JH Choppers, 2006 FXSTI EFI Chopper Project, Frame Modification

Welcome to the JH Choppers 2006 FXSTI EFI Chopper Project Page.

With 12 over fork tubes and a stretched gas tank, the frame will have to be stretched. The Down Tubes and Back Bone are cut out and replaced with longer sections.

Setting the Ride Height: The ride height is set based one air ride system on the rear of the bike. This height is locked down using a block of wood cut to 5.250 inches high. A second block of wood is cut to 5.500 and placed under the front of the frame. The frame is locked down to the table using several racket straps.

Measure Twice and Cut Once: With the goose neck measurement tool installed in the neck, an adjustable rod is placed on the end. This will translate a straight line to the table base through the center of the neck. A plumbob is used to mark several points on the table of the center of the frame. This line will be used to center the back bone and neck during the stretch.

Remove the Down Tubes and Back Bone: Cut the back bone and down tubes out leaving enough room for the motor mounts and forward controls. Prep the cuts areas for welding in the new DOM tubing and tubing inserts.

Prep the Neck: The neck is placed onto the milling machine for cleanup. The Back Bone weld joint is milled clean for the new Back Bone. The Center Support is also milled clean. New DOM Square tubing will slide cleanly back into these original mounting points.

Fabricate the new Back Bone: The stock 2006 has a square back bone, therefore the new stretched back bone will also be made of square DOM tubing to fit into the stock neck. A smaller inner tube is cut, prepared and pressed into the stock neck. The new 4 over back bone is prepared and slid over the inner tube for strong weld joint.

Fabricate the new Down Tubes: The new down tubes are cut and prepared with an inner tube of solid rod. The solid rod is bent to conform with the older frame for a strong weld joint. The stock neck is placed onto the new 8 over down tubes for a quick mock up. These dimensions will be adjusted to fit the stock seat, custom gas tank and 12 over fork tubes before stitch welding of the joints begin.

Install the new 12 Over Fork Tubes: The new 12 over fork tubes are installed into the stock fork lowers. The old fork oil is drained and the stock fork tubes are removed. The new fork tubes are installed and the new seals are pressed in using our delron seal press. The fork tubes are held with a fork tube holder purchased from KBore on eBay

Prototype the Front End: With the new fork tubes installed and placed into the triple trees, the front end is mocked up. This is needed to set the front end ride height based on the control blocks height previously set during the rear mock up. The back bone and down tubes can be adjusted for setting up the front end and gas tank. Spot welds will be used to hold the height until final welds can applied while monitoring the plum bob and goose neck alignments.

Finalize the back bone to the neck: The back bone and neck are placed on the bench and welded together. Since the upper part of the neck will show, additional welds and grinding is done for a smoother look during the power coating process. A second back bone support bar is cut and welded in.

Finalize the down tubes: The new frame is mocked up on the lift table with the plum bob and neck alignment tool in place. Stitch welds are slowly added to the down tubes and back bone seat position while monitoring the alignment tools. The front end is placed back on the bike to verify the ride height is set correctly before the final welds are completed. The final welds will be completed just before the frame is sent out for powder coating.

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