Dual sport yanmar l100w which gearbox?

[Davi]

Hi new to the forum. Planing in converting a dual sport bike in medellin SA. Would the l100w fit in a xl 250 with a gearbox how much room do i need Also i could weld a larger cradel for it but would it fit. Or should i get a larger cradel bike. Also im thinking in buying a baker 6 speed transmission from jpcycles.com but is $$$$ or what other transmissions could i use, how reliable is the royal enfield gearbox is it 5 speed?

[Diesel Dave]

Welcome to the forum.

There are many options on the gearbox front but you may find the XL frame tight even for the L100 motor alone - there are resources online with the workshop manuals that have the dimensions of the engine casings that will guide you initially.

Enfield gearboxes are available in both 4 and 5 speed versions, but unless you have ridden a bike with an old brit gearbox before your in for a learning experience. TBH the 5 speeder is close to a Jap gearbox from the 1970's. They are both easier to fit in RH shift form or else your going to need a set on rods and linkages to swap shift sides.

There are ways to use an old Jap gearbox, but watch your direction of rotation as many are gear primary drive so you could end up with 6 reverse gears. Sam has an RD (RZ in the US?) 350 6 speeder in his VFR750. the casings are mounted vertically and the crank replaced with a plain shaft thats belt driven from the motor. Most of the Jap stuff has the primary drive on the RH side so you will need a cross jack shaft somewhere in the build and this will also increase the space needed.

Just for ref. the L100 with electric starter and Enfield gearbox/clutch is about 2 feet long:

[Davi]

Thanks
how can i make the RE Gearbox LF Shifting. Cant deside beween the 4 speed RE or the comet 700 series ? Really like the diesel kl400 on 21ponies.com

[UAofE]

There are so many options out there, avoid the RE gearboxes. They are some of the worst designed and worst shifting boxes I have ever worked with.

[Davi]

There are so many options out there, avoid the RE gearboxes. They are some of the worst designed and worst shifting boxes I have ever worked with.

Ok thanks

[Tetronator]

There are so many options out there, avoid the RE gearboxes. They are some of the worst designed and worst shifting boxes I have ever worked with.

Well don't blame them too much, they were originally designed for lathes, not motorcycles.

[gilburton]

I believe the original boxes were converted to left hand shifting using a shaft and linkage which could be retro fitted but you will need to weld on some brackets.
The right side shift is actually much better because the conversion linkage has too much slop in it.
You'll soon get used to changing gear with your right foot and braking with your left.

[Davi]

Would the comet 700 series cvt belt burnup quickly going up mounteins?

[UAofE]

If I were to build my bike again, I would not use a CVT.
Its great in theory but it really needs manual or electronic control to work well in low-RPM applications where 500rpm can mean the difference between acceleration and bogging down. They work great in toy applications (snowmobile, ATV) because the gas engines have 6000+ RPM to work with.
If you can find a 6-speed close-ratio manual you'd be much happier.

[gearhead1951]

If I were to use a cvt behind a diesel I would use a 1 to 2 step up to double the cvt rpm and then a 2 to 1 step down to run the rear wheel ! Cvt will run at its optimal rpm range as would the diesel !

[Diesel Dave]

There's a problem doing that, as idle speeds would be in the range 2400 to 2800 on the CVT input.

Had the same problem when I was considering using a scooter rear end with 2:1 gearing between the motor and the crank end of the scooter transmission.

[gearhead1951]

Yeah , it would likely need a clutch at the engine for starting off and sitting at idle in traffic but once under way the cvt would be able to operate as it should !!