route to take is to either proceed to Calgary and turn left on the Trans Canada Highway 1 to Banff. Or you can cut over on Highway 3 near the border and cut over to the south east corner of BC and head north on 93 from Cranbrook. Heading north to Edmonton is a waste of time. The traffic is heavy and the land is flat. Then you have to turn left at Edmonton, more traffic and more flatland until you are close to the Rockies.

                        If you cut west either at Calgary or on Hiway 3/93 north then you have a choice of heading west when you get to Hiway 1 or going north on 93 through the National Parks. Whatever you do make sure you don't miss the parks. The scenery is absolutely spectacular, the best in the world and of course there is plenty of camping. You can catch it either direction, going up or coming back, but don't miss it.

                        I'm on Highway 97 which is in excellent condition these days. They are 4 laning the entire thing and a lot of it is recently repaved with a speed limit of 100 kmh. It is probably better to head south on your way back via 97 as you will be in a bigger hurry to get home on the return and 97 is a more direct route to the US.

                        Incidentally, I will probably be out of town the first week of August as I will be attending the Mt. Kobau Star Party near Oliver in southern BC.
                        Free software for calculating bolt circles and similar: Click Here