Thanks, Harry, for pointing out the obvious! I just used the Index of Ratio calculator. Looks like changing my rear sprocket one tooth nets 1 mph, so that's easy to remember. The 48t will be a good choice giving me 34 mph at 5000 rpm, a good cruising speed, and 54 mph at 8000 rpm. Who needs a transmission with a ton of torque?
Sportsman 200
- Thread starter sportscarpat
- Start date
My 2 cents on this amazing build is that you may want a smaller rear sprocket than 48. I'm going 34 mph at around 4 grand with a 6.4 ratio. Take off is still fine.
Vibration was killing my joy, so I heavily islolated the engine.
Vibration was killing my joy, so I heavily islolated the engine.
I'm personally running a 48 and love it. It's quick and it get's me into the 50 mph range and can take steep hills.
My plan is 48t cruising gear and 52t for around town and the track. I think mid 50 mph range is plenty and gearing changes are quick and easy with these split sprockets.
And is their a way to adapt; convert; pervert; your drive system to bikes built with one piece cranks ( like my modded Worksman)
A few updates on the 200. I finished up the front and top engine mounts. No easy task as there are no real available mounts on the GX200 engine where we need them.
I utilized the four valve cover bolts and tied them all together with a plate (girdle?) system that puts a tab close to the frame middle tube. Frame tube received a vintage style brazed on tab and then both points are bolted together with a couple plates.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Front frame mount is a lug with tab brazed to the down tube like the vintage bikes. From there I designed a plate assembly that bolts to the engine side cover as there is no mount on the front of the engine.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Rear mount was revised as well to spread the load through the bottom bracket and remove the direct load from the frame tubes.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
I utilized the four valve cover bolts and tied them all together with a plate (girdle?) system that puts a tab close to the frame middle tube. Frame tube received a vintage style brazed on tab and then both points are bolted together with a couple plates.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Front frame mount is a lug with tab brazed to the down tube like the vintage bikes. From there I designed a plate assembly that bolts to the engine side cover as there is no mount on the front of the engine.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Rear mount was revised as well to spread the load through the bottom bracket and remove the direct load from the frame tubes.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Here is how the bottom bracket tabs look with the rear engine mount assembly removed.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Updated rear mount that bolts to the tabs with three 3/16 allen head cap bolts. Curved slot is for pedal side tensioner.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Front frame mount is typical BTR design from original bikes. A lug and tab brazed to the down tube.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Since I had the whole bike torn down I threw the frame back in the jig and added more substantial rear dropout as well.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Updated rear mount that bolts to the tabs with three 3/16 allen head cap bolts. Curved slot is for pedal side tensioner.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Front frame mount is typical BTR design from original bikes. A lug and tab brazed to the down tube.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Since I had the whole bike torn down I threw the frame back in the jig and added more substantial rear dropout as well.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Here is it's present configuration with updated mounts and dropouts.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Idler system on the pedal side. Pedal side sprocket is mounted to an adapter that is keyed to the BB shaft. Easily adjusted left to right for chain alignment.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
With the split sprocket system on the engine side and the pedal side idler I swapped from a 48t to a 52t in less than 15 minutes. I still plan to add 1/8" anti-vibration rubber sheet at all three engine mounts to reduce vibration. After all these changes it's easy to understand why I don't paint my bikes!
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Sportsman 200 R2 by Sportsman Flyer, on Flickr
Idler system on the pedal side. Pedal side sprocket is mounted to an adapter that is keyed to the BB shaft. Easily adjusted left to right for chain alignment.
Sportsman 200 R2 by Sportsman Flyer, on Flickr
With the split sprocket system on the engine side and the pedal side idler I swapped from a 48t to a 52t in less than 15 minutes. I still plan to add 1/8" anti-vibration rubber sheet at all three engine mounts to reduce vibration. After all these changes it's easy to understand why I don't paint my bikes!
Sportsman 200 R2 by Sportsman Flyer, on Flickr
WOW Pat! you sure have been really busy. I really love how you used the lug and tab engine mount idea. Obviously you decided that the engine load needed to be spread out to all three tubes and the bottom bracket. How necessary do you think this is. Right now I have minimal mounting braces, attached to the loop and the bb only. You really have thought of everything. That pedal side chain tensioner is really well hidden. Again I am in awe of the build quality. I WANT A TIG WELDER haha
Pat, I have been folowing your build(s) and I certainly respect your work! (and your penchant for Fords) In reference to the viberation, I can just imagine how bad that thing gives you the tingle butt..and I offer this consideration. The method you have constructed the engine plate and the other 2 frame mounts would lend itself readily to the installation of "Barry mount" isolaters with very little re-design. (you will of course need room for them).. The ultralite and light aircraft industry has been using them for years and there are 3 different "hardness" compositions available for as little or as much movement as required. I get mine from Wicks aircarft supply, and out there on the left coast you have Aircraft Spruce and specialties, whom are also great to do biz with. Here is a link to a couple pics of my first forray into this realm of MB's..in which I used these mounts.
http://motorbicycling.com/f6/anti-vibe-mounts-34336.html
And one last thing..one engineer to another..if you can install them on at least 3 different axis..they will be about 20% more efficient in RMS frequencies and 30% to 40% better in Knocking down the peaks. Your Butt will thank you!...not to mention that beautiful frame you have created! IN my experience..adding rubber sheet will do almost nothing.
http://motorbicycling.com/f6/anti-vibe-mounts-34336.html
And one last thing..one engineer to another..if you can install them on at least 3 different axis..they will be about 20% more efficient in RMS frequencies and 30% to 40% better in Knocking down the peaks. Your Butt will thank you!...not to mention that beautiful frame you have created! IN my experience..adding rubber sheet will do almost nothing.
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I'm glad you upgraded your engine mount. I looks much stronger than engine mount 1.0 . The head mount combined with your new lower mount looks like the ticket. I like the way my handle bars and headlamp shake at idle so I won't be using any rubber mounting, Lol. It's a vintage thing 
. The pedal side chain adjuster is a good idea. Now your can mount your rear wheel for alignment and be done with it. The 200 looks really fine Pat. Good work! I want to see it in action.
. The pedal side chain adjuster is a good idea. Now your can mount your rear wheel for alignment and be done with it. The 200 looks really fine Pat. Good work! I want to see it in action.
cf is right, when I was selling my clone bike the guy that bought it from me asked me to start it for him and as soon as he saw the bike roar to life and start to shake he fell in love.
Pat I love your work. It makes me wish I knew how to braze.
Pat I love your work. It makes me wish I knew how to braze.
Brazeing is no harder then sholdering just need a little more heat. And today they have water cleanup flux insted of chiping. You should try it nothing to lose but a little time. The best would be a small torch that put the heat in more of one spot then heating a bigger area,a little better comtral.................Curt
Thanks for all the feedback, guys.
Dagwood,
Your mounts are nicely engineered. I need just a little isolation at this point and all those mounts are so thick. Looks like minimum 3/4". I just am amazed when I look at the old bikes. So much engine solid mounted to the frames. I would guess a v-twin is better balanced than a single. Just yesterday I was carefully checking out a custom Harley and it has a HUGE engine solid bolted to the frame!
Whitey,
Tie that engine in good. No shortcuts. It needs three mounting points. Frame tubing is not super thick. There are lots of ways to tie into tubing and different gusset designs. Some are better than others. Check out this site: Tony Foale Designs, article on stiffening standard motorcycle frames.
Lurker,
We did some finite stress analysis here at the office and compared different gusset designs. Brazing a lug around a tube was much stronger than welding a mount to the tube. Welding to the sides of the tubes with two gussets is far better than welding one gusset to the middle of the tube.
Dagwood,
Your mounts are nicely engineered. I need just a little isolation at this point and all those mounts are so thick. Looks like minimum 3/4". I just am amazed when I look at the old bikes. So much engine solid mounted to the frames. I would guess a v-twin is better balanced than a single. Just yesterday I was carefully checking out a custom Harley and it has a HUGE engine solid bolted to the frame!
Whitey,
Tie that engine in good. No shortcuts. It needs three mounting points. Frame tubing is not super thick. There are lots of ways to tie into tubing and different gusset designs. Some are better than others. Check out this site: Tony Foale Designs, article on stiffening standard motorcycle frames.
Lurker,
We did some finite stress analysis here at the office and compared different gusset designs. Brazing a lug around a tube was much stronger than welding a mount to the tube. Welding to the sides of the tubes with two gussets is far better than welding one gusset to the middle of the tube.
"finite stress analysis here at the office" don't use that language in here mister, your making the rest of us look bad. Hahah seriously tho you take this hobby to a whole new level. Thanks for the link, that should be helpful.
thankyou very much for the link Pat. It will prove very helpful when I go to work on my bike on Monday
The work that Pat is doing does and should raise the bar for all of us. Inevitably, this hobby is going to evolve. Strength and quality levels are getting better and more refined. If you think about it, it's not unlike a hundred years ago, except we have better engines, components and raw materials.
Pat, I really like what you're doing with the Sportsman 200. It's inspiring.
MHF
Pat, I really like what you're doing with the Sportsman 200. It's inspiring.
MHF
Very nice work Pat!
for my 2cents, isolation mounting of an engine is a poor substitute for proper balancing. there will always be a harmonic in a recip engine. best intention is to get it to an rpm that is not in the primary operating range.
Great looking racer!
rc
for my 2cents, isolation mounting of an engine is a poor substitute for proper balancing. there will always be a harmonic in a recip engine. best intention is to get it to an rpm that is not in the primary operating range.
Great looking racer!
rc