Possible Mods To 1970 Model 49 Parts Bike

[rootsman2]

HI, I have a total parts bike: Model 49 motor MAYBE 1970 (with the shift on the right which is unusual in the states), a frame from a 1974 350 (serial number in the 90's) and tank/panels from a real 1970. Except for the brakes, it has been nicely restored including a new electronic ignition. I previously posted about the front brake but have no idea where I posted. I apologize. The front brake is so bad you can forget any downhill and the bike is dangerous to ride. I have two artificial hips so I must have a stopper. I bought a Sherco ST 300 and sold it after 2 months because I hated the modern bike and I don't want to be a xtreame rock hopper. I feel the Bull is a elegant, classy, and I love to ride it. Most of the feedback seems to point to a Pershang front wheel/hub and putting SM shoes all the way around. We have a local rider in expert class with this mod to his 350 and he is up for helping me. Here are some other ideas I would love to have some feedback. (1) I read in this forum (lost the post) about replacing the springs in the forks - any direction here would be great. I read about swapping out OSSA components but I'd rather keep is simple (2) I read the early 325 were 250 bored - how could I find parts/info about boring out my 250? Remember, this is a total parts bike and does not have collector value. (3) My local rider friend welded Sherco footpegs further to the rear. Thoughts? Finally, I really wanted a front disc brake and that seemed a total dead end until I met Yrjo Vesterinen. He build a parts bike over the last three years and - he's got a disc front brake. How did he do that? I'm going to add some photos shortly to this post. I'm for any mod and am not worried about class status ...thank you all so much. Travis

 

If you close at 'WhatBikesThis' I first thought he made a front disc - now I am not so sure but I'd still like to know what system/type it is! Thank you

Edited October 14, 2016 by rootsman2

[johnjsy]

Hi Rootsman,let's see if I can help a little.First off,if you are quite heavy,a recognised mod is to use Pursang springs in the forks as they are a bit longer than the usual Sherpa ones. I use aftermarket Magicals in my Alpina. Next,I have not tried this,but have seen mention to use a Yamaha brake cable on the front as they are made much heavier than others,resulting in the outer not compressing when braking hard.Look for 77-84 YZ or DT 125 MX. The brakes are known to be feeble,another piece of info I came across is to use brake lining used on fork lift trucks. I did this on a road bike,it now brakes really well.Engine. All trials models used a 60 mm stroke. The M92 & Alpina M99 are unique. The crankshaft is slightly bigger in diameter than the 250's , but I think the cases are basically the same. If you put a 250 centre gasket on a M92 case it overlaps inwards a little towards the crankshaft,needing a little careful trimming. This I did when building my M92. Important!!! Use C3 clearance bearings when building the crankshaft. Also a good idea to use a roller bearing on the flywheel mag side. It is a NJ 205 ECP/C3. That's a SKF number. These 326cc motors give loads of torque when set up nicely,a delight to ride.i hope the above is of help,and wish you well.

[rootsman2]

Thank you so much! I decided to leave the 49 motor as is and look for a 325. The springs in the forks is an easy mod so I will work on that; it looks like I am getting a later model (larger) hub next Sunday. I will work on getting the shoe liners from the fork lift. I am about 100 kilos (215 pounds). Thank you so much!