trials frame modification; Wombat

[cuzncletus]

I have a 94A basket case project that I want to make into a trials bike. My brain is full, but I remember reading somewhere a recommendation to de-rake the forks 1.5 degrees. This isn't an issue for me, but I'm wondering if this is beneficial for a novice (older) trials rider like myself.

Also, any tips on getting rusty forks back into shape or reasonable replacements?

[Bullfrog]

Yes, modifications to reduce "trail" can be achieved by reducing "rake". Stock Hodaka steering geometry is 30 degrees of rake (and I'll have to get back to you on the trail spec.) Anyway, by adjusting (reducing) "trail", you'll end up with more neutral steering. The bike won't be trying to (all by itself, due to geometry) straighten out a turn all the time (which the rider has to "fight"). Rake can be reduced by 5 degrees (more if you really know what you are doing). I'll try to get back with some trail information - which ought to be the REAL focus of the modification. NOTE: Hodaka Club Members can access back issues of the Club newsletter, the "Resonator Revisited" where multiple articles on rake and trail and trials bike "builds" are available.
Ed

[viclioce]

I always wondered about converting a Hodaka enduro to a Hodaka trials bike. Don’t you have to make significant changes to the gears on the main and secondary shafts so as to change the gear ratios, making them much lower? Are there separate gear sets out there for doing this? Just asking for clarification. Victor

[Bullfrog]

A whole bunch depends on whether one is doing a "full bore" modification (trying to make a pseudo-factory all-out Trials machine) - or doing a "pretty darn good" modification with what-cha-got.

All-out factory trialers commonly have the 1st three gears closely spaced with a pretty big jump to 4th and another healthy jump to 5th. This allows maximum flexibility matching a gear with the particular challenges of a given trials section, while retaining the ability to get some speed up on open trails or roads.

The vast majority of Hodaka trials builds use the standard transmission which came in the respective engine to begin with . . . and major sprocket changes to "gear" 1st and 2nd for trials use - which results in pretty limited "road" speeds. (But that's OK, cuz the machine is truly intended for handling gnarly off-road stuff.)
Ed

[junker2k]

If you only change one thing it should be the rake, set it at 23.5-24.5 degrees. This seams to be where the bike likes to turn the best and this is where all the modern bikes are set at. The next thing is moving the foot pegs back and set as low a possible. As far as the motor goes I would use the 125 wombat motor. Changing the gear ratio it is done with the crank on the clutch side. Ron L. ( he is on here) takes the 125 crank and splits it and puts a 100 crank half on the clutch side. Hodaka made a few different gear ratios in straight cut gears for the 100's. The article I wrote about building a Hodaka Trials bike will give you all the other things that can be changed. NOTE: Hodaka Club Members can access back issues of the Club newsletter, the "Resonator Revisited" where multiple articles on rake and trail and trials bike "builds" are available.

The worst mistake that can be done building a trials bike is to try to add ground clearance under the motor. All this does is raise the center of gravity and make the bike less stable. Jumping large logs or rocks is NOT done with ground clearance but with technique! Give Jay L. 2 inches of ground clearance on a bike and he will show you how to get over a 3 foot log with both feet on the pegs. KEEP the foot pegs low.
Jack K

[cuzncletus]

Can the rake be set by having the low engine cradle horizontal, then measuring the angle of the steering head?

I'm also having trouble navigating to the Resonator Revisited. Please excuse my computer illiteracy, but I could use a little help.

[Bullfrog]

No, you need to have the machine standing upright on its tires on a level surface when you measure the steering head angle (rake). Measuring trail is a bit more complicated. When you get into the Resonator Revisited articles you'll see.

Log into the Hodaka Club website - up near the top right (right end of the "menu" choices) you'll see a little "box" made up of three short horizontal lines - click on that. Then search for members only stuff and back issues of the club newsletter.

Ed

[matt glascock]

As the Captain stated, there is a wealth of information on the Resonator Revisited back issues page on the Club Website. Also included on the Club site is an index for the back issue tech articles which will streamline your search. Additionally, on the Hodaka-Parts (HPI) website, there is a library of original Hodaka/PABATCO publications including two for trials modification which could also be a good resource for you. There may also be information on the Strictly Hodaka website.

[viclioce]

Great info! Thanks everyone! Not really interested in making a trials bike, just remembering the ones I occasionally got on 40+ years ago! Victor