pschrauber

Hi, that is a very nice SWM you have there and the most powerful twinshock trials bike produced. I have previous build smaller model NW.TL 320 from 1980, which I like very much. To the mixture I use 1:67 or 5l of gasoline to 75ml of synthetic or half synthetic oil with a low burning point together with Ultimate gasoline with ingredients for cleaning up build up carbon, also providing extra octane as at least my SWM tends to ping when it is hot (over 25 degrees celsius). To the engine oil I use Elf HTX 740, because I use in any bikes I own and it improves the clutch action in general a bit most automatic oils work well too. To the Dell'Orto carburator there are carb rebuild kits to each model available which provide all gaskets and seals you need, but I would recommend to look up slide needle needle nozzle and the jets too if they are not showing wear or got damaged by wrong cleaning maintenance. For the right jetting you should provide the carb model and size mounted. The rear suspension looks not to be original and the spring with its many windings looks too to be on the soft side, you might look up Rockshocks from Gary Fleckney. To the front springs I don't have an solution may be Wirth in Germany or Bultaco UK / InMotion?

If you have the inlet the remaining stuff sculpturing a foamfilter is easy. I can sent you template shaped forms of which you can sculp and assemble your own filter.

A cable clamp made out of aluminium or stainless steel is used one fastener is mounted to the screw of the rear light, the other with the fastener of the rear fender to the frame. See here: https://www.esska.de/shop/Befestigungsschelle-NORMA-BSL-einlaschig-Durchmesser-4-bis-24-mm-Breite-10-oder-12-mm-1-oder-2-Leitungen--8578W1111000-4140?adsource=gs&hlid=8578W1111112&gad_source=1&gclid=Cj0KCQiAtOmsBhCnARIsAGPa5yYHfLT_Nwuq_n0Guh1j3Q7FO4E1y5hz5hCKES1n55v-v09Srrvj9hEaAu6wEALw_wcB&hc_fcv=ZZsaaxA1qeZlwqdr~NNgOOv-3KtHhJ-7uzzzzzzzz~NNgOOts3KtHhIE7tzzzzzzzz

I would check the fit of the spokes in the hub. In this case the bearing surface of the offset spoke to the hole in the hub. If the spoke is not in position, bending it back to the required angle may help However, spokes are made of high-strength steel, the nipple has been cold-formed, so re-forming in the same place is hardly possible and would further weaken the strength of the spoke at the weakest point. If it's just for standing down, it's OK, even light driving is fine, but emergency braking or a drop off could cause it to break. When spokes start to break it's a domino effect... Because of bad experience I don't try save on spokes and nipples.

Ethanol is not stable and wil oxidate with oxygen to acetic acid (Essigsäure). Acetic acid is corrosive against most metals like iron (steel), aluminium and even brass. When you ride the fuel inside the tank is pushed around inside the tank and thus gets contaminated with oxygen which comes through the vent hole. Looks like that:

My biggest concern is storability, I do have times when I do not ride the bikes but gasoline mixed with oil left. E10 oil mix got kind of stained especially when stored in winter time, thus I too only use ARAL Ultimate 102 octane ethanol free. The BP Ultimate should be of the same recipy, ARAL and BP are using ether instead of ethanol in their fuel, that is too the reason that fuel does clean up the engine a bit inside.

Yep, but I have figured out with experience and the years it takes a long time until the oil is warmed up and under cold weather conditions it is really thick which can make shifting harder. I now have changed to ELF HTX 740 to all my bikes, from SWM TL NW, Montesa 242, Panda TC 220, Beta TR 34, Yamaha TY and the Bultaco Sherpa to use just that oil to clutch and gearbox.

Very sad story ... and all the effort you have put in ... could you do an arragement depending the effort and diffrenet status of the bike with the owner?

I personal would use the gear oil to the gearbox and ATF for the primary drive and clutch. The ATF is more versatile then gear box oil so a good choice for chain and clutch. Or as already stated Elf HTX 740 for both drives.

I take the chain off for cleaning, then clean it with a brush and an old rag bit after that treatment most dirt from the outside is gone. Now the chain goes into an old kettle with aceton here I "stir" the chain in the solvent for a while, after that treatment the chain is also clean at the inside and free of fine debris. Last treatment is hangig up the chain and use some brake cleaner spray let overflow rinse down the chain into the previous mentioned old kettle and last not least give the chain a rub with an old towel. Then I apply PTFE or dry lube to the chain, then put it on again, that has worked so far very well for me. The chains had very little wear, the chain stays too much cleaner and is super easy to clean too.

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.