pschrauber

Ok I would ask a specialist in suspension tuning, tell him my needs and the specs of my bike and the specs of the springs I have mounted and then they produce a springs to my needs. The price is around 100 Euro a pair. www.fahrwerkstechnik.org

In my personal opinion a protection is useful if the frame coating is still new, when ridden some hours there will occur scratches and rubbing marks If the frame surface is still intact you can use protection foil that you get from VW for Passat or Golf station wagon's. The foil is very thick but so transparent you can't see it. To apply the foil some preparation has to be made. The foil sticks extremely well and as far as the edges are hoded or doesn't get in contact with the boots it will last for year. The protection foil set from VW comes with a good manual, the only things you need are: - water, - soap, - polish for paint, - a cutter scissors, - a rakel with soft tip, - hair dryer or likewise. The look with patina is not so bad, it's just the little extra work of clean and oil blank surfaces regulary when needed. Some patina suits an old bike very well.

In short: The old springs will loose tension with the time, then they will too "shrink" in lenght. There is already a nig difference between pretty well used springs and NOS. Then clean up the inerta of the fork, there is a lot of debris inside, does effect damping. Then new slide seals to the inner piston works wonder too. O hope the stanchions are straight by all means, will otherwise worsen action quite abit. At last are the lower stanchions still circular or already oval inside, the bore wears sadly too, (where most of the debris in the oil comes from. To the springs itself I have one fork rrbuilded fixing all things named and mounted NOS springs and this unit works very well, better then first expected. (so a real "overhaul" is in my opinion at least 80% of the work. An improvement are the Magicals together with adjustable fork nuts, more progressive which is nice to have. Also the ability to adjust the fork is very nice. Non plus ultra for Betor are air cartridge systems fittet to the fork, (there are two version available). Here you have the complete control about the performance to the fork. The cartridges are made to your requirements and you have still three different springs and of course the air pressure. I had recently rebuilded a Betor fork with this system, (two cartridge in each leg, (more weight but in case of trouble ... you have a back up). The performance is really good, but its only worth the effort if all other things to the fork a very well sorted.

Outside of Britain she was named "The iron Lady" and you can be sure that even today her name and here politics are still often quoted, she is still one of the greatest British prime minister in times so far. So she has achieved her place in history already decades ago - but in the hearts of many people she has not found a place.

Autsch ..... As long as all works I would leave it as it is until you will recognise malfunction or heavy incontinence. In the meantime I would search for a replacement. I've done likewise the gear/kickstarter mechanism to my SWM, here the hole shaft of the kickstarter was somehow oval and lead to a not very proper working return mechanism of the kickstarter and heavy incontinence, the last weeks I lost around 20ml gear oil per week. I have now fixed the problem recently in wintertime.

If the motor is set like he is just not reaching the idle speed it's easier ride very tight curves without using the clutch. If the engine still can ignite or "increases" speed while you try to take the turn whilst being at the steering stop this can bring you out of the eem of the balance, provided you drive the old style without the hand on the clutch. Today we are wise just one hand on the clutch and little slip and it works also with an idling engine. Times have changed ...

Thank's for the replies! And the airboxes from post #5 and #17 look very professional. @zuma: Have you done a model first? (out of styrofoam f. e.?) @jc2: It was only a calculation for illustrating what is going one inside the intake, (idid mention this in my post). This is and was far away from any calculation of the airbox size, the airbox size as rule of a thump should be around 6 - 8 times of the capacity of the motor, More sience in english here: http://www.ten-tenths.com/forum/showthread.php?t=76195 if someone is interested. Anyway: I will as an first step clear out the standard airbox from the inside, then cladd the inside with deadening foam (5mm) to reduce roaring sound and the airfilterfoam will be imposed over the top, well we will see how good this work ... If not as good as I aspect ... a custom made airfilter will be taken in consideration. the fiberglass variant is very nice and light ...

Forgot to mention: The threads should be situated in the rear as seen here, when you unscrew the nut you will see them. You need a long extractor for this magneto. You find them f. e. here, or maybe from Bultaco UK: http://www.moninomartinez.es/cast/01extractores.htm I would measure the diameter and the threads of the magneto and of course the shaft lenghts sticking out bevor in forehand and give the spec's with the order just to make clear the Extractor will fit.

Looks slightly different but shoud be the same as just the center is a little bit different in geometry. The other model mounted to the Sherpa is the Femsa, (on the upper left, slighty lighter):

There where two different magneto types mounted to the Bultaco Sherpas. Some magnetos came from Femsa some from Motoplat, the later Bultacos which where build outside Bultaco at the Derbi facilities came with all kinds of magnetos as these bikes where build from the remaining spare parts. A picture would ineed be very helpful. Here a picture of the Motoplat magneto that should be mounted to the Sherpa or Alpina:

To the size of the airbox, as more room you have as less bad influence from the pulsating airflow you will have inside the airbox, if you have a tiny airbox you might use resonators to deal with them as the airbox is a resonance/volume chamber so you can even adjust an engine with the size and geometry of an airbox. In short: as less complicated ways the air has to flow towards the cylinder as easier it is for the engine to get the right amount of mixture ... (The return button doesn't work in this forum ...)

No errors I believe, but sadly I mixed up the units. Air flow is calculated in m/s or m/min and I had to transform the ccm in m³: 175cc are 0,0175 m³ or 174 x 10^-4 but m³ is difficult to imagine so I recalculated it in Liter. I see it's not wise to combine translate and math ... too much tasks at once ... The output of 23 would right here I skipped the internal calculation about the medium flow rate thought first to show up with digits behind the comma but then messed with the comma ... anyway. 23m/s is the right outcome ! I will correct it. And there is another problem my RETURN button doesn't work when I use the editor here ???

@woody: Thank you for the pictures. To the question is air flow a task and why bigger airbox can be an improvement, here some math: engine capacity: 175cc rpm: 1.250 (just above idling) rpm: 3.000 (lower mid range) (engine capacity) 17 5cc x rpm = air volume per minute 0,0175 m³ * 3000rpm = 52,5l/min with a diameter of 22mm the air has an speed of 23,0m/sec or 138,11 m/min which is a speed of around 83km/h. 0,0175m³ 1250rpm = 21,9l/min with a diameter of 22mm the air has an speed of 1,0m/sec or 57,61 m/min which is a speed of around 35km/h In this speed range any edge, ridge in the air flow and yes also the capacity of the airbox makes a difference. For comparison: Drive your car just 35km/h and hold out one hand and turn the hand surface against the airstream and you will see. I think this pictures very well the dynamics you have inside the intake carb and airbox as it is easy for you to try out how much influence a proper design intake system has. Sorry for the math I tried to make it as easy as possible I will not bore anyone here more with the physics then I did already ... correction see bold

That is one good idea. I believe it will work very good when I also take out all the restricting plastic tubes inside the air box where the intake is located. But the bike will snorkle like hell and the noise will increase a lot, that is not so nice for my and others ears. I personal like quite and good sounding bikes. With a cover / panel the airbox keeps the bike also quite, something I don't want to miss. Photos of self build airboxes would be nice ..

Doesn't look Bultacoish I guess a support/holder for cables, you need one where the rear cables go to the rear light, mine looks different, more curved ... and one near the steering stem, also to support the cables. It might be also some self build holder for the airbox, you need three: one in front and two at the rear. Patrik

Hi, I' am rebuilding my twinshock TY, this is a long time project, whenever I have time I do something for the bike .... Anyway the airbox of the TY 125 / 175 is very tiny it has more likely the size of a can of sprats then a airbox for a 175 to 200cc motor. A larger one should improve power output. Can any one tell me where I may get a larger capacity airbox for my TY, also some stories / how to ... for custom made air boxes would be very nice too. Many Thanks Patrik

They also look good with patina: You can't do anything wrong with them beside mounting plastic fenders ...

Very artistic indeed, ... another reason for me (this is my personal view) not to visit the show. There are pretty little really rolling wheels involved. Anyway thank you a lot for posting !!!

Anyway which too choose, I prefer the yellow black ones with 280cc. The color combination is nicer, .. I know not related to the way it performs but I have my own taste ... The 350cc is overpowered for my weight and skills, the 125cc has a flexy fork in my view and when I tried one out, (32mm). Some pic's of the original bike that Burgat rode in 1980 - 1981 would be nice. I believe as Burgat won the GP with the yellow black one this should be his best bike in memory ... this is a guess ... someone should ask him?

One easy improvement is to install as soft brake pads as possible and het rid of decade old brake pads. This is easy done. Second machine the brake pads (mounted to the brake plate) so they are aligned to the drum. Third use the longer steel brake arms front and rear, they don't flex and hive more torque = more braking power, (don't show up very often in craiglists but sometimes). Fourth the lining with steel inserts, standard steel quality SRJ 235 is completely OK. Or new hard chrome linings, but this is the most expensive way to do. You need a professional hardchrome coating company that is specialist for chroming machine components, Wissing-Hartchrom is the only company I can name here, €€€! I would first do 1. then 2. ... until you are satisfied with the outcome. lf you want a perfect result you have to spend a likewise effort in the project which means time and money that has to be named too ...

Bultaco engines where designed to use 1% or 1:100 with synthetic two stroke oil back in the days. With standard mineral oil a ratio of 4% where recommended. If the engine is "fresh rebuild and runned in" (and you use gasoline with less the 5% ethanol in combination with a synthetic oil that can be used up to 1% by the manufacturer), then - also today - 1% is possible. I only used 1:100 / 1% when the two stroke oil made for Bultaco still was availalbe, (which was btw. completly synthetic): Now as ethanol free gasoline is difficult to get and many other indegrents are enclosed in the gasoline I personal use IPONE synthesis at 1:75 mix ratio for trials in every bike SWM, Bultaco, Yamaha, (which is 1,3%). For trails riding with longer routes on lanes up and downhill I use a ratio of 1:67 = 1,5%. Here the front page of the Bultaco quick guide I still have: I personal would use as less oil as possible as puttering around the trees in low rpm will clogg your motor interna and the exhaust very quick. When the engine have already some wear the piston have got some carbon build up, here a good example, old used Bultaco piston on the left, new one on the right side: Many of the full synthetic oils including cleaning agents for the combustion chamber of the motor. When the engine has been used a lot with standard oil I would stay with the oil which was used previous. Otherwise the cleaning agents of the new and different two stroke oil might remove the deposits which then can lead to piston seize.

I only have one photo from me and my Bultaco Sherpa back in the days left: The photo was taken in a trials event in 1981 the conditions where extremly wet and muddy, the front wheel of the bike blocked two times due to the muddy conditions. Oh and I weard my green Italjet rain coat. Guess what bike I rode after the Bul.

welding or brazing the leak area is the best solution. As a workaround depending where the leak area is you might put glas fiber cloth underneath the area and wrap wire around. (this "solution" will not last long ...)

The color stays on the handle bar very long in my experience, here at least a 20 year old yellow painted handle bar ... : Some scratches will occur but what do you expect it's a dirt bike. Patrik

Original the handle bar was black: Anyway some riders painted their handle bar white or mounted alloy bars mostly coated (anodised) in silver or gold back then when I remember right.