bantworm Posted September 14, 2007 Report Share Posted September 14, 2007 Could anyone out there in bogwheel land, please advise me as to the best modifications to do to my 1961 Bantam D7 frame for trials use. I have seen some really good photographs of frames on the Yorshire Classic web site and would like to add some more ground clearence to my frame by removing the lower footrest portion. I was thinking of adding two bashplate tubes under the cases and replacing the feeble front engine mount, with proper engine plates, cross drilling the downtube and welding in crosstubes for the bolts. Is this an advisable mod, or will it stop me being allowed in some Pre-65 competitions. The bike has B40 A/B type forks with QD spindle, though I dont have a front wheel at the moment, having dumped the Yamaha one the bike was shod with. I intend to keep the machine as simple and BSA related as possible, as it might have been in the late 60's if built by an enthusiastic Clubman. I know it won't be the lightest machine on the scene but I look forward to getting it dirty. Any assistance would be most appreciated. Cheers. Steve Quote Link to comment Share on other sites More sharing options...
overthehill Posted September 14, 2007 Report Share Posted September 14, 2007 i made one up many years ago the first thing you will need to do is fit a wider swinging arm to enable a trials tyre to fit - one from a c15 fits i think with some minor mods. throw away the original footrests and hang footrests from the rear footrest plates - fit new trials footrests as close to the bottom bolt as you can. i left the single spine frame under the engine but if you have the skills and the material twin tubes would give you a bit more groundclearance. i cut the rear loop of the frame and made up a flat steel hoop to mount a rear mudguard on. cant remember much more as the engine was so puny that i didnt use it much - a D7 engine is no use for trials - you need a D14-4 speed 175cc unit which you can tune up. which of course were made in about 1969 so it depends how strict your local trials are - although not that many people could tell the difference. good luck Quote Link to comment Share on other sites More sharing options...
bantworm Posted September 15, 2007 Author Report Share Posted September 15, 2007 Thanks for the info. Luckily I bought the bike in part trials trim, though very loosely assembled, and done many years ago. It has already fitted, some very smart footest hangers in thick alloy plate and some nifty, if rusty, folding footests and sprung rear brake lever. The frame is standard and a B175 engine was fitted, again with just two bolts. I bought it from good old fleabay, and it came with a host of bits including, three D7 engines and many other auto jumble trials parts. I have the 1969 B175 engine stripped at present ready for a rebore, as the unit is still on standard. Managed to locate a perfect NOS Hepolite piston for it, again via ebay at little money. I am replacing all bearings and seals and having the crank rebuilt, as it shows a small amount of big end wear. Thinking of having the MZ conrod and big end assembly installed if I cant find an original item. It was the Eastern Block Bantam after all. Plenty of fiddlin to keep me quietly occupied, and the frame is next for the drawing board. Regards and thanks again for your comments. Quote Link to comment Share on other sites More sharing options...
odgie Posted September 17, 2007 Report Share Posted September 17, 2007 I run a (heavily) modified D7 frame on my Sunbeam, which works quite well. If you drop me an e-mail at odgie633@yahoo.co.uk, I'll e-mail you back a shot and some details of what I did to it. :-) Quote Link to comment Share on other sites More sharing options...
bantworm Posted September 17, 2007 Author Report Share Posted September 17, 2007 Hi Odgie. Thanks very much, I look forward to seeing your machine and getting a few pointers. Much appreciated. I have replied by email with a couple of shots of the lump as purchased. Regards. Quote Link to comment Share on other sites More sharing options...
alan_nc Posted September 19, 2007 Report Share Posted September 19, 2007 Hi, I'm currently riding a 59 D7 in AHRMA competition in the U.S.. I have made several frame modifications. The rear frame sections (holds seat) has had the rails flipped - have pictures if you want. Also swapped out the front end for a Yamaha unit - was pretty much a straight bolt on, same bearings, just needed a spacer. I have doubled the rear peg mounts and am using them for my mounts - using Honda pegs. Using Honda rear shocks. Biggest help was an electronic ignition - also a very simple installation. Use a gas tank off a 65 since they are narrower. Also have ground off the tripple tree stops for tighter turns. Using a Triumph Cub swing arm, wheel, brake - it's the only way to fit a modern standard trials tire. If I can answer any questions let me know. Alan Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.