Turning 100 road toad cases into 125 cases

[DGardner]

Can the 100 road toad cases be turned into 125 cases? and if so what transmission can be used in it 94, 95 or just the road toad? Thanks DG

[dirty_rat]

The cases can be converted (as the castings for both are the same). You will have to open up the area where the cylinder spigot goes into the cases as it is too small on the 100 for a 125 cylinder. The cylinder bolt holes MIGHT (I'm not sure on this one as I don't have the two to measure) have to be filled in and moved outward. Hopefully someone with both cylinders or cases can measure and advise.

As for the transmission, the Road Toad had primary kick, and the 94 and 95 did not, so their transmissions will not work (at least without a whole lot of work and extra parts). Another primary kick transmission might work, but I'm not sure which would.

[viclioce]

Mr. Gardner! Just for grins & giggles I reached into my parts bucket and grabbed my .040 Combat Wombat cylinder. It dropped right over the existing Road Toad cylinder bolt rods, nicely centered. Indeed though, the case would have to be machined open to accept the bottom of the cylinder spigot, by about the thickness of the spigot, from casual observation. Didn't measure it though. Here's a photo of a Model 95 cylinder sitting on my Road Toad tranny! And a picture of the nicely centered bolt rods from the top! ; D Victor

[viclioce]

And here is a photo of the CW 125 cylinder spigot overlapping the 100 RT spigot. You can see there is even a bit of a gap between the 100 spigot outer dimension & the 125 inner spigot dimension. The only thing I can't tell you is the overall difference between the port openings in the cases, as I don't have a CW case to measure for comparison with the RT case. ; D Victor

[Bullfrog]

94/95 transmission won't work in RT cases. 03 Trans can work but cases need machining to accept wider gears of the 03.
Ed

[viclioce]

So would it be reasonable/unreasonable to run a 125 top end, assuming you overcome the figment issues, on the RT 100 transmission? I know they made 125 top ends for the 100 Rat/Ace motors. So would the RT tranny run OK with a 125 top or would the gearing be too different? ; D Victor

[Bullfrog]

Transmission ratios for all the Hodie street legal trailbikes were very much alike . . . With changes in sprockets handling the lion's share of the difference between 100cc and 125cc set-ups. The biggest exception to this statement was the early production Model 03 (red tank Wombat) which had a trials transmission. 1,2 & 3 were tightly spaced, then there was a big jump to 4th and another pretty good jump to 5th.

As for running 125cc power thru the Toad trans, that works pretty well and has been done a fair bit.
Ed

[viclioce]

Well I hope all this info & discussion helps answer Mr. Gardner's questions!!! ; D Victor

[DGardner]

Sorry I never got back sooner, I've been at work on a shut down. Thanks for the feed back. DG