feetupfun

Yes Forma Boulders work well for my ample calves. They do take a bit of breaking in though

Clear coat paint on rims usually gets chipped in use and then looks pretty bad. TY twinshock Yamahas had clear paint on the rims and fork sliders from new and it chipped very quickly and looked unsightly.

Both are excellent material choices for a bashplate. I'm keen to see how it ends up looking

You are very fortunate to only have those frame repairs required. The following model Alpina (137/138) was their first attempt at using a fancy alloy steel for the frame tubes and when I rebuilt my model 138, the frame was cracked in about 10 places, which I believe is a fairly common situation. It was worth rebuilding it though. The 138 is a fabulous bike to ride as I'm sure your 115 will be

Neat job. Well done. The 250s are not as sensitive to the condition of the first muffler as the 325s are for smooth running. Yes they are a mechanically noisy motor. I didn't realise quite how mechanically noisy until I watched a video clip of mine and a friend's Bultacos. Probably made worse using my phone to make the video. The late model motors are quite quiet for some reason, maybe the different finning on the head and cylinder and they also usually have fin rubbers.

electric start TRS are selling like hot cakes

As a visual reference, here are photos of a TY250 cylinder I recently had rebored and the Wossner piston that is going in it and a couple of very old original TY250 pistons. The Wossner piston ASSEMBLY is the same weight as an original TY250 piston ASSEMBLY. If you compare just the bare pistons, the Wossner piston is heavier. The Wossner wrist pin is very light.

That combination of Uni brand filter and Yamaha cage that your links bring up works great for me. The only problems I've had over the years with the standard TY250 airbox are the Yamaha brand filter element falls apart quickly and that another aftermarket brand filter was too bulky to fit inside the airbox without it touching the sides.

My model 138 Alpina (engine very similar or identical to model 116) has what I think is a 360 Pursang piston which is not exactly right for the model 138 Alpina but still works great. The Pursang cylinder has a bridged exhaust port so this piston I'm using has holes through the front to lubricated the bridge. The 350 Alpina has an unbridged exhaust port so shouldn't have holes there. The other difference is that Pursangs have additional transfer ports that work in with other holes in the piston and so those piston holes are superfluous in the Alpina engine. Some Bultaco 360/370 pistons might have a shorter rear skirt than the 350 Alpina but from memory the Pursang piston in my Alpina had the same skirt length as the piston that came out. My memory is not that certain though as it was over 20 years ago that the model 138 motor was rebored and I haven't had it apart since then. I don't know of any other brand bikes that use a piston that can be used in a 350 Alpina.

Yes that's the normal arrangement

Engine number prefix will tell you what motor it is. It's not a 350 because it is a round barrel. Lobitos are 100, 125 and 175.

It's not a Sherpa T. It's a Lobito. The frame number prefix will tell you what model Lobito it is.

Some people want to run modern lights (LEDs) which need 12V DC to work so they make that available. Bultacos only came standard with 6V lighting systems. Some Bultaco models had had a rectifier and a battery (so the lights would work with the motor stopped) but Sherpa Ts had no battery and the lights ran on 6V AC

I just tried to post up some contact info for the seller in Australia but suspect I broke a rule for this forum so all I'll say is yes he is still selling them

Jetting a bike using internet forum messages is a bridge too far for me

Over the past few years I've fitted five 26mm OKOs, all from Roger. Some didn't require any change. Some needed the pilot jet swapped and one needed a different slide needle. For that one I bought a range of Keihin needles to try.

Yes those are forwards and down. They are from a Yamaha kit that had those peg mounts, a longer brake pedal, a big seat, a longer swingarm pivot bolt and there could have been a different shift lever too

Yes most of my riding is near sea level and the highest riding in my state is about 4000 feet. When I said it didn't need adjustment when I fitted the B model motor, I meant that changing from one motor to a different motor did not require any adjustments to the carby. Both of the OKOs I fitted to TY250 motors did need adjustment when originally fitted.

Yamaha TY250 trailbike footpeg kit photo

Here's what one of mine looks like. 26mm OKO from Roger. Stretched Yamaha intake hose. This carby was fitted a couple of years ago when this bike had an A model motor. Fitted a B model motor in the bike a few weeks ago and the carby didn't need any adjustments.

My TY250s with the standard points and standard timing sometimes kick back if I give them a half-hearted kick. If you get an ignition with built-in timing curve and set it correctly it will not kick back. This is because at kickstart RPM, the spark timing is closer to TDC than it is with a fixed timing ignition

first gear is at the bottom

I have no idea. You could try phoning them to find out. Just because I bought something many years ago doesn't mean I would buy the same thing again. Things change. If I wanted to buy a TY ignition today it would be from Rex's Speed Shop. Those ignitions from John Cane many years ago are still going perfectly, as are my TYs that have standard Yamaha ignition systems.

That's what I was thinking too

There should be a washer under the clamp screw. Here are some tricks to help you: When changing the points setting, clamp the points just firmly enough so they don't move, but loose enough that you can just move them by twisting a flat, mid-width screwdriver blade. It helps to use a screwdriver that is not attracted to magnets because those flywheel magnets are pretty strong. Make a timing mark on your flywheel rim at the spot where the points should open. You should not have had to take the head or the tank off to set the timing. To find where to put this timing mark, make a mark on the flywheel rim (with the piston at top dead centre) beside one of the holes for the cover screws. From the TDC mark, measure 24mm counter-clockwise around the steel band on the flywheel and make another mark. That's the timing mark. You can find top dead centre on a TY250 with the tank and head in place by putting something down through the plug hole and using it to feel what the piston is doing. Move the flywheel until you can feel that the piston is at the top and that's top dead centre. The 24 mm measured on the flywheel reproduces the piston being whatever the standard timing distance is in mm BTDC. Yes electronic ignition is a popular way to get a bike running well if you are not confident setting points.