feetupfun

Thanks Bondy I've been wanting to see what those tanks look like painted. Very nice job you've done

there is automated content monitoring on these forums that deletes some content automatically. I suspect you might have posted a web address that is on the list.

OK here's a reply about swapping forks There's a bloke here who fitted a TLR250 front end to his Bultaco but it was not for the forks, he wanted to improve the front brakes and it was easiest to do it that way. Another bloke here fitted and upside-down forks front end (Paoli?)off an early model Beta or late model Fantic fitted to a Bultaco, and that was mainly to make it easy to fit a front disc brake. Both of them looked ridiculous. The one with the Paoli front end got converted back to standard so he could ride in Twinshock class, and the bloke with the TLR front end stopped riding it and went back to riding a modern bike. Meanwhile, thousands of other people have not fitted different forks to their Bultacos, and continue to get great enjoyment from riding them that way. If your forks are still topping out with 200ml of 20 weight oil/leg, then there are a few possible causes: Someone has taken the anti-topping springs out, there is way too much fork spring preload, or the forks have been assembled incorrectly

There is usually more required to get the front brakes working well than fitting new shoes and a new cable

Clutch cable has very little load so is not that critical which one you get as long as it is a lined outer. The Yamaha item works very well. The routing of the clutch cable on that bike is important. I have seen some bizarre variations of clutch cable routing on TY175s. Aim to maximise the radii of curves, minimise the number of curves and consider the effect of the steering moving through its full travel

The best front brake cable available for the TY175 is the genuine Yamaha part

The photo of you on the Scorpa is showing rear suspension that looks pretty well spot-on for sag. In trials, having only a small amount of "bump" travel when you are riding flat ground is irrelevant to how it works in the section, because you should be unweighting before hitting things. I would worry a lot less about static sag with you aboard. I'm about that same weight too and find the standard springs on all the modern bikes I have ridden to function perfectly for me. If the rear is going down too far on the Beta and other bikes with the standard suspension settings, maybe you are not positioning your body correctly. There should be no forces acting on your arms when you are standing up and the bike is at equilibrium

the motor covers have been polished instead of the original black paint finish? using Pirelli tyres? AMAL carby (not Bing)?

If you think the stator winding might have a problem, measure the resistance of the winding with it assembled on the stator plate and with the stator plate on the motor Another thought is to check for high resistance between the stator coil earth at the laminations, and the earth side of the HT coil. Sometimes people paint the frame then refit the motor and HT coil without thinking of them needing to be electrically conducting to the frame (unless there is an earth wire joining the stator to the HT coil)

you can change the RPM that the clutch drives at by either doing what paul250 said, or by changing the clutch bobweight spring settings. Our 2010 model GG50 clutch engaged at too high RPM when new and I got it to engage at much lower RPM by removing two of the four bobweight springs. You could also change it by reducing the bobweight spring preload. I suspect that the same motor might also be used in a kids MX bike and all the motors are set up for that application. It only takes a few minutes to make changes to the clutch settings.

a friend of mine has one of those bikes and it also behaves strangely. In his case, the idle speed when warm varies with the angle that the bike is leaned over. He has taken it to the local Honda shop and the mechanic could not find anything wrong with the way the carby was set up. I have ridden it in competition sections and did not notice anything happening with idle speed. The only time I noticed it was with the bike stopped and leaning it over from side to side.

Yes John my memory is definitely going somewhere. Of course you're right, my photo shows my old M99. I just edited the posting

Yes lots of parts are interchangeable but some are not. You just need to tell the people you want to buy parts from which model Bultaco the part is for. If you take decent photos of the bits you are worried about, there are many people on these forums that will be able to identify which model Bultaco it comes from. From what we have seen in your photos it looks like the bike is mostly model 85, but has a later model front wheel and motor. Haven't seen the exhaust yet

That number tells us that the frame is a Model 85 Alpina which was the first 250 Alpina. Here is a photo I took in 1976 of my 1973 model 99 Alpina, which was similar to the M85, but was 325cc

When it was "pushing oil out the clutch side", where was it coming out? If the clutch oil is getting burned, oil will disappear, so you can check for that It's possible to have an air leak via the gasket joint between the crankcase halves, either via the gearbox or direct from the atmosphere. Again you can check for oil loss from the gearbox. If you have a spigot mount carby, the hose between the carby and cylinder may be cracked

that engine number is for a 1976/77 350 Alpina The frame, forks and triple clamps are earlier Sherpa T or Alpina (1972/73?). Front wheel is post 73 Alpina. Tank and seat is 72/73 Alpina. The frame ID number is stamped on the steering head There is some sort of tubular frame in front of the rear wheel that doesn't belong there

I'm sure it is possible. I tried it on a Bultaco M49 engine which is similar in the design of the main bearing fits to the 247. I was pulling the motor apart anyway, so it was just an experiment I did because people said they had done it. I found it was difficult to get enough strength in the weld. I welded a steel tube to the bearing inner and pulled on that. If your 247 has the original conrod/big end bearing, and it has been parked up for a while, I would say it is false economy just changing the main bearings at this point, because even if it currently has no measurable play in the big end, it is likely to fail unexpectedly which may wreck your cylinder bore, piston and rings Also consider that many motors with main bearing setups like the 247 develop a problem where a main bearing outer turns within the casing, or the inner turns on the crankshaft. It's common to require the casings to be sleeved and/or for the crank to be built up.

The primary drive cover does not look like 247. Cylinder looks like 247. From what I can see of the frame it looks like the seat/tank is a tilt-up like a 248. More photos would be helpful

Looks like it is a second hand import from Japan http://www.yamahaty.com/english/arbreen.html

The TY125 was not sold new in Australia so you may need to look up a French or German listing of Yamaha models to prove to yourself about the model prefix 539 meaning TY125

the lack of any numbers after the 539 probably means that the casing has been replaced with a new spare part. It is pretty common for people to fit 66mm barrels on TY125s

The fuel pressure does not need to bend anything to cause the float valve to pass, it just needs to defeat the floatation force applied by the float, which is probably what is happening. A restrictor will not help because it will not reduce the fuel pressure seen by the float valve at times when the fuel flow rate is low (just about the whole time on a trials bike) You could solve your problem by either fitting a fuel pressure regulator, or going back to using gravity to manage the fuel pressure. Bikes only need a fuel pump if the fuel level can go lower than the carby, or for fuel injection. To answer your question, no the float arm tabs won't bend due to fuel pressure, because the float will be pushed down into the fuel before they bend, and as the float is pushed down, the fuel pressure on the float needle will be relieved, and will overfill the float bowl

very nice, wobbler

here is a catalogue listing https://www.blackwoods.com.au/search/flexible-bearings-silentbloc/302024107?c=Product

common problem and is usually caused by the rear pads being worn at an angle, or worn too far down causing slave piston/s to stick in the "on" position, which causes the fluid to boil, which jams the brake on