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Old 10-19-2011, 08:48 PM   #855
Jason F.
Will Ride for Beer...
Jason F.'s Avatar
Joined: Sep 2006
Location: Smyrna, TN
Oddometer: 374
I want something for forest service roads, fire roads, gravel roads, and playing a bit on some farm land. I am poor. So lets talk reasonable goals for weight, front and rear suspension travel, and ground clearance. I am thinking of a new winter project and I have a couple options. I have a parts bike I could scrounge together with parts from the parts bin and I could sell off some parts to fund a better front suspension and rear shock.

What I have is most of an old Bandit 600
599.00 ccm (36.55 cubic inches) Inline 4cyl
74.00 HP (54.0 kW) @ 9500 RPM
99.00 Nm (10.1 kgf-m or 73.0 ft.lbs) @ 9500 RPM
6 speed and chain drive.
199.0 kg (438.7 pounds) Dry Weight
110/70x17 Front w/dual disk brake
150/70x17 Rear
41mm traditional dampener tube front forks.

Pros in terms of use off road:
  • Oil/air cooled motor of simple design.
  • No radiators to smash and only a small oil cooler up high.
  • Simple steel traditional perimeter frame and engine cradle. Easy to fab up skid plates and engine guards.
  • Fairly narrow engine (for an inline 4)
  • Traditional upright riding position and I found it easy to stand up on.
  • I already have it.

Cons in terms of off road use:
  • She is a heavy beast.
  • Factory suspension is poor and has limited travel.
  • Metal tank of odd contours (not easily modified/extended) and limited capacity also frame not designed in a way that would easily allow for adaption of a readily available aftermarket tank like a Clark.
  • I would have to buy a decent off road suspension and some wheels for it.
  • Front triple clamp has a welded in stem so swapping steering stems for triple clamp and fork swaps becomes slightly less easy.

So I am thinking an older but decent set of big dual sport bike forks and a wire spoke wheel to match those forks. Respring them for weight and throw valves in them if they are readily available from someone like race tech. Later model KLR stuff might be an option as it is a 41mm front if I am not mistaken.

It is pretty easy to modify the rear for height and it is common to swap longer GSXR or Busa rear shocks on the Bandits but that does not actually increase travel. It just gives you more ride height and a stiffer spring. If I recall the eye to eye length of the mono shock is in the neighborhood of 12 to 12.5 inches so if I could find something with decent travel close to 13 inches in length I could make that work even if it means making some new linkage bits.

There are not a ton of extra bits and crap on the bike so I am not really sure where I can pull much weight off of it. If I were to go with a narrow spoke wheel setup and a single disk front I am sure that would drop a few pounds. Getting rid of what fairings and plastic is there and making some sort of aluminum brackets for headlight and windscreen mounting would also drop a few pounds.

Other than that I would have to get radical for weight loss:
  • Cut off the steel rear sub frame and source or fabricate an aluminum replacement.
  • Ditch the heavy steel tank in favor of either a custom aluminum under seat tank or a plastic tank of some sort in a more traditional location.
  • Ditch the center stand (hate to do this) for weight and ground clearance.
  • Dump the stock cluster in favor of a digital unit like a Vapor or similar.
  • Ditch the stock 4 into 1 with a big shiny can exhaust in favor of a smaller lighter setup but I want to keep it fairly quiet.

Think is a reasonable starting point for a frankendualsport along the lines of those posted in the pages of this thread?
How light do you think I should try to get it or should I even worry about weight if it is under 500lbs?
Any good thoughts on suspension choices?
I have about a month to plan and brainstorm since I want to start in mid November when work slows down a bit for the holiday season.

Here is my parts bikes sister bike or approximately where I would be starting from, only in worse shape.

"I've come to realize that just about everything is none of my business." Br. Cassian Vigna
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