Why can't 4 strokes have shift kits

[cmb271]

I really don't understand how with the years put into research and development of motorized bicycles how come no one has come up with a shift kit for the 4 stroke engine, I do understand that their is a clearance issue but a shift kit could help with speed, climbing hills and while some people would say go to a 2 stroke, I had a 2 stroke and that thing was a lot more trouble then it was worth to me and after a good 30 mins of riding it would vibrate so bad I couldn't sit while accelerating unlike the 4 stroke where I can go full on and sit somewhat comfortably. I need a shift kit for speed but I need a 4 stroke so I'm not standing all the time, there's always an option but i'm just not seeing it.

 

[Old Bob]

Laws regulating motor bicycles limit what can be done.

 

[Bonefish]

http://www.sickbikeparts.com/catalog/product_info.php?cPath=21&products_id=110

 

[wheelbender6]

The Huasheng 49cc can use a sickbikeparts shift kit.

 

[KCvale]

how come no one has come up with a shift kit for the 4 stroke engine?

As mentioned above sick bike parts has one, and they work pretty well...

You usually need to make some sort of right side tensioner so you don't have to move the engine mount base.

There is also a new 10G 'long shaft' transfer case with the output shaft the length of a jackshaft.
I just got it in an will start the mount base with carrier bearing design later this week.

4-stroke shifter? Ohh ya, there are 4-stroke shifters, I like 'em, a LOT ;-}

 

[cmb271]

well my state law is against it but they don't really check me when I ride past a cop

 

[KCvale]

With an internal shifting wheel, like a shimano 3-speed, it doesn't look like the bike even has gears, hence the yellow bike I posted.

Unless you have some really long uphill rides I find an internal 3-speed to be the perfect wheel for a jackshafted bike.

It has the same range as a typical 7-speed, just fewer steps between lowest and highest gears.
This is good because your engine doesn't need them anyway, it will run with no gears which is about what 2nd gear is.
1st gives you a torquey low gear and 3rd gives you overdrive.

The best part is it's a fixed single rear sprocket, and you can use HD 410 single speed chain.

 

[2old2learn]

After driving a 630 mile round trip yesterday I now have my Honda 50cc four stroke mounted on a 16.75 to 1 reduction drive and a pedal axle shift Kit, that I'll get to install over the next week or so, powering my 21 speed Specialized Rockhopper. I plan to take it by my local Specialized dealer tomorrow to have them install the pedal hub assembly. After that I'll get to mount the egine and reduction drive over the back tire to power it through the pedal hub. While I'll have 21 gears to play with, realistically I'll probably use 7 or 8 most of the time. I still haven't come up with a bike center stand yet, any suggestions?. I've looked at the Ursus Jumbo but I'm afraid it may not be tall enough to use on my 29er. Ive considered using two adjustable side mount stands so I can balance it straight up between them. Might have to find a way to have a parking brake so it won't roll forward or backwards. A center stand would be best.

 

[The_Aleman]

hey 2old2learn, I use a Crow Cycles centerstand on my shift-kitted 4G. It has worked great for over 3 years.

It's a little heavy, but built _very_ well, it can even handle my weight (230lbs). Only $23 + shipping.

link: http://crowcycleco.com/double-leg-kickstand-screw-adjust-black-extra-tall

on my bike: http://www.motoredbikes.com/attachment.php?attachmentid=46760&d=1353142112

 

[2old2learn]

I'm jealous. Awesome bike!!! I'm building a utility bike to be used for a drop vehicle for my outdoor hobbies/passions. My boys have grown up and now I've got to find a way to hike, canoe, backpack and hang glide by myself (no driver). When hang gliding generally there are other pilots so the bike will be a backup option. Due to the steep roads up these thousands of feet high launch sites, pedaling up them after a several hour flight at nearly 60 years old just doesn't appeal to me anymore!