pschrauber

Did all went as expected or did you found any special issues? As I have a 312 too I'am curious about how the build went on?

Yep to any meanical driving gear should be a felt ring soaked with an oel grease mixture btw. The drive to the Sherpa and Alpina is located at the rear not the front to my personal knowledge. Then the gear consist of a hyperboloid gears so it is impossible to tell you the geraing. These rear drive speedometer drives are sadly very rare. I am frequenlty looking for speedo gears front especially but too look at rear ones. I only found one used speedo gear in good shape in the last ten years wich I now have as a spare to myy 199b so far...!!!

Cool to get now information of first hand. recently there was another trialsbike with the frontwheel drive around, this time a Fantic 240 and obvious with the a drive that must have been manufactured by your father. See in this video and the following sequeces from the D-Cup Trial in Augsburg, 01.10.2022: YouTube Video D-Cup Augsburg 01.10.2022 - 03:05 - 03:55, - 05:45 - 06:16 - 16:10 - 17:25 (the best capture I think). Are their still 2 wheel drive set up's left? How many have been build?

You find good Interest groups on Facebook for that purpose, as I have a 242, why I am in the 242 group which indeed has a lot of information depending that model. But isn't this forum and especially this department all about Montesa bikes too? Thus I would like to have all information here and if I can would contribute to this Forum if in need first. So what information do you need?

The Japanese bikes are easiest to work on and of highest build quality, at least Yamaha and Honda. Four strokes have more engine parts and are expensive IF there is a problem. Then the Italian bikes where SWM with it's Austrian Rotax engine stands out in build quality, then Fantic then the other brands. The Spanish bikes are good some very good like the Montesa 242 but in terms of reliability third.

I have a well used original front light lamp mask combo if in need? Details PM.

I would too look up the gas cable installation and how the idle screw that adjust the slide is set up. With new and different carb I adjust the idle screw so that it allows the slide to close completely. When the engine fires up I then use the throttle to keep the motor alive while turning the idle screw in until the engine have a steady run. I then readjust the screw once again when the engine is warmed up and finally when I have adjusted the the petrol or air screw and the jets.

Well cheap stuff has a price and that is quality. It is the same issue with very cheap bicycle tires these are too often uneven in production. I personal buy tires from my workshop and the workshop has to mount them too. It might cost 20 € more but mot to change the tire myself and too being sure to get quality stuff is worth the money in my opinion.

I would in your situation clean the carb, the jets, nozzles, gas sieve and adjustment screws also the gas line and the petcock, then look up for cracks in the manifolds or not thight hoses, last not least replace the plug. Then I would clean up the air filter and make sure that the air flow to the air filter box is good. To the ignition the usual things, points gap, ignition timing, capacitor and how good the wires are connected especially between wire from the coil to the spark plug connector. Last not least wash out the gas tank tank and use fresh petrol. I press my thumps that the bike might start and run then.

Jep the con rod ends should definitely run free of any friction, neither piston pin nor lower crank pin should feel any kind of rough in iny direction. You have chamfered the two holes in the piston?

That is a goid question about the flexible cable and hose, you have to ask the inventor. The idea and the shaft is from the beginning 80's so I don't think there will be much useful information left even if the inventor is still alive and still living there where he lived back then. I have the adress of the inventor from back then if it is of interest?

To my bikes sometimes the inner tire creeps sometimes not. It happens to Michelin and too to IRC. In my experience it did help to get the valve streight again and then during hibernation pump up the tire to 1.5 to 2.0 bar and leave it over the winter / a couple of month, that has cured it so far to my bikes. To reposition the valve my trick for get that done super easy. 1. Loosen the tire fasteners, 2. Just take out the air pressure. 3. Roll backwards while steering sharp curves (backwards slalom) and after a couple of meter the valve should be straight again. Works with front or rear tire! 4. refill air. 5. tighten the tire holder mounts. Takes 5 minutes and is super easy.

There are some dealers in the US, that still have and sell them, too as replicas. Try there. Then there is Orlando Calonder in Buchs near Vaduz in Switzerland / Lichtenstein he has all kind of parts and stuff for Bultaco you never believed still exists, but he is not doing business with Britain. If you know someone from the continent that can order for you no problem.

So I made the measurements The rod is exactly 190mm in length and exactly 5.5mm in diameter. The pushrod is 40mm in length, The mushroom bearing is 3mm in thickness and the edged washer 1.5mm. The balls are 5,0 to 5,5mm in diameter, there are two one between the pushrod and the rod and a second mounted to the clutch lever in the sidecases. See in the photo.

If you want to invest in something really better working in terms of mixing air and fuel try a SmartCarb especially for MX or Enduro bikes. The manufacturer will adjust the carb to your Bultaco and then you never have to adjust the carb again. A Dellorto might be OK, I have a VST mounted to my KTM 500, it is a flat slide and I would suggest something similar but it will be a long and costly journey to get the carb proper adjusted. 3rd Idea is a Mikuni or Keihin here I would ask the Bultaco MX riders in the US as there most of them uses these carbs or SmartCarb on their Pursangs.