First Gen shift kits

[midwestmayhem]

Hey everyone, new guy here

I finally got around to registering, great forum here, been cruisin' it for months...

I have two motorized bikes, one is a 66cc made from a kit, the other is a custom with a robin 5hp. I'll post some pics of them later. Still perfecting both, of course

I did some research on sbp's shift kits and discovered they had two different designs, the first generation, and the style they're selling know-the second generation. Why was the design changed? Did the first put too much stress on the case of the motor? Is the second stronger than the first? Or was is simply changed to make it easier to work on the motor itself? Thanks

 

[BarelyAWake]

Cloned copy of first gen;

Second;

Third (current);


To my knowledge they're on the third release, the first looking very much like the second just w/o the side plate reinforcement (the cloned Chinese copy w/no reinforcement at all is a copy of the first gen). Side plate flex, lateral alignment & complexity still being somewhat problematic with the second, they came up with the third, the "one piece" design currently available...

I've a second gen on my '43 & while I love it, so much in fact wouldn't build another MB w/o a jackshaft - plate flex under heavy load & abusive riding can lead to the cross shaft eventually "walking" out of the bearings, lock collars notwithstanding. It's just a maintenance issue and can be modded to prevent this problem - but the third gen's shorter side plates & unitized design should fare better *shrug*

Second generation, bearing plate on the left side has reinforcement, right side (2nd pic) has no reinforcement, motor mount plate & side plates being separate also allows flex, small L bracket included to affix engine mount plate to right side plate insufficient to prevent flex entirely, metal fatigue caused L bracket to snap eventually (aprox 4000 miles);

 

[midwestmayhem]

So the single piece is actually the third gen. My mistake, I thought the rienforced first gen was still a first gen, and not the second gen.

So flexing is the major issue. Go figure, I'm somewhat of a hard rider too. Anybody ever tried rienforcing the first, second, or even a third gen's bracket? If so, how did you do it? Thanks

Oh ya, and Merry Christmas Eve!

 

[BarelyAWake]

No worries, I don't think the unreinforced first gen was around for long... mebbe it would be better called a prototype *shrug*

I unno if I'd go so far as to call it a "major" issue, I suspect the primary reasons for the one piece 3rd gen is simplicity & ease of installation/maintenance - but a bit of flex has been an ongoing problem with my 2nd gen with it's modded motor (assorted performance alterations), mileage, and ofc my habit of pounding on the thing

TBH, other than when I eventually snapped the small inner L bracket used to support the right side plate (originally aluminum, replaced w/steel) which allowed the side plates to spread enough to dump the shaft (exciting & a fun roadside repair lol) - the flex is minor enough that it usually only requires a periodic readjustment of the jackshaft, sprockets & lock rings' alignment... which while mildly annoying, wasn't quite enough for me to bother altering the shift kit's design... or I've too many projects... or I'm jus' lazy, take yer pick

It is an issue tho and I should prolly do something about it (mebbe bridge the rear of the plates), under hard acceleration you can see the plates spread a fraction & this over time is the only thing that has ever caused me to need to maintain or repair anything at all w/the kit - should I fix this issue, I should be free to ignore the thing save the occasional chain tension adjustment & shot of lube.

 

[midwestmayhem]

cool, I thought the flex issue was major. I've done enough customization, should beable to think something up. I had an idea to bridge them, like you mentioned. Maybe one across the top and another across the bottom, tieing all three plates together.

While on the subject of customization, I'm planning on making my own kit, using the same general idea for the plates as the second gen. I have all the necessary tools and I even have access to a cnc plasma. Anybody have the dimensions of the three second gen plates? Especially the distance between the bolt and jackshaft holes on the two side plates. Pic's with dimentions would be awesome, if at all possible. Thanks

 

[BarelyAWake]

I dunno if I'd go through the effort of trying to replicate the SBP shift kit exactly, if you've fabrication skills & the tools necessary to do that - you may be far better served to design your own, specifically around what you want & for your build.

While I do like the shift kit, the only reason I purchased one was not having to fabricate it - there's a bunch of folks that have made their own, simpler versions (try "jackshaft" w/our google custom search). There's almost limitless potential in design, while obv it won't work w/a standard bicycle (a bottom bracket usually has a pedal crank in it lol), here's a coupla pics of the jackshaft on my taddy project using a low cost BMX freewheel, as an example;

 

[midwestmayhem]

sweet project, looks like those bearings fit into that crank housing pretty well.

The idea I have at the moment is for my 66cc kit bike. The bike is a mountain bike with the normal diamond back frame. My intent is not to completly dulpicate sbp's kit but to get the location of the jackshaft compaired to the motor. Sbp's location of the jackshaft is near perfect for my style of bike. Maybe I can just eyeball it.

 

[midwestmayhem]

I uploaded pics of my 5hp Robin build to my album and to my new thread I'll be making in the general discussion forum. I used a drive system that isn't normally done. Anyone is free to check them out